KR20170051783A - Organic light emitting display device and the method for driving the same - Google Patents

Abstract

The present invention relates to a method of driving an organic light emitting display. According to the present invention, a plurality of sensing values are obtained in a sensing period, and a sensing value included in a predetermined sensing voltage range is selected and compensated, thereby preventing compensation errors and degradation of screen quality. The organic light emitting display device comprises: a sensing unit for acquiring a plurality of sensing values in sensing driving for sensing a degree of deterioration of the organic light emitting diode; a determination unit for determining whether the sensing values are included within a predetermined sensing voltage range; and a final sensing value determiner for selecting one of the sensing values as a final sensing value according to a result of the determination unit, thereby preventing a compensating error and a deterioration of picture quality which occur when the sensing value overflows the sensing voltage range or has an underflow value.

Description

Technical Field [0001] The present invention relates to an organic light emitting diode (OLED) display device,

The present invention relates to an organic light emitting display and a driving method thereof.

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

Such an organic light emitting display device arranges subpixels including organic light emitting diodes in a matrix form and controls the brightness of subpixels selected by the scan signals according to the gradation of data.

Each of the sub-pixels disposed in the display panel of the organic light emitting display device is basically composed of a driving transistor for driving the organic light emitting diode, a switching transistor for transmitting a data voltage to the gate node of the driving transistor, And a storage capacitor serving as a storage capacitor.

Each of the sub-pixel driving transistors becomes degraded as the driving time becomes longer, and characteristic values such as threshold voltage and mobility can be changed. In addition, since the degree of deterioration may be different for each driving transistor, a characteristic value deviation between driving transistors in each sub-pixel may occur.

Since the deterioration of the organic light emitting diodes in each subpixel also progresses as the driving time increases, the characteristic values such as the threshold voltage may change, and the degree of deterioration between the organic light emitting diodes may be different. Deviations may occur.

As described above, the characteristic value deviation between the subpixels caused by the characteristic value deviation between the driving transistors and the characteristic value deviation between the organic light emitting diodes causes a luminance deviation between the subpixels, which causes a screen abnormal phenomenon such as afterimage of the screen, It is possible to cause non-uniformity.

Thus, a technique for compensating for the deviation of characteristic values between subpixels has been developed. In the compensation method, a sensing value (Vsen) is obtained after sensing the characteristic value of the driving transistor or the organic light emitting diode of the subpixel by sensing driving the organic light emitting display device, and data to be applied to the subpixel based on the sensing value (Vsen) As shown in FIG.

In particular, the voltage range of the sensing value (Vsen) obtained by sensing the characteristic value of the subpixel is fixed to a certain range due to limitation of a source driver integrated circuit (SDIC).

However, if the sensing value obtained by the sensing is not within the sensing voltage range in order to compensate the characteristic value between the driving transistors and compensate the characteristic value due to deterioration of the organic light emitting diode, a compensation error occurs such that data compensation is performed with an incorrect value.

Such a compensation error causes an image phenomenon on the display panel, such as a residual image on the screen, which causes the image quality to deteriorate.

The present invention is characterized in that, by obtaining a plurality of sensing values and selecting and compensating a sensing value within the sensing voltage range out of the obtained sensing values, the sensing value overflows the sensing voltage range or has an underflow value An organic light emitting diode (OLED) display, and a driving method thereof.

According to an aspect of the present invention, there is provided an organic light emitting display including: an organic light emitting diode; a display panel including a plurality of sub pixels each having a driving transistor for driving the organic light emitting diode; A data driver for supplying a data voltage to the display panel; and a timing controller for controlling the gate driver and the data driver. In the sensing operation for sensing the degree of deterioration of the organic light emitting diode, A determination unit for determining whether the plurality of sensing values are included within a predetermined sensing voltage range, and a selection unit for selecting any one of the plurality of sensing values as a final sensing value according to a result of the determination unit, The sensing value is set to the sensing voltage range And (overflow) or it is effective to prevent the error compensation and picture quality deterioration is caused to have a bottom (underflow) value

According to another aspect of the present invention, there is provided a method of driving an organic light emitting display including a display panel including a plurality of subpixels each having an organic light emitting diode and a driving transistor for controlling the organic light emitting diode, A driving method of an organic light emitting display including a driving unit, a data driver for supplying a data voltage to the display panel, and a timing controller for controlling the gate driving unit and the data driving unit, The driving includes: obtaining a plurality of sensing values in a sensing period; comparing and determining whether the obtained sensing values are included in a predetermined sensing voltage range; when the sensing values are all included in a predetermined sensing voltage range If only one of them is included, the final sensing value is selected And a step of compensating data based on the selected final sensing value, thereby preventing a compensating error and a screen quality deterioration occurring when the sensing value overflows or has an underflow value, It is effective.

An organic light emitting display device and a driving method thereof according to the present invention are characterized by obtaining a plurality of sensing values and selecting and compensating a sensing value within a sensing voltage range among the obtained sensing values so that the sensing value exceeds an overflow ) Or an underflow value, thereby preventing a compensating error and a deterioration of the picture quality.

1 is a schematic system configuration diagram of an organic light emitting diode display according to the present invention.
FIG. 2 is a view illustrating a sub-pixel structure of an organic light emitting diode display according to an exemplary embodiment of the present invention. Referring to FIG.
3 is a diagram showing distributions of sensing values of an organic light emitting display device.
4 is a view for explaining a principle of obtaining a normal sensing value according to sensing driving of the organic light emitting display according to the present invention.
5 is a block diagram illustrating a sensing and compensation system in accordance with the present invention.
6 is a diagram showing control signals and voltage waveforms for each section in the sensing operation of the organic light emitting diode display according to the present invention.
7A to 7C are diagrams illustrating sensing driving of the OLED display according to the present invention.
8 is a view showing a state in which a plurality of sensing values are obtained in sensing driving of the organic light emitting display according to the present invention.
FIG. 9 is a view showing a specific embodiment of FIG. 8. FIG.
10 and 11 are graphs showing changes in voltage and current according to the degree of deterioration of the organic light emitting diode.
FIG. 12 is a flow chart showing sensing driving of the organic light emitting diode display according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

In the case where the word 'includes', 'having', 'done', etc. are used in this specification, other parts can be added unless '~ only' is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

In the case of a description of a temporal relationship, for example, if a temporal posterior relationship is described by 'after', 'after', 'after', 'before', etc., 'May not be contiguous unless it is used.

The first, second, etc. are used to describe various components, but these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

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

1, a plurality of data lines DL1 to DLm, m is a natural number of 2 or more) and a plurality of gate lines GL1 to GLn (n is a natural number of 2 or more) A display panel 110 in which a plurality of subpixels are arranged in a matrix type, a data driver 120 driving a plurality of data lines DL1 to DLm, a plurality of gate lines GL1 to GLn, A timing controller 140 for controlling the data driver 120 and the gate driver 130, and the like.

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 in accordance with the timing implemented in each frame, switches the input image data inputted from the outside according to the data signal format used by the data driver 120, and outputs the converted image data And controls the data driving at a suitable time according to the scan.

Under the control of the timing controller 140, the gate driver 130 sequentially supplies the scan signals of the On voltage or the Off voltage to the plurality of gate lines to sequentially drive the plurality of gate lines .

1, the gate driver 130 may be located only on one side of the display panel 110, or may be located on both sides, depending on the case.

In addition, the gate driver 130 may include one or more gate driver integrated circuits (GDICs).

Each of the one or more gate driver ICs included in the gate driver 130 may include a shift register, a level shifter, and the like.

When the specific gate line is opened, the data driver 120 converts the image data received from the timing controller 140 into analog data voltages and supplies the data voltages to the data lines to drive the plurality of data lines.

The data driver 120 may include at least one source driver integrated circuit (SDIC) to drive a plurality of data lines.

Each of the source driver integrated circuits included in the data driver 120 may include a logic unit including a shift register and a latch circuit, a digital analog converter (DAC), an output buffer, and the like. (For example, an analog signal) for sensing the characteristics of the subpixel in order to compensate for the characteristics of the subpixel (e.g., the threshold voltage and the mobility of the driving transistor, the threshold voltage of the organic light emitting diode, A digital-to-analog converter (ADC)).

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 image data input from the outside in accordance with the data signal format used by the data driver 120 and output the converted image data. The data driver 120 and the gate 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 to generate various control signals and supplies the generated control signals to the data driver 120 and the gate driver 130 .

For example, in order to control the gate driver 130, the timing controller 140 generates a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable signal GOE : Gate Output Enable), and the like.

Here, the gate start pulse GSP controls the operation start timing of one or more gate driver section integrated circuits constituting the gate driver 130. [ The gate shift clock GSC is a clock signal commonly input to one or more gate driver integrated circuits, and controls the shift timing of the scan signal (gate pulse). The gate output enable signal GOE specifies the timing information of one or more gate driver integrated circuits.

The timing controller 140 includes a source start pulse SSP, a source sampling clock SSC, a source output enable signal SOE, Output enable (DCS) data control signals.

Here, the source start pulse SSP controls the data sampling start timing of one or more source driver integrated circuits constituting the data driver 120. The source sampling clock SSC is a clock signal for controlling sampling timing of data in each of the source driver integrated circuits. The source output enable signal SOE controls the output timing of the data driver 120.

1, the timing controller 140 is connected to a source printed circuit board to which a source driver integrated circuit is bonded and a connection medium such as a flexible flat cable (FFC) or a flexible printed circuit (FPC) To a control printed circuit board (PCB) connected via a printed circuit board (PCB).

A power controller (not shown) for controlling various voltages or currents to supply or supply various voltages or currents to the display panel 110, the data driver 120, the gate driver 130, . These power controllers are also referred to as power management ICs (PMICs).

Each of the plurality of subpixels arranged in the display panel 110 according to the present invention may be constituted by circuit elements such as an organic light emitting diode (OLED), two or more transistors, and at least one capacitor have.

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

FIG. 2 is a view illustrating a sub-pixel structure of an organic light emitting diode display according to an exemplary embodiment of the present invention. Referring to FIG.

2, each of the sub-pixels SP arranged in the display panel 110 according to the present invention includes an organic light emitting diode (OLED), a driving transistor (DRT), a switching transistor (SWT) , A sensing transistor (SENT), and a storage capacitor (Cst).

2, a sub-pixel structure including three transistors (DRT, SWT, SENT) and one capacitor (Cst) is referred to as a 3T (Capacitor) structure.

Referring to FIG. 2, the organic light emitting diode OLED may include a first electrode (e.g., an anode electrode or a cathode electrode), an organic layer, and a second electrode (e.g., a cathode electrode or an anode electrode).

For example, the first electrode of the organic light emitting diode OLED is connected to the N2 node (e.g., a source node or a drain node) of the driving transistor DRT, and the second electrode of the organic light emitting diode OLED is connected to the ground voltage ) May be applied.

2, the driving transistor DRT is a transistor for driving the organic light emitting diode OLED by supplying a driving current to the organic light emitting diode OLED. The driving transistor DRT is a driving voltage line for supplying the driving voltage EVDD DVL) and the first electrode of the organic light emitting diode (OLED).

The driving transistor DRT includes, for example, an N1 node (first node) corresponding to a gate node, an N2 node (second node) corresponding to a source node or a drain node, And an N3 node (third node).

2, the switching transistor SWT is a transistor for transferring the data voltage Vdata to the N1 node of the driving transistor DRT and supplies the N1 node of the driving transistor DRT and the data voltage Vdata And the data lines DL.

The switching transistor SWT may be turned on by the scan signal SCAN applied to the gate node to transfer the data voltage Vdata to the node N1 corresponding to the gate node of the driving transistor DRT.

Referring to FIG. 2, the storage capacitor Cst is a capacitor that maintains a constant voltage for one frame time, and is electrically connected between the node N1 and the node N2 of the driving transistor DRT.

2, the sensing transistor SENT is a transistor which applies the initialization voltage Vpre to the N2 node of the driving transistor DRT or is involved in the voltage sensing of the N2 node of the driving transistor DRT, And is electrically connected between a node N2 of the transistor DRT and a reference voltage line RVL for supplying the initialization voltage Vpre.

The sensing transistor SENT is turned on by a sense signal SENSE which is a kind of a scan signal applied to the gate node so that the initialization voltage Vpre supplied through the reference voltage line RVL is supplied to the driving transistor DRT, The node N2 of FIG.

2, the gate node of the switching transistor SWT and the gate node of the sensing transistor SENT may be electrically connected to the same gate line. In other words, gate signals SCAN and SENSE can be commonly applied to the gate node of the switching transistor SWT and the gate node of the sensing transistor SENT through one identical gate line. At this time, the scan signal SCAN and the sense signal SENSE are the same gate signal.

Alternatively, the gate node of the switching transistor SWT and the gate node of the sensing transistor SENT may be electrically connected to different gate lines. In this case, each of the scan signal SCAN and the sense signal SENSE may be separately applied to the gate node of the switching transistor SWT and the gate node of the sensing transistor SENT through different gate lines.

On the other hand, as shown in FIG. 2, the reference voltage line RVL can receive the initialization voltage by operating the first switch SW1 according to the switch control signal SPRE.

The reference voltage line RVL may be formed with a line capacitor Cline.

On the other hand, each driving transistor DRT has a characteristic value such as a threshold voltage (Vth) and a mobility. In addition, the driving transistor DRT may be degraded according to the driving time, and the characteristic value may be changed.

For this reason, there may be a difference in degree of deterioration between the driving transistors DRT in each sub-pixel, and there may be a characteristic value deviation between the driving transistors DRT in each sub-pixel.

The characteristic value deviation between the driving transistors DRT in each sub-pixel may cause a luminance deviation between each sub-pixel, which may be a main factor causing image quality degradation.

(For example, a threshold voltage deviation and a mobility deviation) between the driving transistors DRT, as well as a deviation in the characteristic value between the organic light emitting diodes OLED due to the difference in degree of deterioration between the organic light emitting diodes OLED in each sub- E.g., threshold voltage deviation, etc.) may also be present.

The deviation of the characteristic value between the driving transistors DRT and the characteristic value deviation between the organic light emitting diodes OLED described above corresponds to the deviation of the subpixel characteristic value and is a factor that causes a luminance deviation between the subpixels and hinders the uniformity of luminance .

Therefore, in order to improve image quality, it is necessary to compensate for the deviation of sub-pixel characteristic values.

Thus, each subpixel in the display panel 110 according to the present invention has a subpixel structure that can be sensed, as shown in FIG.

2, the organic light emitting diode display 100 according to the present invention has a sensing structure for sensing a characteristic value or a characteristic value deviation of each subpixel, and the second switch SW2 is a sampling control signal And an analog digital converter (ADC) that operates in accordance with the reference voltage line (SAM) and is electrically connected to the reference voltage line (RVL).

The analog-to-digital converter (ADC) senses the voltage of the reference voltage line (RVL), converts sensed sensing value (Vsen: sensing voltage value) into a digital value to generate sensing data, To the timing controller 140.

The analog digital converter ADC senses the voltage of the reference voltage line RVL when the sensing transistor SENT is turned on has the same effect as sensing the voltage of the node N2 of the driving transistor DRT.

Here, the voltage of the node N2 of the driving transistor DRT reflects the characteristic value (e.g., threshold voltage, mobility) of the driving transistor DRT and the characteristic value (e.g., threshold voltage) of the organic light emitting diode OLED Lt; / RTI > In the present invention, an OLED deterioration sensing drive for compensating for a change in a characteristic value due to deterioration of an organic light emitting diode (OLED) will be mainly described.

3 is a diagram showing distributions of sensing values of an organic light emitting display device.

Referring to FIG. 3, the sensing voltage range for sensing the characteristic values of the subpixels of the organic light emitting display device is fixed to a certain range due to the voltage range limitation of the source driver integrated circuit (SDIC). Therefore, when the sensing value Vsen obtained through the sensing drive is within the sensing voltage range, the compensation is performed correctly. However, if the sensing voltage exceeds the sensing voltage range, a compensation error occurs in which data compensation is performed with an incorrect compensation value .

As shown in FIG. 3, the cases where the distribution of the sensing value Vsen exceeds the upper limit value and the lower limit value of the sensing voltage range are referred to as overflow and underflow, respectively. Therefore, when a part of the sensing voltage Vsen distribution area exceeds the upper limit of the sensing voltage range, the sensing value Vsen of the excess range exceeds the sensing voltage range, so that an accurate compensation value corresponding to the sensing value Vsen The compensation error occurs.

Also, when a part of the sensing value (Vsen) distribution region exists below the lower limit value of the sensing voltage range, the sensing value (Vsen) below the lower limit value also can not acquire an accurate compensation value, resulting in a compensation error. If a compensation error occurs due to an overflow or an underflow of the sensing value Vsen, accurate compensation data for the deterioration of the organic light emitting diode can not be obtained, thereby degrading the screen quality.

4 is a view for explaining a principle of obtaining a normal sensing value according to sensing driving of the organic light emitting display according to the present invention.

Referring to FIG. 4, the driving of the organic light emitting display includes a display driving for displaying an image and a sensing driving for sensing a characteristic value of the sub-pixel. As shown in the figure, the sensing value (Vsen: sensing voltage) obtained according to the sensing drive has a linearity that increases in proportion to the time (T) in the sensing period.

The organic light emitting display according to the present invention obtains a sensing value Vsen at least two times in a sensing period and takes a sensing value Vsen included in the sensing voltage range among the sensing values Vsen, Improved compensation error due to overflow or underflow of sensing value (Vsen) and improved screen quality.

4, the first sensing value Vsen1 and the second sensing value Vsen2 are obtained at time t1 and t2 in the sensing period, and the obtained first and second sensing values Vsen1, The second sensing value Vsen2 existing within the sensing voltage range of the sensing voltage Vsen2 is selected and data compensation is performed to prevent the image quality degradation due to the overflow or underflow of the sensing value.

5 is a block diagram illustrating a sensing and compensation system in accordance with the present invention.

Referring to FIG. 5 together with FIG. 1, an OLED display 100 of the present invention includes a sensing and compensation system 500. The sensing and compensation system 100 may be disposed inside or outside the tying controller 140. The sensing and compensation system 500 includes a sensing unit 501 for acquiring a plurality of sensing values Vsen in a sensing step for sensing the degree of deterioration of the organic light emitting diode OLED, A determination unit 502 for determining whether a plurality of sensing values Vsen are included in a predetermined sensing voltage range and a determination unit 502 for selecting one of the plurality of sensing values Vsen according to a result of the determination unit 502. [ A sensing value determination unit 503 and a compensation unit 504 for performing data compensation based on the final sensing value determined by the final sensing value determination unit 503. Therefore, the ADC described with reference to FIG. 2 may be disposed between the final sensing value determiner 503 and the compensator 504.

More specifically, the sensing unit 501 sequentially applies a plurality of sampling control signals SAM in the sensing period to the organic light emitting display 100 according to the present invention, (Vsen). Therefore, in the present invention, sampling for acquiring the sensing value (Vsen) in the sensing period can be performed together.

When the sensing unit 501 acquires a plurality of sensing values Vsen, the determination unit 502 determines whether voltages corresponding to the sensing value Vsen are included in a predetermined sensing voltage range.

For example, when two first sensing values Vsen1 and a second sensing value Vsen2 are obtained, the determining unit 502 determines whether the first sensing value Vsen1 and the second sensing value Vsen2 are preset And determines whether or not it is included in the sensing voltage range.

The final sensing value determiner 503 finally selects one of the first sensing value Vsen1 and the second sensing value Vsen2 based on the information of the determination unit 502. [ At this time, when only one of the first and second sensing values Vsen1 and Vsen2 is included in the sensing voltage range, the sensing value included in the sensing voltage is selected, and if both the first and second sensing values Vsen1 and Vsen2 are sensed (Sensing voltage) among the first and second sensing values Vsen1 and Vsen2 is selected.

When the sensing value is selected in the final sensing value determining unit 503, the compensation value is provided to the compensating unit 504, and data compensation is performed based on the selected final sensing value.

As described above, in the present invention, when two or more sensing values are obtained in the sensing step for sensing the degree of deterioration of the organic light emitting diode, if the sensing value exceeds the sensing voltage range (Overflow) or is obtained as Underflow There is an effect of preventing compensation errors and degradation of the screen that can be caused.

FIG. 6 is a diagram illustrating a control signal and a voltage waveform for each section in the sensing operation of the organic light emitting diode display according to the present invention. FIGS. 7A to 7C illustrate sensing driving of the organic light emitting diode display according to the present invention. to be.

6 through 7C, the degradation sensing driving of the organic light emitting diode (OLED) of the organic light emitting diode display 100 according to the present invention includes an initialization period Tint during initialization, a tracking period Ttrac ), A sensing and sampling interval (Tsen & Tsam) in which a sensing step and a sampling step are performed together.

In the initialization period Tint, the scan signal SCAN, the sense signal SENSE and the switch control signal SPRE are applied at ON level and the sampling control signal SAM is applied at OFF level. As a result, the sensing data voltage Vdata_SEN is applied to the N1 node N1 of the driving transistor DRT and the initialization voltage Vpre is applied to the N2 node N2 of the driving transistor DRT, (RVL) and the sensing transistor (SENT).

In the tracking period Ttrac, only the switch control signal SPRE is applied at ON level, and the scan signal SCAN, the sense signal SENSE, and the sampling control signal SAM are applied in off-level.

As a result, as shown in FIG. 7B, the N1 node N1 and the N2 node N2 of the driving transistor DRT are floated and the current between the N3 node N3 and the N2 node (drain-source node) of the driving transistor DRT (Ids) is applied to the organic light emitting diode (OLED). The potential of the N2 node (N2: source node) is boosted by the drain-source node current Ids of the driving transistor DRT and the N1 node N1 electrically coupled to the source node N2 is also boosted It is boosted. When the potential of the source node N2 becomes higher than the operating point voltage of the organic light emitting diode OLED, the organic light emitting diode OLED is turned on.

When the organic light emitting diode OLED is turned on, the potential of the N2 node N2 varies depending on the degree of deterioration, and the potential of the N1 node N1 also changes according to the degree of deterioration.

In the tracking period Ttrac, the scan signal SCAN may be applied at the same time as the sense signal SENSE at the same time, but the scan signal SCAN may be delayed later than the sense signal SENSE as shown in FIG. Off level.

This has the effect that the degree of deterioration of the organic light emitting diode (OLED) at the initial point of the boosting step is reflected to some extent at the N2 node (source node).

In the sensing and sampling period Tsen & Tsam, the sense signal SENSE is applied at the on level, and the switch control signal SPRE is maintained at the on level for a predetermined period and then inverted to the off level. Then, the scan signal SCAN is applied at an off level.

In particular, in the sensing operation of the organic light emitting display device of the present invention, the sampling control signal SAM is maintained at the OFF level in the sensing and sampling period (Tsen & Tsam), and two ON levels are sequentially applied to the first sensing value Vsen1, And the second sensing value Vsen2.

7C, the voltage VN1N2 between the node N1 and the node N2 of the driving transistor DRT is set according to the degree of deterioration of the organic light emitting diode OLED, The node-to-node current Ids of the driving transistor DRT, which is determined according to the voltage VN1N2, is stored in the line capacitor Cline of the reference voltage line RVL.

Since the N2 node (source node) of the driving transistor DRT is floated after receiving the initialization voltage Vpre again, when the potential of the N2 node N2 becomes low, the coupling of the storage capacitor Cst causes the N1 node The potential is also lowered. At this time, the degree of the potential of the N1 node N1 may be lowered depending on the degree of deterioration of the organic light emitting diode OLED.

In other words, the degree of deterioration of the organic light emitting diode (OLED) is represented by the potential difference of the N1 node N1. The voltage difference of the N1 node N1 causes a voltage difference of VN1N2 of the driving transistor DRT, The current flowing in the reference voltage line RVL is changed.

This current is stored in the line capacitor Cline of the reference voltage line RVL. When the current flowing in the reference voltage line RVL is reduced in proportion to the deterioration, the voltage stored in the line capacitor Cline is also reduced. When the charge gradient of the voltage stored in the line capacitor Cline is large, the current flowing through the reference voltage line RVL is large, which means that the degree of deterioration of the organic light emitting diode OLED is small.

Conversely, if the charge gradient of the voltage stored in the line capacitor Cline is small, the current flowing through the reference voltage line RVL is small, which means that the degree of deterioration of the organic light emitting diode OLED is large.

Referring to FIG. 6, it can be seen that the slope of the voltage charged in the line capacitor Cline of the reference voltage line RVL varies according to the deterioration (solid line) and the deterioration (dotted line). By expanding this, the slope of the charged voltage can be varied according to the degree of deterioration of the organic light emitting diode OLED disposed in each subpixel.

In the present invention, the voltage charged in the sensing and sampling period (Tsen & Tsam), that is, the line capacitor Cline of the reference voltage line RVL, is sequentially sensed twice and the first sensing value Vsen1 and the second sensing value Vsen2 ).

The first sensing value Vsen1 may have a different voltage value before and after the deterioration and the second sensing value Vsen2 may have a different voltage depending on deterioration and deterioration. Accordingly, the first and second sensing values Vsen1 and Vsen2 may all be located in the sensing voltage range according to the voltage gradient charged in the line capacitor Cline, and either of them may be in the overflow or underflow position can do. Therefore, when one sensing value is obtained by one sampling operation, a compensation error occurs if the sensing value obtained is not included in the sensing voltage range.

In the present invention, after obtaining the first sensing value Vsen1 and the second sensing value Vsen2 using the point that the sensing value (sensing voltage) has a linearity that increases with time, the sensing and compensation system The final sensing value is determined according to the process described in the above description to prevent a compensating error and a deterioration in the picture quality that may occur when the sensing value exceeds the sensing voltage range (overflow) or underflows.

8 is a view showing a state in which a plurality of sensing values are obtained in the sensing driving of the organic light emitting display according to the present invention, FIG. 9 is a diagram showing a specific embodiment of FIG. 8, and FIGS. 10 and 11 Are voltage and current changes according to the degree of deterioration of the organic light emitting diode.

Referring to FIGS. 10 and 11 together with FIG. 7C, the organic light emitting diode OLED emits light by the N1 node-N2 inter-node voltage VN1N2 of the driving transistor DRT, The voltage of the node N2 is determined according to the voltage distribution law of the first resistor R1 of the driving transistor DRT and the second resistor R2 of the organic light emitting diode OLED.

When the organic light emitting diode OLED is deteriorated, the second resistance R2 is increased and the voltage of the node N2 of the driving transistor DRT is detected according to the increased second resistance R2. In addition, as shown in Fig. 11, since the current Ids between the N3 node and the N2 node of the driving transistor DRT decreases due to the deterioration, the voltage VN1N2 decreases after deterioration rather than before the deterioration (A- > B).

Therefore, since the magnitude of the voltage stored in the line capacitor Cline of the reference voltage line RVL is charged to a small value according to the degree of deterioration, the sensing and sampling period Tsen & The slope of the voltage charged in the line capacitor Cline varies. For example, the slope of the solid line is the slope of the voltage charged in the line capacitor Cline before the deterioration of the organic light emitting diode OLED, and the slope of the dotted line indicates the charge of the line capacitor Cline after the deterioration of the organic light emitting diode OLED The first sensing value Vsen1 has a different value depending on the degree of deterioration as shown in the figure.

Likewise, the second sensing value Vsen2 has a different value depending on the degree of deterioration of the organic light emitting diode OLED. That is, when the organic light emitting display device performs display driving, the degree of deterioration of the organic light emitting diode (OLED) disposed in each subpixel varies due to a difference (gradation difference) of data voltages supplied to the respective subpixels.

Referring to FIG. 9, there is shown a graph in which slopes of voltage charged in the line capacitor Cline of the reference voltage line RVL are different according to the degree of deterioration of the organic light emitting diode OLED (1, 2, 3, 4).

The voltage slope of (1) is the largest and gradually decreases, and the voltage slope of (4) is the smallest. In Fig. 9, when the sensing voltage ranges from 0.5 [V] to 3.5 [V] and the sensing and sampling intervals Tsen & Tsam are set to 80 [ (Vsen1) and the second sensing value (Vsen2).

When the slope of the voltage charged in the line capacitor Cline of the reference voltage line RVL is equal to 1, only the first sensing value Vsen1 is 3.5 V, which is the upper limit of the sensing voltage range, and the second sensing value Vsen2 ), It can be seen that an overflow occurred at 7 [V]. Therefore, in this case, the first sensing value Vsen1 obtained by sampling at 40 [㎲] is selected as the final sensing value, and the data compensation proceeds.

When the slope of the voltage charged in the line capacitor Cline is equal to 2, both the first sensing value Vsen1 and the second sensing value Vsen2 are within the sensing voltage range. In this case, the first sensing value Vsen1 and And selects a larger value of the second sensing value (Vsen2) as the final sensing value to proceed with data compensation. Accordingly, the second sensing value (Vsen2: 3.5 [V]) obtained by sampling at 80 [mu s] is selected as the final sensing value.

Both the first sensing value Vsen1 obtained by sampling at 40 [mu] s and the second sensing value Vsen2 obtained by sampling at 80 [mu] s are within the sensing voltage range, and the voltage of the sensing value The second sensing value Vsen2 of 80 [mu s] is selected as the final sensing value, and the compensation proceeds.

In the case of (4), the first sensing value Vsen1 obtained by sampling at 40 [mu] s is an underflow located below the lower limit of the sensing voltage range, and the second sensing value Vsen2 obtained by sampling at 80 [ Is 0.5 [V] which is the lower limit of the sensing voltage range. Accordingly, the second sensing value (Vsen2) included in the sensing voltage range is selected as the final sensing value, and data compensation is performed.

As described above, in the present invention, a plurality of sensing values are obtained by using a point where the voltage slope charged in the line capacitor Cline differs according to the degree of deterioration of the organic light emitting diode, and then a sensing value included in the sensing voltage range is selected Thereby preventing a compensating error and a deterioration in picture quality caused by the fact that the sensing value does not fall within the sensing voltage range.

FIG. 12 is a flow chart showing sensing driving of the organic light emitting diode display according to the present invention.

12, in the sensing operation of the organic light emitting display according to the present invention, two sampling signals are applied in a sensing step for sensing the degree of deterioration of the organic light emitting diode (OLED) to generate a first sensing value Vsen1, 2 sensing value Vsen2 (S1101). In this case, the two sampling signals can be supplied by dividing the time of the sensing and sampling interval (Tsen & Tsam) of the present invention into two parts. When a plurality of sampling signals are applied to acquire a plurality of sensing values, So that the sampling signals can be supplied.

As described above, when the first sensing value Vsen1 and the second sensing value Vsen2 are acquired, it is determined whether the first and second sensing values Vsen1 and Vsen2 are included in a predetermined sensing voltage range S1102).

Then, one of the first and second sensing values Vsen1 and Vsen2 is selected and determined as a final sensing value (S1103). At this time, when the first and second sensing values Vsen1 and Vsen2 are all within the sensing voltage range, a sensing value having a larger voltage is selected as the final sensing value. If only one of the first and second sensing values Vsen1 and Vsen2 is included in the sensing voltage range, the sensing value is included as the final sensing value.

When the final sensing value among the sensing values is determined as described above, data compensation is performed based on the final sensing value, and the OLED display is driven (S1104).

As described above, the organic light emitting display device and the driving method thereof according to the present invention are characterized by obtaining a plurality of sensing values and selecting and compensating a sensing value within the sensing voltage range among the obtained sensing values, There is an effect of preventing a compensating error and a deterioration in the picture quality caused by having an overflow or an underflow value.

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: organic light emitting display
110: Display panel
120: Data driver
130: Gate driver
140: Timing controller
500: Sensing and compensation system

Claims (9)

A display panel including a plurality of subpixels each having an organic light emitting diode and a driving transistor for driving the organic light emitting diode;
A gate driver for supplying a scan signal to the display panel;
A data driver for supplying a data voltage to the display panel; And
And a timing controller for controlling the gate driver and the data driver,
A sensing unit for acquiring a plurality of sensing values in sensing driving for sensing a degree of deterioration of the organic light emitting diode;
A determination unit for determining whether the plurality of sensing values are included within a predetermined sensing voltage range,
And a final sensing value determiner for selecting one of the plurality of sensing values as a final sensing value according to a result of the determination unit. The method according to claim 1,
And a compensation unit for performing data compensation based on the final sensing value selected by the final sensing value determination unit. The method according to claim 1,
Wherein the plurality of sensing values are a first sensing value and a second sensing value that are sequentially obtained in a sensing period of the sensing drive. The method of claim 3,
Wherein the final sensing value determiner determines the sensing value included in the sensing voltage range as a final sensing value when the voltages of the first sensing value and the second sensing value are included in a predetermined sensing voltage range, . The method of claim 3,
When the voltages of the first sensing value and the second sensing value are all included in the preset sensing voltage range, the final sensing value determiner determines the final sensing value as the final sensing value The organic light emitting display device comprising: A display panel including a plurality of sub-pixels each having an organic light emitting diode and a driving transistor for controlling the organic light emitting diode, a gate driver for supplying a scan signal to the display panel, data for supplying a data voltage to the display panel, A driving method of an OLED display device including a driving unit, and a timing controller for controlling the gate driving unit and the data driving unit,
In the sensing driving for sensing the degree of deterioration of the organic light emitting diode,
Obtaining a plurality of sensing values in a sensing period;
Comparing and determining whether the obtained sensing values are within a predetermined sensing voltage range;
Selecting a final sensing value when the sensing values are all included in a predetermined sensing voltage range or when only one of them is included; And
And advancing data compensation based on the selected final sensing value. The method according to claim 6,
The step of acquiring a plurality of sensing values in the sensing period includes:
And sequentially obtaining a first sensing value and a second sensing value in the sensing period. 8. The method of claim 7,
And selecting a sensing value as a final sensing value when the first and second sensing values are included in a predetermined sensing voltage range. 8. The method of claim 7,
Wherein the first sensing value and the second sensing value are selected as the final sensing value when the first and second sensing values are included in the predetermined sensing voltage range.

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