KR20160083613A - Organic light emitting display device and methdo of driving the same - Google Patents

Abstract

The present invention relates to an organic light emitting display device and a driving method thereof capable of improving a threshold voltage of a driving transistor and sensing performance of electron mobility by changing a sensing parameter of an analog and digital convertor (ADC) in a current sensing method. According to an embodiment of the present invention, the organic light emitting display device includes an organic light emitting diode and a pixel circuit in pixels and outputs a sensing current conducted on the organic light emitting diode of the pixels to the ADC by converting the sensing current into a voltage by using a current-voltage transforming unit. The ADC outputs the voltage inputted by the current-voltage transforming unit to a timing controller by converting the voltage into sensing data. The timing controller generates compensated data to compensate for a data voltage supplied to the pixel circuit based on the inputted sensing data.

Description

TECHNICAL FIELD [0001] The present invention relates to an organic light emitting diode (OLED) display, and a method of driving the OLED display.

The present invention relates to an organic light emitting diode (OLED) display device and a method of driving the same, in which a sensing parameter of an analog digital converter (ADC) is changed in a current sensing scheme to improve a sensing performance of threshold voltage / electron mobility of a driving TFT.

Recently, as the information age has come to the information age, a display field for visually expressing electrical information signals has been rapidly developed. In response to this, a variety of flat display devices having excellent performance such as thinning, light weight, and low power consumption have been developed. Device) is being developed.

Specific examples of such flat panel display devices include a liquid crystal display device (LCD), a plasma display panel (PDP), and an organic light emitting diode (OLED) . Of these flat panel display devices, the organic light emitting display device is a self-luminous device and has a response speed higher than that of other flat panel display devices, and has advantages of high luminous efficiency, luminance and viewing angle, and has been attracting attention as a next generation display device.

1 is a diagram showing an organic light emitting diode (OLED) and a pixel circuit included in a pixel of an OLED display according to a related art. 1 shows an equivalent circuit of one pixel among a plurality of pixels formed on a display panel.

Referring to FIG. 1, a plurality of pixels are arranged in a matrix form in an OLED display. Each pixel is provided with an organic light emitting diode (OLED) and a pixel circuit.

The organic light emitting diode OLED formed in each pixel is electrically connected between the source electrode of the driving TFT DR TFT and the cathode power supply VSS and emits light by the data current I_oled supplied from the driving TFT DR TFT . In this manner, a predetermined image is displayed by controlling the size of the data current I_oled flowing from the driving power source VDD to the organic light emitting diode OLED through the driving TFT (DR TFT) to emit the organic light emitting diode OLED .

The threshold voltage Vth / electron mobility of the driving TFT (DR TFT), the scan TFT (SC TFT) and the sensing TFT (SE TFT) included in the pixel circuit due to the unevenness of the manufacturing process of the TFT (thin film transistor) ) Characteristics can be formed differently for each pixel. Accordingly, even if the same data voltage (Vdata) is applied to the driving TFT (DR TFT) of each pixel, the current flowing in the organic light emitting diode (OLED) is varied, and uniform image quality can not be realized.

In addition, a degradation phenomenon in which the threshold voltage / electron mobility characteristics are changed as the driving time passes in the driving TFT (DR TFT) can be conceived. As the driving time of the driving TFT (DR TFT) elapses, the deterioration becomes worse. Even if the same data voltage (Vdata) is applied, the current flowing through the organic light emitting diode (OLED) gradually decreases to lower the light emission luminance.

In order to solve these problems, the threshold voltage and the electron mobility of the driving TFT (DR TFT) of each pixel are sensed, and the threshold voltage and electron mobility of the driving TFT (DR TFT) A compensation method is proposed.

2 is a view showing a method of sensing a threshold voltage and an electron mobility of a driving TFT of an OLED display according to a related art.

2 shows a method of sensing the threshold voltage and electron mobility of a driving TFT (DR TFT) by a voltage sensing method.

2, the threshold voltage / electron mobility characteristic of the driving TFT (DR TFT) is sensed by a voltage sensing method so that the same current flows in the driving TFT (DR TFT) of all the pixels. At this time, the on / off timing of the scan TFT (SC TFT) of the pixel circuit is adjusted to sense data for estimating the threshold voltage and electron mobility of the driving TFT (DR TFT). Generates compensation data based on the sensed data, and supplies a data voltage reflecting compensation data in the driving mode for displaying an image to each pixel.

Since the organic light emitting diode OLED emits light according to the magnitude of the applied current, an error occurs in the current value estimated by sensing the voltage and the current value actually applied to the organic light emitting diode OLED.

In particular, as the gradation is lowered, the magnitude of the voltage-current becomes smaller, which results in a large influence of the sensing error. In the case of the high gradation and the low gradation, the uniformity after compensation is lowered.

There is a problem that a characteristic of a driving TFT (DR TFT) changes and an afterimage remains on a screen when the organic light emitting display is driven for a long time, and a real time compensation method is applied after the product is shipped to compensate for a change in characteristics of the driving TFT You must.

The voltage sensing method has a disadvantage in that the sensing time is lengthened because sensing is performed in the sensing period of the driving TFT (DR TFT). Thus, there is a problem in that the real-time compensation can not be applied and a change in the characteristics of the driving TFT of all the pixels is sensed at the time when the power of the organic light emitting display device is turned on or off.

The background art described above can not be a known art that has been held by the inventor of the present application for the derivation of the present invention or acquired as a result of the derivation process of the present invention, .

An object of the present invention is to provide an organic light emitting display device and a method of driving the same that can sense a change in characteristics of a driving TFT at a high speed by applying a current sensing method.

The present invention provides an organic light emitting diode (OLED) display device and a method of driving the same, which can improve a sensing performance of a threshold voltage / electron mobility of a driving TFT by changing a sensing parameter of an analog digital converter (ADC) .

Other features and advantages of the invention will be set forth in the description which follows, or may be obvious to those skilled in the art from the description and the claims.

According to an aspect of the present invention, there is provided an organic light emitting display device including an organic light emitting diode and a pixel circuit arranged in a plurality of pixels, Converts the sensed current into a voltage and outputs it to the analog-to-digital converter. The analog-to-digital converter converts the voltage value input from the current-to-voltage converter into sensing data and outputs it to the timing controller. The timing controller generates compensation data so that a data voltage supplied to the pixel circuit is compensated based on the sensing data inputted.

According to an exemplary embodiment of the present invention, there is provided a method of driving an organic light emitting diode display, including the steps of: determining whether an error occurs in a first sensing data and a second sensing data; do. Then, the sensing condition of the sensing data in which the error occurs in the first sensing data and the second sensing data is changed, and the sensing is performed on the line-by-line basis in the area where the error occurred. Then, based on the result of re-sensing Correct the compensation data of the area where the error occurred.

The organic light emitting display device and the driving method thereof according to the present invention can detect a change in characteristics of a driving TFT at a high speed by applying a current sensing method.

The organic light emitting display device and the driving method of the present invention can improve the sensing performance of the threshold voltage / electron mobility of the driving TFT by changing the sensing parameter of the analog digital converter (ADC) in the current sensing method.

In addition, other features and advantages of the present invention may be newly understood through embodiments of the present invention.

1 is a diagram showing an organic light emitting diode (OLED) and a pixel circuit included in a pixel of an OLED display according to a related art.
2 is a view showing a method of sensing a threshold voltage and an electron mobility of a driving TFT of an OLED display according to a related art.
3 is a view schematically showing an organic light emitting display according to an embodiment of the present invention.
FIG. 4 is a diagram showing an organic light emitting diode (OLED) and a pixel circuit and a data driver included in a pixel of an organic light emitting display according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating a current-voltage converting unit of an OLED display according to an exemplary embodiment of the present invention. Referring to FIG.
6 is a waveform diagram of a scan signal supplied to the pixel in the sensing mode and a first switch signal, a second switch signal, and a reference voltage supplied to the current-voltage converter.
7 to 9 are views illustrating a method of driving an OLED display according to an exemplary embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to 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.

It should be noted that, in the specification of the present invention, the same reference numerals as in the drawings denote the same elements, but they are numbered as much as possible even if they are shown in different drawings.

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 the temporal relationship is described by 'after', 'after', 'after', 'before', etc., May not be continuous unless they are not used.

It should be understood that the term "single or double" includes all possible combinations from one or more related items. For example, the meaning of 'at least one of the first item, the second item and the third item' means not only the first item, the second item or the third item, but also the second item, the second item and the third item, Means any combination of items that can be presented from more than one.

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 organic light emitting diode display and the driving method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 schematically illustrates an organic light emitting diode display according to an embodiment of the present invention. FIG. 4 illustrates an organic light emitting diode (OLED) , And a data driver. 4 illustrates one pixel among a plurality of pixels formed in the OLED panel 100. In FIG.

Referring to FIGS. 3 and 4, an organic light emitting display according to an exemplary embodiment of the present invention includes an OLED panel 100 and a driving circuit. The driving circuit unit includes a gate driver 200, a data driver 300, and a timing controller 400.

A plurality of gate lines GL, a plurality of data lines DL, a plurality of driving power supply lines PL, and a plurality of sensing lines SL are arranged in the OLED panel 100. A plurality of pixels P are defined by the lines GL, DL, PL and SL.

Each of the plurality of pixels P may be composed of any one of a red pixel, a green pixel, and a blue pixel. One unit pixel for displaying one image may be composed of a red pixel, a green pixel, and a blue pixel. In addition, one unit pixel may be composed of a red pixel, a green pixel, a blue pixel, and a white pixel. A plurality of pixels P of the organic light emitting diode display according to the exemplary embodiment of the present invention emits light in a top emission or bottom emission manner to display an image.

The timing controller 400 generates a data control signal DCS and a gate control signal GCS for controlling the gate driver 200 and the data driver 300 based on the timing signal TS input from the external system . The gate control signal GCS generated in the timing controller 400 is supplied to the gate driver 200 and the data control signal DCS is supplied to the data driver 300. [

Here, the timing signal TS may be a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable DE, a clock DCLK, or the like. The gate control signal GCS includes a gate start signal and a plurality of clock signals. The data control signal DCS includes a data start signal, a data shift signal, and a data output signal.

The timing controller 400 controls the gate driver 200 and the data driver 300 in a display mode To be driven in the sensing mode.

The timing controller 400 operates the gate driver 200 and the data driver 300 in a display mode. And controls the gate driver 200 to generate a scan signal for displaying an image. Then, the analog image data is converted into digital image data on a frame basis and supplied to the data driver 300. At this time, the timing controller 400 generates compensation data so that the data voltage supplied to the pixel circuit is compensated based on the sensing data input from the ADC 320 of the data driver 300. The compensation data is reflected in the digital image data supplied from the timing controller 400 to the data driver 300.

The DAC 310 of the data driver 300 converts the digital data into an analog voltage and controls the analog voltage to be supplied to each pixel.

The timing controller 400 operates the gate driver 200 and the data driver 300 in the sensing mode. And controls the gate driver 200 to generate a scan signal for sensing. At this time, the threshold voltage and the electron mobility characteristic of the driving TFT (DR TFT) of each pixel in the current sensing manner through the ADC 320 and the current-to-voltage converter 330 of the data driver 300 .

Here, the sensing mode can be applied in real time while displaying the image and the time when the power of the organic light emitting display device is turned on, the power is turned off, and the like.

The gate driver 200 operates in the display mode and the sensing mode according to the mode control of the timing controller 400. [

In the display mode, the gate driver 200 generates a scan signal having a gate-on voltage level for each one horizontal period according to the gate control signal GCS supplied from the timing controller 400. And sequentially supplies a scan signal (scan) to the plurality of gate lines GL. The scan signal scan has a gate-on voltage level during the data charging period of each pixel P and has a gate-off voltage level during the light emission period of each pixel P.

In the sensing mode, the gate driver 200 generates a scan signal of a gate-on voltage level and sequentially supplies a scan signal (scan) to the plurality of gate lines GL. In this way, a scan signal is supplied to the gate line GL so that the threshold voltage and the electron mobility of the driving TFT of a plurality of pixels connected to each gate line GL are sensed.

The gate driver 200 may be formed in the form of an integrated circuit (IC) or may be internalized in a GIP (gate in panel) manner on an array substrate of the OLED panel 100 together with a transistor formation process of each pixel P .

In the display mode, the data driver 300 generates an analog data voltage Vdata according to digital image data and supplies the analog data voltage Vdata to a plurality of data lines DL. The organic light emitting diode OLED formed in each pixel is emitted with a luminance corresponding to the data voltage Vdata. At this time, the data voltage Vdata may be supplied with a negative polarity (-) or a positive polarity (+).

The organic light emitting diode OLED may include an anode electrode, a hole transporting layer, an organic light emitting layer, an electron transporting layer, and a cathode electrode . In the organic light emitting diode (OLED), when a voltage is applied to the anode electrode and the cathode electrode, holes and electrons move to the organic light emitting layer through the hole transporting layer and the electron transporting layer, respectively. The anode electrode of the organic light emitting diode (OLED) is connected to the source electrode of the driving TFT (DR TFT), and the cathode electrode can be connected to the low potential voltage terminal to which the low potential voltage (VSS) is supplied.

In the sensing mode, the data driver 300 uses a current sensing method using the ADC 320 and the current-voltage conversion unit 330 to drive the driving TFTs (DR TFT) of all the pixels or some pixels of the OLED panel 100, And the threshold voltage and the electron mobility characteristic of the transistor. Then, the sensing value is converted into digital sensing data, and the sensing data is supplied to the timing controller 400. The timing controller 400 generates the compensation data based on the received sensing data.

An organic light emitting diode (OLED) and a pixel circuit are arranged in a plurality of pixels (P). The pixel circuit of each pixel P is composed of three TFTs and one storage capacitor Cst. That is, the pixel circuit is composed of 3Tr-1Ccp). The three TFTs of the pixel circuit are composed of a scan TFT (SC TFT), a driving TFT (DR TFT), and a sensing TFT (SE TFT). A data line DL, a driving power supply line PL and a sensing line SL are arranged in the vertical direction in each pixel, and the gate line GL is arranged in the horizontal direction.

The scan TFT (SC TFT), the driving TFT (DR TFT) and the sensing TFT (SE TFT) may be an a-Si TFT, a poly-Si TFT, an oxide TFT, an organic TFT or the like as an N-type TFT. However, the present invention is not limited to this, and the TFTs ST1, ST2, and DT may be formed of a P-type TFT.

A plurality of gate lines GL are arranged in a first direction (for example, a horizontal direction) in the OLED panel 100 and the data lines DL, the driving power supply lines PL and the sensing lines SL Are arranged in two directions (e.g., longitudinal direction).

The gate electrode of the scan TFT (SC TFT) is connected to the gate line GL, the drain electrode thereof is connected to the data line DL, and the source electrode thereof is connected to the first node N1 . The scan TFT (SC TFT) is turned on in accordance with the scan signal of the gate-on voltage level supplied to the gate line GL to supply the data voltage supplied from the data line DL to the driving TFT DR TFT To the first node N1 to which the gate electrode of the first transistor N1 is connected.

The storage capacitor Cst is connected between the gate electrode and the source electrode of the driving TFT (DR TFT). The storage capacitor Cst stores the difference voltage Vg-Vs between the gate voltage Vg and the source voltage Vs of the TFT (DR TFT).

The gate electrode of the sensing TFT (SE TFT) is connected to the gate line GL and the source electrode thereof is connected to the second node N3 connected to the source electrode of the driving TFT (DR TFT) and the anode electrode of the organic light emitting diode (OLED) And the drain electrode is connected to the third node N3 connected to the sensing line SL.

In the sensing mode, the scan TFT (SC TFT) is turned on by the scan signal of the gate-on voltage level supplied to the gate line DL to supply the data voltage supplied from the data line DL to the gate of the driving TFT To the electrode. The driving TFT DR TFT is turned on by the data voltage Vdata so that the current I_oled flows to the anode electrode of the organic light emitting diode OLED.

In the sensing mode, the sensing TFT (SE TFT) is turned on by the scan signal of the gate-on voltage level supplied to the gate line DL to supply the current flowing from the driving TFT (DR TFT) to the organic light- Voltage conversion unit 330. [ That is, in the sensing mode, the sensing TFT (SE TFT) supplies a current (I_oled flowing to the organic light emitting diode OLED) output from the source electrode of the driving TFT (DR TFT) And flows to the sensing line SL.

A driving TFT (DR TFT) is disposed between the driving power supply line (PL) and the organic light emitting diode (OLED). The driving TFT (DR TFT) controls the current I_oled flowing from the driving power supply (VDD) terminal to the organic light emitting diode (OLED) according to the voltage difference between the gate electrode and the source electrode. The gate electrode of the driving TFT (DR TFT) is connected to the drain electrode of the scan TFT (SC TFT), the source electrode is connected to the anode electrode of the organic light emitting diode OLED, and the drain electrode is supplied with the driving power supply VDD And may be connected to the driving power supply line PL.

The organic light emitting display according to the exemplary embodiment of the present invention includes a scan signal supplied to the pixel P and a waveform of a switch signal supplied to the current-voltage converter 330 when the display mode (or the drive mode) Can be different.

FIG. 5 is a diagram illustrating a current-voltage conversion unit of an organic light emitting diode display according to an exemplary embodiment of the present invention. FIG. 6 illustrates a scan signal supplied to a pixel during a sensing mode, A second switch signal, and a reference voltage. Hereinafter, the operation of the pixel P in the sensing mode and the operation in the current-voltage converter 330 will be described with reference to FIGS. 5 and 6. FIG.

The data driver 300 includes a DAC (not shown), an ADC 320, and a current-voltage converter 330.

The current-to-voltage conversion unit 330 receives the first to third switch signals SS1, SS2, and SS3 from the timing controller 400 and receives the reference voltage Vref. At this time, the reference voltage Vref is supplied as a DC voltage.

The first to third switches SW1, SW2 and SW3 of the current-voltage converter 330 are switched according to the first to third switch signals SS1, SS2 and SS3. The reference voltage Vref is supplied to the non-inverting terminal (+) of the operational amplifier AMP of the current-voltage converter 330.

In the sensing mode, one frame period may be divided into first to third periods T1, T2, and T3.

The first period T1 is a period for supplying the first sensing data voltage to the gate electrode of the driving TFT (DR TFT) and initializing the source electrode to the reference voltage Vref.

The second period T is a period for converting the current of the driving TFT (DR TFT) flowing from the pixel P to the sensing line SL into a voltage in accordance with the voltage difference between the gate voltage and the source voltage of the driving TFT (DR TFT) to be.

The third period T3 is a period for converting the voltage Vsen of the sensing node Ns into digital data.

The gate driver 200 supplies a gate-on voltage scan signal to the gate line GL during the first period T1 to the third period T3.

The data driver 300 applies a first sensing data voltage Vdd to the data line during the first period T1 and the second period T2 to supply the data voltage to the pixel P connected to the Nth gate line GL. Can be supplied.

The timing controller 400 supplies the first switch signal SS1 to the first switch SW1 of the current-voltage converter 330 during the first period T1 to the second period T2.

In addition, the timing controller 400 supplies the second switch signal SS2 to the second switch SW2 during the first period T1.

The timing controller 400 supplies the third switch signal SS3 to the third switch SW3 during the sampling period in the third period T3.

The current-to-voltage conversion unit 330 converts the current flowing from the pixel P to the sensing line SL into a voltage and outputs the voltage to the ADC 320. [

To this end, the current-to-voltage converter 330 includes a sensing block 332 and an output block 334. The sensing block 332 includes an operational amplifier AMP, a feedback capacitor C _FB , and a first switch SW1. The output block 334 includes a second switch SW2, a third switch SW3, and a storage capacitor Cs.

The operational amplifier AMP disposed in the sensing block 332 includes an inverting terminal (-), a non-inverting terminal (+), and an output terminal. The inverting terminal (-) is connected to the sensing line SL and the non-inverting terminal (+) is connected to the reference voltage line to which the reference voltage Vref is supplied. The output terminal of the operational amplifier AMP is connected to the second switch SW2.

The reference voltage Vref can be supplied to the non-inverting terminal (+) with the DC voltage as the initializing voltage.

The first switch SW1 is a switch for initializing the integration of the current, and is connected in parallel to the inverting terminal (-) and the output terminal of the conjunctive amplifier AMP.

The first switch signal SS1 supplied from the timing controller 400 is supplied to the first switch SW1 and the first switch SW1 is turned on by the first switch signal SS1. When the first switch SW1 is turned on, the inverting terminal (-) of the operational amplifier AMP is connected to the output terminal.

The feedback capacitor C _FB is connected in parallel to the inverting terminal (-) and the output terminal of the operational amplifier AMP. The feedback capacitor C _FB can be initialized to OV (zero voltage) since the inverting terminal (-) and the output terminal of the operational amplifier AMP are short-circuited when the first switch SW1 is turned on have. Further, the feedback capacitor C _FB is activated by charging the current input through the sensing line SL in the pixel P when the first switch SW1 is turned off and the second switch SW2 is turned on And changes the voltage output to the output terminal of the amplifier AMP.

The second switch signal SS2 supplied from the timing controller 400 is supplied to the second switch SW2 and the second switch SW2 is turned on by the second switch signal SS2. When the second switch SW2 is turned on, the output of the operational amplifier AMP is stored in the storage capacitor Cs.

The storage capacitor Cs is connected between the sensing node Ns and the ground voltage source GND. The storage capacitor Cs stores the voltage output from the operational amplifier AMP and the voltage of the sensing point when the first switch SW1 is turned off and the second switch SW2 is turned on.

The third switch signal SS3 supplied from the timing controller 400 is supplied to the third switch SW3 and the third switch SW3 is turned on by the third switch signal SS3. And connects the storage capacitor Cs to the ADC 320 when the third switch SW3 is turned on.

The voltage stored in the storage capacitor Cs is input to the ADC 320 when the second switch SW2 is turned off and the third switch SW3 is turned on.

The ADC 320 converts the input voltage value into digital sensing data and outputs the sensing data to the timing controller 400.

The voltage sensing method applied in the prior art has a disadvantage that the sensing time is long, and the present invention proposes a current sensing method. The current sensing method of the present invention is advantageous in that the sensing time is shortened because the current flowing to the organic light emitting diode (OLED) is sensed through the current-to-voltage converter 330, thereby eliminating the charging time of the capacitor.

There may occur a case where the measurement range of the ADC 320 of the data driver 300 is exceeded when the current sensing method is applied. Hereinafter, when the measurement range of the ADC 320 is exceeded, the sensing parameter of the ADC 320 is changed A method of sensing the threshold voltage / electron mobility of the driving TFT will be described.

7 to 9 are views illustrating a method of driving an OLED display according to an exemplary embodiment of the present invention.

7 to 9, a driving method of an OLED display according to an exemplary embodiment of the present invention uses a multi-point sensing method to improve sensing accuracy.

The two sensing data are generated by sensing all pixels of one frame under two different sensing conditions (S1). As shown in Fig. 8 (a), the first sensing data (sensing data 1) is generated by sensing all the pixels of one frame under the first sensing condition. Then, the second sensing data (sensing data 2) is generated by sensing all the pixels of one frame under the second sensing condition.

Here, all the pixels of one frame are all pixels constituting an image driven by one frame, and the characteristics of the driving TFTs arranged in all the pixels arranged in the OLED panel in one frame period are sensed.

Next, one-frame compensation data association is performed using the generated first sensing data and second sensing data (S2).

Then, the first sensing data and the second sensing data are checked to see if there is an area where an overrange or an underrange has occurred (step S23). As shown in FIG. 8B, if an overrange or an underrange occurs If there is an area, the information of the line where the error occurred and the information of the area where the error occurred are stored. In this case, the area where the error occurred may be one pixel or a plurality of pixels.

In this case, a sensing error occurs because the sensing value exceeds the measurement range of the ADC and the sensing value of the underrange is small and the sensing range of the ADC does not generate the sensing data.

Subsequently, the sensing parameter is changed to re-sense the line where the error occurred (S4). In the multi-point method, if one of two sensing data errors occurs, normal sensing data can not be used. Therefore, the sensing data in which an error occurs should be corrected by re-sensing.

When an error occurs only in the first sensing data among the first sensing data and the second sensing data, the second sensing data is left as it is and the sensing parameter of the first sensing data in which an error occurs is changed. At this time, as shown in Fig. 8 (c), Vdata remains unchanged and at least one value among the sensing time, the reference voltage (Evref) of the ADC and the capacitance of the feedback capacitor C _FB of the current- Can be changed. In FIG. 8 (c), the sensing time, the reference voltage (EVref) of the ADC, and the capacitance of the feedback capacitor (C _FB ) are all changed.

 Subsequently, after changing the sensing parameters, as shown in FIG. 9A, re-sensing is performed by applying the changed parameters only to the line where the error occurred (S5).

Next, the compensation data association is performed on a line-by-line basis as shown in Fig. 9 (b) by using the sensing data obtained by re-sensing (S6).

Then, the compensation data of the line where the error occurs and the re-sensing is performed is corrected. At this time, instead of correcting the compensation data of all the pixels of the re-sensed line, as shown in Fig. 9C, the compensation data of the specific pixel in which the error occurred is corrected (S7). In FIG. 9 (c), compensation data of a pixel in which an overrange has occurred is shown as being modified. However, the compensation data may be modified for a pixel in which an underrange has occurred.

Subsequently, final compensation data for all the pixels of one frame is generated including correction values of compensation data of pixels in which an error occurs (S8).

As described above, after confirming the position of an area where an over-range or an under-range error occurs in a plurality of sensing data sensed based on an initial sensing condition, the sensing parameter is changed to re- The compensation data of the pixel can be modified. Through the application of the current sensing method, the sensing speed can be increased and the sensing performance of the threshold voltage / electron mobility of the driving TFT can be improved. In other words, it compensates for the problem that the sensing range of the ADC deviates from the current sensing method, so that sensing accuracy can be improved while sensing changes in the characteristics of the driving TFT at high speed.

It will be understood by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: organic light emitting display
100: OLED panel
200: gate driver
300: data driver
310: DAC
320: ADC
330: current-voltage conversion unit
400: timing controller

Claims (7)

A plurality of pixels including an organic light emitting diode and a pixel circuit;
A current-voltage conversion unit converting a sensing current flowing to the organic light emitting diodes of the plurality of pixels into a voltage and outputting the voltage;
An analog-to-digital converter for converting the voltage value input from the current-voltage converter into sensing data and outputting the sensed data; And
And a timing controller for generating compensation data based on the sensing data so that a data voltage supplied to the pixel circuit is compensated. The method according to claim 1,
Wherein the current-
An operational amplifier to which the sensing current is input to the inverting terminal, a reference voltage is input to the non-inverting terminal, and an output terminal is connected to the node to which the analog digital converter is connected;
A feedback capacitor connected in parallel to the inverting terminal and the output terminal; And
And a first switch which is turned on by the first switch signal to connect the inverting terminal and the output terminal. 3. The method of claim 2,
A second switch that is turned on by a second switch signal to control the output of the operational amplifier;
A storage capacitor for storing a voltage output from the operational amplifier; And
And a third switch that is turned on by the second switch signal to control supply of the voltage stored in the storage capacitor to the analog digital converter. Sensing the characteristics of the driving TFT of all the pixels in one frame period by applying first and second sensing conditions, and generating first sensing data and second sensing data;
Checking whether there is an area where an error occurs in the first sensing data and the second sensing data, and storing information of an area where an error occurred;
Changing a sensing condition of sensing data in which an error occurs in the first sensing data and the second sensing data, and performing re-sensing on a line-by-line basis in an error occurrence area; And
And correcting compensation data of a region where an error occurs based on the result of the re-sensing. 5. The method of claim 4,
Wherein the sensing condition includes a sensing time, a reference voltage of the analog-digital converter, and a capacitance of a feedback capacitor of the current-voltage conversion unit. 6. The method of claim 5,
Wherein the at least one of the sensing time, the reference voltage of the analog digital converter, and the capacitance of the feedback capacitor is changed to re-sense the line of the error occurrence area. The method according to claim 6,
Wherein the compensating data calculated from the first sensing data and the second sensing data is reflected in compensation data of the area where the error occurred, thereby generating final compensation data.

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