Display device and driving method thereof

Abstract

To enable detection of a burn-in defect of a display panel while being driven to display images.SOLUTION: Embodiments relate to a display device and driving method thereof, the display device comprising a display panel having sub-pixels arranged thereon to display an image, a power controller configured to supply a reference voltage to the sub-pixels, a sensing unit configured to sense voltage of the sub-pixels during a blank period within each frame while being driven to display an image, and a timing controller configured to detect a defect of the display panel based on the voltage sensed while being driven.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a display device and a driving method thereof. [Background technology]

[0002] Recently, display devices have been in the spotlight as they use organic light emitting diodes (OLEDs), which emit light themselves, and therefore have advantages such as a fast response time, high luminous efficiency, brightness, and a wide viewing angle.

[0003] These display devices have sub-pixels, each including an organic light-emitting diode (OLED) and a driving transistor, arranged in a matrix on a display panel, and control the brightness of the selected sub-pixels by a scanning signal based on the gray level of the data. Such display devices have various signal lines and signal transmission structures for driving.

[0004] If a defect such as an open or short circuit in a signal line or a problem with the connection or bonding of a signal transmission structure occurs, the display device may not function properly and the display panel may burn in, resulting in a panel burn-in phenomenon, which may ultimately lead to a breakdown of the display device and, in the worst case, a fire. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, it is desirable to proactively detect defects that may lead to panel burn before the panel burn phenomenon occurs. Furthermore, it is desirable to accurately identify and efficiently manage detected defects that may cause panel burn. Such management enables prompt and appropriate response when a defect occurs.

[0006] The embodiments provide a display device and a driving method thereof that can detect defects such as panel burn-in during a display driving period in which an image is displayed.

[0007] The embodiments provide a display device and a driving method thereof that can shorten the time of a real-time sensing process.

[0008] The embodiments provide a display device and a driving method thereof that improves detection accuracy by directly detecting the burn-in phenomenon through a reference voltage line in a subpixel during display driving. [Means for solving the problem]

[0009] A display device according to one embodiment may include a display panel in which subpixels are arranged and which displays an image; a power supply controller which supplies a reference voltage to the subpixels; a sensing unit which senses a voltage of the subpixels during a blank period in one frame during display driving which displays the image; and a timing controller which detects defects in the display panel based on the sensed voltage during the display driving.

[0010] The sensing unit may acquire a first sensing voltage through first sensing during a first detection period in which the reference voltage is supplied to the subpixel, and may acquire a second sensing voltage through second sensing during a second detection period in which the supply of the reference voltage is interrupted.

[0011] The display device may further include a first switch that controls a connection between the power supply controller and a reference voltage line of the subpixel, and a second switch that controls a connection between the reference voltage line and the sensing unit.

[0012] During the first detection period, the first switch is turned on, the reference voltage is supplied to the reference voltage line, the second switch is turned on, and the voltage of the reference voltage line that is fed back in response to the reference voltage is sensed; during the second detection period, the first switch is turned off, the second switch is turned on, and the voltage charged to the reference voltage line is sensed.

[0013] The timing controller may determine a defect when a difference between the first sensing voltage and the reference voltage is equal to or greater than a first threshold, and may determine a defect when a difference between the second sensing voltage and the first sensing voltage is equal to or greater than a second threshold.

[0014] The sensing unit may perform the second sensing multiple times on some of the subpixels, and the timing controller may determine that the some of the subpixels are finally defective if the number of times determined to be defective based on the second sensing results is equal to or exceeds a predetermined or selected number.

[0015] The timing controller controls the subpixel to be sensed in a first mode or a second mode, and in the first mode, senses characteristic values ​​of circuit elements included in the subpixel, and in the second mode, can detect defects in the display panel by the first sensing and the second sensing.

[0016] The subpixel may include an organic light emitting diode, a driving transistor that controls a driving current applied to the organic light emitting diode, a switching transistor that transmits a data voltage to the driving transistor, and a sensing transistor that controls a connection between the driving transistor and a reference voltage line to which the reference voltage is applied.

[0017] During the blank period, the switching transistor and the sensing transistor may be turned off.

[0018] The power supply controller may apply a display reference voltage to the reference voltage line during an active period within one frame, and may apply a sensing reference voltage at a level different from the display reference voltage to the reference voltage line during the blank period.

[0019] The sensing reference voltage may have a voltage level greater than the display reference voltage.

[0020] A method for driving a display device according to an embodiment drives the display device for one frame including an active period for displaying an image and a blank period after the active period.

[0021] The method may include a first detection step of supplying a reference voltage to a subpixel during the blank period and sensing a voltage of the subpixel while the reference voltage is being supplied to detect a defect in the display panel, and a second detection step of interrupting the supply of the reference voltage and secondly sensing the voltage of the subpixel to detect a coupling in the display panel.

[0022] The first detecting step may include the steps of interrupting application of a scanning signal and a sensing signal to the subpixel, supplying a reference voltage to the subpixel, and sensing a voltage of a reference voltage line of the subpixel that is fed back in response to the reference voltage.

[0023] The second detecting step may include the steps of interrupting the supply of the reference voltage and sensing the voltage charged to the reference voltage line.

[0024] The first detection step may include a step of comparing the difference between a first sensing voltage obtained by the sensing and the reference voltage with a first threshold, and a step of determining that there is a defect if the difference between the first sensing voltage and the reference voltage is equal to or greater than the first threshold, and the second detection step may include a step of comparing the difference between a second sensing voltage obtained by the second sensing and the first voltage with a second threshold, and a step of determining that there is a defect if the difference between the second sensing voltage and the first sensing voltage is equal to or greater than the second threshold.

[0025] The display device may include a first switch that controls a connection between a power supply controller that outputs the reference voltage and a reference voltage line of the subpixel, and a second switch that controls a connection between the reference voltage line and a sensing unit that senses the voltage of the subpixel, wherein the first detecting step may include a step of turning on the first switch and a step of turning on the second switch while the first switch is turned on, and the second detecting step may include a step of turning off the first switch and a step of turning on the second switch.

[0026] The second detection step may be performed a plurality of times, and if the number of times the subpixel is determined to be defective based on the plurality of second detection results is equal to or exceeds a predetermined or selected number of times, the subpixel may be determined to be a final defect.

[0027] The method may further include sensing a characteristic value of a circuit element included in the subpixel during the blank period in a sensing mode.

[0028] The method may further include applying a display reference voltage, which is at a level different from the reference voltage, to the subpixel during the active period. [Effects of the Invention]

[0029] The display device and the driving method thereof according to the embodiment can detect the burn-in defect of the display panel during display driving for displaying an image, thereby shortening the time required to detect the burn-in defect of the display panel and reducing the blank period.

[0030] The display device and the driving method thereof according to the embodiment can increase the driving frequency of the display device by reducing the blank period within one frame, and as a result, can quickly drive a high-brightness display device.

[0031] The display device and the driving method thereof according to the embodiment directly supplies a reference voltage to the reference voltage line and detects burn-in using the reference voltage line, thereby improving detection accuracy.

[0032] The display device and the driving method thereof according to the embodiment can detect burn-in defects in real time during display driving, allowing for quick response and preventing further damage. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a system configuration diagram of a display device according to an embodiment. [Figure 2] 1 is a diagram illustrating a sub-pixel structure of a display device according to an embodiment; [Figure 3] 10 is a diagram illustrating another sub-pixel structure and a compensation circuit of a display device according to an embodiment. [Figure 4] FIG. 4 is a diagram illustrating sensing timing of a display device according to an embodiment. [Figure 5] 1 is a diagram for explaining the operation of a real-time sensing process. [Figure 6] 1A and 1B are diagrams for explaining a panel burn-in phenomenon in a display device according to an embodiment. [Figure 7] 1 illustrates a connection relationship between a sensing unit, a timing controller, and a power supply controller in a display device according to an embodiment. [Figure 8] 1 is a diagram for explaining a burn-in detection operation according to an embodiment. [Figure 9] 9 is a diagram showing a driving state of the sub-pixel in the first detection period of FIG. 8. FIG. [Figure 10] 9 is a diagram showing a driving state of the sub-pixel in a second detection period of FIG. 8. FIG. [Figure 11] FIG. 1 is a flowchart illustrating a method for detecting burn-in according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, examples will be described with reference to the drawings. In this specification, when a component (or region, layer, portion, etc.) is referred to as being "on," "connected," or "coupled" to another component, this means that it may be directly connected / coupled to the other component, or that a third component may be disposed therebetween.

[0035] The same reference numerals refer to the same elements. In the drawings, the thickness, ratio, and dimensions of the elements are exaggerated for the purpose of effectively explaining the technical contents. "And / or" includes all one or more combinations that can define the related configuration.

[0036] Terms such as "first," "second," etc. may be used to describe various components, but the components are not limited by these terms. These terms are used only to distinguish one component from another. For example, a first component may be designated a "second component," and similarly, a second component may be designated a "first component," without departing from the scope of the present embodiment. A singular term includes a plural term unless the context clearly dictates otherwise.

[0037] Terms such as "under," "below," "on," and "above" are used to describe the relative relationships of features shown in the drawings. These terms are relative concepts and are described with reference to the directions shown in the drawings.

[0038] The use of terms such as "comprises" or "having" is intended to specify the presence of any feature, number, step, operation, component, part, or combination thereof stated in the specification, and is to be understood as not precluding the possible presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0039] 1 is a system configuration diagram of a display device 100 according to an embodiment. Referring to FIG. 1, the display device 100 according to an embodiment includes a display panel 110 on which a plurality of data lines DL1 to DLm and a plurality of gate lines GL1 to GLn are arranged, a plurality of sub-pixels SP defined by the plurality of data lines DL1 to DLm and the plurality of gate lines GL1 to GLn or located in overlapping regions thereof are arranged in a matrix, a data driver 120 for driving the plurality of data lines DL1 to DLm, a gate driver 130 for driving the plurality of gate lines GL1 to GLn, and a timing controller 140 for controlling the data driver 120 and the gate driver 130.

[0040] The timing controller 140 controls the data driver 120 and the gate driver 130 by supplying various control signals to the data driver 120 and the gate driver 130.

[0041] The timing controller 140 starts scanning according to the timing of each frame, converts input image data input from the outside into a data signal format used by the data driver 120, outputs the converted image data, and controls data driving at an appropriate time according to the scanning.

[0042] The data driver 120 drives the data lines DL1 to DLm by supplying data voltages to the data lines DL1 to DLm. Here, the data driver 120 is also called a "source driver." The data driver 120 includes at least one source driver integrated circuit (SDIC) and can drive the data lines DL1 to DLm.

[0043] The gate driver 130 sequentially drives the gate lines GL1 to GLn by supplying scan signals to the gate lines GL1 to GLn. Here, the gate driver 130 is also referred to as a "scan driver." The gate driver 130 includes at least one gate driver integrated circuit (GDIC) and can drive the gate lines GL1 to GLn.

[0044] The gate driver 130 sequentially supplies a scan signal of an on voltage or an off voltage to the gate lines GL1 to GLn under the control of the timing controller 140.

[0045] When a specific gate line is opened by the gate driver 130, the data driver 120 converts the image data received from the timing controller 140 into an analog data voltage and supplies it to the plurality of data lines DL1 to DLm.

[0046] In FIG. 1, the data driver 120 is located on only one side (e.g., the top or bottom) of the display panel 110, but it can also be located on both sides (e.g., the top and bottom) of the display panel 110 depending on the driving method, panel design method, etc.

[0047] In FIG. 1, the gate driver 130 is located on only one side (e.g., the left or right side) of the display panel 110, but it can also be located on both sides (e.g., the left and right sides) of the display panel 110 depending on the driving method, panel design method, etc.

[0048] The timing controller 140 described above receives various timing signals, including a vertical synchronization signal, a horizontal synchronization signal, an input data enable signal, a clock signal, and the like, along with input video data from an external device (eg, a host system).

[0049] The timing controller 140 receives timing signals such as a vertical synchronization signal, a horizontal synchronization signal, an input DE signal, and a clock signal to control the data driver 120 and the gate driver 130, generates various control signals, and outputs them to the data driver 120 and the gate driver 130.

[0050] For example, the timing controller 140 outputs various gate control signals (GCS) including a gate start pulse, a gate shift clock, a gate output enable signal, etc. to control the gate driver 130.

[0051] The timing controller 140 also outputs various data control signals (DCS) including a source start pulse, a source sampling clock, a source output enable signal, etc. to control the data driver 120.

[0052] Each sub-pixel (SP) arranged in the display panel 110 may be configured to include a circuit element such as a transistor. For example, each sub-pixel (SP) may be configured to include an organic light emitting diode (OLED) and a circuit element such as a driving transistor for driving the OLED. The type and number of circuit elements constituting each sub-pixel (SP) may be determined in various ways depending on the intended function and design method.

[0053] FIG. 2 is a diagram illustrating the structure of a sub-pixel (SP) of a display device (100) according to an embodiment.

[0054] Referring to FIG. 2, in a display device 100 according to an embodiment, each subpixel may basically include an organic light emitting diode (OLED), a driving transistor (DRT) that controls a driving current applied to the organic light emitting diode (OLED), a switching transistor (SWT) that transfers a data voltage to a gate node of the driving transistor (DRT), and a storage capacitor (Cstg) that maintains a data voltage corresponding to an image signal voltage or a voltage corresponding thereto for one frame time.

[0055] An organic light-emitting diode (OLED) may include a first electrode (eg, an anode electrode), an organic layer, and a second electrode (eg, a cathode electrode).

[0056] The driving transistor (DRT) drives the organic light emitting diode (OLED) by supplying a driving current to the organic light emitting diode (OLED). In the driving transistor (DRT), the first node (N1) may be electrically connected to a first electrode of the organic light emitting diode (OLED) and may be a source node or a drain node. The second node (N2) may be electrically connected to a source node or a drain node of the switching transistor (SWT) and may be a gate node. The third node (N3) may be electrically connected to a driving voltage line (DVL) that supplies a high potential driving voltage (EVDD) and may be a drain node or a source node.

[0057] The switching transistor (SWT) may be electrically connected between the data line (DL) and the second node (N2) of the driving transistor (DRT), and may be controlled by applying a scan signal (SCAN) to the gate node via the gate line. The switching transistor (SWT) may be turned on by the scan signal (SCAN) and transfer a data voltage (Vdata) supplied from the data line (DL) to the second node (N2) of the driving transistor (DRT).

[0058] The storage capacitor (Cstg) may be electrically connected between the first node (N1) and the second node (N2) of the drive transistor (DRT). Such a storage capacitor (Cstg) is not a parasitic capacitor, which is an internal capacitor, present between the first node (N1) and the second node (N2) of the drive transistor (DRT), but is an external capacitor intentionally designed outside the drive transistor (DRT).

[0059] Meanwhile, in the display device 100 according to an embodiment, as the driving time of each subpixel SP increases, degradation of circuit elements such as an organic light emitting diode (OLED) and a driving transistor (DRT) may progress. This may cause changes in the inherent characteristic values ​​of the circuit elements. Here, the characteristic values ​​of the circuit elements may include the threshold voltage and mobility of the driving transistor (DRT) and the threshold voltage of the organic light emitting diode (OLED). Such changes in the characteristic values ​​of the circuit elements cause changes in the luminance of the corresponding subpixel, reducing the luminance uniformity of the display panel 110 and degrading image quality.

[0060] The display device (100) according to one embodiment can provide a sensing function for sensing characteristic values ​​or changes in characteristic values ​​of circuit elements, and a compensation function for compensating for characteristic value deviations between circuit elements using the sensing results.

[0061] FIG. 3 is a diagram illustrating another sub-pixel structure and compensation circuit of a display device 100 according to an embodiment.

[0062] Referring to FIG. 3, each subpixel arranged in a display panel 110 according to one embodiment may further include, for example, a sensing transistor (SENT) in addition to an organic light emitting diode (OLED), a driving transistor (DRT), a switching transistor (SWT), and a storage capacitor (Cstg).

[0063] The sensing transistor (SENT) may be electrically connected between the first node (N1) of the driving transistor (DRT) and a reference voltage line (RVL) that supplies a reference voltage (Vprer), and may be controlled by applying a sensing signal (SENSE), which is a type of scan signal, to a gate node. The sensing transistor (SENT) is turned on by the sensing signal (SENSE) and applies the reference voltage (Vprer), which is supplied via the reference voltage line (RVL), to the first node (N1) of the driving transistor (DRT). The sensing transistor (SENT) may also be used as one of the voltage sensing paths for the first node (N1) of the driving transistor (DRT).

[0064] Alternatively, the scan signal (SCAN) and the sensing signal (SENSE) may be separate gate signals. In this case, the scan signal (SCAN) and the sensing signal (SENSE) may be applied to the gate node of the switching transistor (SWT) and the gate node of the sensing transistor (SENT), respectively, via separate gate lines. In another embodiment, the scan signal (SCAN) and the sensing signal (SENSE) may be the same gate signal. In this case, the scan signal (SCAN) and the sensing signal (SENSE) may be commonly applied to the gate node of the switching transistor (SWT) and the gate node of the sensing transistor (SENT) via the same gate line.

[0065] The driving transistor (DRT), the switching transistor (SWT), and the sensing transistor (SENT) may be configured as either an n-type or a p-type.

[0066] Referring to FIG. 3, a display device (100) according to one embodiment may include a sensing unit or circuit (310) that senses a characteristic value of a sub-pixel (characteristic value of a driving transistor, characteristic value of an organic light emitting diode) or an electrical signal (e.g., voltage) reflecting a change therein, converts the sensed electrical signal into a digital value, and outputs the digital value as sensing data (Vsen), a memory (320) that stores the sensing data (Vsen), and a compensation unit or circuit (330) that performs a compensation process to compensate for the characteristic value or characteristic value deviation of the sub-pixel using the sensing data (Vsen).

[0067] The sensing unit 310 may include at least one analog-to-digital converter. Each analog-to-digital converter may be included within a source driver integrated circuit (SDIC), or may be included outside the source driver integrated circuit (SDIC) in some cases. The sensing data output from the sensing unit 310 may be in a Low Voltage Differential Signaling (LVDS) data format, for example.

[0068] The compensation unit 330 may be included inside the timing controller 140, or in some cases, may be included outside the timing controller 140.

[0069] In one embodiment, the display device (100) may include a first switch (SW1) that controls whether or not a reference voltage (Vprer) is supplied to the reference voltage line (RVL) in order to control the sensing drive, and a second switch (SW2) that switches the connection between the reference voltage line (RVL) and the sensing unit (310).

[0070] The first switch (SW1) controls a connection between the power supply controller and the reference voltage line (RVL). When the first switch (SW1) is turned on, the reference voltage (Vprer) is supplied to the reference voltage line (RVL). The reference voltage (Vprer) supplied to the reference voltage line (RVL) may be applied to the first node (N1) of the drive transistor (DRT) through the turned-on sensing transistor (SENT).

[0071] Meanwhile, when the voltage of the first node (N1) of the driving transistor (DRT) becomes a voltage state reflecting the characteristic value of the sub-pixel, the voltage of the reference voltage line (RVL), which may be at the same potential as the first node (N1) of the driving transistor (DRT), may also become a voltage state reflecting the characteristic value of the sub-pixel. At this time, a line capacitor formed on the reference voltage line (RVL) may be charged with a voltage reflecting the characteristic value of the sub-pixel. That is, when the sensing transistor (SENT) is turned on, the voltage of the first node (N1) of the driving transistor (DRT) may be the same as the voltage of the reference voltage line (RVL) and the voltage charged in the line capacitor formed on the reference voltage line (RVL).

[0072] When the voltage of the first node N1 of the driving transistor DRT reaches a voltage state reflecting the characteristic value of the subpixel, the second switch SW2 is turned on, connecting the sensing unit 310 to the reference voltage line RVL. As a result, the sensing unit 310 senses the voltage of the reference voltage line RVL, which is a voltage state reflecting the characteristic value of the subpixel. Here, the reference voltage line RVL is also referred to as a sensing line. That is, the sensing unit 310 senses the voltage of the first node N1 of the driving transistor DRT.

[0073] For example, such a reference voltage line (RVL) may be arranged for each subpixel column, or for each two or more subpixel columns. For example, if one pixel is composed of four subpixels (red subpixels, white subpixels, green subpixels, and blue subpixels), one reference voltage line (RVL) may be arranged for each pixel column including four subpixel columns (red subpixel column, white subpixel column, green subpixel column, and blue subpixel column).

[0074] The voltage sensed by the sensing unit 310 may be a voltage value (Vdata-Vth or Vdata-ΔVth) including the threshold voltage (Vth) or a threshold voltage change (ΔVth) of the driving transistor (DRT) in the case of sensing the threshold voltage of the driving transistor (DRT). Also, the voltage sensed by the sensing unit 310 may be a voltage value for sensing the mobility of the driving transistor (DRT) in the case of mobility sensing of the driving transistor (DRT).

[0075] The sensing unit 310 converts the sensed voltage into a digital value, generates and outputs sensing data Vsen including the converted digital value (sensing value). The sensing data Vsen output from the sensing unit 310 may be stored in the memory 320 or provided to the compensation unit 330.

[0076] The compensation unit 330 can determine the characteristic value (e.g., threshold voltage, mobility) of the driving transistor (DRT) in the corresponding subpixel or a change in the characteristic value (e.g., change in threshold voltage, change in mobility) of the driving transistor (DRT) based on the sensing data stored in the memory 320 or provided from the sensing unit 310, and perform a characteristic value compensation process.

[0077] Here, the change in the characteristic value of the drive transistor (DRT) may mean that the current sensing data (Vsen) has changed based on the previous sensing data (Vsen), or may mean that the current sensing data (Vsen) has changed based on the reference sensing data (Vsen).

[0078] Here, by comparing the characteristic values ​​or changes in the characteristic values ​​between the drive transistors (DRT), it is possible to determine the deviation in the characteristic values ​​between the drive transistors (DRT). If the change in the characteristic value of the drive transistor (DRT) means that the current sensing data (Vsen) has changed based on the reference sensing data (Vsen), it is also possible to determine the deviation in the characteristic value (i.e., sub-pixel luminance deviation) between the drive transistors (DRT) from the change in the characteristic value of the drive transistor (DRT).

[0079] The characteristic value compensation process may include a threshold voltage compensation process for compensating for the threshold voltage of the drive transistor (DRT) and a mobility compensation process for compensating for the mobility of the drive transistor (DRT). The compensator 330 may modify the image data (Data) through the threshold voltage compensation process or the mobility compensation process and supply the modified data to a corresponding source driver integrated circuit (SDIC) in the data driver 120. The corresponding source driver integrated circuit (SDIC) then converts the data modified by the compensator 330 into a data voltage using a digital-to-analog converter 340 and supplies the data to the corresponding subpixel, thereby actually performing characteristic value compensation for the subpixel. This subpixel characteristic value compensation reduces or prevents brightness deviations between subpixels, thereby improving brightness uniformity of the display panel 110 and improving image quality.

[0080] FIG. 4 is a diagram showing the sensing timing of the display device 100 according to an embodiment, and FIG. 5 is a diagram for explaining the operation of the real-time sensing process.

[0081] 4, a display device 100 according to an embodiment may sense characteristic values ​​of circuit elements in each sub-pixel disposed on a display panel 110 after a power-off signal is generated by a user input, etc. Such sensing performed after the generation of the power-off signal is referred to as “off sensing.”

[0082] In addition, the display device 100 according to an embodiment may sense characteristic values ​​of circuit elements in each subpixel disposed in the display panel 110 after a power-on signal is generated by a user input, etc., and before display driving (normal driving) is started. This sensing performed after the power-on signal is generated and before display driving is started is referred to as "on sensing."

[0083] In addition, the display device 100 according to an embodiment may sense characteristic values ​​of circuit elements in each subpixel arranged on the display panel 110 during display driving. Sensing performed during display driving in this manner is called "real time sensing (RT sensing)." Real time sensing may be performed every blank time between active times based on a vertical synchronization signal.

[0084] Meanwhile, if one or more of the signal lines (DL, RVL, GL, DVL) arranged on the display panel 110 are open or two or more of the signal lines are shorted, an abnormal sensing value may be obtained. Therefore, if the difference between the sensing value obtained through the above-mentioned sensing process and the reference sensing value (the sensing value obtained when the signal lines are normal) exceeds a predetermined range, it can be determined that the signal line is defective.

[0085] 5, real-time sensing can be performed during blank periods between active periods activated by a data enable signal (DEN) within a frame divided based on a vertical synchronization signal (Vsync). Here, the active period is a period during which the data driver 120 outputs a data voltage (Vdata) through the plurality of data lines (DL1 to DLm) while the gate driver 130 sequentially drives the plurality of gate lines (GL1 to GLn).

[0086] In one embodiment, sensing of characteristic values ​​in the real-time sensing process may be performed for pixel lines connected to one or more selected gate lines (GL1 to GLn) during one blank period. Also, sensing of characteristic values ​​may be performed for sub-pixels (SP) of a specific color on one or more selected pixel lines during one blank period. Sensing of characteristic values ​​may be performed for pixel lines in sequence during multiple blank periods.

[0087] As the brightness of the display panel 110 increases, the length of the active period for programming the data voltage Vdata to the subpixels SP can become longer. For a given driving frequency, as the active time becomes longer, a shorter blank time is more beneficial. This requires a method that can complete a real-time sensing process within a short time.

[0088] FIG. 6 is a diagram for explaining the panel burn phenomenon in the display device 100 according to one embodiment.

[0089] Referring to FIG. 6, the data driver 120 includes at least one source driver integrated circuit (SDIC) and can drive a plurality of data lines DL1 to DLm.

[0090] Each source driver integrated circuit (SDIC) may be connected to a bonding pad of the display panel 110 by tape automated bonding or chip on glass, or may be directly disposed on the display panel 110, or may be integrated into the display panel 110 in some cases. Also, each source driver integrated circuit (SDIC) may be configured as a chip on film, mounted on a source-side film (FS) connected to the display panel 110, as shown in FIG. 2.

[0091] Each source driver integrated circuit (SDIC) may include a shift register, a latch circuit, a digital to analog converter, an output buffer, etc. Each source driver integrated circuit (SDIC) may further include an analog to digital converter in some cases.

[0092] The gate driver 130 includes at least one gate driver integrated circuit (GDIC) and can drive a plurality of gate lines (GL1 to GLn). Each gate driver integrated circuit (GDIC) can be connected to a bonding pad of the display panel 110 using tape automated bonding or chip-on-glass technology, or can be configured as a GIP (Gate In Panel) type and directly mounted on the display panel 110. In some cases, it can be integrated into the display panel 110. Also, as shown in FIG. 6, each gate driver integrated circuit (GDIC) can be configured as a chip-on-film type and mounted on a gate-side film (FG) connected to the display panel 110. Each gate driver integrated circuit (GDIC) can include a shift register, a level shifter, etc.

[0093] According to an embodiment, the display device 100 may include at least one source printed circuit board (S-PCB) required for circuit connection to at least one source driver integrated circuit (SDIC) and a control printed circuit board (C-PCB) for mounting control components and various electrical devices. At least one source driver integrated circuit (SDIC) may be mounted on the at least one source printed circuit board (S-PCB), or a source side film (FS) on which at least one source driver integrated circuit (SDIC) is mounted may be connected. The control printed circuit board (C-PCB) may also include a timing controller 140 for controlling the operation of the data driver 120 and gate driver 130, and a power supply controller for supplying or controlling various voltages or currents to the display panel 110, data driver 120, and gate driver 130. At least one source printed circuit board (S-PCB) and a control printed circuit board (C-PCB) may be circuit-connected via at least one flexible flat cable (FFC1).

[0094] The display device 100 may further include a main printed circuit board (M-PCB) on which a main controller (M-CON) and other components are mounted, in addition to at least one source printed circuit board (S-PCB) and control printed circuit board (C-PCB). The main printed circuit board (M-PCB) may be connected to the control printed circuit board (C-PCB) via at least one flexible flat cable (FFC2). Two or more of the at least one source printed circuit board (S-PCB), control printed circuit board (C-PCB), and main printed circuit board (M-PCB) may be integrated into a single printed circuit board.

[0095] In one embodiment, the display panel 110 may experience panel burn-in due to various defects, such as shorts or opens in signal lines (DL, GL, DVL, RVL, gate voltage wiring, etc.) arranged on the display panel 110, bonding errors between the display panel 110 and the gate-side film (FG) or source-side film (FS), electrical connection problems between the source printed circuit board (S-PCB) and the control printed circuit board (C-PCB) due to, for example, an unconnected flexible flat cable (FFC1), and electrical connection problems between the control printed circuit board (C-PCB) and the main printed circuit board (M-PCB) due to, for example, an unconnected flexible flat cable (FFC2).

[0096] If such a defect occurs, the display panel 110 may burn in, causing a panel burn-in phenomenon, which may prevent the display device 100 from operating normally, and may even cause the display device 100 to malfunction, or in the worst case, lead to a fire.

[0097] Therefore, it is absolutely necessary to detect defects that cause panel burn-in before they actually occur, so that immediate and appropriate measures can be taken when a defect occurs.

[0098] In one embodiment, the detection of burn-in may be performed during the on-sensing process, the off-sensing process, and / or the real-time sensing process. For example, the detection of burn-in may be performed before or after the sensing of the characteristic values ​​of the sub-pixels described above. In another embodiment, the sensing of the characteristic values ​​of the sub-pixels may be omitted during the real-time sensing process, and only the detection of burn-in may be performed. In this case, a very short blank period may be configured by minimizing or shortening the time required for the detection of burn-in.

[0099] The following describes in more detail how to detect panel burn-in during the sensing process.

[0100] FIG. 7 illustrates a connection relationship between a sensing unit, a timing controller, and a power controller in a display device according to an embodiment.

[0101] Referring to FIG. 7, a display device 100 according to an embodiment includes a timing controller 140, a power controller 900, and a sensing unit 310.

[0102] The sensing unit 310 may perform panel sensing based on a control signal received from the timing controller 140. In one embodiment, the sensing unit 310 may be controlled to perform sensing in either a first mode or a second mode during a real-time sensing process. In the first mode, the sensing unit 310 may sense characteristic values ​​of the sub-pixels (SP), such as threshold voltages and mobilities. In the first mode, a scan signal (SCAN), a sensing signal (SENSE), and a sensing data voltage (Vdata) may be applied to the sub-pixels (SP). In the second mode, the sensing unit 310 may perform sensing for detecting defects such as panel burn-in. In the second mode, the scan signal (SCAN), the sensing signal (SENSE), and the sensing data voltage (Vdata) may not be applied to the sub-pixels (SP).

[0103] In order to sense the characteristic value of the sub-pixel (SP), a time is required for the first node (N1) of the sub-pixel (SP) to be charged, so a relatively long blank period may be required in the first mode. To shorten the blank period, sensing the characteristic value of the sub-pixel (SP) may be omitted. In this case, the second mode may be performed to detect defects such as panel burn-in. A pattern detection method for minimizing or shortening the length of the blank period in the second mode will be described with reference to FIGS. 8 to 10.

[0104] The timing controller 140 can detect the characteristic value of the sub-pixels SP and / or panel burn-in based on the sensing data Vsen transmitted via the sensing unit 310. The timing controller can perform a compensation process to compensate the data voltage Vdata based on the characteristic value of the sub-pixels SP.

[0105] When burn-in is detected, the timing controller 140 may generate and output a corresponding BDP signal (BDP). In one embodiment, the timing controller 140 may output the BDP signal (BDP) to an external host system or the like.

[0106] The timing controller 140 may perform a power-off process based on the burn-in detection result. For example, the timing controller 140 may perform a power-off process for a high-potential driving voltage (EVDD) for driving an organic light-emitting diode (OLED). Such a power-off process by the timing controller 140 can prevent further damage to the display panel 110.

[0107] The power supply controller 900 may apply a driving voltage to the subpixel (SP). The power supply controller 900 may also apply a reference voltage (Vprer) to the reference voltage line (RVL) of the subpixel (SP). The power supply controller 900 may apply a first level reference voltage to the subpixel (SP) during an active period within one frame, and a second level reference voltage to the subpixel (SP) during a blank period. The first and second levels may be different voltage levels, and the first level reference voltage may be referred to as a "display reference voltage," and the second level reference voltage may be referred to as a "sensing reference voltage." The sensing reference voltage may be applied at different levels for first-mode sensing and second-mode sensing.

[0108] Fig. 8 is a diagram illustrating a burn-in detection operation according to one embodiment. Fig. 9 is a diagram illustrating a driving state of the sub-pixel in a first detection period of Fig. 8. Fig. 10 is a diagram illustrating a driving state of the sub-pixel in a second detection period of Fig. 8.

[0109] 8, during a blank time in one frame, a data voltage (Vdata) is not applied to the subpixel (SP). Also, during the blank time, a scan signal (SCAN) and a sensing signal (SENSE) are not applied to the subpixel (SP). Then, the switching transistor (SWT) and the sensing transistor (SENT) in the subpixel (SP) are turned off, and the reference voltage line (RVL) can be isolated from the circuit elements of the subpixel (SP).

[0110] The blank period may include a first detection period (T1, first detection step) and a second detection period (T2, second detection step).

[0111] The first detection period (T1) is a period for sensing the reference voltage (Vprer) output through the reference voltage line (RVL). Referring to Figure 9, during the first detection period (T1), the first switch (SW1) is turned on and the reference voltage (Vprer) (e.g., a reference voltage for sensing) is applied to the reference voltage line (RVL).

[0112] Here, the magnitude of the reference voltage (Vprere) is not particularly limited. However, the reference voltage (Vprere) may be set to a level large enough to detect the occurrence of leakage during a second detection period (T2) described below. To this end, in the real-time sensing processor, the second level of the reference voltage (Vprere) may be higher than the first level of the reference voltage (Vprere) provided during display driving in the active period, for example, but not limited to, about 5V or more.

[0113] While the reference voltage (Vprer) is applied, the second switch (SW2) is turned on at least once in response to the sampling signal (SAM). Then, the voltage of the reference voltage line (RVL) fed back in response to the reference voltage (Vprer) can be sensed by the sensing unit 310. In one embodiment, the turn-on period of the second switch (SW2) may be, but is not limited to, about 1 us.

[0114] If the corresponding subpixel (SP) does not have a defect such as burn-in, the reference voltage (Vprer) applied to the reference voltage line (RVL) and the sensing voltage of the reference voltage line (RVL) (hereinafter referred to as the first sensing voltage) may be substantially the same in magnitude. On the other hand, if the corresponding subpixel (SP) has burn-in, current leaks from the reference voltage line (RVL), so the first sensing voltage may be lower than the applied reference voltage (Vprer).

[0115] The sensing unit 310 converts the first sensing voltage into sensing data Vsen and provides the sensing data Vsen to the timing controller 140. The timing controller 140 can detect burn-in based on the sensing data Vsen. For example, the timing controller 140 can determine that burn-in has occurred in a corresponding subpixel SP when a difference between the reference voltage Vprer and the first sensing voltage is equal to or greater than a preset or selected first threshold.

[0116] When performing real-time sensing on a pixel line basis during one blank period, the timing controller 140 may determine that burn-in has occurred in a pixel row if the average value of the first sensing voltage measured in one pixel line is equal to or greater than the preset or selected first threshold value. Alternatively, the timing controller 140 may finally determine that burn-in has occurred in the pixel row if the number of sub-pixels SP determined to have burn-in in one pixel line is greater than a preset or selected value.

[0117] Meanwhile, if the reference voltage (Vprer) is applied for a sufficient time during the first detection period (T1), the reference voltage line (RVL) may be charged to the reference voltage (Vprer) (Vchg) as shown in FIG. 10. Then, if the supply of the reference voltage (Vprer) is interrupted, the reference voltage line (RVL) becomes floating. The interruption of the supply includes, for example, the first switch being opened, which causes the reference voltage Vprer to no longer be supplied to the reference voltage line RVL. Note that "floating" includes the meaning of being electrically isolated from the power supply control unit 900 and shorted to, for example, a power supply node via a subpixel having a burn defect. Because the first switch is open, RVL may become floating with respect to the power controller 900.

[0118] At this time, if there is no defect in the reference voltage line (RVL), the charged voltage (Vchg) should be maintained. However, if a burn-in defect such as a short occurs in the reference voltage line (RVL), the charged voltage (Vchg) of the reference voltage line (RVL) may decrease due to leakage. For example, if a reference voltage (Vprer) of approximately 5V is applied during the first detection period (T1), the charged voltage (Vchg) of the reference voltage line (RVL) where the defect occurs may decrease to approximately 1 to 2V due to leakage.

[0119] In order to detect such short defects, the blank period further includes a second detection period T2, which is a period for sensing the charging voltage Vchg of the floating reference voltage line RVL.

[0120] During the second detection period T2, the second switch SW2 is turned on at least once in response to the sampling signal SAM, and the voltage charged on the reference voltage line RVL is sensed via the sensing unit 310. In one embodiment, the turn-on period of the second switch SW2 may be, but is not limited to, approximately 1 us.

[0121] The sensing unit 310 converts the sensed voltage (hereinafter, referred to as a second sensing voltage) into sensing data Vsen and provides the sensing data Vsen to the timing controller 140. The timing controller 140 can detect burn-in based on the sensing data Vsen. For example, the timing controller 140 can determine that burn-in has occurred in a corresponding subpixel SP when a difference between the reference voltage Vprer or the first sensing voltage acquired in the first detection and the second sensing voltage is equal to or greater than a preset or selected second threshold.

[0122] Generally, voltage fluctuations due to leakage are small and may not be easy to measure. Accordingly, the display device 100 according to one embodiment may sense the charging voltage of the reference voltage line RVL for each subpixel SP multiple times. In this embodiment, the timing controller 140 may ultimately determine that a subpixel SP has burned in a case where burn-in is detected in the subpixel SP a predetermined or selected number of times or more.

[0123] In one embodiment, multiple second detection periods (T2) may be included in one blank period. That is, the timing controller 140 may perform multiple second detections on the same sub-pixel (SP) (or pixel line) during one blank period. Alternatively, to prevent the blank period from becoming too long, the timing controller 140 may perform multiple second detections on the same sub-pixel (SP) (or pixel line) over multiple blank periods spanning multiple frames.

[0124] As described above, the display device 100 according to one embodiment can detect defects such as panel burn-in in real time during display driving in which an image is displayed through the display panel 110. When panel burn-in is detected during display driving, real-time sensing in which characteristic values ​​of the sub-pixels (SP) are sensed may be omitted.

[0125] Specifically, the defect detection performed during display driving may be performed through a first detection period (T1) and a second detection period (T2) during a blank period. The turn-on period of the second switch (SW2) during the first detection period (T1) and the turn-on period of the second switch (SW2) during the second detection period (T2) may be set to have an interval of approximately 1 to several tens of microseconds. That is, the display device (100) according to this embodiment can detect burn-in more accurately by performing the first detection (i.e., detection of the output voltage of the reference voltage line (RVL) relative to the reference voltage (Vprer)) and the second detection (i.e., detection of the floating voltage of the reference voltage line (RVL)) within a short time interval, thereby significantly shortening the blank period.

[0126] 11 is a flowchart illustrating a method for detecting image sticking according to an embodiment. Referring to FIG. 11, the method for driving the display device 100 according to an embodiment detects defects such as panel sticking during display driving in which an image is displayed.

[0127] The driving method includes a step S2210 of turning off the sensing signal (SENSE) switching transistor (SWT) and the sensing transistor (SENT) by controlling a scan signal (SCAN) applied to the subpixel (SP) to a turn-off level during a blank period within one frame, and a step S2220 of turning on a first switch (SW1) to apply a reference voltage (Vprer) to a reference voltage line (RVL). The driving method further includes a step S2230 of first turning on a sampling signal (SAM) to obtain a first sensing voltage (Vsen1) of the reference voltage line (RVL) while the reference voltage (Vprer) is being applied, and a step S2250 of determining that burn-in has occurred if a difference between the reference voltage (Vprer) and the first sensing voltage (Vsen1) is equal to or greater than a first threshold (TH1) (S2240).

[0128] If the difference between the reference voltage (Vprer) and the first sensing voltage (Vsen1) is not equal to or greater than the first threshold (TH1), the driving method further includes the step of interrupting the application of the reference voltage (Vprer) and turning on the second switch (SW2) a second time to acquire a second sensing voltage (Vsen2) of the reference voltage line (RVL) (S2260), and if the difference between the first sensing voltage (Vsen1) and the second sensing voltage (Vsen2) is equal to or greater than the second threshold (TH2) (S2270), the step of incrementing a count value (Count) (S2280). The driving method may perform N-th sensing of the second sensing voltage (Vsen2) while repeatedly turning on and off the second switch (SW2) N times, and determine whether the difference between the first sensing voltage (Vsen1) and the second sensing voltage (Vsen2) is equal to or greater than the second threshold (TH2) (S2290). The driving method further includes a step of determining that burn-in has occurred (S2310) if the final count value (Count) is greater than a third threshold value (TH3) (S2300).

[0129] According to the above driving method, the time required to detect burn-in defects in the display panel 110 can be shortened, the blank period can be reduced, and the reference voltage is directly supplied to the reference voltage line and the burn-in is detected using the reference voltage line, thereby improving the detection accuracy.

[0130] Although the present invention has been described above with reference to the accompanying drawings, those skilled in the art will understand that the technical configuration of the present invention described above can be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and not limiting. At the same time, the scope of the present invention is defined by the claims that follow rather than the above detailed description. Furthermore, all modifications and variations derived from the meaning and scope of the claims and their equivalents should be construed as being within the scope of the present invention. [Explanation of symbols]

[0131] 100:Display device 110: Display panel 120: Data Driver 130: Gate driver 140: Timing controller

Claims

1. a display panel in which subpixels are arranged and which displays an image; a power supply controller for supplying a reference voltage to the subpixel; a sensing unit that senses a voltage of the subpixel during a blank period within one frame; a timing controller that detects a defect in the display panel based on the sensed voltage during the blank period; obtaining a first sensing voltage by first sensing during a first sensing period in which the reference voltage is supplied to the subpixel; The display device further comprises: a display device configured to acquire a second sensing voltage by second sensing during a second sensing period in which the supply of the reference voltage is interrupted;

2. a reference voltage line connected to the subpixel; a first switch controlling a first connection between the power supply controller and the reference voltage line of the subpixel; The display device of claim 1 , further comprising: a second switch that controls a second connection between the reference voltage line and the sensing unit.

3. During the first detection period, the first switch is turned on, the reference voltage is supplied to the reference voltage line, and the second switch is turned on; a voltage of the reference voltage line that is fed back in response to the reference voltage is sensed; The display device of claim 2 , wherein during the second detection period, the first switch is turned off, the second switch is turned on, and the voltage charged to the reference voltage line is sensed.

4. The timing controller 2. The display device of claim 1, wherein a defect is determined when a difference between the first sensing voltage and the reference voltage is equal to or greater than a first threshold, and a defect is determined when a difference between the second sensing voltage and the first sensing voltage is equal to or greater than a second threshold.

5. The sensing unit performing the second sensing a plurality of times on some subpixels among the plurality of subpixels; The timing controller The display device of claim 4 , wherein the display device determines the partial sub-pixels as being finally defective when the number of times determined as defects based on the second sensing result is equal to or exceeds a predetermined number.

6. The timing controller Controlling the sub-pixel to sense in a first mode or a second mode; In the first mode, sensing a characteristic value of a circuit element included in the subpixel; The display device according to claim 1 , wherein in the second mode, defects of the display panel are detected by the first sensing and the second sensing.

7. The subpixels are an organic light-emitting diode; a driving transistor for controlling a driving current applied to the organic light emitting diode; a switching transistor for transmitting a data voltage to the driving transistor; 2. The display device according to claim 1, further comprising: a sensing transistor that controls a connection between the driving transistor and a reference voltage line to which the reference voltage is applied.

8. The display device of claim 7 , wherein the switching transistor and the sensing transistor are turned off during the blank period.

9. The power supply controller 8. The display device of claim 7, wherein a display reference voltage is applied to the reference voltage line during an active period within one frame, and a sensing reference voltage having a level different from the display reference voltage is applied to the reference voltage line during the blank period.

10. The display device of claim 9 , wherein the sensing reference voltage has a voltage level greater than the display reference voltage.

11. A method for driving a display device during one frame including an active period for displaying a video and a blank period after the active period, comprising: a first detection step of supplying a reference voltage to a subpixel during the blank period, and first sensing a voltage of the subpixel while the reference voltage is being supplied, thereby detecting a defect in the display panel; a second detecting step of interrupting the supply of the reference voltage during the blanking period and second sensing the voltage of the subpixel to detect a coupling of the display panel.

12. The first detection step interrupting application of the scanning signal and the sensing signal to the subpixel; applying the reference voltage to the subpixel; and sensing a voltage on a reference voltage line of the subpixel that is fed back in response to the reference voltage.

13. The second detection step interrupting the supply of the reference voltage; and sensing the voltage charged to the reference voltage line.

14. The first detection step comparing a difference between a first sensing voltage acquired by the first sensing and the reference voltage with a first threshold; determining that a defect has occurred when a difference between the first sensing voltage and the reference voltage is equal to or greater than the first threshold value; The second detection step comparing a difference between a second sensing voltage obtained by the second sensing and the first sensing voltage with a second threshold; The method of claim 11 , further comprising determining a defect when a difference between the second sensing voltage and the first sensing voltage is equal to or greater than the second threshold.

15. the display device includes a first switch that controls a connection between a power supply controller that outputs the reference voltage and a reference voltage line of the subpixel, and a second switch that controls a connection between the reference voltage line and a sensing unit that senses the voltage of the subpixel, The first detection step turning on the first switch; and turning on the second switch while the first switch is turned on; The second detection step turning off the first switch; and turning on the second switch.

16. The method according to claim 11 , wherein the second detection step is performed a plurality of times, and when the number of times the subpixel is determined to be a defect based on the plurality of second detection results is equal to or exceeds a predetermined number, the subpixel is determined to be a final defect.

17. The method of claim 11 , further comprising sensing a characteristic value of a circuit element included in the subpixel during the blank period in a sensing mode.

18. The method of claim 11 , further comprising applying a display reference voltage to the subpixel during the active period, the display reference voltage being at a level different from the reference voltage.

19. a display panel in which subpixels are arranged; a reference voltage line associated with said subpixel; a power controller that provides a reference voltage; a detection circuit for detecting a voltage on the reference voltage line; a first switch that connects the reference voltage line to the power controller during a first detection period during a blank period in one frame, charges the reference voltage line with the reference voltage, and disconnects the reference voltage line from the power controller during a second detection period following the first detection period; a second switch that connects the reference voltage line to the detection circuit in response to a sampling signal during the first and second detection periods; and a timing controller that detects defects in the subpixel based on at least one of a first detection voltage generated by the detection circuit by sampling the voltage on the reference voltage line during the first detection period and a second detection voltage generated by the detection circuit by sampling the voltage on the reference voltage line during the second detection period.

20. The timing controller determining whether a difference between the reference voltage and the first detection voltage exceeds a first threshold during the first detection period, and determining that a defect exists in the subpixel in response to the difference exceeding the first threshold; 20. The display device of claim 19, wherein during the second detection period, it is determined whether a difference between the first detection voltage and the second detection voltage exceeds a second threshold, and in response to the difference exceeding the second threshold, it is determined that a defect exists in the subpixel.

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