KR100629585B1 - Light emitting display and driving method thereof - Google Patents

Abstract

The present invention relates to a light emitting display device capable of preventing motion blur.

A light emitting display device according to the present invention comprises: a scan driver for sequentially supplying scan signals to scan lines and sequentially supplying light emission control signals to light emission control lines; A data driver for supplying a data signal to the data lines; An image display unit connected to the scanning line, the emission control line and the data line to display an image corresponding to the data signal, and including a plurality of pixels whose image display time is controlled by the emission control signal; The light emission control signal is supplied for a period longer than a period during which the two scan signals are supplied.

By such a configuration, the present invention can prevent the motion blur phenomenon from occurring.

Description

Light Emitting Display and Driving Method Thereof

1 is a view showing a general light emitting device.

2 is a view showing a light emitting display device according to an embodiment of the present invention;

FIG. 3 is a circuit diagram showing a first embodiment of the pixel shown in FIG.

4 and 5 are waveform diagrams showing drive waveforms supplied from the scan driver shown in FIG.

FIG. 6 is a circuit diagram showing a second embodiment of the pixel shown in FIG. 2; FIG.

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

20: anode electrode 21: cathode electrode

110: scan driver 120: data driver

130: image display unit 140: pixels

142: pixel circuit 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 capable of preventing a motion blur phenomenon.

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 flat panel display devices, the light emitting display device includes a plurality of light emitting devices, and the light emitting devices generate predetermined 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.

1 is a view showing a conventional general light emitting device.

Referring to FIG. 1, the light emitting device includes an emission layer (EL), a hole transfer layer (HTL), and an electron transport layer (ETL) formed between the anode electrode 20 and the cathode electrode 21. ).

The anode electrode 20 is connected to the first power source to supply holes to the light emitting layer EL. The cathode electrode 21 is connected to a second power source lower than the first power source to supply electrons to the light emitting layer EL. That is, the anode electrode 20 has a higher potential of positive polarity (+) than the cathode electrode 21, and the cathode electrode 21 has a relatively low polarity (−) than the anode electrode 20. Has a potential.

The hole transport layer HTL accelerates holes supplied from the anode electrode 20 and supplies them to the light emitting layer EL. The electron transport layer ETL accelerates and supplies electrons supplied from the cathode electrode 21 to the emission layer EL. Holes supplied from the hole transport layer HTL and electrons supplied from the electron transport layer ETL recombine in the emission layer EL. At this time, predetermined light is generated in the light emitting layer EL. Subsequently, the emission layer EL is formed of an organic material to generate light of one of red (R), green (G), and blue (B) when electrons and holes recombine.

Meanwhile, the light emitting device includes a hole injection layer (HIL) located between the hole transport layer (HTL) and the anode electrode 20, and an electron injection layer located between the electron transport layer (ETL) and the cathode electrode 21. (Electron Injection Layer: EIL) is further included. The hole injection layer HIL supplies holes to the hole transport layer HTL. The electron injection layer EIL supplies electrons to the electron transport layer ETL.

Such a light emitting device is provided for each pixel of the light emitting display to generate a predetermined light corresponding to the current supplied to the light emitting device. Here, each pixel includes at least one capacitor for supplying current to the light emitting device for one frame of time. That is, in the conventional light emitting display device, a predetermined voltage is charged in a capacitor provided for each pixel, and a predetermined current is supplied to the light emitting device by using the charged voltage.

However, as shown in the related art, when a predetermined image is displayed on a pixel for one frame period by using a voltage charged in a capacitor, a motion blur phenomenon occurs. That is, when the current corresponding to the voltage charged in the capacitor is continuously supplied to the light emitting device during the frame period, a motion blur phenomenon occurs in which the image is blurred due to the afterimage effect of eyes when displaying a moving image. When such a motion blur occurs, the display quality of the light emitting display device is degraded.

Accordingly, an object of the present invention is to provide a light emitting display device and a driving method thereof capable of preventing a motion blur phenomenon.

In order to achieve the above object, the first aspect of the present invention includes a scan driver for sequentially supplying the scanning signal to the scanning lines, and sequentially supplying the emission control signal to the emission control lines; A data driver for supplying a data signal to the data lines; An image display unit connected to the scanning line, the emission control line and the data line to display an image corresponding to the data signal, and including a plurality of pixels whose image display time is controlled by the emission control signal; The light emission control signal provides a light emitting display device which is supplied for a period longer than a period during which the two scan signals are supplied.

Preferably, the light emission control signal is supplied for a period equal to or shorter than a period of one frame and a half. The black screen is displayed on the pixels during the period in which the emission control signal is supplied.

According to a second aspect of the present invention, there is provided a method of sequentially supplying a scan signal to scan lines, supplying a data signal to pixels selected by the scan signal, and emitting light in response to the data signal at the pixels. A method of driving a light emitting display device is provided, the method comprising: supplying a light emission control signal to control a predetermined time period, wherein the light emission control signal is supplied for a period longer than a period during which the two scan signals are supplied.

Preferably, the light emission control signal is supplied for a period equal to or shorter than a period of one frame and a half. The pixel is set to a black state while the light emission control signal is supplied.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2 to 6 that can be easily implemented by those skilled in the art.

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

Referring to FIG. 2, a light emitting display device according to an exemplary embodiment of the present invention includes an image display unit 130 including pixels 140 formed at an intersection area of scan lines S1 to Sn and data lines D1 to Dm. And 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 driver 120. A timing controller 150 for controlling is provided.

The timing controller 150 generates a data drive control signal DCS and a scan drive control signal SCS using a synchronization signal supplied from the outside. 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 scan driver 110 receives the scan driving control signal SCS from the timing controller 150. The scan driver 110 supplied with the scan driving control signal SCS sequentially supplies the scan signals to the first scan line S1 to the nth scan line Sn. The scan driver 110 supplied with the scan driving control signal SCS sequentially supplies the emission control signal to the first emission control line E1 to the nth emission control line En. The driving waveform supplied from the scan driver 110 will be described in detail 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 supplies the data signals to the data lines D1 to Dm whenever the scan signal is supplied.

The image display unit 130 receives the first power source ELVDD and the second power source ELVSS. The first power source ELVDD and the second power source ELVSS supplied to the image display unit 130 are supplied to the respective pixels 140.

FIG. 3 is a diagram illustrating a first embodiment of the pixel illustrated in FIG. 2. In FIG. 3, pixels connected to the nth scan line Sn and the mth data line Dm are illustrated for convenience of description.

Referring to FIG. 3, the pixel 140 of the present invention is connected to the light emitting device OLED, the light emitting device OLED, the data line Dm, the light emission control line En, and the scanning line Sn to form a light emitting device ( And a pixel circuit 142 for emitting OLEDs.

The anode of the light emitting device OLED is connected to the pixel circuit 142, and the cathode is connected to the second power source ELVSS. The light emitting device OLED generates light corresponding to a current supplied from the pixel circuit 142.

The pixel circuit 142 includes a second transistor M2 and a third transistor M3, a second transistor M2, a data line Dm, and a second transistor M2 connected between the first power source ELVDD and the light emitting device OLED. The first transistor M1 is connected between the scan lines Sn, and the storage capacitor C is connected between the gate electrode of the second transistor M2 and the first power source ELVDD.

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 side of the storage capacitor C and the gate electrode of the second transistor M2. As described above, 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. At this time, the storage capacitor C is charged with a voltage corresponding to the data signal. On the other hand, the first electrode is set to any one of the source electrode and the drain electrode, 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 gate electrode of the second transistor M2 is connected to one side of the storage capacitor C, and the first electrode is connected to the first power source ELVDD. 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 ELVDD to the light emitting device OLED in response to the voltage stored in the storage capacitor C.

The gate electrode of the third transistor M3 is connected to the emission control line En, and the first electrode is connected to the second electrode of the second transistor M2. The second electrode of the third transistor M3 is connected to the light emitting element OLED. The third transistor M3 is turned on when the emission control signal is not supplied to supply the current supplied from the second transistor M2 to the light emitting device OLED. That is, the third transistor M3 controls the supply time of the current supplied from the second transistor M2 to the light emitting device OLED.

4 and 5 are diagrams showing driving waveforms supplied from the scan driver.

4 and 5, the scan driver 110 of the present invention sequentially supplies scan signals to the first scan line S1 to the nth scan line Sn in each frame period. At this time, the data driver 120 supplies the data signal DS to the data lines D1 to Dm whenever the scan signal is supplied.

The scan driver 110 sequentially supplies the emission control signal to the first emission control line E1 to the nth emission control line En. Here, since the third transistor M3 included in each of the pixels 140 is turned off during the period in which the emission control signal is supplied, light is not generated in the light emitting device OLED. That is, when the emission control signal is supplied, each of the pixels 140 displays a black screen.

On the other hand, the width T2 (or supply time) of the light emission control signal supplied from the scan driver 110 is set wider than the width T1 of the two scan signals as shown in FIG. 4 (that is, T2> In other words, the light emission control signal is supplied for more time than the time when two scanning signals are supplied continuously. Then, the period in which the black screen is displayed in each of the pixels 140 is set to be wider than the period in which the two scanning signals are supplied, thereby preventing the motion blur. In detail, when the width of the emission control signal is set to be wide, the time for generating light in the pixel 140 for one frame time is limited. That is, in the present invention, the light is generated in the pixel 140 for a short period of one frame time, and the motion blur phenomenon is prevented from occurring by setting the pixel 140 to the black state for the remaining period.

Then, the scan driver 110 supplies the light emission control signal for less than half of one frame as shown in FIG. 5 (that is, T3? 1 / 2F). In fact, the supply time of the light emission control signal in one frame is 1/2. When the frame period is exceeded, the time for setting each of the pixels 140 to the black state becomes long, which may cause flicker in the image display unit 140. Therefore, the scan driver 110 of the present invention is longer than a period in which two scan signals are supplied to prevent flickering and motion blur in the image display unit 140 and is equal to a half frame period. Or supply the light emission control signal for a short period of time.

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

Referring to FIG. 6, the pixel 140 according to the second exemplary embodiment of the present invention is connected to the light emitting device OLED, the data line Dm, the scanning line Sn, and the light emission control line En so that the light emitting device ( And a pixel circuit 142 for emitting OLEDs.

The anode of the light emitting device OLED is connected to the pixel circuit 142, and the cathode is connected to the second power source ELVSS. The light emitting device OLED generates light corresponding to a current supplied from the pixel circuit 142.

The pixel circuit 142 includes a storage capacitor C and a sixth transistor M6 connected between the first power supply ELVDD and the n−1 th scan line Sn−1, the first power supply ELVDD, and a data line. The first and fourth transistors M1 and M4 connected between the first and second transistors M3 and M3 connected to the light emitting element OLED and the emission control line En, and the first node N1. ) And a second transistor M2 connected between the third transistor M3 and a fifth transistor M5 connected between the gate electrode and the second electrode of the second transistor M2.

The first electrode of the second transistor M2 is connected to the first node N1, and the second electrode is connected to the first electrode of the third transistor M3. The gate electrode 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 OLED.

The fifth transistor M5 is connected between the second electrode and the gate electrode of the second transistor M2. The gate electrode of the fifth transistor M5 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. That is, when the fifth transistor M5 is turned on, the second transistor M2 is connected in the form of a diode.

The first electrode of the first transistor M1 is connected to the data line Dm, and the second electrode is connected to the first node N1. The gate electrode of the first transistor M1 is connected to the nth scan line Sn. The first transistor M1 is turned on when the scan signal is supplied to the nth scan line Sn and supplies the data signal supplied to the data line D to the first node N1.

The second electrode of the fourth transistor M4 is connected to the first node N1, and the first electrode is connected to the first power source ELVDD. The gate electrode of the fourth transistor M4 is connected to the emission control line En. The fourth transistor M4 is turned on when the emission control signal is not supplied to electrically connect the first power supply ELVDD and the first node N1.

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 light emitting device OLED. The gate electrode of the third transistor M3 is connected to the emission control line En. The third transistor M3 is turned on when the emission control signal is not supplied to supply the current supplied from the second transistor M2 to the light emitting device OLED.

The first electrode of the sixth transistor M6 is connected to the storage capacitor C, and the second electrode and the gate electrode are connected to the n−1 th scan line Sn−1. The sixth transistor M6 is turned on when the scan signal is supplied to the n-1 th scan line Sn-1 to initialize the gate electrodes of the storage capacitor C and the second transistor M2.

The operation process will be described in detail. First, the sixth transistor M6 is turned on by the scan signal 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 electrode and the storage capacitor C of the second transistor M2. In this case, the gate electrode and the storage capacitor C of the second transistor M2 are initialized by the voltage value of the scan signal.

Thereafter, the first transistor M1 and the fifth transistor M5 are turned on by the scan signal supplied to the nth scan line Sn. When the first transistor M1 is turned on, the data signal supplied to the data line Dm is supplied to the first node N1. At this time, since the second transistor M2 is connected in the form of a diode, the data signal supplied to the first node N1 is supplied to the storage capacitor C via the second transistor M2 and the fifth transistor M5. do. At this time, the storage capacitor C is charged with a threshold voltage of the second transistor M2 and a voltage corresponding to the data signal.

On the other hand, the fourth transistor M4 and the third transistor M3 are turned off by the light emission control signal during the period in which the scan signal is supplied to the n-1 th scan line Sn-1 and the n th scan line Sn. . Substantially, the light emission control signal is supplied for a period longer than the time that two scan signals are supplied and equal to or shorter than one half frame so as to prevent afterimages without flickering. Then, the motion blur phenomenon can be prevented from occurring in the image display unit 130.

Subsequently, when supply of the emission control signal is stopped and the fourth transistor M4 and the third transistor M3 are turned on, a current corresponding to the voltage stored in the storage capacitor C is supplied from the second transistor M2. It is supplied to (OLED) and a predetermined image is displayed. Meanwhile, the pixel of the present invention is not limited to the structures shown in FIGS. 3 and 6, and may be set to various pixels including transistors connected to emission control lines.

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

As described above, according to the light emitting display device and the driving method thereof according to the embodiment of the present invention, the emission time of the pixel is limited by supplying the emission control signal for a period between two scan signals and 1/2 frame. do. That is, the present invention can prevent the motion blur from occurring by emitting a pixel for a short time and expressing black in the pixel for the remaining period.

Claims (8)

A scan driver for sequentially supplying scan signals to scan lines and sequentially supplying light emission control signals to light emission control lines; A data driver for supplying a data signal to the data lines; An image display unit connected to the scanning line, the emission control line and the data line to display an image corresponding to the data signal, and including a plurality of pixels whose image display time is controlled by the emission control signal; And the emission control signal is supplied for a longer period than the period during which the two scan signals are supplied. The method of claim 1, And the emission control signal is supplied for a period equal to or shorter than one half of a frame. The method of claim 2, And a black screen is displayed on the pixels while the emission control signal is supplied. The method of claim 2, Each of the pixels A first transistor connected to an nth (n is a natural number) scan line and a data line, A storage capacitor for charging a voltage corresponding to the data signal when the first transistor is turned on; A second transistor for controlling a current supplied to the light emitting device in response to the voltage charged in the storage capacitor; And a third transistor connected between the second transistor and the light emitting element to be turned off when the light emission control signal is supplied to the light emission control line, and to be turned on elsewhere.  The method of claim 4, wherein Each of the pixels A fourth transistor connected between the second transistor and a first power source, the fourth transistor being turned on and off simultaneously with the third transistor; A fifth transistor connected between the gate electrode and the second electrode of the second transistor; And a sixth transistor connected to the gate electrode and the storage capacitor of the second transistor and turned on when the scan signal is supplied to the n-th scan line. Sequentially supplying scan signals to scan lines; Supplying a data signal to pixels selected by the scan signal; Supplying an emission control signal to control the time for which light is emitted in correspondence with the data signal in the pixels, And the light emission control signal is supplied for a period longer than a period during which the two scan signals are supplied. The method of claim 6, And the light emission control signal is supplied for a period equal to or shorter than one frame half. The method of claim 7, wherein And the pixel is set to a black state while the emission control signal is supplied.

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