KR102281007B1 - Organic Light Emitting Display Device - Google Patents

Abstract

The present invention provides an organic light emitting display device including a display panel, a data driver, a scan driver, and a sensing circuit. The display panel includes sub-pixels that emit light. The data driver supplies a data signal to the display panel. The scan driver supplies a scan signal to the display panel. The sensing circuit unit senses the threshold voltage of the organic light emitting diode included in the sub-pixel and provides compensation data. In order to sense the threshold voltage of the organic light emitting diode, the sensing circuit unit supplies a precharge voltage to the gate electrode of the driving transistor included in the sub-pixel and supplies an initialization voltage to the second electrode connected to the anode electrode of the organic light emitting diode.

Description

Organic Light Emitting Display Device

The present invention relates to an organic light emitting display device.

As information technology develops, the market for display devices, which is a connection medium between users and information, is growing. Accordingly, the use of display devices such as an organic light emitting display (OLED), a liquid crystal display (LCD), and a plasma display panel (PDP) is increasing.

Among the display devices described above, the organic light emitting display device includes a display panel including a plurality of sub-pixels and a driving unit for driving the display panel. The driver includes a scan driver that supplies a scan signal (or scan signal) to the display panel, and a data driver that supplies a data signal to the display panel.

In the organic light emitting display device, when a scan signal and a data signal are supplied to sub-pixels arranged in a matrix form, the selected sub-pixel emits light, so that an image can be displayed.

The organic light emitting display device has various problems such as a decrease in the lifetime or luminance of the device according to the driving time because the characteristics (threshold voltage, current mobility, etc.) of the device included in the sub-pixel change when used for a long time, and improvement is required. .

SUMMARY OF THE INVENTION The present invention for solving the problems of the above-described background art increases the lifespan of a device included in a sub-pixel and improves display quality.

As a means for solving the above problems, the present invention provides an organic light emitting display device including a display panel, a data driver, a scan driver, and a sensing circuit. The display panel includes sub-pixels that emit light. The data driver supplies a data signal to the display panel. The scan driver supplies a scan signal to the display panel. The sensing circuit unit senses the threshold voltage of the organic light emitting diode included in the sub-pixel and provides compensation data. In order to sense the threshold voltage of the organic light emitting diode, the sensing circuit unit supplies a precharge voltage to the gate electrode of the driving transistor included in the sub-pixel and supplies an initialization voltage to the second electrode connected to the anode electrode of the organic light emitting diode.

The sensing circuit unit may sense the threshold voltage of the driving transistor included in the sub-pixel in a section different from the section sensing the threshold voltage of the organic light emitting diode.

The sensing circuit unit may provide compensation data based on the threshold voltage of the organic light emitting diode, the threshold voltage of the driving transistor, or the threshold voltage of the organic light emitting diode and the threshold voltage of the driving transistor.

The sensing circuit unit includes a first sampling unit sensing a threshold voltage of the organic light emitting diode, a second sampling unit sensing a threshold voltage of the driving transistor, a voltage output unit generating and outputting an initialization voltage and a precharge voltage; It may include an AD converter that converts the threshold voltage of the diode and the threshold voltage of the driving transistor from an analog form to a digital form, and a compensation data generator that generates compensation data based on the threshold voltage value supplied from the AD converter.

In the sub-pixel, a capacitor may exist between the gate electrode of the driving transistor and the second electrode serving as the source electrode.

The present invention is effective in providing an organic light emitting display device capable of increasing the lifespan of elements included in sub-pixels and improving display quality.

1 is an exemplary configuration diagram of an organic light emitting display device according to a first embodiment of the present invention;
FIG. 2 is a diagram for explaining a sensing sequence of sub-pixels configured in a display panel according to a first embodiment of the present invention; FIG.
FIG. 3 is an exemplary circuit configuration diagram of the sub-pixel shown in FIG. 1;
4 is a view for explaining a method of sensing a threshold voltage of an organic light emitting diode in a source-following manner;
5 is a block diagram illustrating a sensing circuit unit according to a first embodiment of the present invention.
6 is a waveform diagram for explaining a sensing timing in connection with the sensing circuit shown in FIG. 5;
7 and 8 are graphs of a threshold voltage sensing result of an organic light emitting diode using the organic light emitting display device according to the first embodiment of the present invention.
9 is a simulation waveform diagram illustrating a compensation operation using the organic light emitting display device according to the first embodiment of the present invention.
10 is a block diagram illustrating a data driver including a sensing circuit unit according to a second embodiment of the present invention;

Hereinafter, specific details for carrying out the present invention will be described with reference to the accompanying drawings.

<First embodiment>

1 is an exemplary configuration diagram of an organic light emitting display device according to a first embodiment of the present invention, and FIG. 2 is a diagram for explaining a sensing sequence of sub-pixels configured in a display panel according to the first embodiment of the present invention .

As shown in FIG. 1 , in the organic light emitting display device according to the first embodiment of the present invention, a timing controller 110 , a scan driver 120 , a data driver 130 , a sensing circuit 140 , and a display panel ( 160) is included.

The timing controller 110 uses timing signals such as a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), a data enable signal (DE), and a clock signal (CLK) supplied from the outside to the scan driver ( 120) and the operation timing of the data driver 130 are controlled.

Since the timing controller 110 may determine the frame period by counting the data enable signal DE of one horizontal period, the vertical synchronization signal Vsync and the horizontal synchronization signal Hsync supplied from the outside may be omitted. The control signals generated by the timing controller 110 include a gate timing control signal GDC for controlling the operation timing of the scan driver 120 and a data timing control signal DDC for controlling the operation timing of the data driver 130 . ) is included.

The scan driver 120 sequentially generates scan signals while shifting the level of the gate driving voltage in response to the gate timing control signal GDC supplied from the timing controller 110 .

The scan driver 120 supplies a scan signal through the scan lines SL1 to SLm connected to the sub-pixels SP included in the display panel 160 . The scan driver 120 is formed in the form of an integrated circuit (IC) and mounted on an external substrate or formed in the bezel area of the display panel 160 in the form of a gate in panel through a thin film process.

The data driver 130 samples and latches the data signal DATA supplied from the timing controller 110 in response to the data timing control signal DDC supplied from the timing controller 110 to convert it into parallel data type data. . The data driver 130 converts the data signal DATA in a digital form into an analog form in response to the gamma reference voltage.

The data driver 130 supplies the data signal DATA through the data lines DL1 to DLn connected to the sub-pixels SP included in the display panel 160 . The data driver 130 is formed in the form of an integrated circuit (IC) and mounted on an external substrate or mounted on a bezel area of the display panel 160 .

The display panel 160 includes sub-pixels SP arranged in a matrix form. The sub-pixels SP include the scan signal and data signal supplied from the scan driver 120 and the data driver 130 as well as the first potential voltage line EVDD and the second potential voltage line EVSS. Light is emitted in response to the potential voltage (high voltage) and the second potential voltage (low voltage).

The sub-pixels SP of the display panel 160 include a red sub-pixel, a green sub-pixel, and a blue sub-pixel, or, in some cases, a white sub-pixel. When a white sub-pixel is included, the display panel 160 may emit white light without emitting red, green, and blue light from the light-emitting layer of the sub-pixels SP. In this case, the light emitted in white is converted into red, green, and blue by the RGB color filter. However, the white sub-pixel may emit white light as it is.

The sensing circuit unit 140 measures the threshold voltage of the organic light emitting diode included in the sub-pixel of the display panel 160 and prepares compensation data C_Data capable of compensating the data signal based on the measured value.

The threshold voltage sensing method of the organic light emitting diode by the sensing circuit unit 140 may be formed in various forms. As a first example, the sensing circuit unit 140 may sense (defined as line sensing) a threshold voltage of an organic light emitting diode included in a sub-pixel for each scan line of the display panel 160 . The line sensing method is defined as sensing a threshold voltage of an organic light emitting diode included in a sub-pixel of one line.

As a second example, the sensing circuit unit 140 may block the scan lines of the display panel 160 and sense (defined as block sensing) the threshold voltage of the organic light emitting diode included in the sub-pixel for each block. The block sensing method is defined as sensing a threshold voltage of an organic light emitting diode included in sub-pixels of N (N is an integer greater than or equal to 2) lines.

As a third example, the sensing circuit unit 140 may sense a threshold voltage of an organic light emitting diode included in a sub-pixel for each frame of the display panel 160 (defined as frame sensing). The frame sensing method is defined as sensing threshold voltages of organic light emitting diodes included in all sub-pixels of the display panel 160 .

As a fourth example, the sensing circuit unit 140 randomly selects line sensing, block sensing, and frame sensing in response to various states, conditions, or situations of the display panel 160 and determines the threshold voltage of the organic light emitting diode included in the sub-pixel. It can be sensed (defined as random sensing).

1 and 2 , the sub-pixels SP of the display panel 160 include a red sub-pixel (R), a green sub-pixel (G), a blue sub-pixel (B), and a white sub-pixel (W). ), and one pixel may be formed. The sensing circuit unit 140 may perform line sensing on the sub-pixels SP of the display panel 160 . A specific example of line sensing will be described.

The sensing circuit unit 140 obtains a sensing value corresponding to the threshold voltage of the organic light emitting diode in the order of R->W->G->B sub-pixel SP as shown in FIG. As shown in (b), a sensing value corresponding to the threshold voltage of the organic light emitting diode is obtained in the order of W->R->G->B sub-pixel (SP), or R->G as shown in FIG. 2(c) A sensing value corresponding to the threshold voltage of the organic light emitting diode may be obtained in the order of ->B->W sub-pixel SP.

However, the above order is only an example based on the fact that the display panel 160 is composed of four sub-pixels SP including RGBW, and is not limited thereto. Accordingly, although not shown, in the case of three sub-pixels SP including RGB instead of four sub-pixels SP including RGBW, the threshold voltage of the driving transistor is R->G->B in the order of R->G->B. It is possible to obtain a sensing value corresponding to .

In general, organic light emitting display devices change the characteristics (threshold voltage, current mobility, etc.) of elements (driving transistors or organic light emitting diodes) included in sub-pixels when used for a long period of time. There are various problems. The sensing circuit unit 140 described above is included in the organic light emitting display device to improve this problem, and a description thereof will be provided below.

FIG. 3 is an exemplary circuit configuration diagram of the sub-pixel shown in FIG. 1 , and FIG. 4 is a diagram for explaining a method of sensing a threshold voltage of an organic light emitting diode in a source-following manner.

3 , the sub-pixel according to the first embodiment of the present invention includes a storage capacitor Cst, a switching transistor SW, a driving transistor DT, a compensation transistor ST, and an organic light emitting diode (OLED). is included

A connection relationship and a function between elements included in a sub-pixel will be schematically described as follows.

The switching transistor SW has a gate electrode connected to the first scan line SCAN, a first electrode connected to the data line DL1, and a second electrode connected to the gate electrode of the driving transistor DT. The switching transistor SW serves as a switch between the data line DL1 and the first node Va to which the storage capacitor Cst is connected so that the data voltage is stored in the storage capacitor Cst.

In the driving transistor DT, the gate electrode is connected to the second electrode of the switching transistor SW, the first electrode is connected to the first potential voltage line EVDD, and the second electrode is connected to the anode electrode of the organic light emitting diode (OLED). Connected. The driving transistor DT serves to supply a driving current to the organic light emitting diode OLED.

One end of the storage capacitor Cst is connected to the gate electrode of the driving transistor DT and the other end is connected to the second electrode of the driving transistor DT. The storage capacitor Cst serves to store a data signal as a data voltage.

In the organic light emitting diode OLED, an anode electrode is connected to a second electrode of the driving transistor DT and a cathode electrode is connected to a second potential voltage line EVSS. The organic light emitting diode (OLED) serves to emit light in response to a driving current.

The compensation transistor ST has a gate electrode connected to the second scan line SENSE, an anode electrode of the organic light emitting diode OLED and a first electrode connected to a second electrode of the driving transistor DT, and a reference line REF. The second electrode is connected to The compensation transistor ST serves as a switch between the second node Vx and the third node Vz so that an initialization voltage is supplied to the anode electrode of the organic light emitting diode OLED.

The circuit configuration of the sub-pixel described above is only an example, and the present invention is not limited thereto. For example, at least one of the transistors SW, DT, and ST included in the sub-pixel may be configured as a P-type instead of an N-type. In addition to the illustrated transistors SW, DT, and ST, transistors or capacitors performing other functions may be further included. Meanwhile, in the above description, the source electrode and the drain electrode of the transistor are expressed as the first electrode and the second electrode or the second electrode and the first electrode, which means that the transistors SW, DT, and ST are N-type or P-type. It should be understood that this is because it can be configured.

As shown in FIG. 4 , in the first embodiment of the present invention, the threshold voltage of the organic light emitting diode (OLED) is sensed through the data line (DL1) and data is based on the sensed threshold voltage of the organic light emitting diode (OLED). The signal or the first potential voltage is compensated. To this end, in the first embodiment of the present invention, the driving transistor DT is driven in a source-follower manner to sense the threshold voltage of the organic light emitting diode OLED through the data line DL1.

In the first embodiment of the present invention, before the threshold voltage of the organic light emitting diode (OLED) is sensed, the compensation transistor ST is turned on and then an initialization voltage is supplied through the reference line REF. Then, since the parasitic voltage remaining at the anode node of the organic light emitting diode OLED is removed, it is possible to sense the threshold voltage changed in response to the deterioration state of the organic light emitting diode OLED (Sensing OLED Vth).

Thereafter, the switching transistor SW is turned on to sense the threshold voltage of the organic light emitting diode OLED through the data line DL1, and the first potential voltage of the driving transistor DT corresponds to the precharge voltage at the gate electrode. data signal is supplied.

By this process, a boosting effect occurs in the storage capacitor Cst that is charged to a voltage value reflecting the threshold voltage OLED Vth of the organic light emitting diode OLED (refer to the left graph of FIG. 4, A is the OLED It means the voltage fluctuation range according to the degree of deterioration, so it should be understood as indicating an arbitrary voltage range).

As a result of the experiment, the voltage values charged in the first to third nodes Va, Vx, and Vz are different, but the voltage values charged in the storage capacitor Cst are also different from the second node Vx or the third node Vz. It was found to be sufficient to infer a voltage value similar to the threshold voltage of the sensed organic light emitting diode (OLED).

As described above, in the first embodiment of the present invention, the threshold voltage of the organic light emitting diode OLED can be sensed through the data line DL1. To this end, the driving transistor DT included in the sub-pixel is used as a source-follower method. It should be capable of driving, and a capacitor should exist between the gate electrode of the driving transistor DT and the second electrode serving as the source electrode. Only when the driving transistor DT and the storage capacitor Cst included in the sub-pixel are configured as above, the threshold voltage of the organic light emitting diode (OLED) and the threshold voltage of the driving transistor DT can be easily sensed under selective conditions. there is.

Therefore, the first embodiment of the present invention has a sub-pixel structure in which the driving transistor DT can be driven in a source-follower manner and a capacitor exists between the gate electrode and the second electrode serving as the source electrode of the driving transistor DT. As applicable to , the circuit configuration and structure of the sub-pixel are not limited to the above description.

Hereinafter, the description of the first embodiment of the present invention based on the sensing circuit unit for sensing the threshold voltage of the organic light emitting diode (OLED) and the sensing timing will be detailed.

5 is a detailed block diagram of the sensing circuit according to the first embodiment of the present invention, FIG. 6 is a waveform diagram for explaining the sensing timing in connection with the sensing circuit shown in FIG. 5, and FIGS. 7 and 8 are The threshold voltage sensing result of the organic light emitting diode using the organic light emitting display device according to the first embodiment of the present invention is a graph, and FIG. 9 is an experiment on the compensation operation using the organic light emitting display device according to the first embodiment of the present invention. This is a simulation waveform diagram.

As shown in FIG. 5 , the sensing circuit unit 140 according to the first embodiment of the present invention may be included in the data driver 130 or some of them may be implemented as a separate circuit (eg, IC) differently from the illustration. can

The sensing circuit unit 140 includes a first sampling unit SAM1 , a second sampling unit SAM2 , a voltage output unit SPRE , an AD conversion unit 139 , and a compensation data generation unit 137 . The first sampling unit SAM1 , the second sampling unit SAM2 , the voltage output unit SPRE , the AD conversion unit 139 , and the compensation data generation unit 137 are generated inside or outside the sensing circuit unit 140 . It operates according to the control signal.

The first sampling unit SAM1 serves to sense the threshold voltage of the organic light emitting diode OLED through the data line DL1 . The first sampling unit SAM1 outputs the precharge voltage through the data line DL1 before the data signal is output through the data line DL1 or the threshold voltage of the organic light emitting diode OLED after the precharge voltage is output. to perform a sensing operation.

The first sampling unit SAM1 senses the threshold voltage of the organic light emitting diode OLED by a sampling method, and then transmits the sensed threshold voltage value of the organic light emitting diode OLED to the second sampling unit SAM2 . Although the first sampling unit SAM1 is illustrated in the form of a simple switch, it is not limited thereto and may be implemented as an active element and a passive element.

The second sampling unit SAM2 serves to selectively supply the threshold voltage value of the organic light emitting diode OLED sensed from the first sampling unit SAM1 to the AD conversion unit 139 . The first sampling unit SAM1 performs a sensing operation throughout all times except for a time when a data signal is output and a time when the organic light emitting diode OLED is emitting light. For this reason, the second sampling unit SAM2 converts the threshold voltage value of the organic light emitting diode (OLED) sensed from the first sampling unit SAM1 only when it corresponds to the compensation time set in the circuit (if necessary) to the AD conversion unit ( 139) is supplied.

In addition, the second sampling unit SAM2 may operate only after sampling of the threshold voltage value of the organic light emitting diode OLED is completed by the first sampling unit SAM1 in order to minimize the influence of noise. The reason is to consider the effect of noise, etc. because the output line output from the voltage output unit SPRE and the input line through which the threshold voltage value of the organic light emitting diode OLED of the first sampling unit SAM1 is transmitted are shared. . However, since this is for alleviating noise, a case in which the first sampling unit SAM1 and the second sampling unit SAM2 operate simultaneously to exchange sampling values will be described below as an example.

In addition, the second sampling unit SAM2 performs a sensing function to sense the threshold voltage of the driving transistor DT. The second sampling unit SAM2 is turned on in synchronization with the compensation transistor ST and senses a threshold voltage value of the driving transistor DT.

The voltage output unit SPRE serves to output _{the initialization voltage generated by the voltage source V PRE} to the reference line REF and the precharge voltage through the data line DL1, respectively. The initialization voltage and the precharge voltage generated by the voltage source V _PRE are generated as a voltage between the first potential voltage and the second potential voltage. The precharge voltage and the initialization voltage may be set to similar or identical voltages.

The reason that the voltage output through the reference line REF and the data line DL1 is divided into the initialization voltage and the precharge voltage is because the role of the voltage is different for each input position.

The voltage output unit SPRE maintains a stopped state when the first sampling unit SAM1 and the second sampling unit SAM2 supply the threshold voltage value of the organic light emitting diode OLED to the AD conversion unit 139 . . That is, the voltage output unit SPRE operates only when outputting the initialization voltage and the pre-charge voltage through the reference line REF and the data line DL1, respectively.

The voltage output unit SPRE outputs a pre-charge voltage and an initialization voltage through the data line DL1 and the reference line REF, respectively, before the data signal is output. Only during this period, the voltage output unit SPRE and the first sampling unit SAM1 operate simultaneously.

The AD converter 139 receives the threshold voltage value of the organic light emitting diode OLED and the threshold voltage value of the driving transistor DT from the second sampling unit SAM2, respectively, and converts the analog voltage value to the digital voltage value. convert to The AD conversion unit 139 transfers the voltage value converted to the digital system to the compensation data generation unit 137 .

The compensation data generating unit 137 receives the threshold voltage value of the digital organic light emitting diode (OLED) and the threshold voltage value of the driving transistor DT from the AD conversion unit 139, respectively, and based on the received compensation data (C_Data) create

The compensation data generator 137 may generate compensation data C_Data based on (1) a threshold voltage value of the organic light emitting diode OLED. Also, the compensation data generator 137 may generate the compensation data C_Data based on (2) a threshold voltage value of the driving transistor DT. Also, the compensation data generator 137 may generate the compensation data C_Data based on (3) the threshold voltage value of the organic light emitting diode OLED and the threshold voltage value of the driving transistor DT.

That is, the compensation data generator 137 generates compensation data C_Data based on one of the threshold voltage value of the organic light emitting diode OLED and the threshold voltage value of the driving transistor DT or compensates by considering both values. Data (C_Data) can be created. In this way, the compensation data generator 137 can generate the compensation data C_Data with one selected from (1) to (3), so when there is a time constraint or when an image needs to be displayed under a specific condition (high-resolution implementation) In response, the reward conditions can be adjusted.

The data controller 135 modulates the data signal based on the compensation data C_Data supplied from the compensation data generator 137 and then generates a compensation data signal. The data controller 135 generates a compensation data signal by modulating the data signal in the form of adding the compensation data C_Data to the currently supplied data signal (or adjusting the gain of the data signal).

The DA converter 132 receives the compensation data signal from the data controller 135 and converts the digital compensation data signal into an analog compensation data signal. The DA converter 132 converts the digital compensation data signal into an analog compensation data signal in response to the gamma reference voltage.

Meanwhile, in the above description, it has been described that the sensing circuit unit 140 is included in the data driver 130 as an example. However, some of the circuits included in the sensing circuit unit 140 (eg, the data control unit 135 ) may be included in the timing control unit 110 .

6 shows a first scan signal Scan supplied to the first scan line, a voltage output signal Spre supplied to the voltage output unit, a second scan signal Sense supplied to the second scan line, and a first sampling unit. The first control signal Sam1 supplied to , the second control signal Sam2 supplied to the second sampling unit, and the precharge voltage Vpre are shown.

The first scan signal Scan maintains a logic high for an N-th time (N is an integer smaller than Ts_1H) of one horizontal period Ts_1H. The voltage output signal Spre, the second scan signal Sense, and the first control signal Sam1 also change to a logic high level in response to a time point (a rising edge) at which the first scan signal Scan changes to a logic high level. Then, before the first scan signal Scan is changed to the logic low, the voltage output signal Spre, the second scan signal Sense, and the first control signal Sam1 are changed to the logic low.

The first control signal Sam1 is changed to a logic low after maintaining the logic high at least twice during the period in which the first scan signal Scan maintains the logic high. The first control signal Sam1 is first toggled from logic low to logic high in response to the rising edge of the first scan signal Scan, and then from logic low to logic high in response to the falling edge of the first scan signal Scan. is toggled second. However, in the drawings, the timing at which the second toggle of the first control signal Sam1 ends and the falling edge of the first scan signal Scan are synchronized as an example, but the present invention is not limited thereto and may be delayed until before or after.

The second control signal Sam2 maintains a logic high once during a period in which the first scan signal Scan maintains a logic high, and then changes to a logic low. The period during which the second control signal Sam2 maintains the logic high may correspond to the second toggle period of the first control signal Sam1 .

As the first scan signal Scan changes to logic high, the switching transistor SW is turned on. As the voltage output signal Spre is changed to logic high, the precharge voltage is transferred to the first sampling unit. As the first control signal Sam1 changes to logic high, the sampling unit operates, the precharge voltage Vpre is transferred to the data line DL1, and the initialization voltage is transferred to the reference line REF.

Thereafter, as the first control signal Sam1 and the second control signal Sam2 change to logic high before the first scan signal Scan is changed to the logic low, the threshold voltage value of the organic light emitting diode OLED becomes the first It is transmitted to the AD conversion unit through the sampling unit and the second sampling unit.

Meanwhile, the second scan signal Sense toggles from logic low to logic high in synchronization with the first control signal Sam1 and the second control signal Sam2 during the period in which the threshold voltage value of the organic light emitting diode OLED is sensed. Then, the threshold voltage value of the organic light emitting diode (OLED) and the threshold voltage value of the driving transistor (DT) are mixed. To avoid this, the threshold voltage value of the driving transistor DT is temporarily sensed only when the display panel is turned off or on.

As described above, since the precharge voltage and the initialization voltage are similar or identical, the voltage supplied to the first node Va, which is the gate electrode of the driving transistor DT, and the second node Vx, which is the source electrode of the driving transistor DT. The voltage supplied to can be simplified to "Vpre".

For this reason, both ends of the gate electrode and the second electrode serving as the source electrode of the driving transistor DT are charged with a similar or the same Vpre voltage. In addition, the voltage Vpre supplied to the first node Va and the second node Vx is gradually discharged during the period in which the threshold voltage value of the organic light emitting diode OLED is sensed, and the threshold voltage of the driving transistor DT is gradually discharged by the voltage Vpre. The voltage is set to Vpre - Vth.

Thereafter, the sensing circuit unit prepares real-time compensation data based on the threshold voltage value of the organic light emitting diode (OLED) or real-time compensation data based on the threshold voltage value of the organic light emitting diode (OLED) and the threshold voltage value of the driving transistor (DT). Compensation operations such as providing

An organic light emitting display device was manufactured using a display panel having sub-pixels as shown in FIG. 7, and an experiment was conducted to examine the effectiveness and effect of the compensation operation based on the first embodiment of the present invention.

In the experiment, the deterioration of OLED I-V over time was modeled by measuring the deterioration of the organic light emitting diode (OLED) in the circuit of FIG. 7 and creating a graph of voltage versus current. Then, the threshold voltage value of the organic light emitting diode (OLED) was sensed as shown in FIG. 8 in the same manner as in the first embodiment of the present invention.

As a result, it was proved that deterioration of the organic light emitting diode (OLED) can be predicted by using a value obtained by sensing and sampling the threshold voltage of the organic light emitting diode (OLED) in the same manner as in the first embodiment of the present invention. In addition, it was concluded that, if the data signal is compensated according to the prediction result, problems such as a decrease in the lifetime or luminance of a device such as an organic light emitting diode (OLED) depending on driving time can be improved.

As shown in FIG. 9 , the sub-pixel according to the first embodiment of the present invention includes an initialization step (①), a data writing step (②), a data retention step (③), a data transfer step (④), and a light emission step ( ⑤) operates in the order of

In the initialization step (①), a precharge voltage is supplied to the gate electrode of the driving transistor included in the sub-pixel in order to sense the threshold voltage of the organic light emitting diode, and the initialization voltage is supplied to the second electrode connected to the anode electrode of the organic light emitting diode. is a step to

The data writing step (②) is a step of supplying a data signal through a data line. The data retention step (③) is a step in which the data signal is charged in the form of a data voltage in the storage capacitor. The data transfer step (④) is a step in which the data voltage stored in the storage capacitor is transferred to the gate electrode of the driving transistor. The light emitting step (5) is a step in which the organic light emitting diode emits light by the driving current generated by the driving transistor.

As can be seen from the waveform of FIG. 9 , the gate electrode DTG (or the first node Va) and the source electrode DTS (or the second node Vx) of the driving transistor are similar or identical by the precharge voltage and the initialization voltage. voltage is formed. Then, it can be seen that boosting occurs due to a change in the source electrode node (or the second node Vx). For this reason, the driving transistor is turned on from the light emitting step (⑤), and the generated driving current is supplied in the direction of the anode electrode of the organic light emitting diode.

Meanwhile, in the above description, it was said that the compensation operation can be performed in real time. However, the compensation method based on the threshold voltage value of the organic light emitting diode may increase the compensation accuracy (accuracy) as the sensing time increases or the number of sampling times increases. Therefore, it is preferable to perform the compensation operation according to the first embodiment of the present invention after the display panel is converted to a non-display state during a time for turning off the display panel.

<Second embodiment>

10 is a block diagram illustrating a data driver including a sensing circuit unit according to a second embodiment of the present invention.

As shown in FIG. 10 , according to the second embodiment of the present invention, the data driving units 130 and 140 including the sensing circuit unit include a red sub-pixel (R), a white sub-pixel (W), and a green sub-pixel (G). and a threshold voltage value of the organic light emitting diode OLED included in the blue sub-pixel B, respectively.

To this end, the OLED sampling units SAM_OLED sets the threshold voltage value of the organic light emitting diode OLED included in the red sub-pixel R, the white sub-pixel W, the green sub-pixel G, and the blue sub-pixel B. are separated to sense each. In addition, the OLED sampling units SAM_OLED operate for different times, and the organic light emitting diodes (R) included in the red sub-pixel (R), the white sub-pixel (W), the green sub-pixel (G), and the blue sub-pixel (B) (B). The threshold voltage values of OLED) are sensed respectively.

On the other hand, a TFT sampling unit SAM_TFT that senses the threshold voltage value of the driving transistor DT included in the red sub-pixel R, the white sub-pixel W, the green sub-pixel G, and the blue sub-pixel B are united into one

As described above, the reason for dividing the OLED sampling units SAM_OLED into a red sub-pixel (R), a white sub-pixel (W), a green sub-pixel (G), and a blue sub-pixel (B) is the light emitting layer of the organic light emitting diode (OLED). This is because the tendency of deterioration is different depending on the materials constituting it.

The AD converter 139 receives the threshold voltage value of the organic light emitting diode (OLED) and the threshold voltage value of the driving transistor DT from the OLED sampling units SAM_OLED and the TFT sampling unit SAM_TFT, respectively, and receives an analog voltage value is converted to a voltage value in digital form. The AD conversion unit 139 transmits the voltage value converted into a digital system to a compensation data generation unit (not shown).

However, the period in which the threshold voltage value of the organic light emitting diode OLED is sensed by the OLED sampling units SAM_OLED is different from the period in which the threshold voltage value of the driving transistor DT is sensed by the TFT sampling unit SAM_TFT. Therefore, the AD converter 139 receives the threshold voltage value of the organic light emitting diode (OLED) and the threshold voltage value of the driving transistor (DT) at different times or in different sections without being simultaneously supplied.

Although not shown, the data driving units 130 and 140 including the sensing circuit unit further include a compensation data generating unit, a data adjusting unit, and a DA converting unit. However, the data controller may be included in the timing controller.

The compensation data generating unit receives the threshold voltage value of the digital organic light emitting diode (OLED) and the threshold voltage value of the driving transistor (DT) from the AD conversion unit 139, respectively, and generates compensation data based thereon.

The data control unit generates a compensation data signal after modulating the data signal based on the compensation data supplied from the compensation data generation unit. The data controller generates a compensation data signal by modulating the data signal in the form of adding compensation data to the currently supplied data signal (or adjusting the gain of the data signal).

The DA converter receives the compensation data signal from the data controller and converts the digital compensation data signal into an analog compensation data signal. The DA converter converts the digital compensation data signal into an analog compensation data signal in response to the gamma reference voltage.

As described above, the present invention provides an organic light emitting display device capable of increasing the lifespan of elements included in sub-pixels and improving display quality by compensating using at least one of the threshold voltage of the organic light emitting diode and the threshold voltage of the driving transistor. has the effect of providing.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical configuration of the present invention can be changed to other specific forms by those skilled in the art to which the present invention pertains without changing the technical spirit or essential features of the present invention. It will be appreciated that this may be practiced. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. In addition, the scope of the present invention is indicated by the claims to be described later rather than the above detailed description. In addition, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

110: timing control unit 130: data driving unit
120: scan driver 160: display panel
140: sensing unit SP: sub-pixel
REF: reference line 139: AD conversion unit
137: compensation data generation unit 135: data control unit
SAM1: first sampling unit SAM2: second sampling unit
SPRE: voltage output

Claims (8)

a display panel including sub-pixels;
a data driver supplying a data signal to the display panel;
a scan driver supplying a scan signal to the display panel; and
a sensing circuit for sensing a threshold voltage of the organic light emitting diode included in the sub-pixel and providing compensation data;
The sensing circuit unit supplies a pre-charge voltage to the gate electrode of the driving transistor included in the sub-pixel to sense the threshold voltage of the organic light emitting diode and supplies an initialization voltage to the anode electrode of the organic light emitting diode;
The sub-pixel includes a capacitor between the gate electrode of the driving transistor and the second electrode serving as the source electrode. According to claim 1,
The sensing circuit unit
and sensing the threshold voltage of the driving transistor included in the sub-pixel in a section different from the section sensing the threshold voltage of the organic light emitting diode. 3. The method of claim 2,
The sensing circuit unit
and providing the compensation data based on a threshold voltage of the organic light emitting diode, a threshold voltage of the driving transistor, or a threshold voltage of the organic light emitting diode and a threshold voltage of the driving transistor. 3. The method of claim 2,
The sensing circuit unit
a first sampling unit sensing a threshold voltage of the organic light emitting diode;
a second sampling unit sensing a threshold voltage of the driving transistor;
a voltage output unit generating and outputting the initialization voltage and the precharge voltage;
an AD converter converting the threshold voltage of the organic light emitting diode and the threshold voltage of the driving transistor from an analog form to a digital form;
and a compensation data generator configured to generate the compensation data based on the threshold voltage value supplied from the AD converter. delete 5. The method of claim 4,
The sensing circuit unit
turning on a compensation transistor included in the sub-pixel, and supplying the initialization voltage through a reference line connected to the compensation transistor;
An organic light emitting display device for turning on a switching transistor included in the sub-pixel and supplying the precharge voltage through a data line connected to the switching transistor. 7. The method of claim 6,
The initialization voltage and the pre-charge voltage are set to the same voltage. 7. The method of claim 6,
The first sampling unit
sensing a threshold voltage of the organic light emitting diode through the data line;
The second sampling unit
An organic light emitting display device for sensing a threshold voltage of the driving transistor through the reference line.

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