KR102229393B1 - Organic light emitting diode display device - Google Patents

Abstract

An object of the present invention relates to an organic light emitting diode display capable of effectively detecting the characteristics of a driving TFT to display a constant image quality, and the organic light emitting diode display according to the present invention comprises a plurality of gate lines and a plurality of data. A display panel having a plurality of pixels provided in a cross region of lines, a gate driver supplying a scan signal to each of the plurality of gate lines for selection of the pixel, and a data voltage or characteristic to the pixel selected by the scan signal A data driver for supplying a detection signal and detecting a characteristic value for each pixel by the test signal, and a sampling pixel line to which the characteristic detection signal is to be supplied from among a plurality of pixel lines configured in the plurality of pixels, and the A pixel-specific characteristic value of all of the plurality of pixels is determined based on the pixel-specific characteristic value of the pixel of the sampling pixel line, and a compensation value of each of the pixels according to the pixel-specific characteristic value detected for the entire pixel And a timing controller that determines and transmits the data voltage to which the compensation value is applied to the data driver.

Description

Organic light emitting diode display {ORGANIC LIGHT EMITTING DIODE DISPLAY DEVICE}

The present invention relates to an organic light emitting diode display, and more particularly, to an organic light emitting diode display capable of effectively detecting the characteristics of a driving TFT to display a constant image quality.

An organic light emitting diode (OLED) display device is a self-luminous device that emits an organic light emitting layer through recombination of electrons and holes, and is expected to be a next-generation display device because of its high luminance, low driving voltage, and ultra-thin film.

Each of the pixels constituting the OLED display includes an OLED composed of an organic light emitting layer between an anode and a cathode, and a pixel driving circuit for independently driving the OLED. The pixel driving circuit mainly includes a switching thin film transistor (hereinafter referred to as TFT), a capacitor and a driving TFT. The switch TFT charges the capacitor with a voltage corresponding to the data voltage in response to the gate pulse, and the driving TFT controls the light emission of the OLED by controlling the amount of current supplied to the OLED according to the magnitude of the voltage charged in the capacitor. The amount of light emitted by this OLED is proportional to the current supplied from the driving TFT.

Therefore, in order to realize a high-quality image, the amount of current supplied to the OLED by the driving TFT must be accurately controlled and kept constant. However, the driving TFTs of each of the plurality of sub-pixels in one display device have different characteristics, especially mobility and threshold voltage characteristics, and these characteristics include the elapse of the driving time and the amount of current supplied through the driving TFT. , And the temperature of the driving TFT continuously changes.

For this reason, conventionally, a method of detecting a change in driving TFT characteristics every frame and applying a compensation value for compensating the change in driving TFT characteristics allows an image to be displayed with a certain quality even if the characteristics of the driving TFT change.

However, since such a conventional detection network method is performed for all pixels every frame, there are problems in that the stress of the detection device increases, heat generation, and deterioration of the driving TFT occur.

Accordingly, an object of the present invention is to provide an organic light-emitting diode display device capable of effectively detecting the characteristics of a driving TFT to display a constant image quality.

In order to achieve the above object, the organic light emitting diode display according to the present invention includes a display panel having a plurality of pixels provided in a cross region between a plurality of gate lines and a plurality of data lines, and a plurality of the gate lines for selecting the pixels. A gate driver supplying a scan signal to each, a data driver supplying a data voltage or a characteristic detection signal to the pixel selected by the scan signal, and detecting a characteristic value for each pixel by the test signal, and a plurality of the Determines a sampling pixel line to which the characteristic detection signal is supplied from among a plurality of pixel lines configured in a pixel, and whether or not a characteristic value for each pixel of all of the plurality of pixels is detected based on the characteristic value for each pixel of the pixel of the sampling pixel line And a timing controller configured to transmit the data voltage to which the compensation value is applied to the data driver by determining a compensation value of each pixel according to the characteristic value of each pixel detected for the entire pixel.

The present invention detects characteristic values for pixels of a sampling pixel line, determines whether a characteristic value has changed, and does not apply characteristic values of some pixels to all pixels based on the determination result. It is used only as a basis for determining whether to perform the calculation of the compensation value, and when a change occurs, the characteristic value and compensation value of all pixels are calculated and applied. Through this, the present invention prevents deterioration of image quality that may occur when the characteristic values of some pixels are applied, and while maintaining high display quality by accurately calculating and applying the characteristic values of each pixel, the burden of the display device for detecting this Becomes possible to minimize.

1 is an exemplary view illustrating an organic light emitting diode display according to the present invention.
FIG. 2 is an exemplary diagram for explaining selection and characteristic detection of a sampling pixel line in FIG. 1.
3 is a circuit diagram illustrating an example of a pixel configured in a display panel.
4 is an exemplary diagram illustrating a method of determining whether or not a characteristic value of all pixels is detected by comparing a characteristic value with a reference value.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement them. It should be noted that, in the accompanying drawings, the same reference number is used as much as possible when indicating the same configuration in other drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known function or a known configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, certain features presented in the drawings are enlarged or reduced or simplified for ease of description, and the drawings and their components are not necessarily drawn to scale. However, those skilled in the art will readily understand these details.

1 is an exemplary diagram illustrating an organic light emitting diode display according to an exemplary embodiment of the present invention, and FIG. 2 is an exemplary diagram illustrating selection and characteristic detection of a sampling pixel line in FIG. 1. 3 is a circuit diagram showing an example of a pixel configured in the display panel.

1 to 3, the organic light emitting diode display device (hereinafter referred to as “OLED display device”) according to the present invention includes data lines DLm formed in a first direction of the display panel 10: DL1 to DLm. m is a natural number), a gate line (GLn: GL1 to GLn, where n is a natural number) formed in a direction orthogonal to the data line DLm, a pixel defined at the intersection of the gate line GLn and the data line DLm It is formed in the region and includes a pixel P having a pixel circuit.

The present invention detects a characteristic value for each pixel only for a sampling pixel line, which is a partial pixel line selected by the timing controller 40, during a detection period for detecting the characteristic of each pixel P that is distinguished from the period in which an image is displayed. . And, if the detected characteristic value for each pixel satisfies a predetermined criterion, the characteristic value for each pixel is calculated for all pixels, a compensation value for each pixel is determined according to the calculated characteristic value, and the data to which the determined compensation value is applied is calculated. It is supplied to each pixel.

The detection period for detecting the characteristic value for each pixel is configured for each frame, so that each frame period can be divided into a display period and a detection period. Alternatively, the detection period may be inserted once per several frames, or the detection period may be allocated only when a specific condition is satisfied, but this does not limit the present invention.

In the following, the present invention will be described in detail by taking an example in which one frame period is divided into a display period and a detection period, and characteristic values are detected for each frame period.

Such an OLED display device includes a display panel 10, a data driver 20, a gate driver 30, and a timing controller 40. In addition, a data processing unit (not shown) may be further configured inside the timing controller 40 or between the timing controller 40 and the data driver 20.

The timing controller 40 operates the data driver 20 and the gate driver 30 in the display mode during the display period and in the detection mode during the detection period.

Specifically, the timing controller 40 selects the sampling pixel lines PLi, PLj, and PLk during the detection period, drives the gate driver 30 so that the selected sampling pixel lines PLi, PLj, and PLk are selected, and selects sampling. A characteristic detection signal is supplied to the pixels included in the pixel lines PLi, PLj, and PLk to detect the characteristics of the driving transistor DT of each pixel, that is, a threshold voltage or mobility. As described above, the detection period may be provided for every frame period, once every several frame periods, or the detection period may be inserted only at a time set by the user, but this does not limit the present invention.

In addition, the timing controller 40 compares the pixel-specific characteristic values detected from the pixels of the sampling pixel lines PLi, PLj, and PLk with a predetermined reference value, and when a predetermined condition is satisfied, the pixels of the entire display panel 10 are In contrast, the data driving unit 20 and the gate driving unit 30 are controlled so that the characteristic values for each pixel are detected. A process of determining whether to detect all pixels by comparing the detected characteristic value for each pixel with a reference value will be described in more detail below. In addition, when the characteristic values for each pixel for all pixels are detected, the timing controller 40 determines the characteristic compensation value for each pixel by applying it to a predetermined compensation value table.

In particular, the timing controller 40 divides the sampling pixel lines PLi, PLj, and PLk into virtual regions SE1 to SE3 of the display panel 10, and each region has one or less than a predetermined number. The pixel lines PLi, PLj, and PLk are selected as the sampling pixel lines PLi, PLj, and PLk. In addition, the timing controller 40 performs only characteristic value detection on the sampling pixel lines PLi, PLj, and PLk during each detection period, and uses the pixel-specific characteristic values detected for the sampling pixel lines PLi, PLj, and PLk. Thus, it is determined whether to detect the characteristic values for each pixel of all the pixels. In addition, the sampling pixel lines PLi, PLj, and PLk may be selected so that different pixel lines PLm (PL1 to PLm) are selected for each detection period, but the present invention is not limited thereto.

Each of these virtual regions SE1 to SE3 is divided by a gate line GLn to include a plurality of pixel lines PLm. For example, when the display panel 10 including gate lines of 1050 lines is divided into three regions SE1 to SE3, each of 350 gate lines GLn may be divided into one region. Here, the size of each area is not necessarily the same, and the number and size of the areas can be freely changed.

In addition, the timing controller 40 includes a data control signal for driving the pixel P connected to each gate line GLn in units of one horizontal period based on the timing synchronization signal TSS input from the external system during the display period. DCS: Data Control Signal) and Gate Control Signal (GCS) are generated, and the data driver 20 and the gate driver 30 are controlled in a display mode by using them. Here, the timing synchronization signal TSS may be a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal DE, a clock signal DCLK, or the like. In addition, the gate control signal GCS may be composed of a gate start signal and a plurality of clock signals, and the data control signal DCS may be composed of a data start signal, a data shift signal, and a data output signal.

In addition, the timing controller 40 generates pixel data DATA that compensates for input data Idata input from the outside based on the compensation value for each pixel determined in the detection mode, and uses the generated pixel data DATA as data. It is supplied to the drive unit 20. At this time, the pixel data DATA to be supplied to each pixel P has a voltage level to which a compensation value determined by detecting a characteristic value for each pixel is applied.

In the present invention, the input data Idata and the pixel data DATA may be red, green, and blue data to be supplied to one unit pixel, and further include white data when a white subpixel is formed on the display panel 10 However, it is not intended to limit the present invention.

The data driver 20 is connected to the plurality of data lines DLm and operates in a display mode and a detection mode according to the mode control of the timing controller 40.

In the display mode, the data driver 20 converts the pixel data DATA provided from the timing controller 40 into a data voltage Vdata and supplies it to the corresponding data line DLm. In this case, the pixel data DATA may be data in which a compensation value determined for each pixel is compensated according to detection of a characteristic value for each pixel for all pixels, as described above. In the display mode, the pixel data DATA is converted into a data voltage Vdata by the data driver 20 and transmitted to the pixel.

In the detection mode, the data driver 20 supplies the characteristic detection signal to the reference line REF for detection, and detects the detection pixel data DATA supplied from the timing controller 40 for detection. It is converted into a voltage Vdata and supplied to the data line DLm. In addition, the data driver 20 charges each reference line with a voltage corresponding to the current flowing through the driving TFT DT of the pixel P by the detection data voltage Vdata and the detection reference voltage Vref. After each reference line is floated, the voltage charged in the reference line is transferred to the timing controller 40 as a characteristic value Dsen for each pixel.

The gate driver 30 supplies a gate signal to the gate line GLn of the display panel 10 in response to the gate control signal GCS from the timing controller 40. The gate driver 30 supplies a gate signal for sequentially driving the gate lines GLn in response to the gate control signal GCS from the timing controller 40 in the display mode. In addition, in the detection mode, the gate driver 30 supplies a detection gate signal for driving the gate lines GLi, GLj, and GLk corresponding to the sampling pixel lines selected for each region.

The display panel 10 includes a plurality of data lines DLm connected to the data driving unit 20, a plurality of gate lines GLn connected to the gate driving unit 30 and crossing the data line DLm, and a data driving unit. It is configured to include a plurality of reference lines REF connected to 20 and a pixel P formed in a pixel region defined in an intersection region thereof.

A plurality of pixels P are formed on the display panel 10, and each of the pixels P is composed of any one pixel P of red (R), green (G), and blue (B), or red ( It may be composed of any one of R), green (G), blue (B), and white (w) pixels. As described above, the pixel P is selected by a gate signal or a detection gate signal sequentially supplied from the gate driver 30 to the gate line GLn, and when selected, the data voltage supplied from the data driver 20 The (Vdata) is charged to emit light, or the characteristic value (Dsen) for each pixel is returned to the data driver 20 by the detection data voltage. An example of such a pixel P is shown in FIG. 3.

Referring to FIG. 3, each pixel P may include first and second switching TFTs SW1 and SW2, a driving TFT DT, a storage capacitor Cst, and an OLED element OLED. . Here, the circuit diagram of the pixel P illustrated in FIG. 3 is provided as an example, and various known configurations may be applied, and the present invention is not limited by the suggestions.

In the first switching TFT SW1 of the pixel P, the gate electrode is connected to the gate line Glo, the first electrode is connected to the data line DLp, and the second electrode is connected to the first node n1. It is connected to the gate electrode of the driving TFT DT. In addition, in the driving TFT SW2, a gate electrode is connected to the first node n1, the first electrode is connected to the first power line VDD, and the second electrode is connected to the second node n2. The storage capacitor Cst is connected between the first node n1 and the second node n2, and the OLED device OLED is connected between the second node n2 and the second power line Vss. In addition, in the second switching TFT SW2, the first electrode is connected to the reference line REF, the second electrode is connected to the second node, and the gate electrode is connected to the signal line to which the characteristic detection signal is input. Here, the signal line may be one of the gate lines or a separately formed signal line, but the present invention is not limited thereto.

During the display period, the second switching TFT SW2 supplies a reference voltage supplied through the reference line to the second node n2 to initialize the second node n2, and the first switching TFT SW1 is the gate line ( The data voltage supplied through the data line DLp by being driven on by the gate signal supplied to GLo) is supplied to the first node n1. In addition, during the detection period, the second switching TFT (SW2) is driven on to supply the characteristic detection signal to the second node (n2), and the second node in which the difference voltage between the detection data voltage (Vdata) and the characteristic detection signal is charged ( By connecting n2) and the reference line REF, a characteristic value for each pixel, which is a difference voltage, can be transferred to the data driver 20.

The storage capacitor Cst is charged with a voltage difference between the data voltage Vdata and the reference voltage in the display mode, and turns on the driving TFT by the charged voltage.

The driving TFT (DT) is driven on by the voltage supplied from the storage capacitor (Cst) and supplies the current supplied by the power supplied from the first power line to the OLED device (OLED) to emit the OLED device (OLED). Let it.

4 is an exemplary diagram illustrating a method of determining whether or not a characteristic value of all pixels is detected by comparing a characteristic value with a reference value.

Referring to FIG. 4, as described above, the present invention detects a change in characteristics of a driving TFT accompanying a change in a driving time or a change in a driving condition, performs data compensation, and displays an image through the compensated data. Even when the characteristics of the driving TFT change, a constant image display quality can be maintained.

In particular, in order to detect such a change in the characteristics of the driving TFT, the present invention does not detect the change in the characteristics of all pixels at each detection period, and performs sampling for some pixels. It is possible to reduce the stress, deterioration, and burden applied to the driving units 20 and 30, the timing controller 40, and the driving TFT DT of each pixel P.

Specifically, the present invention divides the display panel 10 into a plurality of regions SE1 to SE3, and selects one or a few sampling pixel lines PLi, PLj, and PLk for each region to include pixels included in the sampling pixel line. The characteristic value Dsen of each pixel is detected. The characteristic value Dsen for each pixel is compared with a predetermined reference value, and when the predetermined condition is satisfied, the characteristic value Dsen for each pixel is detected for all pixels of the display panel 10. Then, by analyzing the characteristic value Dsen for each pixel, a compensation value is determined according to the changed characteristic value for each pixel, data is regenerated by applying the determined compensation value, and supplied to the pixel to display an image. Through this, the present invention minimizes the burden of the driver, the controller, and the driving TFT for determining this by determining whether the characteristic value for each pixel has changed by detecting the characteristic value for each pixel at a high frequency. On the other hand, when a pixel whose characteristic value is changed is detected, the characteristic value for each pixel (Dsen) is detected for all pixels, and an accurate compensation value is determined for each pixel. It becomes possible to prevent possible image quality degradation and to maintain a high level of image display quality.

To this end, the present invention performs a process of comparing the sampled and detected pixel-specific characteristic value Dsen with a predetermined reference value.

Specifically, the timing controller 40 of the present invention compares the pixel-specific characteristic value Dsen detected for the sampling pixel lines PLi, PLj, and PLk with a reference value, and determines whether the comparison result satisfies a predetermined condition. .

More specifically, the timing controller 40 of the present invention compares the average of the characteristic values Dsen for each pixel detected for all pixels of the sampling pixel lines PLi, PLj, and PLk with the average value, which is a predetermined reference value. When the average of the characteristic values Dsen is equal to or greater than the average value, the characteristic value Dsen for each pixel is detected for all pixels (a). Alternatively, the timing controller 40 may continuously detect the pixel-specific characteristic values of the sampling pixel lines PLi, PLj, and PLk that differ from the predetermined reference values for each pixel. Value (Dsen) detection is performed (b). Alternatively, the timing controller 40 includes pixels for all pixels when the number of pixels having a characteristic value for each pixel different from a predetermined reference value among the pixels P constituting the sampling pixel lines PLi, PLj, and PLk is equal to or greater than a predetermined number or ratio. Star characteristic value (Dsen) is detected (c).

First, as shown in (a) of FIG. 4, the timing controller 40 compares the average of the characteristic values Dsen for each pixel detected for all the pixels of the sampling pixel lines PLi, PLj, and PLk with the average value, which is a predetermined reference value. Accordingly, when the average of the characteristic values Dsen for each pixel is equal to or greater than the average value, the characteristic value Dsen for each pixel is detected.

Specifically, each pixel is stored for each pixel by detecting an initial characteristic value of each of the driving TFTs DT in advance so that a constant image may be expressed by compensating the characteristics of each driving TFT (DT) configured in each pixel (P). Each of the characteristic values prepared in advance for each of these pixels becomes a reference value for comparison with the characteristic values of each pixel detected for the subsequent sampling pixel lines PLi, PLj, and PLk.

The timing controller 40 uses the sampling pixel lines PLi, PLj, and PLk when the pixel-specific characteristic values for the sampling pixel lines PLi, PLj, and PLk are detected in order to determine whether to detect the pixel-specific characteristic values for all pixels. Initial characteristic values for each of the pixels of the determined pixel line are checked, and an average value of the initial characteristic values is calculated. In addition, the timing controller 40 calculates a characteristic value for each pixel of the sampling pixel lines PLi, PLj, and PLk, calculates a sampling average value, and then compares the average value of the initial characteristic value with the sampling average value. At this time, when the sampling average value is different from the average value of the initial characteristic value, in particular, when the sampling average value is greater than the average of the initial characteristic value, the timing controller 40 calculates and calculates the characteristic value for each pixel for the entire pixel of the display panel 10. Compensation is performed based on the characteristic values for each pixel.

In addition, by using the same method as in FIG. 4B, the pixel-specific characteristic value for all pixels may be calculated and compensation based on the calculated pixel-specific characteristic value may be determined.

In more detail, the timing controller 40 determines that the pixel-specific characteristic values of the sampling pixel lines PLi, PLj, and PLk differ from the predetermined reference value for each pixel are successively detected. The characteristic value (Dsen) is detected.

When the timing controller 40 calculates the characteristic values for each pixel for the sampling pixel lines PLi, PLj, and PLk, the timing controller 40 compares the calculated characteristic values for each pixel and the pre-calculated and stored initial characteristic values for each pixel P. . At this time, pixels in which the detected characteristic value for each pixel and the initial characteristic value differ by more than a predetermined value are detected, and pixels (Px) in which the characteristic value for each pixel and the initial characteristic value differ by more than a predetermined value are continuously arranged. In this case, the timing controller 40 detects a pixel-specific characteristic value Dsen for all pixels and determines a compensation value for each pixel.

In particular, the timing controller 40 may detect and compensate for the characteristic value Dsen for all pixels when the pixels in which the difference in characteristic values are generated are continuous more than a predetermined number of pixels.

In addition, it is possible to detect a characteristic value for each pixel and determine a compensation value for all pixels by using a method as shown in FIG. 4C.

In more detail, the timing controller 40 applies to all pixels when the number of pixels having a characteristic value for each pixel different from a predetermined reference value among the pixels P constituting the sampling pixel lines PLi, PLj, and PLk is equal to or greater than a predetermined number or ratio. The characteristic values for each pixel are detected. That is, even if they are not continuous as shown in (b), the number of pixels in which the initial characteristic value and the sampled characteristic value of each pixel differ by more than a predetermined value among all the pixels of one sampling pixel line (PLi, PLj, PLk). When the ratio is greater than or equal to a predetermined ratio for each of the pixels of the display panel, a characteristic value for each pixel and a compensation value may be determined.

As described above, the present invention detects characteristic values for pixels of the sampling pixel lines PLi, PLj, and PLk, and determines whether a change in the characteristic value has occurred. In addition, based on the determination result, the characteristic values of some pixels are not applied to all pixels, but are used only as a basis for determining whether to calculate the characteristic values and compensation values of all pixels, and when a change occurs, the characteristic values and compensation values of all pixels are calculated. It will be applied by performing. Through this, the present invention prevents deterioration of image quality that may occur when the characteristic values of some pixels are applied, and while maintaining high display quality by accurately calculating and applying the characteristic values of each pixel, the burden of the display device for detecting this Becomes possible to minimize.

Although shown and described in specific embodiments to illustrate the technical idea of the present invention, the present invention is not limited to the same configuration and operation as the specific embodiment as described above, and various modifications are within the scope of the present invention. Can be carried out in Therefore, such modifications should be regarded as belonging to the scope of the present invention, and the scope of the present invention should be determined by the claims to be described later.

10: display panel
20: data driver
30: gate driver
40: timing controller

Claims (6)

A display panel having a plurality of pixels provided in an intersection area between a plurality of gate lines and a plurality of data lines;
A gate driver supplying a scan signal to each of the plurality of gate lines to select the pixel;
A data driver for supplying a data voltage or a characteristic detection signal to the pixel selected by the scan signal and detecting a characteristic value for each pixel by the characteristic detection signal; And
A sampling pixel line to which the characteristic detection signal is supplied from among a plurality of pixel lines configured in the plurality of pixels, is determined, and the pixel-specific characteristics of all of the plurality of pixels based on the pixel-specific characteristic value of the pixel of the sampling pixel line A timing controller configured to determine whether to detect a value, determine a compensation value for each pixel according to the characteristic value for each pixel detected for the entire pixel, and transmit the data voltage to which the compensation value is applied to the data driver,
The timing controller is
When the average of the characteristic values for each pixel of each pixel of the sampling pixel line is equal to or greater than a predetermined reference value,
When the pixel-specific characteristic value of the pixel having a predetermined ratio or more among the pixels constituting the sampling pixel line is different from the reference value, and
If any one or more of the pixels in the sampling pixel line, the pixel-specific characteristic value differing from a predetermined reference value and a predetermined value or more, are successively satisfied, the pixel-specific characteristic for all of the plurality of pixels An organic light emitting diode display that detects a value. The method of claim 1,
The timing controller is
Dividing the display panel into a plurality of regions, and selecting each of the sampling pixel lines for each of the plurality of regions. The method of claim 2,
Wherein the plurality of regions are divided in units of gate lines or pixel lines to include a plurality of pixel lines divided by the plurality of gate lines. delete The method of claim 1,
The characteristic value for each pixel is a mobility or a threshold voltage of a driving transistor provided in the pixel. The method of claim 1,
The display panel further includes a plurality of reference lines,
And the data driver transmits the characteristic detection signal to the pixel through the plurality of reference lines, and detects the characteristic value of each pixel from the pixel.

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