KR20170081106A - Organic light emitting display panel, organic light emitting display device, and the method for driving the organic light emitting display device - Google Patents

Abstract

The present embodiment is characterized in that threshold voltage first compensation value for the driving transistor and threshold voltage sensing during the previous threshold voltage sensing during the next threshold voltage sensing before stopping when the threshold voltage sensing is stopped during the threshold voltage sensing of the driving transistor of the subpixels And accumulating and storing a threshold voltage second compensation value for a driving transistor from a subpixel at a stopped position in the memory as a new threshold voltage compensation value, and a driving method thereof.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display panel, an organic light emitting display device, and a method of driving the same. BACKGROUND ART [0002]

The present embodiments relate to an organic light emitting display panel, an organic light emitting display, and a driving method thereof.

2. Description of the Related Art Recently, an organic light emitting diode (OLED) display device that has been spotlighted as a display device has a high response speed, a high contrast ratio, a high luminous efficiency, a high luminance and a wide viewing angle by using an organic light emitting diode (OLED) There are advantages.

Each of the sub-pixels disposed in the organic light emitting display panel of the organic light emitting diode display device basically includes an organic light emitting diode and a driving transistor for driving the organic light emitting diode.

In such an organic light emitting display, the brightness of the organic light emitting diode is adjusted by the driving current of the driving transistor determined based on the data voltage output from the data driver, thereby displaying an image.

On the other hand, the driving transistors in each sub-pixel on the organic light emitting display panel have intrinsic characteristics such as a threshold voltage. In such a driving transistor, as the driving time increases, the degradation proceeds and the threshold voltage changes.

Such deterioration of the driving transistor causes a threshold voltage deviation between the driving transistors in each subpixel, causing a luminance deviation between the subpixels, which may degrade the image quality.

Thus, a technique for compensating for luminance deviation between subpixels, that is, a technique for compensating for a threshold voltage deviation between driving transistors has been proposed.

However, in order to compensate the threshold voltage deviation of the driving transistor, the voltage of the source node or the gate node of the driving transistor is made to be in a state in which the threshold voltage can be sensed, and a sensing process of sensing the voltage of the source node or the drain node of the driving transistor Is required.

However, since the threshold voltage sensing is interrupted during the threshold voltage sensing for compensating the threshold voltage deviation for various reasons, the OLED display device can not use the already-sensed threshold voltage compensation value, resulting in image quality deterioration.

It is an object of the present embodiments to provide an organic light emitting display device and a method of driving the same that can appropriately compensate a subpixel threshold voltage.

Another object of the present invention is to provide an organic light emitting display device and a method of driving the same that can prevent image quality deterioration due to stop of threshold voltage sensing.

One embodiment includes an organic light emitting display panel in which a plurality of data lines and a plurality of gate lines are arranged and in which two or more subpixels including respective organic light emitting diodes and driving transistors are disposed, a data driver connected to the organic light emitting display panel, A memory for storing a compensation value of a threshold voltage for the driving transistor of all the subpixels of the light emitting display panel, a sensing unit for sensing a threshold voltage of the driving transistor, and a threshold voltage compensating process based on the threshold voltage compensation value stored in the memory And an organic light emitting diode (OLED) display device including the compensator.

In this organic light emitting display, the compensating unit compensates for the threshold voltage first compensation value for the driving transistor until the threshold voltage sensing is stopped during the threshold voltage sensing of the driving transistor of the subpixels, and the previous threshold voltage sensing for the next threshold voltage sensing. The second threshold voltage compensation value for the driving transistor from the subpixel at the position where the threshold voltage sensing is stopped can be accumulated and stored in the memory as a new threshold voltage compensation value.

Another embodiment provides a method of driving an organic light emitting display in which two or more subpixels each including an organic light emitting diode and a driving transistor for driving the organic light emitting diode are arranged.

A method of driving an organic light emitting display includes sensing a threshold voltage of a driving transistor of a subpixel and controlling a threshold value of a driving transistor of the subpixel until the threshold voltage sensing is stopped during a threshold voltage sensing of the driving transistor. Storing a first voltage compensation value in a memory as a new threshold voltage compensation value; sensing a threshold voltage of the driving transistor of the subpixels from a subpixel at a position where threshold voltage sensing is stopped during previous threshold voltage sensing, Accumulating the threshold voltage second compensation value in a memory and storing the threshold voltage compensation value as a new threshold voltage compensation value, and performing a threshold voltage compensation process based on the threshold voltage compensation value stored in the memory.

According to the embodiments described above, it is possible to provide an organic light emitting display device and a driving method thereof that can appropriately compensate a subpixel threshold voltage.

According to the embodiments, it is possible to provide an organic light emitting display device and a method of driving the same that can prevent image quality deterioration due to stop of threshold voltage sensing.

1 is a schematic system configuration diagram of an organic light emitting display according to the present embodiments.
2 is a view illustrating a sub-pixel circuit of an OLED display according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating a subpixel compensation circuit of the OLED display according to the present embodiments. Referring to FIG.
4 is a view for explaining a principle of threshold voltage sensing for a driving transistor of an organic light emitting diode display according to embodiments of the present invention.
5 is a timing chart of threshold voltage sensing of a driving transistor in a sub-pixel of the OLED display according to the present embodiments.
6 is a flowchart of a general threshold voltage sensing and compensation process.
FIG. 7 is a flowchart illustrating a threshold voltage sensing and compensation process when the threshold voltage sensing is interrupted by the power forced off during threshold voltage sensing in FIG.
FIG. 8 illustrates a time sequence for the threshold voltage sensing and compensation process when the threshold voltage sensing is interrupted by the power forced off during threshold voltage sensing in FIG.
9 is a configuration diagram of an organic light emitting display according to an embodiment.
FIG. 10 illustrates a time sequence for threshold voltage sensing and compensation in an organic light emitting display according to an exemplary embodiment. Referring to FIG.
11 is a flowchart of a method of driving an OLED display according to another embodiment of the present invention.
12 is a flowchart of a method of driving an OLED display according to another embodiment of the present invention.
FIG. 13 is a flowchart of a step of correcting N threshold voltage compensation values to compensate for a deviation of threshold voltage compensation values of subpixels according to the difference of the threshold voltage sensing time of FIG.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In the drawings, like reference numerals are used to denote like elements throughout the drawings, even if they are shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the components from other components, and the terms do not limit the nature, order, order, or number of the components. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; intervening "or that each component may be" connected, "" coupled, "or " connected" through other components.

FIG. 1 is a schematic system configuration diagram of an organic light emitting diode display 100 according to the present embodiments.

1, the OLED display 100 according to the present embodiment includes a plurality of data lines DL1 to DLm and a plurality of gate lines GL1 to GLn, A data driver 120 connected to the upper or lower end of the display panel 110 and driving a plurality of data lines DL1 to DLm; A timing controller 140 for controlling the data driver 120 and the gate driver 130, and the like.

Referring to FIG. 1, a plurality of subpixels SP are arranged in a matrix type on a display panel 110. Accordingly, a plurality of sub pixel lines exist in the display panel 110, and the sub pixel lines may be sub pixel rows or sub pixel columns. In the following, subpixel rows are described as subpixel lines.

The data driver 120 drives the plurality of data lines DL1 to DLm by supplying data voltages to the plurality of data lines DL1 to DLm. Here, the data driver 120 is also referred to as a source driver.

The gate driver 130 sequentially drives the plurality of gate lines GL1 to GLn by sequentially supplying scan signals to the plurality of gate lines GL1 to GLn. Here, the gate driver 130 is also referred to as a scan driver.

The timing controller 140 supplies various control signals to the data driver 120 and the gate driver 130 to control the data driver 120 and the gate driver 130.

The timing controller 140 starts scanning according to the timing implemented in each frame and switches the input image data inputted from the outside according to the data signal format used by the data driver 120 to output the converted image data Data ), And controls the data driving at a proper time according to the scan.

The gate driver 130 sequentially supplies a scan signal of an On voltage or an Off voltage to the plurality of gate lines GL1 to GLn in accordance with the control of the timing controller 140, (GL1 to GLn) sequentially.

When the specific gate line is opened, the data driver 120 converts the image data Data received from the timing controller 140 into analog data voltages Vdata and supplies them to the plurality of data lines DL1 to DLm , And drives the plurality of data lines DL1 to DLm.

The data driver 120 may include a logic portion including a shift register, a latch circuit, etc., a digital analog converter (DAC), an output buffer, and the like, (310 in FIG. 4) for sensing the characteristics of the subpixel in order to compensate for, for example, the threshold voltage and the mobility of the driving transistor, the threshold voltage of the organic light emitting diode, and the luminance of the subpixel) .

On the other hand, the timing controller 140 includes a vertical synchronizing signal Vsync, a horizontal synchronizing signal Hsync, an input data enable (DE) signal, a clock signal CLK, and the like And receives various timing signals from the outside (e.g., the host system).

The timing controller 140 may switch the input video data input from the outside in accordance with the data signal format used by the data driver 120 and output the converted video data Data, In order to control the driver 130, a timing signal such as a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, an input DE signal, and a clock signal is received to generate various control signals, And outputs it to the driver 130.

The organic light emitting diode display 100 according to the present embodiment is an organic light emitting display device in which each sub pixel SP includes an organic light emitting diode (OLED) And a transistor (DRT: Driving Transistor).

The types and the number of the circuit elements constituting each subpixel SP can be variously determined depending on the providing function, the design method, and the like.

On the other hand, in the organic light emitting diode display 100, circuit elements such as the organic light emitting diode OLED and the driving transistor DRT are deteriorated as the driving time of each subpixel SP becomes longer, Inherent characteristic values (e.g., threshold voltage, mobility, etc.) of the circuit elements such as the diode OLED and the driving transistor DRT are changed.

The degree of change in the characteristic value between the circuit elements may be different due to the difference in degree of deterioration between the circuit elements.

Due to such characteristic deviations of the circuit elements, a luminance deviation may occur between the sub-pixels SP. Accordingly, the luminance uniformity of the display panel 110 is deteriorated, and the image quality may be deteriorated.

Accordingly, the organic light emitting diode display 100 according to the present embodiments can provide a "pixel compensation function" for compensating a characteristic value deviation of a circuit element between subpixels SP.

In the organic light emitting diode display 100 according to the present embodiments, each subpixel SP has a structure capable of sensing the subpixel characteristic value and compensating for the subpixel characteristic value deviation.

In addition, the OLED display 100 according to the exemplary embodiments of the present invention includes a sensing configuration for sensing a sub-pixel characteristic value to provide a sub-pixel compensation function, a sensing configuration for sensing a characteristic value deviation between sub- To compensate for < / RTI >

Here, the subpixel characteristic value may include, for example, a characteristic value such as a threshold voltage of the organic light emitting diode OLED, a threshold voltage of the driving transistor DRT, a characteristic value such as mobility, and the like. In the following, the threshold voltage and the mobility of the driving transistor DRT are exemplified as the sub-pixel characteristic values.

2 is a diagram illustrating a sub-pixel circuit of the OLED display 100 according to the present embodiments.

The exemplary subpixel in FIG. 2 is any subpixel supplied with the data voltage (Vdata) from the i-th data line (DLi, 1? I? M) and can compensate for the subpixel property value sensing and subpixel property value deviation compensation. .

Referring to FIG. 2, each sub-pixel of the OLED display 100 according to the present embodiment includes an organic light emitting diode (OLED) and a driving circuit for driving the organic light emitting diode OLED.

The driving circuit may include a driving transistor DRT, a switching transistor SWT, a sensing transistor SENT, and a storage capacitor Cst.

The driving transistor DRT drives the organic light emitting diode OLED by supplying a driving current to the organic light emitting diode OLED. The driving transistor DRT may be connected between the organic light emitting diode OLED and the driving voltage line DVL for supplying the driving voltage EVDD. The driving transistor DRT has a first node N1 corresponding to a source node or a drain node, a second node N2 corresponding to a gate node, and a third node N3 corresponding to a drain node or a source node .

The switching transistor SWT is connected between the data line DLi and the second node N2 of the driving transistor DRT and is turned on by receiving the scan signal SCAN to the gate node. The switching transistor SWT is turned on by the scan signal SCAN to transfer the data voltage Vdata supplied from the data line DLi to the second node N2 of the driving transistor DRT.

The sensing transistor SENT is connected between a first node N1 of the driving transistor DRT and a reference voltage line RVL for supplying a reference voltage VREF and supplies a sensing signal SENSE ) And is turned on. The sensing transistor SENT is turned on by the sensing signal SENSE to apply the reference voltage VREF supplied through the reference voltage line RVL to the first node N1 of the driving transistor DRT. This sensing transistor SENT can also serve as a sensing path so that the sensing configuration can sense the voltage of the first node N1 of the driving transistor DRT.

The scan signal SCAN and the sense signal SENSE may be respectively applied to the gate node of the switching transistor SWT and the gate node of the sensing transistor SENT through another gate line.

In some cases, the scan signal SCAN and the sense signal SENSE may be the same signal and may be respectively applied to the gate node of the switching transistor SWT and the gate node of the sensing transistor SENT through the same gate line.

3 is a diagram illustrating a subpixel compensation circuit of the OLED display 100 according to the present embodiments.

3, the OLED display 100 includes a sensing unit 310 for sensing a sub-pixel characteristic value, a memory 320 for storing a sensing result of the sensing unit 310, And a compensation unit 330 for compensating the deviation of the subpixel characteristic value.

Here, as an example, the sensing unit 310 may be included in the source driver integrated circuit, and the compensating unit 330 may be included in the timing controller 140.

The organic light emitting diode display 100 according to the present exemplary embodiment is configured to control the driving of the driving transistor DRT within the subpixel SP by controlling the voltage application state of the first node N1 in the subpixel SP, And may further include a switch SW for controlling the state necessary for sensing.

One end Nc of the reference voltage line RVL may be connected to the reference voltage supply node Na or the node Nb of the sensing unit 310 through the switch SW.

Referring to FIG. 3, the reference voltage line RVL is basically a line for supplying the reference voltage VREF to the first node N1 of the driving transistor DRT through the sensing transistor SENT.

Meanwhile, a line capacitor Cline is formed in the reference voltage line RVL. The sensing unit 310 senses a voltage charged in the line capacitor Cline on the reference voltage line RVL at a necessary time. Therefore, in the following, the reference voltage line RVL is also referred to as a sensing line.

The reference voltage lines RVL may be arranged, for example, one for each sub-pixel column, or one for each of two or more sub-pixel columns.

For example, if one pixel is composed of four subpixels (red subpixel, white subpixel, green subpixel, and blue subpixel), one pixel may be arranged for each one pixel column.

The sensing unit 310 includes a sensing line electrically connected to a first node N1 of a driving transistor DRT in a sub-pixel on a sensing sub-pixel line (SSPL) in which sensing driving is performed among a plurality of sub- RVL), and outputs a sensing value, thereby performing the sensing process.

The sensing unit 310 can sense the voltage charged in the line capacitor Cline on the sensing line RVL by the current flowing to the sensing line RVL.

Here, the voltage charged in the line capacitor Cline is the voltage of the sensing line RVL, and the first node N1 of the driving transistor DRT, which reflects the characteristic value (threshold voltage, mobility) ).

The voltage of the first node N1 of the driving transistor DRT is stored in the line capacitor Cline and the sensing unit 310 changes the voltage of the first node N1 of the driving transistor DRT directly Sensing the charging voltage of the line capacitor Cline storing the voltage of the first node N1 of the driving transistor DRT and not sensing the charging voltage of the driving transistor DRT even when the sensing transistor SENT is turned off, DRT) of the first node N1.

Each sub-pixel may be driven for threshold voltage sensing of the driving transistor DRT and for driving the driving transistor DRT.

The sensing value sensed by the sensing unit 310 may be a sensing value for sensing the threshold voltage Vth of the driving transistor DRT or a sensing value for sensing the mobility of the driving transistor DRT. have.

When the subpixel is driven for the threshold voltage sensing of the driving transistor DRT, in accordance with this threshold voltage sensing driving, the first node N1 and the second node N2 of the driving transistor DRT, respectively, The first node N1 of the driving transistor DRT is floated so that the voltage of the first node N1 of the driving transistor DRT becomes equal to the reference voltage VREF The voltage of the first node N1 of the driving transistor DRT becomes saturated.

At this time, the saturated voltage Vdata-Vth of the first node N1 of the driving transistor DRT is charged in the line capacitor Cline on the sensing line RVL.

The sensing unit 310 senses the voltage charged in the line capacitor Cline when the sensing timing (sampling timing) is reached. At this time, the sensed voltage Vsense corresponds to a voltage obtained by subtracting the threshold voltage Vth of the driving transistor DRT from the data voltage Vdata.

The sensing unit 310 senses the voltage Vsense charged in the line capacitor Cline on the sensing line RVL.

The memory 320 may store sensing values of the sensing sub-pixel lines by a predetermined number N of sensing sub-pixel lines.

The predetermined number N of sensing subpixel lines may be equal to the number of all subpixel lines existing in the display panel 110 in accordance with the usable capacity of the memory 320 or the like, It is possible.

The compensation unit 330 can perform property value compensation processing by grasping a characteristic value (e.g., threshold voltage, mobility) of the driving transistor DRT in the corresponding subpixel based on the sensing value stored in the memory 320. [ Here, the characteristic value compensation process may include a threshold voltage compensation process for compensating a threshold voltage of the driving transistor DRT.

The threshold voltage compensation process may include a process of calculating a compensation value for compensating the threshold voltage, storing the calculated compensation value in the memory 320, or changing the corresponding video data Data with the calculated compensation value .

The compensation unit 330 may change the image data Data through the threshold voltage compensation process and supply the changed data to the source driver integrated circuit.

At this time, a digital analog converter (DAC) 300 in the source driver integrated circuit converts the data voltage Vdata corresponding to the analog voltage and supplies the converted data voltage to the corresponding subpixel so that characteristic value compensation (threshold voltage compensation, mobility compensation ) Is actually applied.

Through the compensator 330 described above, the characteristic value of the driving transistor can be compensated to reduce or prevent the luminance deviation between the subpixels.

The principle of sensing the threshold voltage (Vth) of the driving transistor DRT in order to compensate for the threshold voltage deviation between the driving transistors DRT will be briefly described below with reference to FIG.

The sensing unit 310 may be implemented as an analog digital converter (ADC) for converting an analog voltage value into a digital value.

FIG. 4 is a view for explaining the threshold voltage sensing principle of the driving transistor DRT of the OLED display 100 according to the present embodiments. Referring to FIG. However, it is assumed that the first node N1 of the driving transistor DRT is the source node.

4, the threshold voltage sensing principle will be briefly described. The voltage Vs of the source node N1 of the driving transistor DRT follows the voltage Vg of the gate node N2 Source follow operation and the voltage Vs of the source node N1 of the driving transistor DRT after the voltage Vs of the source node N1 of the driving transistor DRT becomes saturated, Is sensed as a sensing voltage (Vsense). At this time, the threshold voltage variation of the driving transistor DRT can be grasped based on the sensed sensing voltage Vsense.

The threshold voltage sensing of the driving transistor DRT is characterized in that the sensing speed is slow because it must wait until the driving transistor DRT is turned off. Therefore, the threshold voltage sensing mode is also referred to as a slow mode (S-Mode).

The voltage Vg applied to the gate node N2 of the driving transistor DRT is the data voltage Vdata supplied from the corresponding source driver IC SDIC.

5 is a timing chart of the threshold voltage sensing of the driving transistor DRT in the sub-pixel of the OLED display 100 according to the present embodiment.

3 and 5, a driving method for threshold voltage sensing of the driving transistor DRT initializes the voltages of the N1 node (gate node) and N2 node (source node or drain node) of the driving transistor DRT A second step STEP 2 of floating the N2 node of the driving transistor DRT to raise the voltage of the N2 node of the driving transistor DRT, (STEP 3) of sensing the saturated voltage of the node N2 of the driving transistor DRT, and the like.

In the first step (STEP 1), the scan signal SCAN is applied to the gate node of the switching transistor SWT, so that the switching transistor SWT is turned on. Further, the sense signal SENSE is applied to the gate node of the sensing transistor SENT, and the sensing transistor SENT is turned on.

In the first step (STEP 1), the data voltage Vdata supplied to the data line DL is applied to the N1 node of the driving transistor DRT through the turned-on switching transistor SWT.

In the first step (STEP 1), the first switch SPRE is turned on, and the reference voltage Vref is supplied to the reference voltage line RVL. The reference voltage Vref supplied to the reference voltage line RVL is applied to the node N2 of the driving transistor DRT through the sensing transistor SENT turned on.

Therefore, in the first step (STEP 1), the N1 node (gate node) of the driving transistor DRT is initialized to the data voltage Vdata and the N2 node (source node or drain node) Is initialized to the voltage Vref.

Accordingly, as shown in FIG. 5, in the first step (STEP 1), the voltage Vsl of the reference voltage line RVL corresponding to the sensing line SL corresponds to the reference voltage Vref.

In the second step STEP 2 after the first step STEP 1, the scan signal SCAN is continuously applied to the gate node of the switching transistor SWT, so that the switching transistor SWT maintains the ON state. Also, the sense signal SENSE is continuously applied to the gate node of the sensing transistor SENT, so that the sensing transistor SENT can be maintained in the ON state.

However, in the second step (STEP 2), the first switch SPRE is turned off and the reference voltage Vref is not supplied to the reference voltage line RVL. Thus, the N2 node of the driving transistor DRT is floated.

As the node N2 of the driving transistor DRT floats, the voltage of the node N2 of the driving transistor DRT begins to rise at the reference voltage Vref.

The voltage rise of the N2 node of the driving transistor DRT is performed until a difference between the data voltage Vdata and the constant voltage Vth is reached.

That is, when the voltage of the N2 node of the driving transistor DRT becomes Vdata-Vth, the voltage of the N2 node of the driving transistor DRT becomes saturated. At this time, the threshold voltage Vth of the driving transistor DRT may be a positive value or a negative value.

In the third stage (STEP 3) that proceeds after the second step (STEP 2), the sense signal SENSE is not applied to the gate node of the sensing transistor SENT. That is, the sensing transistor SENT is off.

In the third step STEP 3, the second switch SAM is turned on, and the reference voltage line RVL corresponding to the sensing line SL is connected to the sensing unit 310.

Therefore, the sensing unit 310 can sense the voltage of the reference voltage line RVL, that is, the voltage of the sensing line SL.

The sensing unit 310 may sense a potential difference (voltage) formed at both ends of the reference voltage line RVL, that is, the sensing line capacitor Csl connected to the sensing line SL.

That the sensing unit 310 senses the voltage of the sensing line SL, that is, sensing the potential difference (voltage) formed at both ends of the sensing line capacitor Csl, means that the N2 node of the driving transistor DRT Quot; sense " of < / RTI >

At this time, the voltage Vsen sensed by the sensing unit 310 is "Vdata-Vth ".

When the sensing unit 310 senses (senses) the sensing voltage Vsen, the data voltage Vdata is a known value, so that the threshold voltage Vth of the driving transistor DRT can be known.

The compensation unit 330 can perform a threshold voltage compensation process by determining the threshold voltage of the driving transistor DRT in the corresponding subpixel based on the threshold voltage sensing value stored in the memory 320. [ The compensation unit 330 may change the image data Data through the threshold voltage compensation process and supply the changed data to the source driver integrated circuit.

According to the driving method for threshold voltage sensing as described above, in order to accurately sense the threshold voltage, when the voltage of the node N2 of the driving transistor DRT is saturated, that is, when the voltage of the reference voltage line A long sensing time may be required since the voltage of the RVL must be saturated.

Nowadays, for high resolution implementation, pixel size is getting smaller. Accordingly, the size of the driving transistor DRT is also decreasing.

The reduction in the size of the driving transistor DRT according to such a high resolution implementation leads to a reduction in the current driving capability of the driving transistor DRT, and the charging time of the sensing line capacitor Csl becomes long. As a result, the sensing time required for sensing the threshold voltage becomes longer.

In consideration of this point, in order to minimize the inconvenience of the user, the threshold voltage sensing may be performed, for example, when a power-off signal is input.

6 is a flowchart of a general threshold voltage sensing and compensation process.

Referring to FIG. 6, when a power off signal is received (S610), threshold voltage sensing is performed on all subpixels or some subpixels disposed on the display panel 110 (S620). When the threshold voltage sensing is completed, the power-off process that was performed when the power-off signal is generated is performed (S630).

When the power-on signal is received (S640), the sensing value of the sensed threshold voltage is reflected in step S620, and an image is displayed on the display panel 110 through the threshold voltage compensating process (S650).

FIG. 7 is a flowchart illustrating a threshold voltage sensing and compensation process when the threshold voltage sensing is interrupted by the power forced off during threshold voltage sensing in FIG. FIG. 8 illustrates a time sequence for the threshold voltage sensing and compensation process when the threshold voltage sensing is interrupted by the power forced off during threshold voltage sensing in FIG.

Referring to FIG. 7, when a power off signal is received (S710), threshold voltage sensing is performed on all subpixels or some subpixels disposed on the display panel 110 (S720).

However, when threshold voltage sensing is performed on all the subpixels in step S720, the threshold voltage sensing time may be at least one minute (in the case of a high-resolution display panel, several ten minutes). Accordingly, the power can be forcibly turned off by the user during the threshold voltage sensing in step S720 (S732). In this case, in step S720, the threshold voltage sensing is not performed on all the subpixels, and the threshold voltage sensing is stopped in step S734.

When the power-on signal is received again (S740), the updated threshold voltage sensing value, which is performed when the threshold voltage sensing is stopped in step S734, is ignored, and the image is displayed on the display panel 110 by reflecting the existing threshold voltage sensing value (S750).

If the threshold voltage sensing is repeated in accordance with the forced power-off, appropriate compensation is not performed on the changed portion of the characteristic value of each subpixel, and image quality degradation may occur.

As shown in FIG. 8, if threshold voltage sensing is not performed for all the subpixels in step S720 and the threshold voltage sensing is stopped, the threshold voltage sensing values for all the subpixels are not stored in the memory 320 The updated threshold voltage sensing value can not be applied in step S750 and the conventional threshold voltage sensing value can not be applied. Accordingly, the update threshold voltage sensing value stored in the memory 320 is deleted, and the existing threshold voltage sensing value previously stored in the memory 320 is maintained. Accordingly, since the threshold voltage compensation process is performed by applying the existing threshold voltage sensing value stored in the memory 320 when the power-on signal is received in step S740, the problem that the characteristic value of each subpixel is not appropriately compensated for , And if this situation continues for a long time, image quality degradation may occur

9 is a configuration diagram of an organic light emitting display according to an embodiment. FIG. 10 illustrates a time sequence for threshold voltage sensing and compensation in an organic light emitting display according to an exemplary embodiment. Referring to FIG.

1 and 9, an OLED display 100 includes a plurality of data lines and a plurality of gate lines, each of which includes at least two sub-pixels including an organic light emitting diode OLED and a driving transistor DRT, A data driver 120 connected to the organic light emitting display panel 110, a threshold voltage compensation value for the driving transistor DRT of all the subpixels of the organic light emitting display panel 110, A sensing unit 310 for sensing a threshold voltage of the driving transistor, and a compensation unit 330 for performing threshold voltage compensation based on a threshold voltage compensation value stored in the memory 320 .

10, when the threshold voltage sensing is stopped during the threshold voltage sensing of the driving transistor DRT of the sub-pixels, the compensating unit 330 compensates the threshold voltage first compensation for the driving transistor DRT, And a threshold voltage second compensation value for the driving transistor DRT from a subpixel at a position where the threshold voltage sensing is stopped during the previous threshold voltage sensing at the next threshold voltage sensing to the memory 320 as a new threshold voltage compensation value 320A. As shown in FIG.

As shown in FIG. 10, when the organic light emitting diode display 100 receives the power off signal, it starts to perform threshold voltage driving and sensing operations. The threshold voltage first compensation value for the driving transistor DRT is set to the new threshold voltage compensation value 320A in the memory 320 until the threshold voltage sensing is stopped during the threshold voltage sensing of the driving transistor DRT of the sub- .

The organic light emitting diode display 100 receives a power-on signal and displays an image normally. When the power-off signal is received, the organic light emitting diode display 100 performs a threshold voltage driving and sensing operation. At the next threshold voltage sensing, the second threshold voltage compensation value for the driving transistor DRT from the subpixel at the position where the threshold voltage sensing is stopped during the previous threshold voltage sensing is set as the new threshold voltage compensation value 320A to the memory 320 Can be accumulated and stored.

At this time, the power supply may be forcibly turned off to stop the threshold voltage sensing. However, the present invention is not limited to this, and the threshold voltage sensing may be stopped due to various causes such as self-failure or operation error of the organic light emitting display device 100. The user of the organic light emitting diode display 100 may be forced to turn off the power, but the organic light emitting diode display 100 is not turned off due to the threshold voltage sensing operation, A terminal for supplying power to the light emitting display device 100 and the like can be separated.

At this time, the memory 320 also stores the previous threshold voltage compensation value 320B. The compensating unit 330 compensates the previous threshold voltage compensation value 320B stored in the memory 320 until the sensing unit 310 senses the threshold voltage of the driving transistor of all the subpixels of the organic light emitting display panel 110. [ The threshold voltage compensation process can be performed. As described above, since the threshold voltage sensing value for all subpixels is not stored in the memory 320, the updated threshold voltage sensing value can not be applied and the conventional threshold voltage sensing value can not be applied.

The threshold voltage first accumulated value accumulated in the memory 320 until the sensing unit 310 senses the threshold voltage of the driving transistor DRT of all the subpixels of the organic light emitting display panel 110 and the second threshold voltage And updates the threshold voltage compensation values N times (N is a natural number greater than 2) including the compensation value to the new threshold voltage compensation value. In other words, the new threshold voltage compensation value 320A including N (N is a natural number greater than 2) threshold voltage compensation values is updated with the threshold voltage compensation value 320B used for performing the threshold voltage compensation process.

For example, as shown in FIG. 10, the memory 320 is divided into at least two first and second storage spaces 320A and 320B, a new threshold voltage compensation value is stored in one first storage space 320A, And store the threshold voltage compensation value used for performing the threshold voltage compensation process in the second storage area 320B. When the threshold voltage compensation values of the driving transistors DRT of all the sub-pixels of the organic light emitting display panel 110 are accumulated in the first storage space 320A with the threshold voltage compensation values of N times (N is a natural number greater than 2) The threshold voltage compensation value stored in the first storage space 320A may be copied into the second storage space 320B and the threshold voltage compensation value used to perform the threshold voltage compensation process may be updated to a new threshold voltage compensation value.

The compensation unit 330 senses the threshold voltage of the driving transistor DRT of all the subpixels of the organic light emitting display panel 110 and then supplies the memory 330 with a threshold voltage based on the updated threshold voltage compensation value 320B. Voltage compensation processing can be performed.

When the sensing unit 310 updates the threshold voltage compensation value 320B stored in the memory 320 with the new threshold voltage compensation value 320A, the threshold voltage compensation value of the subpixels corresponding to the difference in the threshold voltage sensing time To compensate for the deviation, N threshold voltage compensation values are corrected and updated to the new threshold voltage compensation value 320B. For example, as described above, the threshold voltage compensation value stored in the first storage space 320A is copied to the second storage space 320B, and the threshold voltage compensation value used to perform the threshold voltage compensation process is set as a new threshold voltage The threshold voltage compensation value stored in the first storage space 320A is not copied into the second storage space 320B as it is. Instead, the threshold voltage compensation value is corrected according to the brightness level difference compensation performing process described below, And may be stored in the second storage space 320B.

For example, the sensing unit 310 may calculate the average luminance value of the previously stored threshold voltage compensation values 320B, calculate the average luminance value of the N threshold voltage compensation values included in the new threshold voltage compensation value 320A Calculates the average luminance value of the calculated pre-stored threshold voltage compensation values 320B and the average luminance value deviations of the N threshold voltage compensation values, calculates an average value of the calculated average luminance value deviations, And corrects the N threshold voltage compensation values according to the average value of the average luminance value deviations. This will be described later with reference to FIG.

11 is a flowchart of a method of driving an OLED display according to another embodiment of the present invention.

11, in a method of driving an organic light emitting display according to another exemplary embodiment in which two or more subpixels each including an organic light emitting diode and a driving transistor for driving the organic light emitting diode are disposed, (S910), and threshold voltage sensing is performed on all the subpixels or some subpixels disposed in the display device 100 (S920).

In step S920, the power can be forcibly turned off by the user during the threshold voltage sensing (S932). In this case, in step S920, threshold voltage sensing is not performed on all the subpixels, and the threshold voltage sensing is stopped in step S934.

Next, the threshold voltage first compensation value for the driving transistor is stored in the memory 320 as a new threshold voltage compensation value until the threshold voltage sensing is stopped during the threshold voltage sensing of the driving transistor of the subpixels (S936 ).

When the power ON signal is received again (S940), the threshold voltage compensation process is performed based on the previous threshold voltage compensation value stored in the memory 320 until the threshold voltage of the driving transistor of all the subpixels of the OLED display device is sensed (S950).

When a power off signal is received (S960), threshold voltage sensing is performed on all subpixels or some subpixels disposed in the OLED display 100 (S970). When sensing the threshold voltage of the driving transistor of the subpixels in step S970, the threshold voltage of the driving transistor is sensed from the subpixel at the position where the threshold voltage sensing is stopped during the previous threshold voltage sensing in step S934, The second threshold voltage compensation value is accumulated in the memory 320 and stored as a new threshold voltage compensation value (S975).

At this time, when the threshold voltage sensing is stopped during the threshold voltage sensing of the driving transistors of the sub-pixels, the above-described steps S932 to S970 are repeated. In other words, N times (N = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 2) is updated with the new threshold voltage compensation value.

When the power ON signal is received again (S980), the threshold voltage compensation process is performed based on the updated new threshold voltage compensation value in the memory 320 after sensing the threshold voltage of the driving transistor of all the subpixels of the OLED display (S990).

According to the above-described embodiment, although the threshold voltage sensing is repeated according to the forced power-off, the threshold voltage compensation value sensed before the threshold voltage sensing is maximized to improve the image quality as much as possible.

Specifically, when the threshold voltage sensing is interrupted, the compensation values are not deleted until power off. In the threshold voltage sensing operation, threshold voltage sensing is performed from a position where the threshold voltage sensing is not performed with reference to the previous threshold voltage sensing value. Even if the threshold voltage sensing operation is stopped in the middle regardless of the number of threshold voltage sensing operations, the threshold value sensing value of all the subpixels of all the subpixels of the organic light emitting diode display 100, Update the value.

When sensing the threshold voltage of the driving transistor of the next subpixel when the threshold voltage sensing is interrupted, the threshold voltage of the driving transistor is sensed from the subpixel at the position where the threshold voltage sensing is stopped during the previous threshold voltage sensing, And accumulating in the memory 320 for the driving transistor to a new threshold voltage compensation value will be described again.

12 is a flowchart of a method of driving an OLED display according to another embodiment of the present invention.

Referring to FIG. 12, in the driving method of an OLED display according to another embodiment, when a power off signal is received (S1100), a position where threshold voltage sensing is stopped during a previous threshold voltage sensing is checked (S1120) The threshold voltage of the driving transistor is sensed from the subpixel (S1130). At this time, the threshold voltage compensation value for the driving transistor from the subpixel at the position where the threshold voltage sensing is stopped during the previous threshold voltage sensing is accumulated in the memory 320 and is stored as a new threshold voltage compensation value.

Next, it is determined whether the sensing of the threshold voltage of the driving transistor of all the subpixels of the organic light emitting diode display has ended (S1150).

If it is determined in step S1150 that the sensing of the threshold voltage of the driving transistor of all the subpixels of the OLED display has not been completed, the threshold voltage compensation process is performed based on the previous threshold voltage compensation value stored in the memory 320 (S1160 ).

If it is determined in step S1150 that the sensing of the threshold voltage of the driving transistor of all the subpixels of the OLED display is completed, the threshold voltage compensation process is performed based on the updated previous threshold voltage compensation value in the memory 320 (S1180).

In order to compensate the deviation of the threshold voltage compensation values of the subpixels according to the difference of the threshold voltage sensing time when the threshold voltage compensation value stored in the memory 320 is updated to the new threshold voltage compensation value, (Step 1170). ≪ / RTI >

FIG. 13 is a flowchart of a step 1170 of correcting N threshold voltage compensation values to compensate for a deviation of threshold voltage compensation values of subpixels according to the difference of the threshold voltage sensing time of FIG.

The step of correcting N threshold voltage compensation values 1170 calculates an average luminance value of pre-stored threshold voltage compensation values (S1210), and calculates an average luminance of the N threshold voltage compensation values included in the new threshold voltage compensation value (S1220). The average luminance value of the calculated pre-stored threshold voltage compensation values and the average luminance value deviations of the threshold voltage compensation values N times are calculated (S1230), and an average value of the calculated average luminance value deviations is calculated (S1240), and correction of N threshold voltage compensation values is performed in accordance with the average value of the calculated average luminance value deviations (S1250). N th threshold voltage compensation values to update the corrected N threshold voltage compensation values to a new threshold voltage compensation value.

According to the above-described embodiment, when the threshold voltage sensing is interrupted, the threshold voltage compensation value according to the threshold voltage sensing is accumulated without discarding, and finally updated to the new threshold voltage compensation value. It is possible to prevent the deterioration of image quality caused by the interruption.

According to the embodiments, it is possible to provide an organic light emitting display device capable of appropriately compensating a subpixel threshold voltage and a driving method thereof.

According to the embodiments, it is possible to provide an organic light emitting display device and a method of driving the same that can prevent image quality deterioration due to stop of threshold voltage sensing.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. , Separation, substitution, and alteration of the invention will be apparent to those skilled in the art. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: display device 110: display panel
120: Data driver 130: Gate driver
140: timing controller 310: sensing unit
320: memory 330: compensation unit

Claims (12)

An organic light emitting display panel in which a plurality of data lines and a plurality of gate lines are arranged and in which two or more subpixels each including an organic light emitting diode and a driving transistor are arranged;
A data driver coupled to the organic light emitting display panel;
A memory for storing a compensation value of a threshold voltage of the driving transistor of all the subpixels of the organic light emitting display panel;
A sensing unit for sensing a threshold voltage of the driving transistor; And
And a compensation unit for performing a threshold voltage compensation process based on a threshold voltage compensation value stored in the memory,
Wherein the compensation unit compensates for a threshold voltage first compensation value for the driving transistor and a threshold voltage during a next threshold voltage sensing until the threshold voltage sensing is stopped during the threshold voltage sensing of the driving transistor of the subpixels, And accumulating and storing a second threshold voltage compensation value for the driving transistor from a subpixel at a position where sensing is stopped to a new threshold voltage compensation value in the memory. The method according to claim 1,
The power is forcibly turned off and the threshold voltage sensing is stopped. The method according to claim 1,
Wherein the sensing unit senses the threshold voltage of the driving transistor of all the subpixels of the OLED display panel,
Wherein the compensation unit performs a threshold voltage compensation process based on a previous threshold voltage compensation value previously stored in the memory. The method according to claim 1,
Wherein the sensing unit is configured to sense the threshold voltage of the driving transistor of all the subpixels of the organic light emitting display panel in the Nth (including the first threshold voltage compensation value and the second threshold voltage compensation value accumulated in the memory) N is a natural number greater than 2) to a new threshold voltage compensation value,
Wherein the compensation unit performs a threshold voltage compensation process based on an updated new threshold voltage compensation value in the memory after sensing a threshold voltage of a driving transistor of all subpixels of the OLED display panel. 5. The method of claim 4,
Wherein the sensing unit updates the threshold voltage compensation value stored in the memory to the new threshold voltage compensation value to compensate the deviation of the threshold voltage compensation values of the subpixels according to the difference in the threshold voltage sensing time, And corrects the threshold voltage compensation values to update the new threshold voltage compensation value. 6. The method of claim 5,
The sensing unit includes:
Calculating an average luminance value of pre-stored threshold voltage compensation values,
Calculating an average luminance value of the N threshold voltage compensation values included in the new threshold voltage compensation value,
Calculating an average luminance value of the calculated pre-stored threshold voltage compensation values and average luminance value deviations of the N threshold voltage compensation values,
Calculating an average value of the calculated average luminance value deviations,
And compensates the N threshold voltage compensation values according to an average value of the calculated average luminance value deviations. There is provided a method of driving an organic light emitting diode display having two or more subpixels each including an organic light emitting diode and a driving transistor for driving the organic light emitting diode,
Sensing a threshold voltage of the driving transistor of the subpixels; And
Storing a threshold voltage first compensation value for the driving transistor as a new threshold voltage compensation value in a memory until the threshold voltage sensing is stopped during threshold voltage sensing of the driving transistor of the subpixels;
Wherein when the threshold voltage of the driving transistor of the subpixels is sensed, a second threshold voltage compensation value for the driving transistor is accumulated in the memory from a subpixel at a position where the threshold voltage sensing is stopped during previous threshold voltage sensing, Storing as a compensation value; And
And performing a threshold voltage compensation process based on a threshold voltage compensation value stored in the memory. 8. The method of claim 7,
Wherein the power is forcibly turned off to stop the threshold voltage sensing. 8. The method of claim 7,
The threshold voltage compensation process is performed based on the previous threshold voltage compensation value previously stored in the memory until the threshold voltage of the driving transistor of all the subpixels of the OLED display device is sensed A method of driving an organic light emitting display device. 8. The method of claim 7,
(N is 2), which includes the threshold voltage first compensation value accumulated in the memory and the second threshold voltage compensation value until the threshold voltage of the driving transistor of all the subpixels of the organic light emitting display is sensed, Lt; / RTI > to a new threshold voltage compensation value,
In the step of performing the threshold voltage compensation process,
Wherein the threshold voltage compensation process is performed based on an updated new threshold voltage compensation value in the memory after sensing a threshold voltage of a driving transistor of all the subpixels of the organic light emitting diode display. 11. The method of claim 10,
A threshold voltage compensation unit for compensating a deviation of the threshold voltage compensation values of the subpixels according to a difference in a threshold voltage sensing time when the threshold voltage compensation value previously stored in the memory is updated to the new threshold voltage compensation value, Further comprising the step of calibrating the values,
Wherein the step of updating the new threshold voltage compensation value with the new threshold voltage compensation value updates the compensated N threshold voltage compensation values with the new threshold voltage compensation value. 12. The method of claim 11,
Wherein the step of correcting the N threshold voltage compensation values comprises:
Calculating an average luminance value of pre-stored threshold voltage compensation values,
Calculating an average luminance value of the N threshold voltage compensation values included in the new threshold voltage compensation value,
Calculating an average luminance value of the calculated pre-stored threshold voltage compensation values and average luminance value deviations of the N threshold voltage compensation values,
Calculating an average value of the calculated average luminance value deviations,
And compensates the N threshold voltage compensations according to an average value of the calculated average luminance value deviations.

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