KR20160039759A - Organic Light Emitting diode Display and Driving Method thereof - Google Patents

Abstract

The present invention relates to an organic light emitting diode display device including a display panel, a data driving unit, and a timing controller. The display panel includes first to third color pixels and a dummy pixel. The data driving unit converts sensing voltage provided from the first to third color pixels and the dummy pixel into sensing data. The timing controller generates compensation data generated by compensating image data based on a sensing data change amount of each of the first to third color pixels, and provides the compensation data to the data driving unit. The timing controller generates compensation data by using any one of the sensing data change amount of the dummy pixel and the sensing data change amounts of the first to third color pixels as a correction.

Description

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

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

2. Description of the Related Art Flat panel displays (FPDs) are widely used not only for monitors of desktop computers but also for portable computers such as notebook computers and PDAs, as well as mobile phone terminals, because they are advantageous in downsizing and light weight. Such a flat panel display device includes a liquid crystal display (LCD) (LCD), a plasma display panel (PDP), a field emission display (FED) and an organic light emitting diode display (OLED).

Among these organic light emitting diode display devices, the organic light emitting diode display device has a high response speed, high luminance efficiency, and a large viewing angle. In general, an organic light emitting diode display device applies a data voltage to a gate electrode of a driving transistor by using a switching element transistor turned on by a scan signal, and by using the data voltage supplied to the driving transistor, . That is, the current supplied to the organic light emitting diode is controlled by the data voltage applied to the gate electrode of the driving transistor.

The organic light emitting diode is deteriorated by driving, and the light emitting characteristic of the organic light emitting diode is deteriorated by deterioration. Therefore, the organic light emitting diode display device has a problem that the emission characteristics are deteriorated and the display quality is deteriorated over time.

The present invention provides an organic light emitting diode (OLED) display device capable of improving the degradation of light emission characteristics and deterioration of display quality due to deterioration of an organic light emitting diode.

The organic light emitting diode display of the present invention includes a display panel, a data driver, and a timing controller. The display panel includes first to third color pixels and dummy pixels. The data driver converts the sensing voltages supplied from the first to third color pixels and dummy pixels into sensing data. The timing controller generates compensation data that compensates the image data based on the sensing data variation amount of each of the first to third color pixels, and provides compensation data to the data driver. The timing controller generates compensation data by using any one of the sensing data variation of the dummy pixel or the sensing data variation of the first to third color pixels as a correction value.

The organic light emitting diode display according to the present invention can sense the threshold voltage of the organic light emitting diode at predetermined intervals and compensate the degree of deterioration of the organic light emitting diode based on the variation of the threshold voltage. Particularly, the present invention can add a dummy pixel, and use a dummy pixel that is not driven to correct a factor attributable to the panel characteristic at a threshold voltage variation amount of the organic light emitting diode. Accordingly, the present invention can compensate for the deterioration of the organic light emitting diode by precisely calculating the influence of the panel characteristics.

1 is a view showing an organic light emitting diode display device according to the present invention.
Figure 2 shows a pixel array of the present invention.
3 is a diagram showing a pixel structure of the present invention.
4A and 4B are diagrams illustrating a method of sensing a threshold voltage of an organic light emitting diode.
5 is a view for explaining a section for sensing compensation data of the organic light emitting diode according to the present invention.
6 is a flowchart showing a method of generating compensation data of an organic light emitting diode according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

FIG. 1 is a view showing a configuration of an organic light emitting diode display device according to the present invention, and FIG. 2 is a view showing a connection structure of a pixel structure and a data line part of the present invention. The organic light emitting diode display device of the present invention will be described with reference to FIGS. 1 and 2. FIG.

The organic light emitting diode display device according to the present invention includes a display panel 10 in which pixels P are arranged in a matrix form, a data driver 12, a gate driver 13, a timing controller 11, and a memory 16 Respectively.

The display panel 10 includes a plurality of pixels P. The red pixel R, the green pixel G and the blue pixel B constitute a group to display a specific image. A plurality of pixels P are arranged in a matrix form in the display panel 10 by arranging a plurality of pixels on the first to m-th horizontal lines at regular intervals.

The data lines 14 correspond to n (n is a positive integer) pixel columns, and include n data voltage supply lines 14A_1 to 14A_n and n reference voltage lines 14B_1 to 14B_n. The reference voltage lines 14B_1 to 14B_n correspond one-to-one with the pixel column. The data voltage supply lines 14A_1 to 14A_n correspond one-to-one to each of the pixels P as shown in the figure. Alternatively, the data lines may group the red pixel R, the green pixel G1, the blue pixel B, and the dummy pixel G2, which are pixels belonging to one group, to provide the same data voltage. In the display panel 10 of the present invention, since the reference voltage lines 14B_1 to 14B_n correspond to one pixel column on a one-to-one basis, different reference voltages can be provided to each pixel column. Therefore, the present invention can provide a gradation representation by making the reference voltage different and providing the data voltage commonly to one pixel group.

The gate lines 15 include m scan lines 15A_1 to 15A_m and m sense lines 15B_1 to 15B_m corresponding to m (n is a positive integer) horizontal lines HL1 to HLm .

Each of the pixels P is supplied with a high potential driving voltage EVDD and a low potential driving voltage EVSS from a power source not shown. A unit pixel for representing one color includes first to third color pixels and dummy pixels. The first through third color pixels may be a green pixel G1, a red pixel R, and a blue pixel B, respectively. The dummy pixel G2 is a pixel for correcting the threshold voltage change due to the panel characteristics in the process of calculating the threshold voltage change of the organic light emitting diode OLED. The dummy pixel G2 may be formed for each unit pixel composed of three primary color pixels and may be a pixel for displaying any one of the primary colors. Fig. 2 shows an example in which the dummy pixel G2 is formed in green. The dummy pixel G2 can be formed by using a pixel having the smallest change in the lifetime characteristic of the light emitting device due to the manufacturing process variation.

The pixels P arranged in the first column are connected to the first data voltage supply line 14A_1 and the first reference voltage line 14B_1 and the pixels P arranged in the second column are connected to the second data voltage supply line 14A_2 And the second reference voltage line 14B_2. Similarly, the pixels P arranged in the i-th column (i is a natural number of n or less) are connected to the i-th data voltage supply line 14A_i and the i-th reference voltage line 14B_.

The pixels P arranged in the first horizontal line HL1 are connected to the first scan line 15A_1 and the first sense line 15B_1 and the pixels P arranged in the second horizontal line HL2 are connected to the first scan line 15A_1 and the first sense line 15B_1, 2 scan line 15A_2 and the second sense line 15B_2. Similarly, the pixels P arranged in the horizontal line HLj of j (j is a natural number of m or less) connect to the j-th scan line 15A_j and the j-th sense line 15B_j.

The timing controller 11 controls the driving timings of the data driver 12 and the gate driver 13. The timing controller 11 rearranges the digital video data RGB input from the outside according to the resolution of the display panel 10 and supplies the digital video data RGB to the data driver 12. The timing controller 11 controls the operation of the data driver 12 based on the timing signals such as the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, the dot clock signal DCLK and the data enable signal DE A data control signal DDC for controlling the timing and a gate control signal GDC for controlling the operation timing of the gate driver 13. [

The timing controller 11 modulates the digital video data DATA by referring to the digital sensing data supplied from the data driver 12 to generate digital compensation data MDATA. The digital compensation data (MDATA) is for compensating the deterioration of the organic light emitting diode (OLED). The timing controller 11 supplies the generated digital compensation data MDATA to the data driver 12. The timing controller 11 may update the digital sensing data supplied from the data driver 12 periodically to the memory 16. [ In this process, the timing controller 11 controls the first and second switching elements SW1 and SW2 to acquire digital sensing data.

The data driver 12 converts the digital video data RGB input from the timing controller 11 into an analog data voltage based on the data control signal DDC and supplies the analog data voltage to the data lines 14. The data driver 12 also includes an analog-to-digital converter (ADC) 12 for converting the sensing voltage for sensing the threshold voltage Vth of the organic light emitting diode OLED fed back from each pixel P into sensing data SD -Digital-Converter (ADC). The ADC provides the converted sensing data (SD) to the memory (16). The data driver 12 supplies a predetermined data voltage to the pixels P and drives the pixels P through the reference voltage lines 14B_1 to 14B_m when driving the threshold voltage compensation of the organic light emitting diode OLED. The input sensing voltages may be converted into digital values and supplied to the timing controller 11. [

The data driver 12 is connected to the pixel P via the data voltage supply line 14A and the reference voltage line 14B. As shown in FIG. 3, the data driver 12 includes a digital-analog converter (DAC) for converting the digital compensation data MDATA into the image display data voltage MVdata, an analog sensing voltage An analog-to-digital converter (ADC) which is operated to convert the voltage into a digital sensing value, a first switching device SW2 for supplying an initialization voltage Vref, and a second switching device SW2 for detecting a sensing voltage can do.

The gate driver 13 generates the scan signal W1 and the sense signal W2 using the gate control signal GDC supplied from the timing controller 11. [ The gate control signal GDC includes a gate start pulse GSP indicating a start scan line at which a scan is started, a gate shift clock GSC for sequentially shifting a gate start pulse GSP, And a gate output enable (GOE) for indicating the output of the gate driver.

3 is a diagram showing a pixel structure according to the present invention.

Referring to FIG. 3, each of the pixels P includes an organic light emitting diode (OLED), a driving transistor DT, a scan transistor T1, a sense transistor T2, and a storage capacitor Cst.

In the organic light emitting diode OLED, the anode electrode is connected to the second node N2 and the cathode electrode is connected to the low potential power supply EVSS.

The driving transistor DT controls the current Ioled flowing in the organic light emitting diode OLED according to the gate-source voltage Vgs. The driving transistor DT has a gate electrode connected to the first node N1, a drain electrode connected to the high potential power supply EVDD, and a source electrode connected to the second node N2.

The storage capacitor Cst is connected between the first node N1 and the second node N2.

The scan transistor ST1 is switched according to the scan signal WS1 to supply a data voltage or a compensated data voltage MVdata compensated for a threshold voltage change of the organic light emitting diode OLED to the data voltage supply line 14A, (N1). The scan transistor ST1 has a gate electrode connected to the scan line 15A, a drain electrode connected to the data voltage supply line 14A, and a source electrode connected to the first node N1.

The sense transistor ST2 is switched in accordance with the sense signal WS2 and applies the initialization voltage Vref provided from the reference line 14B to the second node N2. The sense transistor ST2 is also switched according to the sense signal W2 to provide the threshold voltage sensing voltage of the organic light emitting diode OLED to the ADC. The gate electrode of the sense transistor ST2 is connected to the second gate line 15B, the drain electrode is connected to the second node N2, and the source electrode is connected to the reference line 14B.

The present invention detects the threshold voltage of the organic light emitting diode, determines the degree of deterioration of the organic light emitting diode based on the threshold voltage, and compensates the image data (DATA) to generate compensation data (MDATA). The compensation data MDATA is generated in consideration of the threshold voltage Vth variation due to an external factor based on the threshold voltage Vth of the dummy pixel G2 in the process of compensating the video data DATA.

A process of detecting the threshold voltage Vth of the organic light emitting diode OLED of each pixel P will be described with reference to FIGS. 4A and 4B.

In order to detect the threshold voltage of the organic light emitting diode OLED, the sense transistor ST2 is turned on in response to the sense signal W2 as shown in FIG. 4A, and the first switching device SW1 is also turned- Is turned on. Accordingly, the reference voltage Vref is supplied to the organic light emitting diode OLED through the reference voltage line 14B. The organic light emitting diode (OLED) emits light when a voltage equal to or higher than a threshold voltage is applied while the voltage is being increased.

After a sufficient time has elapsed to allow the organic light emitting diode OLED to saturate to a threshold voltage Vth or more, the first switching device SW1 is turned off and the second switching device SW2 is turned off as shown in FIG. - Turns on. Accordingly, the ADC can acquire the threshold voltage (Vth) of the organic light emitting diode (OLED) as the sensing voltage. The ADC provides a sensing voltage to the timing controller 11, and the timing controller 11 converts the sensing voltage into sensing data SD.

5 is a diagram showing a period during which the sensing data SD is acquired. The period during which the sensing data SD is obtained is obtained by dividing the first non-display period X1 arranged at the previous stage of the image display period DP and / or the second non-display period X2 arranged at the rear stage of the image display period X0 ). ≪ / RTI > In this case, the first non-display period X1 is defined as a period from immediately after the application of driving power to before the image is displayed, and the second non-display period X2 is defined as a period in which the driving power is cut off And the time interval from the start to the end. The period for acquiring the sensing data SD may be performed in at least one of the non-display periods X1 and X2 shown in FIG. 5, but it may be acquired during a blank period of the display period.

The compensating data is generated by using the threshold voltage (Vth) of the organic light emitting diode, and the degradation compensation process of the organic light emitting diode will be described below.

6 is a flowchart showing a threshold voltage compensation method of an organic light emitting diode (OLED) according to the present invention. Referring to FIGS. 1 to 6, a method of compensating a threshold voltage of an organic light emitting diode will now be described.

First, the timing controller 11 calculates the organic light emitting diode threshold voltage Vth of the first to third color pixels G1, R, and B and the dummy pixel G2 at the first time point. Then, the timing controller 11 calculates the first to fourth sensing data SDG1_1, SDR_1, SDB_1, and SDG2_1 at the first time point. The first sensing data SDG is sensed data of the organic light emitting diode threshold voltage Vth of the first color pixel G1 and the second sensing data SDR is sensed data of the organic light emitting diode threshold Is the sensing data for the voltage (Vth). The third sensing data SDB is the sensing data of the organic light emitting diode threshold voltage Vth of the third color pixel b and the fourth sensing data SDG2 is the sensing data of the organic light emitting diode threshold voltage Vth of the dummy pixel G2 Vth). The first through fourth sensing data SDG1_1, SDR_1, SDB_1, and SDG2_1 at the first point of time can be obtained using the method described above with reference to FIGS. 4A and 4B. (S601)

The timing controller 11 provides the data voltages DATA to the first through third color pixels G1, R and B to drive the first through third color pixels G1, R and B. Then, the timing controller 11 controls not to drive the dummy pixel G2 (S603)

After a certain period of time has elapsed, the timing controller 11 calculates the organic light emitting diode threshold voltage Vth of the first to third color pixels G1, R and B and the dummy pixel G2 at the second time point. Then, the timing controller 11 calculates the first to fourth sensing data SDG1_2, SDR_2, SDB_2 and SDG2_2 at the second time point. The timing controller 11 regards the sensing data SD of the dummy pixel G2, which has not been driven for a predetermined period of time after the first point in time, as a correction value. (S605, S607)

The timing controller 11 calculates the amount of change in the sensing data of the first to third color pixels G1, R and B from the first time point to the second time point. For example, the first sensing data SDG1_1 at the first time point is subtracted from the first sensing data SDG1_2 at the second time point to calculate the sensing data variation for the first color pixel G1. Likewise, the timing controller 11 calculates the amount of change in the sensing data of the second and third color pixels (R, B). The amount of sensing data variation calculated is proportional to the degree of deterioration of the organic light emitting diode (OLED). That is, the timing controller 11 determines that the degradation of the organic light emitting diode (OLED) has progressed severely as the sensing data variation amount increases, and generates compensated data (MDATA) by compensating the image data based thereon.

At this time, the timing controller 11 of the present invention generates the compensation data MDATA by using the sensing data change amount of the dummy pixel G2 as the correction value.

The threshold voltage (Vth) of the organic light emitting diode (OLED) changes due to a deterioration phenomenon caused by driving a pixel, but may also vary due to the characteristics of a panel such as an external temperature. The sensing data change amount of the dummy pixel G2 is a correction value for excluding the external influence in the process of determining the deterioration degree of the organic light emitting diode OLED based on the first to third sensing data variation amounts. For example, supposing that the amount of change in the sensing data of the dummy pixel G2 that is not driven is'? SD4 ', the amount of sensing data change by? SD4' can be regarded as a change due to external factors rather than by pixel driving. Accordingly, the timing controller 11 calculates the sensing data variation amount corrected based on subtraction of the first to third sensing data variation amounts by? SD4. For example, if the first sensing data change amount is'? SD1 ', the timing controller 11 can calculate? SD1-? SD4' as the corrected sensing data change amount. As a result, the timing controller 11 can compensate the image data of the first to third color pixels G1, R, and B based on the corrected sensing data variation amount (S609)

After the second point in time, the timing controller 11 regards the second color pixel R, which is the same color pixel as the dummy pixel G2, as a dummy pixel. That is, the timing controller 11 drives the second and third color pixels R and B, and the dummy pixel G2. The sensing data for the first color pixel G1 is regarded as a correction value after a lapse of a predetermined period of the first color pixel G1 without driving the first color pixel G1. The sensing data change amount of the second and third color pixels R and B and the dummy pixel G2 is calculated and the sensing data variation amount of the first color pixel G1 is corrected to the correction value, And calculates the corrected sensing data variation of the color pixels R and B and the dummy pixel G2 (S611 to S617)

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 invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

10: Display panel 11: Timing controller
12: Data driver 13: Gate driver
14: data line section 15: gate line section

Claims (10)

An organic light emitting diode display panel including first to third color pixels and dummy pixels;
A data driver for converting the sensing voltage provided from the first to third color pixels and dummy pixels into sensing data; And
And a timing controller for generating compensation data by compensating the image data based on the sensing data variation amount of each of the first to third color pixels and providing the compensation data to the data driver,
Wherein the timing controller generates the compensation data by using any one of a sensing data variation amount of the dummy pixel or a sensing data variation amount of the first to third color pixels as a correction value.
The method according to claim 1,
Each of the first through third color pixels and each of the dummy pixels includes
Organic light emitting diodes;
A reference voltage line connected to an anode electrode of the organic light emitting diode;
A first switching device for connecting the reference voltage line to a reference voltage source;
And a second switching element for connecting the reference voltage line and the analog-digital converter.
3. The method of claim 2,
The timing controller
The first switching device is operated to connect the reference voltage source to the anode electrode of the organic light emitting diode,
And controls the second switching device to operate so that the analog digital converter can obtain the sensing voltage of the organic light emitting diode.
The method according to claim 1,
Wherein the dummy pixel is the same color pixel as the first color pixel,
The timing controller
And controls the first color pixel and the dummy pixel to be alternately driven.
A method of driving an organic light emitting diode display device including first to fourth color pixels and dummy pixels,
Calculating a variation amount of sensing data of the first to fourth color pixels and dummy pixels; And
The degree of deterioration of the second and third color pixels and dummy pixels is calculated using the amount of change in the sensing data of the first color pixel or the dummy pixel as the correction value or the degree of deterioration of the first to third color pixels is calculated And driving the organic light emitting diode display.
6. The method of claim 5,
And calculating compensation data based on the degree of deterioration of the pixels.
The method according to claim 6,
The step of calculating the compensation data of each of the pixels
Calculating a sensing data variation amount of the first to third color pixels and the dummy pixel for a predetermined period of time, considering the sensing data variation amount of the dummy pixel as a correction value,
Calculating a first correction sensing data variation amount by subtracting a sensing data variation amount of the dummy pixel from a sensing data variation amount of the first color pixel;
Calculating a second correction sensing data variation by subtracting a sensing data variation of the dummy pixel from a sensing data variation of the second color pixel;
Calculating a third correction sensing data variation amount by subtracting a sensing data variation amount of the dummy pixel from a sensing data variation amount of the third color pixel; And
And calculating the compensation data based on the variation amounts of the first to third correction sensing data.
6. The method of claim 5,
Wherein the dummy pixel is a pixel of the same color as the first color pixel,
Wherein the first color pixel and the dummy pixel are alternately driven.
9. The method of claim 8,
The step of calculating the degree of deterioration of each of the pixels
The dummy pixel is not driven during the i-th (i is a natural number) period, and the sensing data change amount for the dummy pixel during the i-th period is corrected to the correction value, 1 to the third correction sensing data variation; And
The first color pixel is not driven during the (i + 1) th period, the sensing data change amount for the first color pixel during the (i + 1) And calculating the second and third correction sensing data variation amounts and dummy sensing data variation amounts by correcting the sensing data variation amounts of the dummy pixels.
10. The method of claim 9,
The step of calculating the first to third correction sensing data changes during the i < th >
Calculating a first correction sensing data change amount by subtracting a sensing data variation amount of the dummy pixel from a sensing data variation amount of the first color pixel;
Calculating a second correction sensing data change amount by subtracting a sensing data variation amount of the dummy pixel from a sensing data variation amount of the second color pixel; And
And subtracting the sensing data variation amount of the dummy pixel from the sensing data variation amount of the third color pixel to calculate the third correction sensing data variation amount.

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