KR100645699B1 - Light Emitting Display and Driving Method Thereof - Google Patents

Abstract

The present invention relates to a light emitting display device capable of displaying a uniform image.

The light emitting display device of the present invention includes a scan driver for sequentially supplying a scan signal to scan lines during a first period of a frame, a data driver for supplying a data signal to data lines during the first period; And an image display unit including a plurality of pixels positioned to be connected to the scan line and the data line, and a light emission control line commonly connected to the pixels, wherein the scan driver is configured to keep the pixels in a non-emission state during the first period. A light emission control signal is supplied to the light emission control line so as to be set.

With this arrangement, in the present invention, the pixels are set to the non-emission state during the data writing period in which the data signal is supplied to the pixels, thereby displaying a uniform image irrespective of the pattern of the image and the like.

Description

Light Emitting Display and Driving Method Thereof

1 illustrates a conventional light emitting display device.

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

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

4 is a waveform diagram illustrating a method of driving a light emitting display device according to an exemplary embodiment of the present invention.

FIG. 5 is a circuit diagram illustrating a second embodiment of the pixel illustrated in FIG. 2.

<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: pixel

50,150: timing controller 142: pixel circuit

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 displaying a uniform image.

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 view illustrating a conventional general light emitting display device.

Referring to FIG. 1, a conventional light emitting display device includes an image display unit 30 including pixels 40 formed at an intersection area of scan lines S1 to Sn and data lines D1 to Dm, and scan lines ( A timing controller for controlling the scan driver 10 for driving S1 to Sn, the data driver 20 for driving the data lines D1 to Dm, and the scan driver 10 and the data driver 20. 50 is provided.

The scan driver 10 generates a scan signal in response to the scan drive control signals SCS from the timing controller 50, and sequentially supplies the generated scan signal to the scan lines S1 to Sn.

The data driver 20 generates data signals in response to the data driving control signals DCS from the timing controller 50, and supplies the generated data signals to the data lines D1 to Dm. In this case, the data driver 20 supplies data signals of one horizontal line to the data lines D1 to Dm every one horizontal period.

The timing controller 50 generates a data drive control signal DCS and a scan drive control signal SCS in response to the synchronization signals supplied from the outside. The data drive control signal DCS generated by the timing controller 50 is supplied to the data driver 20, and the scan drive control signal SCS is supplied to the scan driver 10. The timing controller 50 rearranges the data Data supplied from the outside and supplies the data to the data driver 20.

The image display unit 30 receives the first power source ELVDD and the second power source ELVSS from the outside. Here, the first power source ELVDD and the second power source ELVSS are supplied to the respective pixels 40. Each of the pixels 40 supplied with the first power supply ELVDD and the second power supply ELVSS displays an image corresponding to the data signal.

However, in the conventional light emitting display device, there is a problem in that the voltage of the first power source ELVDD is changed according to whether the pixels 40 emit light, that is, the pattern and luminance of the image displayed on the image display unit 30. . In detail, the load applied to the first power source ELVDD during each frame period is set differently depending on whether the pixels 40 emit light. In other words, a high load is applied to the first power supply ELVDD when many pixels 40 emit light during one frame, and a low load is applied to the first power supply ELVDD when less pixels 40 emit light during one frame. Is applied. Accordingly, in the conventional light emitting display device, a voltage difference between the first power supply ELVDD supplied to the pixels 40 is generated corresponding to the pattern of the image, thereby causing a problem in that an image of uniform luminance cannot be displayed. .

In the conventional light emitting display device, the voltage of the first power source ELVDD is differently applied according to the position of the pixel 40 formed in the image display unit 30 due to a voltage drop phenomenon, thereby displaying an image of uniform luminance. Can not.

Accordingly, it is an object of the present invention to provide a light emitting display device and a method of driving the same, capable of displaying a uniform image.

In order to achieve the above object, a first aspect of the present invention provides a scan driver for sequentially supplying a scan signal to scan lines during a first period, which is a part of one frame, and a data signal through data lines during the first period. And a data display unit for supplying, an image display unit including a plurality of pixels positioned to be connected to the scan line and the data line, and a light emission control line commonly connected to the pixels, wherein the scan driver is provided for the first period. A light emitting display device is provided, wherein a light emitting control signal is supplied to the light emitting control line so that the pixels are set to a non-light emitting state.

Preferably, the scan driver does not supply the emission control signal so that the pixels emit light for a second period except the first period in the one frame. Each of the pixels includes 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, and the storage capacitor. A second transistor for controlling a current supplied to the light emitting element in response to the voltage charged in the second; and connected between the second transistor and the light emitting element and turned off when the light emission control signal is supplied; A third transistor to be turned on.

The second aspect of the present invention is a first step of charging a predetermined voltage to the storage capacitor included in each of the pixels during the first period of one frame, and a second step of setting the pixels in a non-emitting state during the first period And a third step of causing the pixels to emit light during a second period except the first period of the one frame.

Preferably, the emission control signal is supplied to an emission control line commonly connected to the pixels such that the pixels are set to a non-emission state during the first period. The first step includes supplying a scan signal sequentially to select pixels, and supplying a data signal to the selected pixels to charge a voltage corresponding to the data signal to the storage capacitor.

Hereinafter, preferred embodiments of the present invention may be easily implemented by those skilled in the art with reference to FIGS. 2 to 5 as follows.

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 supplies the emission control signal to the emission control line E. FIG. In this case, the emission control line E is commonly connected to the respective pixels 140. 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 from the outside. 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 E, and the scanning line Sn, so that the light emitting device ( Pixel circuit 142 for supplying current to the OLED).

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 a predetermined light corresponding to the 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, and a data line Dm connected between the first power supply ELVDD and the light emitting device OLED. And a first capacitor M1 connected between the scan line Sn and a storage capacitor C 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, and the second electrode is set to a different electrode 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 E, 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.

When the light emission control signal is supplied and the third transistor M3 is turned off, no current is supplied to the light emitting device OLED. Here, since the emission control line E is commonly connected to all the pixels 140, the period image display unit 130 to which the emission control signal is supplied displays the black screen.

4 is a waveform diagram illustrating a method of driving a light emitting display device according to an exemplary embodiment of the present invention.

Referring to Fig. 4, one frame 1F period is divided into a data writing period (or first period) and a light emitting period (or second period) in the present invention. During the data writing period, the scan driver 110 sequentially supplies scan signals to the first scan line S1 to the nth scan line Sn. During the data writing period, 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 supplies the light emission control signal to the light emission control line E during the data writing period. When the emission control signal is supplied to the emission control line E during the data writing period, all the pixels are set to the non-emission state, and thus the image display unit 130 can display a uniform image.

In detail, since the emission control signal is supplied to the emission control line E during the data writing period, the third transistor M3 included in each of the pixels 140 is set to a turn-off state. When the third transistor M3 is set to the turn-off state, current is not supplied to the light emitting element OLED during the data writing period, so that each of the pixels 140 is maintained in the non-light emitting state. Here, when the pixels 140 are set to the non-emission state, no current is supplied to the pixels 140 from the first power source ELVDD.

In other words, no current is supplied from the first power source ELVDD to the pixels 140 during the data writing period, so that no voltage drop occurs in the first power source ELVDD. As such, when no voltage drop occurs in the first power supply ELVDD during the data writing period, the storage capacitor C included in each of the pixels 140 is charged with the correct voltage corresponding to the data signal DS. That is, in the present invention, the voltage drop of the first power source ELVDD is prevented by setting the pixels 140 to the non-emission state during the data writing period, thereby displaying a uniform image. In fact, in the present invention, by setting the pixels 140 to the non-emission state during the data writing period, a uniform image can be displayed regardless of the pattern of the image.

Thereafter, the emission control signal is not supplied to the emission control line E during the emission period. When the emission control signal is not supplied to the emission control line E, the third transistor M3 included in each of the pixels 140 is turned on. When the third transistor M3 is turned on, a current corresponding to the voltage charged in the storage capacitor C in each of the pixels 140 is supplied to the light emitting device OLED. Accordingly, during the light emission period, the image display unit 130 displays a predetermined image corresponding to the data signal DS.

On the other hand, since a current is supplied from the first power source ELVDD during the light emission period, a predetermined voltage drop occurs. When the voltage drop occurs in the first power source ELVDD, the voltage of the gate electrode of the second transistor M2 connected to the first power source ELVDD in each pixel 140 via the storage capacitor C It changes in response to the voltage fluctuation amount of the 1st power supply ELVDD. In other words, the gate electrode voltage of the second transistor M2 is changed by the voltage variation of the first power supply ELVDD by the coupling of the storage capacitor C, and thus the voltage variation of the first power supply ELVDD Regardless, the voltage difference between the gate electrode and the first electrode of the second transistor M2 is kept the same. Therefore, in the present invention, a uniform image can be displayed corresponding to the voltage charged in the storage capacitor C. FIG.

In the present invention, the structure of the pixel 140 is not limited to the structure shown in FIG. 3, and may be selected from any one of various pixels including the transistor M3 connected to the emission control line. For example, in the present invention, the structure of the pixel 140 may be set as shown in FIG. 5.

FIG. 5 is a diagram illustrating a second embodiment of the pixel illustrated in FIG. 2.

Referring to FIG. 5, the pixel 140 according to the second exemplary embodiment of the present invention is connected to a light emitting element OLED, a data line Dm, a scan line Sn, and a light emission control line E so that the light emitting element ( 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 source ELVDD and the n-1 th scan line Sn-1, the first power source ELVDD and the data line. A first transistor M1 and a fourth transistor M4 connected between the Dm, a third transistor M3 connected to the light emitting element OLED and the emission control line E, and a 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 Dm 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 light emission control line E. The fourth transistor M4 is turned on when the emission control signal is not supplied to electrically connect the first power source ELVDD and the first node N1. Here, the light emission control signal is supplied during the data writing period and not supplied during the light emitting period.

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 light emission control line E. 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.

In detail, the sixth transistor M6 is turned on by the scan signal supplied to the n-th scan line Sn-1 during the data writing period. 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. In this case, the storage capacitor C is charged with a threshold voltage of the second transistor M2 and a voltage corresponding to the data signal.

Meanwhile, the fourth transistor M4 and the third transistor M3 are turned on by the light emission control signal during the data writing period in which the scan signals are supplied to the n-1 th scan line Sn-1 and the n th scan line Sn. Is off.

Thereafter, the supply of the emission control signal is stopped during the emission period, so that the fourth transistor M4 and the third transistor M3 are turned on. When the fourth transistor M4 and the third transistor M3 are turned on, a current corresponding to the voltage charged in the storage capacitor C is supplied from the second transistor M2 to the light emitting device OLED to provide a predetermined image. Is displayed.

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, the pixels are set to the non-emission state during the data writing period in which the data signal is supplied to the pixels. When the pixels are set to the non-emission state during the data writing period, the voltage drop of the first power supply can be prevented, and thus a uniform image can be displayed regardless of the pattern of the image. When the pixels are set to the non-emission state during the data writing period, the voltage drop of the first power supply is prevented to display a uniform image regardless of the position of the pixels.

Claims (7)

A scan driver for sequentially supplying a scan signal to the scan lines during a first period which is a part of one frame; A data driver for supplying a data signal to the data lines during the first period; An image display unit including a plurality of pixels positioned to be connected to the scan line and the data line; A light emission control line connected to the pixels in common; And the scan driver supplies an emission control signal to the emission control line so that the pixels are set to a non-emission state during the first period. The method of claim 1, And the scan driver does not supply the emission control signal so that the pixels emit light for a second period except the first period in the one frame. The method of claim 1, 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 corresponding to the voltage charged in the storage capacitor; And a third transistor connected between the second transistor and the light emitting element and turned off when the light emission control signal is supplied, and other than the third transistor. The method of claim 3, wherein Each of the pixels A fourth transistor connected between the second transistor and a first power source and simultaneously turned on and off 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. A first step of charging a predetermined voltage to a storage capacitor included in each of the pixels during a first period of one frame; A second step of setting the pixels to a non-emission state during the first period; And driving the pixels to emit light for a second period except the first period of the one frame. The method of claim 5, And a light emission control signal supplied to a light emission control line commonly connected to the pixels such that the pixels are set to a non-emission state during the first period. The method of claim 5, The first step is Supplying scan signals sequentially to select pixels; And supplying a data signal to the selected pixels to charge a voltage corresponding to the data signal to the storage capacitor.

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