KR20230103623A - Display device, method for driving the same, and timing controller - Google Patents

Abstract

The present invention relates to a display device capable of selectively sensing and compensating for subpixels having a large cumulative stress when a display panel is driven. A timing controller of a display device according to an embodiment counts input image data for each subpixel. Using the data counting information of the pixel, a subpixel whose characteristic change is expected is selected, the characteristics of the selected subpixel are sensed through the panel driver, and the data counting information on the selected subpixel and the characteristic sensing information of the subpixel are used to select the subpixel. A compensation value may be updated, and image data of each subpixel may be compensated by applying the updated compensation value.

Description

Display device and its driving method and timing controller {DISPLAY DEVICE, METHOD FOR DRIVING THE SAME, AND TIMING CONTROLLER}

The present invention relates to a display device capable of selectively sensing and compensating for subpixels having a large cumulative stress when driving a display panel, and a method for driving the same.

A light emitting display device displays an image by supplying a current corresponding to a gray level to a light emitting element disposed in each subpixel to emit light. The light emitting display device has advantages such as high luminance, low driving voltage, ultra-thin film, and free shape implementation.

In the light emitting display device, luminance variation may occur due to variations in electrical characteristics of each subpixel. In order to solve this problem, the light emitting display device applies an external compensation method in which electrical characteristics of each subpixel are sensed and compensated for.

In the light emitting display device, subpixels that are sequentially sensed by one horizontal line for each vertical blank period can be recognized, or the power is not turned off because the time for sensing the driving TFT threshold voltage (Vth) of each subpixel is considerable during the power-off time. There is a problem that the power-off time is long.

The present invention provides a display device capable of selectively sensing and compensating for subpixels having a large cumulative stress when driving a display panel, and a method for driving the same.

A display device according to an embodiment includes a panel including a plurality of subpixels; a panel driving unit driving the display panel; and a timing controller controlling the panel driver, wherein the timing controller selects a subpixel whose characteristic change is expected by using data counting information of each subpixel obtained by counting input image data for each subpixel, and the panel driver The characteristics of the selected subpixel are sensed through, the compensation value is updated using the data counting information for the selected subpixel and the characteristic sensing information of the subpixel, and the image data of each subpixel is obtained by applying the updated compensation value. Compensation may be performed and output to the panel driving unit.

According to an exemplary embodiment, a method of driving a display device includes counting input image data for each subpixel in a timing controller and selecting a subpixel whose characteristics are expected to change using data counting information of each subpixel; sensing a characteristic of a selected subpixel in a panel driver; updating a compensation value by using data counting information for a subpixel selected by the timing controller and characteristic sensing information of the subpixel; and compensating the image data of each subpixel by adding the compensation value updated by the timing controller and outputting the compensated image data to the panel driver.

The timing controller according to an embodiment selects a subpixel whose characteristic change is expected using data counting information of each subpixel obtained by counting the input image data for each subpixel, and senses the characteristic of the selected subpixel through a panel driver. , Compensation values may be updated using data counting information for the selected subpixel and characteristic sensing information of the subpixel, and image data of each subpixel may be compensated and output by applying the updated compensation value.

The display device according to an embodiment of the present invention may sense the characteristic change of the selected subpixels in the vertical blank period of each frame by preferentially selecting subpixels whose characteristics are expected to change due to accumulated stress using data counting information. there is.

The display device according to an embodiment of the present invention determines the amount of change in characteristics of the selected subpixels by combining sensing information and data counting information of the selected subpixels, and updates the compensation value reflecting the amount of change in characteristics in a memory to change the characteristics of the subpixels. can be compensated in real time.

The display device according to an embodiment of the present invention does not require a power-on sensing time and a power-off sensing time, thereby reducing the power-on time and the power-off time, and a sub-characteristic change expected in each vertical blank period of each frame. By randomly sensing and distributing the pixels, it is possible to prevent the sensed subpixels from being recognized.

1 is a block diagram showing the configuration of a display device according to an embodiment of the present invention.
2 is a circuit diagram showing the configuration of one pixel circuit and a data driver according to an embodiment of the present invention.
3 is a flowchart illustrating a method of driving a display device according to an embodiment of the present invention.
4 is a block diagram showing configurations of a timing controller and a data driver of a display device according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a block diagram showing the configuration of a display device according to an exemplary embodiment, and FIG. 2 is a circuit diagram showing the configuration of one pixel circuit and a data driver according to an exemplary embodiment.

An electroluminescent display may be applied to the display device according to an embodiment. An organic light emitting diode (OLED) display device, a quantum-dot light emitting diode display device, or an inorganic light emitting diode display device may be used as the electroluminescent display device. there is.

1 and 2, the display device includes a display panel 100, a gate driver 200, a data driver 300, a timing controller 400, a gamma voltage generator 500, a memory 700, and the like. can include The gate driver 200 and the data driver 300 may be defined as display panel drivers that drive the display panel 100 . The gate driver 200, the data driver 300, the timing controller 400, and the gamma voltage generator 500 may all be defined as a display driver.

The display panel 100 displays an image through a display area DA corresponding to a pixel array area in which subpixels P are arranged in a matrix form. A basic unit pixel consists of three or four color subpixels among red subpixels emitting red light, green subpixels emitting green light, blue subpixels emitting blue light, and white subpixels emitting white light, or two-color subpixels. can be made up of subpixels

Each subpixel P includes a light emitting element and a pixel circuit independently driving the light emitting element. As the light emitting device, organic light emitting diodes, quantum-dot light emitting diodes, or inorganic light emitting diodes may be applied. The pixel circuit stores a driving voltage (Vgs) corresponding to a data signal supplied through a plurality of TFTs including at least a driving TFT for driving a light emitting element and a switching TFT for supplying a data signal to the driving TFT. A storage capacitor supplied to the driving TFT is included. In addition, the pixel circuit further includes a plurality of TFTs that initialize the three electrodes (gate, source, and drain) of the driving TFT, respectively, connect the driving TFT with a diode structure to compensate for the threshold voltage, or control the light emission time of the light emitting element. can do. Various configurations such as 3T1C (3 TFTs, 1 capacitor) and 7T1C (7 TFTs, 1 capacitor) may be applied to the configuration of the pixel circuit.

For example, as shown in FIG. 2 , each subpixel P is connected to a high-potential power supply voltage (first power supply voltage; EVDD) line and connected to a low-potential power supply voltage (second power supply voltage; EVSS) line. A pixel circuit including at least a light emitting element ED, first and second switching TFTs ST1 and ST2, a driving TFT DT, and a storage capacitor Cst to independently drive the light emitting element ED. can be provided

The light emitting element ED includes an anode connected to the source node N2 of the driving TFT DT, a cathode connected to the EVSS line, and a light emitting layer between the anode and the cathode. The anode is independent for each subpixel, but the cathode may be a common electrode shared by all subpixels. In the light emitting element ED, when a driving current is supplied from the driving TFT DT, electrons injected into the light emitting layer from the cathode and holes injected from the anode into the light emitting layer combine to generate excitons, and the generated excitons enter an excited state ( By emitting a fluorescent or phosphorescent material while falling from an excited state to a ground state, light of brightness proportional to the current value of the driving current is generated. The light emitting material may be made of an organic material or may be made of an inorganic material such as a quantum dot.

The first switching TFT (ST1) is driven by a first gate pulse supplied from the gate driver 200 to the first gate line (GLi, i = an integer of 1 to n), and is driven by the data driver 300. The data voltage supplied to the data line DLj (j = an integer of 1 to m) is supplied to the gate node N1 of the driving TFT DT.

The second switching TFT (ST2) is driven by the second gate pulse supplied from the gate driver 200 to the second gate line (SGLi, i = an integer of 1 to n), and is driven by the data driver 300. The reference voltage supplied to the sensing line SLj (j = an integer of 1 to m) is supplied to the source node N2 of the driving TFT DT. Meanwhile, in the sensing mode, the second switching TFT ST2 may provide a current reflecting the characteristics of the driving TFT DT or the characteristics of the light emitting device ED to the sensing line SLj.

As shown in FIG. 2 , the first and second switching TFTs ST1 and ST2 may be controlled by different gate lines GLi and SGLi or controlled by the same gate line.

The storage capacitor Cst connected between the gate node N1 and the source node N2 of the driving TFT DT connects the gate node N1 and the source node ( The difference between the data voltage and the reference voltage supplied to N2) is charged as the driving voltage (Vgs) of the driving TFT (DT), and charged during the light emission period in which the first and second switching TFTs (ST1, ST2) are turned off. The driving voltage (Vgs) is held.

The driving TFT (DT) controls the current supplied from the EVDD line according to the driving voltage (Vgs) supplied from the storage capacitor (Cst) and supplies the driving current determined by the driving voltage (Vgs) to the light emitting element (ED) to emit light. The element ED may emit light.

The gate driver 200 is controlled according to a plurality of gate control signals supplied from the timing controller 400 and can individually drive the gate lines of the display panel 100 . The gate driver 200 supplies a gate-on voltage pulse signal to the corresponding gate line during the driving period of each gate line (GLi, SGLi), and applies a gate-off voltage during the non-driving period of each gate line (GLi, SGLi). supply to the gate line.

The gate driver 200 may be directly formed on a substrate by the same process as the TFT array in the display area of the display panel 100 and may be disposed and embedded in the bezel area of the display panel 100 .

The gamma voltage generator 500 generates a plurality of reference gamma voltages having different voltage levels and supplies them to the data driver 300 . The gamma voltage generator 500 may generate a plurality of reference gamma voltages corresponding to the gamma characteristics of the display device under the control of the timing controller 400 and supply them to the data driver 300 . The gamma voltage generator 500 may adjust the reference gamma voltage level according to the gamma data supplied from the timing controller 400 and output the adjusted reference gamma voltage level to the data driver 300 .

The data driver 300 is controlled according to the data control signal supplied from the timing controller 400, converts the digital data supplied from the timing controller 400 into an analog data signal through a digital-to-analog converter, and displays the panel 100 A corresponding data signal may be supplied to each data line DLj of . The data driver 300 may convert digital data into an analog data signal using grayscale voltages in which a plurality of reference gamma voltages supplied from the gamma voltage generator 500 are subdivided.

The data driver 300 may supply a reference voltage to the sensing line SLj of the display panel 100 under the control of the timing controller 400 . The data driver 300 may separately supply reference voltages for display and sensing under the control of the timing controller 400 .

The data driver 300 may be composed of a plurality of data integrated circuits (ICs), individually mounted on a chip on film (COF), and connected to the panel 100 through the COF.

The data driver 300 uses a sensing unit under the control of the timing controller 400 to sense a signal representing the driving characteristics of each subpixel through each sensing line SLj using a voltage sensing method or a current sensing method, and senses the signal. may be converted into sensing data through an analog-to-digital converter and supplied to the timing controller 400 .

The timing controller 400 may control the gate driver 200 and the data driver 300 using timing control signals supplied from the host system and timing setting information stored therein. The host system may be any one of a system of a portable terminal such as a computer, a TV system, a set-top box, a tablet or a mobile phone. The timing control signals may include a dot clock, a data enable signal, a vertical sync signal, a horizontal sync signal, and the like.

The timing controller 400 may generate a plurality of gate control signals for controlling driving timing of the gate driver 200 and supply them to the gate driver 400 . The timing controller 400 may generate and supply a plurality of data control signals for controlling driving timing of the data driver 300 to the data driver 300 .

The timing controller 400 may perform various image processing as a pre-processing operation on image data supplied from the host system and output the pre-processed data. The timing controller 400 may perform various image processing for image quality improvement on image data as a pre-processing operation, and reduce power consumption by analyzing image data and controlling peak luminance.

The timing controller 400 applies the compensation value of each subpixel stored in the memory 700 to the image data before outputting the preprocessed data to the data driver 300 to compensate for the characteristic deviation of each subpixel P. and can output the compensated data to the data driver 300.

The timing controller 400 may preferentially select subpixels whose characteristics are expected to change due to accumulated stress using counting information obtained by counting data of each subpixel (P), and select subpixels selected in the vertical blank period of each frame. Characteristic changes may be read out through the data driver 300 and sensed.

The timing controller 400 determines the amount of change in the characteristics of the selected subpixels by combining the sensing information and the data counting information of the selected subpixels, and updates the memory 700 with a compensation value reflecting the amount of change in the characteristics to detect changes in the characteristics of the subpixels in real time. can be compensated with A detailed description of this will be described later.

Referring to FIG. 2 , the data driver 300 includes a driving circuit 310 for driving the data lines DL1 to DLm and driving characteristics of each subpixel P, for example, the threshold voltage of the driving TFT DT. The readout circuit 320 may be configured to sense the pixel current in which Vth, the mobility of the driving TFT DT, or the degree of deterioration (threshold voltage) of the light emitting element ED is reflected, using a voltage sensing method.

The driving circuit 310 of the data driver 300 converts the data for sensing supplied from the timing controller 400 into a data voltage, supplies it to each data line DLj (j = 1 to m), and generates a reference voltage for sensing. It can be supplied to each sensing line (SLj, j = 1 ~ m). In the sub-pixel P selected by the gate lines GLi, SGLi, i = 1 to n driven by the gate driver 200, the driving TFT DT is for sensing supplied through the first switching TFT ST1. It may be driven by the data voltage and the sensing reference voltage supplied through the second switching TFT ST2. The pixel current reflecting the electrical characteristics (threshold voltage, mobility) of the driving TFT (DT) or the deterioration characteristics (threshold voltage) of the light emitting element (ED) is provided through the second switching TFT (ST2), and the sensing line is in a floating state. The line capacitor of (SLj) can be charged.

The read-out circuit 320 of the data driver 300 samples and holds the sensing voltage of each sub-pixel P charged in the plurality of sensing lines SL1 to SLm, and converts an analog-to-digital converter (ADC). Through this, it may be converted into sensing data and provided to the timing controller 400 .

3 is a purity diagram illustrating a method of driving a display device according to an embodiment of the present invention.

The display device first performs a first compensation step (S100) of sensing the characteristic deviation of each subpixel in the inspection step of the manufacturing process, determining a compensation value for compensating for the characteristic deviation of each subpixel, and storing it in the memory 700. can be done/

The display device may perform an operation of being powered on (S210), receiving input image data, and displaying the input image data on the display panel 100 (S220). The display device may shorten the power-on time by omitting a compensation operation for updating the compensation value of the memory 700 by sensing the characteristics of subpixels during the power-on time.

In the display device, the timing controller 400 may receive input image data and count data in subpixels (S230). For example, the timing controller 400 may reduce data counting information stored in a memory by up-counting input data and down-counting by deducting minimum data within one frame. The timing controller 400 may determine the degree of accumulated stress received by each subpixel P by using the counting information, and may select a horizontal line in which subpixels whose characteristics are expected to change due to the large accumulated stress are positioned.

The timing controller 400 performs normal driving to display the input image data on the display panel 100 for each active period of each frame (S222), and when the blank period of each frame (S224, Yes) occurs, the selected horizontal line Characteristic changes of subpixels may be read out through the data driver 300 and sensed (S232).

The timing controller 400 may determine the amount of change in characteristics of each selected subpixel by using the data counting information of each subpixel of the selected horizontal line and the sensed characteristic sensing information of each subpixel (S234).

The timing controller 400 may update the memory 700 by calculating a compensation value for compensating for the amount of change in characteristics of each selected subpixel (S236).

The timing controller 400 compensates the image data of each subpixel by applying the updated compensation value to the memory 700 (S226), supplies the compensated data to the data driver 300, and displays the data on the display panel 100. can do.

The timing controller 400 may first select and sense subpixels having a large cumulative stress level by using the data counting information of each subpixel in each vertical blank period of each frame, and randomly select a horizontal line in consideration of the accumulated stress level. can be sensed. Accordingly, since the positions of the subpixels sensed in each vertical blank period are distributed, even if the subpixels sensed are turned off in the sensing period, they can be prevented from being recognized.

When the power is turned off, the display device may end display driving (S240). The display device may omit a compensation operation for updating the compensation value of the memory 700 by sensing the characteristics of subpixels, in particular, the threshold value of the driving TFT, during the power-off time, thereby reducing the power-off time.

4 is a block diagram showing configurations of a timing controller and a data driver according to an embodiment of the present invention.

Referring to FIG. 4 , a timing controller 400 according to an exemplary embodiment may include a preprocessor 410, a compensator 420, a data counter 430, and a characteristic change predictor 440. The data driver 300 may include a driving circuit 310 and a readout circuit 320 .

The preprocessor 410 may perform various image processing on input image data and output the preprocessed data to the compensator 400 .

The data counter 430 may receive input image data, count and store data for each subpixel, and output data counting information of each subpixel to the characteristic change predictor 440 . The data counter 430 may reduce data counting information stored in the memory by performing up-counting of input image data and down-counting by deducting minimum image data within one frame.

The characteristic change predictor 440 predicts the characteristic change of each subpixel according to the cumulative stress level using the data counting information of each subpixel, and transfers the location information of the subpixels whose characteristic change is predicted to the compensator 420. can be printed out.

The compensator 420 selects a horizontal line on which subpixels whose characteristics are predicted to change in the vertical blank period of each frame are located, and selects the selected horizontal line through the driving circuit 310 of the gate driver 200 and the data driver 300. The subpixels of the line can be driven. The readout circuit 320 of the data driver 300 may sense a characteristic change of each selected subpixel and output the sensed data to the characteristic change predictor 440 of the timing controller 400 .

The characteristic change predictor 440 determines the amount of change in the characteristic of each selected subpixel by using the data counting information of each subpixel of the selected horizontal line and the sensed characteristic sensing information of each subpixel, and the characteristic of each subpixel. The memory 700 may be updated by calculating a compensation value for compensating for the amount of change.

The compensation unit 420 compensates the image data of each subpixel by applying the updated compensation value to the memory 700 (S226), and supplies the compensated data to the driving circuit 310 of the data driver 300 for display. Data obtained by compensating for changes in characteristics of each subpixel may be displayed on the panel 100 .

As such, the display device according to an embodiment of the present invention preferentially selects subpixels whose characteristics are expected to change due to accumulated stress using data counting information, and detects changes in the characteristics of the selected subpixels in the vertical blank period of each frame. can sense

The display device according to an embodiment of the present invention determines the amount of change in characteristics of the selected subpixels by combining sensing information and data counting information of the selected subpixels, and updates the compensation value reflecting the amount of change in characteristics in a memory to change the characteristics of the subpixels. can be compensated in real time.

The display device according to an embodiment of the present invention does not require a power-on sensing time and a power-off sensing time, thereby reducing the power-on time and the power-off time, and a sub-characteristic change expected in each vertical blank period of each frame. By randomly sensing and distributing the pixels, it is possible to prevent the sensed subpixels from being recognized.

A display device according to an embodiment may be applied to various display devices. For example, a display device according to an embodiment may include a mobile device, a video phone, a smart watch, a watch phone, a wearable device, a foldable device, and a rollable device. (rollable device), bendable device, flexible device, curved device, electronic notebook, e-book, portable multimedia player (PMP), personal digital assistant (PDA), MP3 player , mobile medical device, desktop PC, laptop PC, netbook computer, workstation, navigation, vehicle navigation, vehicle display, television, wallpaper display , can be applied to display devices such as signage devices, game devices, laptop computers, monitors, cameras, camcorders, and home appliances.

Features, structures, effects, etc. described in various examples of the above-described specification are included in at least one example of the present specification, and are not necessarily limited to only one example. Furthermore, the features, structures, effects, etc. illustrated in at least one example in this specification can be combined or modified with respect to other examples by those skilled in the art to which the technical idea of this specification belongs. Therefore, contents related to these combinations and variations should be construed as being included in the technical scope or scope of rights of this specification.

The present specification described above is not limited to the foregoing embodiments and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes are possible within a range that does not deviate from the technical spirit of the present specification. It will be clear to those who have knowledge of Therefore, the scope of the present specification is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be construed as being included in the scope of the present specification.

100: display panel 200: gate driver
300: data driver 400: timing controller
500: gamma voltage generator 700: memory

Claims (10)

a panel including a plurality of subpixels;
a panel driving unit driving the display panel; and
A timing controller controlling the panel driving unit;
The timing controller
A subpixel whose characteristic change is expected is selected using data counting information of each subpixel obtained by counting the input image data for each subpixel, the characteristic of the selected subpixel is sensed through the panel driver, and the data for the selected subpixel is sensed. A display device for updating a compensation value by using counting information and sensing information on characteristics of subpixels, and compensating for image data of each subpixel by applying the updated compensation value, and outputting the image data to the panel driver. The method of claim 1,
The timing controller
For each vertical blank period of each frame, select a horizontal line on which subpixels where the characteristic change is expected are located;
A display device for sensing characteristics of each subpixel of a selected horizontal line. The method of claim 1,
The timing controller
A cumulative stress level is determined using the data counting information of each subpixel, subpixels having a large cumulative stress level are selected in each vertical blank period, and the cumulative stress level is decreasing in order for each vertical blank period. A display device that selects one horizontal line each time. counting input image data for each subpixel in a timing controller and selecting a subpixel whose characteristics are expected to change using data counting information of each subpixel;
sensing a characteristic of a selected subpixel in a panel driver;
updating a compensation value by using data counting information for a subpixel selected by the timing controller and characteristic sensing information of the subpixel; and
and compensating the image data of each subpixel by applying the compensation value updated by the timing controller and outputting the compensated image data to the panel driver. The method of claim 4,
The timing controller
For each vertical blank period of each frame, select a horizontal line on which subpixels where the characteristic change is expected are located;
A method of driving a display device for sensing characteristics of each subpixel of a selected horizontal line. The method of claim 4,
The timing controller
A cumulative stress level is determined using the data counting information of each subpixel, subpixels having a large cumulative stress level are selected in each vertical blank period, and the cumulative stress level is decreasing in order for each vertical blank period. A method of driving a display device that selects one horizontal line at each time. Selecting a subpixel whose characteristics are expected to change using data counting information of each subpixel obtained by counting the input image data for each subpixel;
Sensing the characteristics of the selected subpixel through the panel driver;
Updating a compensation value using data counting information for a selected subpixel and characteristic sensing information of the subpixel;
A timing controller that compensates and outputs the image data of each subpixel by applying the updated compensation value. The method of claim 7,
A timing controller configured to select a horizontal line in which subpixels whose characteristics are expected to change are positioned in each vertical blank period of each frame, and to sense characteristics of each subpixel of the selected horizontal line through the panel driving unit. The method of claim 7,
A cumulative stress level is determined using the data counting information of each subpixel, subpixels having a large cumulative stress level are selected in each vertical blank period, and the cumulative stress level is decreasing in order for each vertical blank period. A timing controller that selects one horizontal line at each time. The method of claim 7,
A timing controller configured to obtain counting information of each subpixel by up-counting image data of each subpixel and down-counting minimum data of each frame.

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