KR100590064B1 - Light emitting display device and driving method thereof - Google Patents

Abstract

The present invention relates to an organic EL light emitting display device and a driving method thereof. According to the present invention, there is provided a light emitting display device comprising: a display panel configured to emit light by emitting a plurality of pixels respectively connected to a plurality of data lines and a scan line; A scan driver for sequentially applying a selection signal to the plurality of scan lines, respectively; A data driver which applies a data voltage corresponding to an image signal to each pixel selected by the plurality of scan lines, and inverts the data voltage by a negative and positive conversion signal to output the data voltage; And a driving controller for driving the data driver and the scan driver and generating the yin-yang conversion signal when the same still image is continuously displayed, wherein the driving control unit continuously provides the yin-yang conversion signal for a predetermined time, The yin-yang conversion signal is provided at a predetermined cycle in correspondence to the time when the same still image is continuously displayed. According to the present invention, the flicker or sticking phenomenon can be prevented by inverting the display data at regular intervals so that the same still image is not displayed continuously, thereby preventing deterioration of the organic EL light emitting display device.

Light emitting display, organic EL, still image, yin and yang reversed, sticking

Description

A light emitting display device and a method of driving the same

1 is a diagram showing the light emission principle of an organic EL.

2 is a schematic block diagram of an organic EL display device according to an embodiment of the present invention.

3 is a diagram illustrating an organic EL display panel using an active driving method using a thin film transistor (TFT) according to an embodiment of the present invention.

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

5 is a diagram schematically illustrating a data driver outputting an inverted data voltage according to an exemplary embodiment of the present invention.

6 is a waveform diagram illustrating an example in which a display panel according to an exemplary embodiment of the present invention is inverted at regular cycles.

7A and 7B are diagrams illustrating normal display and reverse display, respectively, in a display panel according to an exemplary embodiment of the present invention.

8 is a flowchart illustrating a method of driving a light emitting display device according to an exemplary embodiment of the present invention.

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

An organic electroluminescence (EL) display device is a device for displaying an image by controlling an amount of current flowing through these organic materials by dividing an organic material emitting light when the current flows into pixels in a matrix form. Such an organic EL display device is expected to be a next generation display device due to advantages such as low voltage driving, light weight, wide viewing angle, and high speed response.

1 is a diagram showing the light emission principle of organic EL, respectively.

In general, an organic EL display device is a display device for electrically exciting a fluorescent organic compound to emit light, and is capable of displaying an image by driving voltage or current by driving N × M organic light emitting cells. As shown in FIG. 1, the organic light emitting cell structure has a structure of an indium tin oxide (ITO) pixel electrode, an organic thin film, and a metal layer, and the organic thin film has a good balance between electrons and holes to improve light emission efficiency. In order to achieve this, a multi-layered structure including an emitting layer (EML), an electron transport layer (ETL), and a hole transport layer (HTL) is formed, and a separate electron injection layer (EIL) is used. ) And a hole injecting layer (HIL).

As such a method of driving the organic light emitting cell, there is a simple matrix method and an active matrix method using a TFT. In the simple matrix method, the anode and the cathode are orthogonal and the line is selected and driven, whereas the active driving method is a driving method in which a TFT and a capacitor are connected to respective pixel electrodes to maintain a voltage by capacitor capacitance.

However, the conventional organic EL light emitting display has a problem in that when the same still image is displayed continuously for a long time, the organic EL light emitting display is deteriorated by a flicker or sticking phenomenon in which the afterimage remains. .

SUMMARY OF THE INVENTION An object of the present invention for solving the above problems is to provide a light emitting display device and a driving method thereof capable of preventing a sticking phenomenon by inverting display data at regular intervals so that the same still image is not displayed continuously.

As a means for achieving the above object, the light emitting display device according to the present invention,

A display panel configured to emit light by emitting a plurality of pixels respectively connected to the plurality of data lines and the scan lines;

A scan driver for sequentially applying a selection signal to the plurality of scan lines, respectively;

A data driver which applies a data voltage corresponding to an image signal to each pixel selected by the plurality of scan lines, and inverts the data voltage by a negative and positive conversion signal to output the data voltage; And

 A driving control unit which drives the data driving unit and the scanning driving unit and generates the yin-yang conversion signal when the same still image is continuously displayed;

Characterized in that it comprises a.

The driving control unit may continuously provide the yin-yang conversion signal for a predetermined time or provide the yin-yang conversion signal at a predetermined period corresponding to the time when the same still image is continuously displayed.

Here, the still image is characterized in that the black and white still image.

Here, the data driver is characterized in that for changing the output direction of the data voltage in accordance with the negative and positive conversion signal.

The data driver may include an inverter for inverting and outputting the data voltage according to the negative and positive conversion signals, and the inverters may be installed on red, green, and blue data lines respectively output from the data driver and input to the display panel. It is characterized by.

On the other hand, as a means for achieving the above object, the driving method of the light emitting display device according to the present invention,

In the method of driving a light emitting display device having a plurality of pixels, a scan driver and a data driver,

Iii) determining whether the still image is continuously displayed for a predetermined time or more;

Ii) generating a positive and negative conversion signal when the still image is displayed continuously;

Inverting a data voltage applied from the data driver according to the yin-yang conversion signal; And

Iii) applying the inverted data voltage to a display panel according to a preset output mode;

Characterized in that it comprises a.

The method of driving a light emitting display device according to the present invention may include: checking whether a display of the still image is changed while applying the inverted data voltage to the display panel; And when the display of the still image is changed, applying a data voltage to the display panel normally.

Here, the data voltage of step iii) is inverted using an inverter.

Here, the predetermined output mode of step iii) may include a mode for maintaining the inverted output for a predetermined time and a mode for inverting the data at a predetermined period.

According to the present invention, the flicker or sticking phenomenon can be prevented by inverting the display data at regular intervals so that the same still image is not displayed continuously, thereby preventing deterioration of the organic EL light emitting display device.

Hereinafter, a light emitting display device and a driving method thereof according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic block diagram of an organic EL display device according to an embodiment of the present invention.

Referring to FIG. 2, an organic EL display device according to an exemplary embodiment of the present invention includes a video controller 100, a panel controller 200, a power module 300, a scan driver 400, a data driver 500, and an organic EL. It may be made of a panel 600.

In the organic EL display device according to the embodiment of the present invention, a plurality of signals passing through the analog interface and the digital interface are respectively arranged in the organic EL panel 600 by the scan driver 440 and the data driver 500. It is provided in the row direction.

Specifically, various analog signals such as R, G, B signals, and synchronization signals are input to the video controller 100 and then converted into digital signals, and the panel controller 200 controls them to sequentially scan the driver 400. And the data driver 500, the organic EL panel 600 is provided by the scan driver 400 and the data driver 500, and the power supply device 400. An n × m organic light emitting cell is driven by voltage or current by a power supply to represent an image.

3 is a diagram illustrating an organic EL display panel using an active driving method using a TFT according to an embodiment of the present invention.

Referring to FIG. 3, an organic EL display device according to an exemplary embodiment of the present invention includes an organic EL display panel 600, a data driver 400, and a scan driver 500.

The organic EL display panel 600 includes m data lines D1, D2, ..., Dm extending in the column direction, n scan lines S1, S2, ..., Sn extending in the row direction, and n × m. Pixel circuits. The m data lines D1, D2, ..., Dm transfer data signals representing an image signal to the pixel circuits, and the n scan lines S1, S2, ..., Sn transfer respective selection signals to the pixel circuits. . Here, the pixel circuit is formed in one pixel region 610 defined by two neighboring data lines D1, D2,..., And Dm and two neighboring scan lines S1, S2,..., Sn.

The scan driver 400 sequentially applies selection signals to the n scan lines S1, S2,..., And Sn, and the data driver 500 images the m data lines D1, D2,..., And Dm. The data voltage corresponding to the signal is applied.

In addition, the scan driver 330 and / or the data driver 320 may be electrically connected to the organic EL display panel 600, or a tape carrier adhered to and electrically connected to the organic EL display panel 600. The package may be mounted in a chip carrier package (TCP). Alternatively, the display panel 600 may be attached to a flexible printed circuit (FPC) or a film that is adhered to and electrically connected to the display panel 600 in the form of a chip.

In addition, the scan driver 400 and / or the data driver 500 may be directly mounted on the glass substrate of the organic EL display panel 600, or may be formed of the same layers as the scan line, the data line, and the thin film transistor on the glass substrate. It may be replaced with the driving circuit formed or may be directly mounted.

The pixel circuit also includes an organic EL element OLED, two transistors SM and DM and a capacitor Cst. For example, the two transistors SM and DM may be formed as PMOS transistors.

The driving transistor DM has a source connected to the power supply voltage VDD, and a capacitor Cst connected between the gate and the source. The capacitor Cst maintains the gate-source voltage of the driving transistor DM for a predetermined period, and the driving transistor DM corresponds to a voltage held by the capacitor Cst, that is, a voltage between the gate and the source. Output the current. The switching transistor SM transfers the data signal from the data line Dm to the driving transistor DM in response to the selection signal from the current scan line Sn.

The organic EL element OLED has a cathode connected to a reference voltage Vss and emits light corresponding to a current applied through the driving transistor DM. Here, the power source Vss connected to the cathode of the organic EL element OLED is a voltage having a lower level than the power source VDD, and a ground voltage or the like may be used.

4 is a schematic configuration diagram of a light emitting display device according to an exemplary embodiment of the present invention and may include a display panel 600, a scan driver 400, a data driver 500, and a driving controller 700. .

Referring to FIG. 4, in the light emitting display device according to the present invention, the scan driver 400 sequentially applies a selection signal to each of the plurality of scan lines, and the data driver 500 corresponds to a data voltage corresponding to an image signal. Is applied to each pixel selected by the plurality of scan lines, and the display panel 600 is displayed by emitting a plurality of pixels respectively connected to the plurality of data lines and the scan lines.

The driving controller 700 drives the data driver 500 and the scan driver 400, and generates a yin-yang conversion signal when the same still image, for example, a monochrome still image is continuously displayed. In this case, the driving controller 700 continuously provides the yin-yang conversion signal for a predetermined time or provides the yin-yang conversion signal at a predetermined period corresponding to the time when the same still image is continuously displayed.

5 is a diagram schematically illustrating a data driver outputting an inverted data voltage according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the data driver 500 according to an exemplary embodiment of the present invention switches the output direction of the data voltage according to the negative and positive conversion signals. Here, reference numerals 511, 521 and 531 indicate that the output direction of the data voltage is switched, for example, may be implemented using a switch.

In addition, the data driver 500 includes inverters 512, 522, and 532 for inverting and outputting the data voltage according to the negative and positive conversion signals, and the inverters 512, 522, and 532 are the data drivers 500. ) May be installed on the red, green, and blue data lines respectively outputted from the input line and input to the display panel 600.

Accordingly, the data driver 500 applies the data voltage inverted by the inverters 512, 522, and 532 to the display panel 600 or normal data. Such inverted data or normal data may be repeatedly provided at regular intervals according to a preset output mode.

6 is a waveform diagram illustrating an example in which the display panel according to the exemplary embodiment of the present invention is inverted at regular cycles.

Referring to FIG. 6, in the light emitting display device according to an exemplary embodiment of the present invention, when the positive and negative conversion signals have a low logic value, when the original image is normally output and provided with a high logic value, the red, green, and blue data are respectively provided. Is inverted and outputted, and the original image and the inverted image may be repeatedly displayed every predetermined time at regular intervals. Of course, as described above, when the still image is repeated for a long time, the display panel may be driven by continuously maintaining the inverted data for a predetermined time. 7A and 7B illustrate a case where the normal display 710 and the reverse display 720 are respectively displayed in the display panel according to the exemplary embodiment of the present invention.

8 is a flowchart illustrating a method of driving a light emitting display device according to an exemplary embodiment of the present invention.

Referring to FIG. 8, a method of driving a light emitting display device according to an embodiment of the present invention is a method of driving a light emitting display device including a plurality of pixels, a scan driver, and a data driver. In operation S810, it is determined whether the still image is continuously displayed for a predetermined time or more (S820).

Subsequently, when the still image is continuously displayed, the driving controller generates a yin-yang conversion signal (S830).

Next, by checking whether the negative and positive conversion signal is inverted at a predetermined period (S840), the data voltage applied from the data driver is inverted at a predetermined period and outputted (S850), or a predetermined time inverted output is maintained (S860). That is, the inverted data voltage is applied to the display panel according to a preset output mode. In this case, the data voltage may be inverted using an inverter.

Thereafter, while applying the inverted data voltage to the display panel, it is checked whether the display of the still image is changed (S870), and when the display of the still image is changed, the data voltage is normally applied to the display panel. (S880).

As a result, according to an exemplary embodiment of the present invention, the display data may be inverted and output so that the same still image is not displayed continuously, thereby preventing flickering or sticking.

While the invention has been shown and described in connection with specific embodiments thereof, it will be appreciated that various modifications and changes can be made without departing from the spirit and scope of the invention as indicated by the claims. Anyone who owns it can easily find out.

According to the present invention, the flicker or sticking phenomenon can be prevented by inverting the display data at regular intervals so that the same still image is not displayed continuously, thereby preventing deterioration of the organic EL light emitting display device.

Claims (12)

A display panel configured to emit light by emitting a plurality of pixels respectively connected to the plurality of data lines and the scan lines; A scan driver for sequentially applying a selection signal to the plurality of scan lines, respectively; A data driver which applies a data voltage corresponding to an image signal to each pixel selected by the plurality of scan lines, and inverts the data voltage by a negative and positive conversion signal to output the data voltage; And  A driving control unit which drives the data driving unit and the scanning driving unit and generates the yin-yang conversion signal when the same still image is continuously displayed; Light emitting display device comprising a. The method of claim 1, And the driving controller provides the yin-yang conversion signal for a predetermined time. The method of claim 1, And the driving controller provides the yin-yang conversion signal at regular intervals in correspondence to the time when the same still image is continuously displayed. The method of claim 1, The still image is a light emitting display device, characterized in that the black and white still image. The method of claim 1, And the data driver changes the output direction of the data voltage according to the negative and positive conversion signals. The method of claim 1, The data driver includes an inverter for inverting and outputting the data voltage according to the yin-yang conversion signal. The method of claim 6, And the inverters are respectively provided on red, green, and blue data lines output from the data driver and input to the display panel. In the method of driving a light emitting display device having a plurality of pixels, a scan driver and a data driver, Iii) determining whether the still image is continuously displayed for a predetermined time or more; Ii) generating a positive and negative conversion signal when the still image is displayed continuously; Inverting a data voltage applied from the data driver according to the yin-yang conversion signal; And Iii) applying the inverted data voltage to a display panel according to a preset output mode; Method of driving a light emitting display device comprising a. The method of claim 8, Checking whether a display of the still image is changed while applying the inverted data voltage to the display panel; And When the display of the still image is changed, applying a data voltage to the display panel normally A driving method of a light emitting display device further comprising. The method of claim 8, And the data voltage of step (iii) is inverted using an inverter. The method of claim 8, The preset output mode of step (iii) includes a mode for maintaining an inverted output for a predetermined time and a mode for inverting and outputting data at a predetermined period. The method of claim 8, And the still image is a black and white still image.

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