KR102573344B1 - Organic light emitting display device, timing controller and method for driving the timing controller - Google Patents

Abstract

The present embodiments relate to an organic light emitting display device that stably expresses image data of all gradations within a maximum output voltage range of a data driver. The reference voltage applied when driving the light emitting diode is set differently and the reference voltage is raised only when expressing low-grayscale image data, thereby reducing the boosting time when expressing low-grayscale image data to stably express low-grayscale image data. and prevents the occurrence of insufficient voltage margin due to the upward adjustment of the reference voltage when expressing high-grayscale image data.

Description

Organic light emitting display, timing controller, and driving method of timing controller

The present embodiments relate to a timing controller, a method for driving the timing controller, and an organic light emitting display device including the timing controller.

An organic light emitting display device that has recently been in the limelight as a display device uses organic light emitting diodes (OLEDs) that emit light by itself, and thus has advantages of fast response speed, high contrast ratio, luminous efficiency, luminance, and viewing angle.

Such an organic light emitting display device includes an organic light emitting display panel including a plurality of subpixels in which a plurality of gate lines and a plurality of data lines are disposed and disposed in an area where the gate lines and the data lines intersect, and driving the plurality of gate lines. may include a gate driver for driving, a data driver for driving a plurality of data lines, a timing controller for controlling driving of the gate driver and the data driver, and each subpixel may include an organic light emitting diode (OLED) and an organic light emitting diode (OLED). (OLED) may include a driving transistor.

The timing controller receives image data from the outside, converts the received image data into a signal format used by the data driver, outputs the data to the data driver, and controls the gate driver to control the data voltage output from the data driver at the time of driving the gate line. to be supplied to each subpixel.

An organic light emitting diode (OLED) included in a subpixel emits light according to a gray level indicated by a data voltage output from a data driver so that an image is displayed through an organic light emitting display panel.

The organic light emitting diode (OLED) exhibits a constant luminance change according to the supplied data voltage, and as the efficiency of the organic light emitting diode (OLED) improves, the luminance change ratio to the data voltage may increase.

That is, as the efficiency of the organic light emitting diode (OLED) increases, the slope of a gamma curve representing a relationship between a data voltage supplied to the organic light emitting diode (OLED) and luminance increases.

At this time, as the slope of the gamma curve increases, the organic light emitting diode (OLED) exhibits high efficiency when expressing high-grayscale image data, but generates noise or inverts grayscale when expressing low-grayscale image data. There is a problem that screen abnormality appears due to the occurrence of the phenomenon.

Therefore, in the case of expressing low-gray image data while maintaining high efficiency of the luminance characteristics versus data voltage of the organic light-emitting diode (OLED), it is possible to stably express low-gray image data by preventing noise or a gray-level reversal phenomenon. this is required

An object of the present embodiments is to provide an organic light emitting display device that prevents screen abnormalities occurring when displaying low grayscale image data as the efficiency of an organic light emitting diode (OLED) improves.

An object of the present embodiments is to provide an organic light emitting display device capable of stably expressing image data of all gray levels while maintaining high efficiency of an organic light emitting diode (OLED).

An exemplary embodiment includes an organic light emitting display panel in which a plurality of gate lines, a plurality of data lines, and a plurality of reference voltage lines are disposed and a plurality of subpixels are disposed in an area where the gate lines and the data lines intersect, and the organic light emitting display panel An organic light emitting display device including a timing controller controlling driving of an organic light emitting display device, wherein the timing controller differently sets reference voltages supplied to reference voltage lines disposed on the organic light emitting display panel according to image data received from the outside. A display device may be provided.

In another embodiment, an image data processing unit that receives image data from the outside, processes the received image data, and outputs a reference voltage control signal according to a gray level of the received image data, and generates a reference voltage according to the reference voltage control signal. A timing controller including a reference voltage generator and a data output unit outputting processed image data and the generated reference voltage may be provided.

For example, the reference voltage generator may generate a first reference voltage when the received image data is low grayscale image data and generate a second reference voltage set lower than the first reference voltage when the received image data is high grayscale image data.

Accordingly, the data output unit may output low grayscale image data and a first reference voltage or output high grayscale image data and a second reference voltage.

Another embodiment includes the steps of receiving image data from the outside, processing the received image data, identifying gray levels of the image data and generating a reference voltage according to the gray levels of the image data, and processing the processed image data. and outputting the generated reference voltage.

According to the present embodiments, the reference voltage is set differently according to the gradation of image data represented by the organic light emitting diode (OLED), so that image data of all gradations can be stably expressed.

According to the present embodiments, when expressing low-grayscale image data, a reference voltage set higher than a reference voltage when expressing high-grayscale image data is applied, thereby preventing noise or a gradation reversal phenomenon that occurs when expressing low-grayscale image data. To prevent this, it is possible to stably express low-grayscale image data.

According to the present embodiments, the reference voltage is set high only when low grayscale image data is expressed, so that when the reference voltage is raised as a whole, the problem of insufficient voltage margin occurring when expressing high grayscale image data can be solved.

1 is a diagram showing a schematic configuration of an organic light emitting display device according to the present embodiments.
2 is a diagram showing an example of a sub-pixel structure of an organic light emitting display device according to the present embodiments.
3 is a diagram for explaining a process of driving an organic light emitting diode of an organic light emitting display device according to the present embodiments.
4 is a graph showing an example of luminance according to gray levels of an organic light emitting diode of an organic light emitting display device according to example embodiments.
5 is a diagram for explaining a problem when the organic light emitting display device according to the present embodiments increases a reference voltage.
6 is a block diagram showing the configuration of a timing controller of an organic light emitting display device according to the present embodiments.
7 and 8 are diagrams illustrating examples of reference voltages applied according to gray levels of image data represented by sub-pixels of an organic light emitting display device according to the present embodiments.
9 is a diagram illustrating an example of a voltage output by a data driver when the organic light emitting display according to the present embodiments adjusts the reference voltage according to the gradation of image data.
10 is a flowchart illustrating a process of a method of driving a timing controller of an organic light emitting display device according to the exemplary embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention are described in detail below with reference to exemplary drawings. In adding reference numerals to components of each drawing, the same components may have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description may be omitted.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the nature, sequence, order, or number of the corresponding component is not limited by the term. When an element is described as being “connected,” “coupled to,” or “connected” to another element, that element is or may be directly connected to that other element, but intervenes between each element. It will be understood that may be "interposed", or each component may be "connected", "coupled" or "connected" through other components.

1 shows a schematic configuration of an organic light emitting display device 100 according to the present embodiments.

Referring to FIG. 1 , in an organic light emitting display device 100 according to the present embodiments, a plurality of gate lines GL and a plurality of data lines DL are disposed, and the gate lines GL and data lines DL An organic light emitting display panel 110 including a plurality of subpixels (SP) disposed in the crossing area, a gate driver 120 driving a plurality of gate lines (GL), and a plurality of data lines (DL). It includes a data driver 130 for supplying a data voltage, and a timing controller 140 (T-CON) for controlling the gate driver 120 and the data driver 130.

The gate driver 120 sequentially drives the plurality of gate lines GL by sequentially supplying scan signals to the plurality of gate lines GL.

The gate driver 120 sequentially supplies scan signals of an on voltage or an off voltage to the plurality of gate lines GL under the control of the timing controller 140 to generate the plurality of gate lines GL. run sequentially.

The gate driver 120 may be located on only one side or both sides of the organic light emitting display panel 110 according to a driving method.

In addition, the gate driver 120 may include one or more gate driver integrated circuits.

Each gate driver integrated circuit is connected to a bonding pad of the organic light emitting display panel 110 by a tape automated bonding (TAB) method or a chip on glass (COG) method, or It can be implemented as a GIP (Gate In Panel) type and directly disposed on the organic light emitting display panel 110 .

In addition, it may be integrated and disposed on the organic light emitting display panel 110, or may be implemented in a chip on film (COF) method mounted on a film connected to the organic light emitting display panel 110.

The data driver 130 drives the plurality of data lines DL by supplying data voltages to the plurality of data lines DL.

When a specific gate line GL is opened, the data driver 130 converts the image data received from the timing controller 140 into analog data voltages and supplies them to the plurality of data lines DL, thereby providing a plurality of data lines DL. ) to drive

The data driver 130 may include at least one source driver integrated circuit to drive a plurality of data lines DL.

Each source driver integrated circuit is connected to a bonding pad of the organic light emitting display panel 110 by a tape automated bonding (TAB) method or a chip on glass (COG) method, or It may be directly disposed on the organic light emitting display panel 110 or may be integrated and disposed on the organic light emitting display panel 110 .

In addition, each source driver integrated circuit may be implemented in a Chip On Film (COF) method. In this case, one end of each source driver integrated circuit is bonded to at least one source printed circuit board, and the other end is bonded to the organic light emitting display panel 110 .

The timing controller 140 controls the driving of the gate driver 120 and the data driver 130 by supplying various control signals to the gate driver 120 and the data driver 130 .

The timing controller 140 starts scanning according to the timing implemented in each frame, converts externally input image data according to the data signal format used by the data driver 130, and outputs the converted image data. and controls data driving at an appropriate time according to the scan.

The timing controller 140 includes various timing signals including a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), an input data enable (DE) signal, and a clock signal (CLK) together with input image data. are received from outside (e.g. host system).

The timing controller 140 converts the input image data input from the outside to suit the data signal format used by the data driver 130 and outputs the converted image data, as well as the gate driver 120 and the data driver 130. ), receive timing signals such as the vertical sync signal (Vsync), the horizontal sync signal (Hsync), the input data enable signal (DE), and the clock signal (CLK), and generate various control signals to generate gate drivers (120) and the data driver (130).

For example, the timing controller 140 may include a gate start pulse (GSP), a gate shift clock (GSC), and a gate output enable signal (GOE) to control the gate driver 120 . : Gate Output Enable) and various gate control signals (GCS: Gate Control Signal) are output.

Here, the gate start pulse GSP controls the operation start timing of one or more gate driver integrated circuits constituting the gate driver 120 . The gate shift clock (GSC) is a clock signal commonly input to one or more gate driver integrated circuits and controls shift timing of scan signals (gate pulses). The gate output enable signal GOE specifies timing information of one or more gate driver integrated circuits.

In addition, the timing controller 140, in order to control the data driver 130, a source start pulse (SSP: Source Start Pulse), a source sampling clock (SSC: Source Sampling Clock), a source output enable signal (SOE: Source It outputs various data control signals (DCS: Data Control Signal) including Output Enable) and the like.

Here, the source start pulse SSP controls data sampling start timing of one or more source driver integrated circuits constituting the data driver 130 . The source sampling clock (SSC) is a clock signal that controls sampling timing of data in each source driver integrated circuit. The source output enable signal SOE controls output timing of the data driver 130 .

The timing controller 140 is a source printed circuit board bonded with a source driver integrated circuit and a control printed circuit connected through a connection medium such as a flexible flat cable (FFC) or a flexible printed circuit (FPC). It may be disposed on a board (Control Printed Circuit Board).

On such a control printed circuit board, a power controller (not shown) supplies various voltages or currents to the organic light emitting display panel 110, the gate driver 120, and the data driver 130 or controls various voltages or currents to be supplied. more can be placed. Such a power controller is also referred to as a power management integrated circuit.

Each subpixel SP disposed on the organic light emitting display panel 110 may include a circuit element such as a transistor.

For example, in the organic light emitting display panel 110, each subpixel SP is composed of an organic light emitting diode (OLED) and a circuit element such as a driving transistor (DRT) for driving the organic light emitting diode (OLED). It can be.

The type and number of circuit elements constituting each sub-pixel SP may be variously determined according to a provided function and a design method.

2 illustrates an example of a sub-pixel (SP) structure of the organic light emitting display device 100 according to the present embodiments.

Referring to FIG. 2 , in the organic light emitting display device 100 according to the present embodiments, each subpixel SP includes an organic light emitting diode OLED and a driving transistor DRT for driving the organic light emitting diode OLED. ) and a sensing transistor (SENT: Sensing Transistor) electrically connected between the first node (N1) of the driving transistor (DRT) and a reference voltage line (RVL) supplying a reference voltage (Vref Reference Voltage). ), a switching transistor (SWT) electrically connected between the second node N2 of the driving transistor DRT and the data line DL supplying the data voltage Vdata, and the driving transistor DRT It is configured to include a storage capacitor (Cstg) electrically connected between the first node N1 and the second node N2 of the .

The organic light emitting diode (OLED) may include a first electrode (eg, an anode electrode or a cathode electrode), an organic layer, and a second electrode (eg, a cathode electrode or an anode electrode), and the like, and each subpixel (SP) is an organic light emitting diode (OLED) may include an organic light emitting diode capacitor (Coled: OLED Capacitor) connected between the first electrode and the second electrode.

The driving transistor DRT drives the organic light emitting diode OLED by supplying a driving current to the organic light emitting diode OLED.

The first node N1 of the driving transistor DRT may be electrically connected to the first electrode of the organic light emitting diode OLED, and may be a source node or a drain node. The second node N2 of the driving transistor DRT may be electrically connected to a source node or a drain node of the switching transistor SWT and may be a gate node. The third node N3 of the driving transistor DRT may be electrically connected to a driving voltage line (DVL) that supplies the driving voltage EVDD, and may be a drain node or a source node.

The sensing transistor SENT may be turned on by the scan signal to apply the reference voltage Vref to the first node N1 of the driving transistor DRT.

Also, when the sensing transistor SENT is turned on, it may be used as a voltage sensing path for the first node N1 of the driving transistor DRT.

When turned on by the scan signal, the switching transistor SWT transfers the data voltage Vdata supplied through the data line DL to the second node N2 of the driving transistor DRT.

In this case, the sensing transistor SENT and the switching transistor SWT may be connected to different gate lines GL to be separately controlled on-off or connected to the same gate line GL to be controlled.

The storage capacitor Cstg is electrically connected between the first node N1 and the second node N2 of the driving transistor DRT to provide a data voltage Vdata corresponding to the video signal voltage or a voltage corresponding thereto. It can be maintained for one frame time.

FIG. 3 is to explain in detail the driving process of the organic light emitting diode (OLED) in the subpixel (SP) structure of the organic light emitting display device 100 according to the present embodiments, and the organic light emitting diode (OLED) boosts It shows the process of boosting.

The driving process of the organic light emitting diode (OLED) proceeds in the order of (1) discharge and voltage application (2) kick-back generation (3) boosting (4) light emission during one frame time. The luminance visually perceived according to light emission of the light emitting diode (OLED) corresponds to an average value of luminance during one frame time.

In step (1), the switching transistor SWT and the sensing transistor SENT included in the subpixel SP are operated by the scan signal, and the first node N1 and the second node ( The driving reference voltage VpreR and the data voltage Vdata are respectively applied to N2).

In the step (2), a kick-back phenomenon occurs due to the parasitic capacitance of the switching transistor (SWT) and the sensing transistor (SENT), and in the step (3), the switching transistor (SWT) and the sensing transistor (SENT) is turned off and a boosting process in which the voltage (or current) applied to the OLED is increased.

When the voltage applied to the organic light emitting diode (OLED) in step (3) exceeds the threshold voltage of the organic light emitting diode (OLED), current flows through the organic light emitting diode (OLED) in step (4), so that the organic light emitting diode (OLED) emits light.

That is, the organic light emitting diode (OLED) is in a state of not emitting light in steps (1) to (3) of the driving process of the organic light emitting diode (OLED), and is in a state of emitting light in step (4) of one frame time. .

Therefore, since the luminance displayed through the organic light emitting diode (OLED) is the average value of luminance displayed during 1 frame time, and the time for the organic light emitting diode (OLED) to emit light is the time corresponding to the step (4) of 1 frame time, 1 frame In terms of time, steps (1) to (3), in particular, the time required for step (3) affects the luminance of the organic light emitting diode (OLED).

At this time, when the organic light emitting diode (OLED) expresses low grayscale image data, the current for charging the organic light emitting diode capacitor (Coled) is small, so the time required in step (3) is further increased, and the low grayscale image Data may not be represented reliably.

In particular, as the slope of the gamma curve representing the luminance characteristics versus the data voltage applied to the organic light emitting diode (OLED) increases, noise or gray level reversal occurs when expressing low gray level image data, resulting in low gray levels. There is a problem in that image data cannot be stably expressed and screen abnormalities may appear.

4 is a graph showing an example of luminance change for each gray level according to the efficiency of the organic light emitting diode (OLED) in the organic light emitting display device 100 according to the present embodiments, and illustrates a case in which low gray level image data is not stably expressed. It is to explain.

Referring to FIG. 4, 401 indicates a change in luminance when expressing a low gray scale when the slope of a gamma curve representing luminance characteristics versus data voltage applied to an organic light emitting diode (OLED) is large. In the case where the slope of the gamma curve of the organic light emitting diode (OLED) is smaller than that of the case of 401, it shows the change in luminance that appears when expressing low gradations.

When the slope of the gamma curve of the organic light emitting diode (OLED) is large, such as 401, it can be seen that the luminance is greater when expressing the same gray level compared to the case of 402, but when expressing low gray level image data As shown in 403, it can be confirmed that noise or grayscale reversal occurs.

Therefore, as the efficiency of the organic light emitting diode (OLED) improves, the applied data voltage vs. luminance characteristic improves. there are problems with

In order to stably express low grayscale image data, the driving reference voltage (VpreR) applied in step (1) of the organic light emitting diode (OLED) driving process is increased to reduce the time required in step (3). However, there is a problem in that the voltage margin output from the data driver 130 may be insufficient when expressing high grayscale image data due to the upward adjustment of the driving reference voltage VpreR.

5 is an organic light emitting display device 100 according to the present embodiments, in order to stably express low grayscale image data, the driving reference voltage VpreR applied during driving of the organic light emitting diode (OLED) is increased. In one case, an example of a high grayscale image data output voltage is shown.

Referring to FIG. 5 , in the case of outputting voltages for high-grayscale image data as shown in (a) and (b) of FIG. As shown, the margin for the compensation voltage may be insufficient.

For example, a margin for a voltage for compensating for a change or deviation of a threshold voltage, which is a characteristic value of the driving transistor DRT included in the subpixel SP, may be insufficient.

Therefore, in the case of expressing high grayscale image data, the driving reference voltage VpreR cannot be increased due to the maximum output voltage limit of the data driver 130 .

In the present embodiments, a driving reference applied when driving an organic light emitting diode (OLED) in order to ensure that a margin for an output voltage is not insufficient when expressing high grayscale image data while stably expressing low grayscale image data. A driving method for variably setting the voltage VpreR is provided.

6 illustrates the configuration of the timing controller 110 of the organic light emitting display device 100 according to the present embodiments.

Referring to FIG. 6 , the timing controller 140 according to the present exemplary embodiments includes an image data processing unit 141 , a reference voltage generator 142 and a data output unit 143 .

The image data processor 141 receives image data from the outside, converts the received image data into a signal format used by the data driver 130, and outputs the converted image data.

Also, the image data processing unit 141 may analyze the gray level of the image data received from the outside and output a reference voltage control signal according to the gray level of the image data.

For example, if the image data received from the outside is low grayscale image data, the image data processing unit 141 converts the driving reference voltage VpreR applied during driving of the organic light emitting diode (OLED) to the first reference voltage. It outputs a reference voltage control signal instructing to generate a level of .

In addition, if the image data received from the outside is high grayscale image data, a reference voltage control command to generate the driving reference voltage VpreR applied during driving of the organic light emitting diode (OLED) at the level of the second reference voltage. output a signal

Whether or not the received image data is low grayscale image data can be checked using information on frame data of the received image data. For example, image data of 50 grayscale or less can be classified as low grayscale image data.

The first reference voltage is a voltage set higher than the second reference voltage, and the image data processor 141 supplies the second reference voltage as the driving reference voltage VpreR when the image data received from the outside is high grayscale image data. and if the image data received from the outside is low grayscale image data, the first reference voltage set higher than the second reference voltage is supplied as the driving reference voltage VpreR.

That is, the image data processing unit 141 sets the second reference voltage as the driving reference voltage VpreR when expressing high grayscale image data, so that the organic light emitting diode (OLED) is within the maximum output voltage range of the data driver 130. ) to be driven, and in the case of expressing low grayscale image data, the first reference voltage set higher than the second reference voltage is set as the driving reference voltage (VpreR) so that low grayscale image data can be stably expressed. .

Also, the image data processing unit 141 may check the level of the data voltage representing the gray level of the image data received from the outside and output a reference voltage control signal according to the level of the data voltage.

For example, if the level of the data voltage representing the gray level of the image data is equal to or less than a preset level (eg, 5V), a reference voltage control signal instructing generation of a first reference voltage is output, and the level of the data voltage is equal to or less than the preset level. If it is higher than the first reference voltage, a reference voltage control signal instructing generation of a second reference voltage set to be lower than the first reference voltage may be output.

That is, stable representation of low-gradation image data is achieved by increasing the driving reference voltage VpreR applied when expressing image data only when low-gradation image data is output based on the level of the data voltage representing the gradation of the image data. In addition, it is possible to ensure that the voltage margin is not insufficient when expressing high-grayscale image data due to the upward adjustment of the driving reference voltage VpreR.

The reference voltage generator 142 generates a reference voltage according to the reference voltage control signal output by the image data processor 141 and transfers the generated reference voltage to the data output unit 143 .

Since the reference voltage generator 142 generates the reference voltage according to the reference voltage control signal output by the image data processor 141, the reference voltage is different according to the gray level of the image data received by the image data processor 141. to create

For example, when the image data processing unit 141 receives low grayscale image data from the outside, the reference voltage generator 142 generates a first reference voltage and transfers it to the data output unit 143, and transmits the image data to the data output unit 143. When the processing unit 141 receives high grayscale image data from the outside, a second reference voltage is generated and transmitted to the data output unit 143 .

The data output unit 143 outputs the image data received from the image data processing unit 141 and the reference voltage generated by the reference voltage generator 142 to the data driver 130 .

Therefore, the data output unit 143 outputs the high grayscale image data and the second reference voltage to the data driver 130, or outputs the low grayscale image data and the first reference voltage set higher than the second reference voltage to the data driver 130. ) is output as

7 and 8 illustrate examples of reference voltages supplied according to gray levels of image data represented by each sub-pixel SP in the organic light emitting display device 100 according to the present embodiments.

Referring to FIG. 7 , when the subpixel SP of the organic light emitting display device 100 expresses low grayscale image data, the data line DL ), the data voltage Vdata corresponding to the low grayscale image data is supplied, and the driving reference voltage VpreR, which is increased to the first reference voltage, is supplied to the reference voltage line RVL.

As the voltage raised to the driving reference voltage (VpreR) is applied, the charging current of the organic light emitting diode capacitor (Coled) is reduced, thereby reducing the time required for boosting during the driving process of the organic light emitting diode (OLED). , the rate of decrease of the voltage applied to the driving transistor DRT during the boosting time is reduced.

Therefore, the upwardly adjusted first reference voltage is applied as the driving reference voltage VpreR to reduce the boosting time and to alleviate the voltage decrease rate applied to the driving transistor DRT, thereby expressing low grayscale image data. It enables low-grayscale image data to be expressed stably without occurrence of visual noise or grayscale reversal.

Referring to FIG. 8 , when the subpixel SP of the organic light emitting display device 100 expresses high grayscale image data, the data line DL ), the data voltage Vdata corresponding to the high grayscale image data is supplied, and the driving reference voltage VpreR set as the second reference voltage is supplied to the reference voltage line RVL.

Since the second reference voltage is a voltage set lower than the first reference voltage applied when expressing low grayscale image data, when expressing high grayscale image data, the organic light emitting diode (OLED) is within the maximum output voltage range of the data driver 130 ( OLED), and the margin for the compensation voltage is not insufficient due to the upward adjustment of the driving reference voltage (VpreR).

9 illustrates examples of voltages output from the data driver 130 when low grayscale image data is expressed and when high grayscale image data is expressed in the organic light emitting display device 100 according to the present embodiments. .

Referring to FIG. 9, (c) of FIG. 9 shows an example of a voltage output from the data driver 130 when expressing low grayscale image data, and (d) of FIG. 9 represents high grayscale image data. In this case, an example of the voltage output from the data driver 130 is shown.

As shown in FIG. 9 , the organic light emitting display device 100 according to the present embodiments increases the driving reference voltage VpreR applied when driving the organic light emitting diode (OLED) only when expressing low grayscale image data. In the case of expressing low grayscale image data, it can be seen that the margin for the voltage output from the data driver 130 is not insufficient even if the driving reference voltage VpreR is increased by 0.5V.

Therefore, when expressing low grayscale image data, it is possible to stably express low grayscale image data by reducing the boosting time by increasing the driving reference voltage (VpreR) and mitigating the voltage decrease rate applied to the driving transistor (DRT). let it be

And, in the case of expressing high grayscale image data as shown in (d) of FIG. 9, by outputting a voltage set lower than the driving reference voltage VpreR applied when expressing low grayscale image data, high grayscale image data is expressed. The organic light emitting diode (OLED) may be driven within the maximum output voltage range of the data driver 130 and the margin for the compensation voltage may not be insufficient.

10 illustrates a process of a driving method of the timing controller 140 of the organic light emitting display device 100 according to the present embodiments.

Referring to FIG. 10 , the timing controller 140 of the organic light emitting display device 100 according to the present embodiments receives image data from the outside (S1000) and uses the received image data in the data driver 130. The signal format is converted and the gradation of the image data is checked (S1010).

When the image data received from the outside is low grayscale image data (S1020), the timing controller 140 generates a first reference voltage using the driving reference voltage VpreR applied when the organic light emitting diode (OLED) is driven (S1030). ), and high grayscale image data, a second reference voltage set lower than the first reference voltage is generated as a driving reference voltage (VpreR) (S1040).

The timing controller 140 outputs the image data and the generated reference voltage to the data driver 130 (S1050).

Accordingly, the timing controller 140 outputs low grayscale image data and a first reference voltage or outputs high grayscale image data and a second reference voltage to the data driver 130 .

According to the present embodiments, in the case of expressing low-grayscale image data, the first reference voltage set higher than the second reference voltage is applied as the driving reference voltage VpreR, thereby boosting when the organic light-emitting diode (OLED) is driven. (Boosting) time is reduced to prevent noise and gradation reversal, and to stably express low-gradation image data.

In addition, in the case of expressing high grayscale image data, the second reference voltage that has not been increased is applied as the driving reference voltage VpreR, so that the data driver 130 operates due to the upward adjustment of the driving reference voltage VpreR. Make sure that the voltage required for output does not exceed the maximum output voltage.

Accordingly, according to the present embodiments, the driving reference voltage VpreR is increased only when low gray level image data is expressed, so that the margin for the voltage output from the data driver 130 is not insufficient and the low gray level is not insufficient. It enables stable representation of image data.

The above description is merely illustrative of the technical idea of the present invention, and various modifications and variations will be possible to those skilled in the art without departing from the essential characteristics of the present invention. Since the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to explain, the scope of the technical idea of the present invention is not limited by these embodiments.

100: organic light emitting display device 110: organic light emitting display panel
120: gate driver 130: data driver
140: timing controller 141: image data processor
142: reference voltage generator 143: data output unit

Claims (10)

A plurality of gate lines and a plurality of data lines are disposed to intersect, a plurality of reference voltage lines are disposed in parallel with the data lines, and a plurality of subpixels are disposed in an area where the gate lines and the data lines intersect. Each subpixel of is an organic light emitting diode, a driving transistor connected to the organic light emitting diode and a first node and driving the organic light emitting diode, a sensing transistor electrically connected between the first node of the driving transistor and a reference voltage line, an organic light emitting display panel including a switching transistor electrically connected between the second node of the driving transistor and a data line;
a gate driver driving the plurality of gate lines;
a data driver that drives the plurality of data lines and outputs a data voltage corresponding to the high grayscale image data higher than a data voltage corresponding to the low grayscale image data; and
Controls driving of the gate driver and the data driver, receives image data from the outside, and supplies the received image data to the first node connected to the first electrode of the organic light emitting diode through the reference voltage line according to the gradation of the received image data. Timing controller that sets the reference voltage to be different
An organic light emitting display device comprising a.
delete According to claim 1,
The timing controller,
When the image data is the low grayscale image data, the reference voltage supplied to the reference voltage line is set as a first reference voltage, and when the image data is the high grayscale image data, the reference voltage supplied to the reference voltage line is set as a second reference voltage. set as a reference voltage, wherein the first reference voltage is higher than the second reference voltage.
According to claim 1,
The timing controller,
The organic light emitting display device differently sets the reference voltage supplied to the reference voltage line according to the level of the data voltage representing the gradation of the image data.
According to claim 4,
The timing controller,
When the level of the data voltage is less than or equal to a preset level, the reference voltage supplied to the reference voltage line is set as a first reference voltage, and when the level of the data voltage is higher than the preset level, the reference voltage supplied to the reference voltage line is set. set as a second reference voltage, wherein the first reference voltage is higher than the second reference voltage.
an image data processing unit that receives image data from the outside, processes the received image data, and outputs a reference voltage control signal according to a gray level of the received image data;
a reference voltage generator configured to generate a reference voltage applied to a first node connected to a driving transistor and a first electrode of an organic light emitting diode according to the reference voltage control signal; and
A data output unit outputting the processed image data and the generated reference voltage;
A data voltage supplied to a second node that is a gate node of the driving transistor increases as the gray level of the image data increases.
According to claim 6,
The image data processing unit,
If the received image data is low grayscale image data, a reference voltage control signal is output to instruct generation of a first reference voltage, and if the received image data is high grayscale image data, a reference voltage instructs generation of a second reference voltage. A timing controller that outputs a control signal, wherein the first reference voltage is a voltage set higher than the second reference voltage.
According to claim 7,
The data output unit,
A timing controller configured to output low grayscale image data and the first reference voltage or to output high grayscale image data and the second reference voltage.
Receiving image data from the outside;
processing the received image data;
checking a gray level of the image data and generating a reference voltage applied to a first node connected to a driving transistor and a first electrode of an organic light emitting diode according to the gray level of the image data; and
outputting the processed image data and the generated reference voltage;
The data voltage supplied to the second node, which is the gate node of the driving transistor, increases as the gray level of the image data increases.
According to claim 9,
The step of generating a reference voltage according to the gradation of the image data,
generating a first reference voltage when the image data is low grayscale image data; and
and generating a second reference voltage set lower than the first reference voltage when the image data is high grayscale image data.

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