Display device and driving method thereof

Abstract

Disclosed is a display device including: a display panel including sub-pixels disposed in a display area and dummy sub-pixels disposed in an outer area; and a circuit configured to output a data voltage for driving the display panel during a first period and acquire a sensing value from the display panel during a second period, in which the circuit increases or decreases a number of sensing target dummy sub-pixels among the dummy sub-pixels in response to a driving frequency of the display panel.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of Korean Patent Application No. 10 - 2024 - 0008829, filed on January 19, 2024, which is incorporated herein by reference in its entirety as if fully set forth herein. Technical field

[0003] The present invention relates to a display device and a driving method thereof. Background art

[0004] With the development of information technology, the market for display devices, as a communication medium between users and information, is growing. Accordingly, display devices such as light - emitting diode (LED) devices, quantum dot display (QDD) devices, and liquid crystal display (LCD) devices are being used more and more.

[0005] A display device includes a display panel having sub - pixels, a driver that outputs driving signals for driving the display panel, and a power supply that generates power supplied to the display panel or the driver.

[0006] In such a display device, when driving signals such as a scan signal and a data signal are provided to sub - pixels formed in the display panel, the selected sub - pixels transmit light or emit light directly, thereby displaying an image. Summary of the invention

[0007] Accordingly, the present invention relates to a display device and a method of driving the same, which substantially solve one or more problems caused by limitations and disadvantages of the prior art.

[0008] An object of the present invention is to solve the problem of difficulty in ensuring a sensing time that may occur in a high - resolution and high - frequency driving environment (difficult to sense during a short blanking period when driving a display panel). In addition, an object of the present invention is to increase or decrease the number of sensed target pseudo - sub - pixels in response to a change in the driving frequency during the rail driving of the display panel, thereby detecting whether there is a defect in the display panel.

[0009] Other advantages, objects, and features of the present invention will be set forth to some extent in the following description, and to some extent will become apparent to those of ordinary skill in the art upon examination of the following, or may be learned by practice of the present invention. The objects and other advantages of the present invention may be realized and obtained by means of the structures particularly pointed out in the written description and claims and the drawings.

[0010] To achieve these objects and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, a display device includes a display panel and a circuit. The display panel includes sub-pixels disposed in a display area and pseudo sub-pixels disposed in an outer area. The circuit is configured to output a data voltage for driving the display panel during a first period and obtain a sensed value from the display panel during a second period. Wherein, the circuit increases or decreases the number of sensed target pseudo sub-pixels in the pseudo sub-pixels in response to an increase or decrease in the driving frequency of the display panel.

[0011] The circuit may increase the number of sensed target pseudo sub-pixels as the driving frequency increases.

[0012] The circuit may set a reference driving frequency of the display panel, increase the number of sensed target pseudo sub-pixels when the driving frequency becomes higher than the reference driving frequency, and decrease the number of sensed target pseudo sub-pixels when the driving frequency becomes lower than the reference driving frequency.

[0013] When the position of the image displayed on the display panel moves upward, downward, leftward, or rightward, the circuit defines a pseudo sub-pixel line that displays black during the blanking period of the display panel as a sensing object.

[0014] The circuit may determine whether there is a defect in the display panel based on the sensed value obtained from the sensed target pseudo sub-pixel line.

[0015] The circuit may provide a sensed data voltage through a pseudo data line connected to the pseudo sub-pixel line and obtain a sensed value through a reference line connected to the pseudo sub-pixel line during the blanking period of the display panel.

[0016] In another aspect of the present invention, a method for driving a display device includes: displaying a protection image based on sub-pixels disposed in a display area of the display panel and moving the display position of the protection image, displaying a black image on at least one of the pseudo sub-pixels disposed in an outer area of the display panel, and moving the position of the black image whenever the display position of the protection image is moved. And when the position of the image displayed on the display panel moves upward, downward, leftward, or rightward, defining the pseudo sub-pixels that display black among the pseudo sub-pixels as sensed targets, and sensing the sensed target pseudo sub-pixels while changing the number of sensed target pseudo sub-pixels in response to the driving frequency of the display panel.

[0017] Sensing the sensed target pseudo sub-pixels may include increasing the number of sensed target pseudo sub-pixels as the driving frequency of the display panel increases.

[0018] The method may further include determining whether there is a defect in the display panel based on the sensed value obtained from the sensed target pseudo sub-pixel line.

[0019] The sensing target pseudo sub-pixels can be sensed during the blanking period of the display panel.

[0020] It should be understood that the above general description and the following detailed description of the present invention are both exemplary and explanatory, and are intended to provide further explanation of the claimed invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings provide a further understanding of the present invention and are incorporated into and constitute a part of this application. The drawings illustrate embodiments of the present invention and, together with the description, are used to explain the principles of the present invention. In the drawings:

[0022] Figure 1 is a block diagram schematically showing a light-emitting display device;

[0023] Figure 2 schematically shows Figure 1 the configuration diagram of the sub-pixels shown in;

[0024] Figure 3 is a schematic diagram showing a pixel composed of sub-pixels;

[0025] Figure 4 is a schematic diagram showing the configuration of a gate-in-panel type gate driver;

[0026] Figure 5 is a schematic diagram showing the configuration of a gate-in-panel type gate driver;

[0027] Figure 6 is a schematic diagram showing an example of the configuration of a gate-in-panel type gate driver;

[0028] Figure 7 is a schematic diagram schematically showing sub-pixels and a data driver according to a first embodiment;

[0029] Figure 8 is a schematic diagram schematically showing sub-pixels and a data driver according to a second embodiment;

[0030] Figure 9 is a waveform diagram showing a sensing period and a display period according to this embodiment;

[0031] Figure 10 is a schematic diagram showing in more detail some components included in the data driver according to this embodiment;

[0032] Figure 11 is a schematic diagram showing a sensing method of a display panel according to this embodiment;

[0033] Figure 12 is a schematic diagram showing a sensing method of a display panel according to this embodiment;

[0034] Figure 13 is a schematic diagram showing a pseudo-pixel group included in a display panel of a light-emitting display device according to an embodiment;

[0035] Figures 14 to 16 is a schematic diagram showing a track driving method of a display panel according to an embodiment;

[0036] Figures 17 to 20 is a schematic diagram showing a method of sensing one pseudo-subpixel included in a display panel at a first frequency according to an embodiment;

[0037] Figures 21 to 24 is a schematic diagram showing a method of sensing a plurality of pseudo-subpixels included in a display panel at a second frequency according to an embodiment;

[0038] Figures 25 to 27 is a schematic diagram showing a change in driving timing when using an adaptive sensing method in response to a frequency change according to an embodiment; and

[0039] Figure 28 is a flowchart showing a driving method of a light-emitting display device according to an embodiment. Detailed Description

[0040] The display device according to the present invention can be implemented as a television system, an image player, a personal computer (PC), a home theater, automotive electrical equipment, a smart phone, etc., but is not limited thereto. The display device according to the present invention can be implemented as a light-emitting display (LED) device, a quantum dot display (QDD) device, a liquid crystal display (LCD) device, etc. However, for the sake of convenience of description, as an example, a light-emitting display device that directly emits light based on an inorganic light-emitting diode or an organic light-emitting diode will be described below.

[0041] Figure 1 is a block diagram schematically showing a light-emitting display device, Figure 2 is schematically showing Figure 1 a configuration diagram of sub-pixels shown in Figure 3 and is a schematic diagram showing a pixel composed of sub-pixels.

[0042] As Figure 1 、 Figure 2 and Figure 3 shown, the light-emitting display device may include a timing controller 120, a gate driver 130, a data driver 140, a display panel 150, a power supply 180, etc.

[0043] The image providing device 110 (set-top box or host system) can output various driving signals and an externally provided image data signal or an image data signal stored in an internal memory. The image providing device 110 can provide a data signal and various driving signals to the timing controller 120.

[0044] The timing controller 120 can output a gate timing control signal GDC for controlling the operation timing of the gate driver 130, a data timing control signal DDC for controlling the operation timing of the data driver 140, and various synchronization signals. The timing controller 120 can provide the data signal DATA provided from the image providing device 110 to the data driver 140 together with the data timing control signal DDC. The timing controller 120 can be implemented in the form of an integrated circuit (IC) and mounted on a printed circuit board, but is not limited thereto.

[0045] The gate driver 130 can output a gate signal (or gate voltage) in response to the gate timing control signal GDC provided by the timing controller 120. The gate driver 130 can also provide a gate signal to the sub-pixels included in the display panel 150 through the gate lines GL1 to GLm. The gate driver 130 can be implemented in the form of an IC, or directly formed on the display panel 150 in an in-panel gate structure, but is not limited thereto.

[0046] The data driver 140 can sample and latch the data signal DATA in response to the data timing control signal DDC provided by the timing controller 120, convert the digital data signal into an analog data voltage based on a gamma reference voltage, and output the analog data voltage. The data driver 140 can also provide a data voltage to the sub-pixels included in the display panel 150 through the data lines DL1 to DLn. The data driver 140 can be implemented in the form of an integrated circuit (IC) and mounted on the display panel 150 or on a printed circuit board, but is not limited thereto.

[0047] The power supply 180 can generate a high-level first power and a low-level second power based on an externally provided external input voltage. The power supply 180 can output the first power through a first power supply line EVDD and output the second power through a second power supply line EVSS. The power supply 180 can generate and output a voltage required to drive the gate driver 130 (e.g., a high scan voltage and a low scan voltage) and a voltage required to drive the data driver 140 (e.g., a drain voltage and half of the drain voltage), as well as the first power and the second power.

[0048] The display panel 150 can display an image in response to driving signals including a scan signal and a data voltage, a first power, and a second power. Sub-pixels of the display panel 150 can emit light directly. The display panel 150 can be manufactured based on a rigid or flexible substrate such as glass, silicon, polyimide, etc. For example, a sub-pixel SP can be connected to a first data line DL1, a first gate line GL1, a first power line EVDD, and a second power line EVSS, and can include a pixel circuit including a switching transistor, a driving transistor, a capacitor, an organic light-emitting diode, etc.

[0049] The sub-pixel SP in the light-emitting display device emits light directly, so its circuit structure is complex. In addition, there are various compensation circuits that not only compensate for the deterioration of the organic light-emitting diode that emits light, but also compensate for the deterioration (threshold voltage, mobility, etc.) of the driving transistor that provides the driving current required to drive the organic light-emitting diode. Therefore, the sub-pixel SP is simply shown as a box.

[0050] The light-emitting sub-pixels can include a red sub-pixel SPR, a green sub-pixel SPG, and a blue sub-pixel SPB, or can include a red sub-pixel SPR, a green sub-pixel SPG, a blue sub-pixel SPB, and a white sub-pixel SPW. For example, a pixel PX can include a red sub-pixel SPR (SP1) connected to a first data line DL1, a white sub-pixel SPW (SP2) connected to a second data line DL2, a green sub-pixel SPG (SP3) connected to a third data line DL3, and a blue sub-pixel SPB (SP4) connected to a fourth data line DL4. In addition, the red sub-pixel SPR, the white sub-pixel SPW, the green sub-pixel SPG, and the blue sub-pixel SPB can be commonly connected to a first reference line VREF1. The first reference line VREF1 can be used to sense the element deterioration included in one of the red sub-pixel SPR, the white sub-pixel SPW, the green sub-pixel SPG, and the blue sub-pixel SPB, which will be described below.

[0051] Meanwhile, the timing controller 120, the gate driver 130, and the data driver 140 are described as separate components. However, depending on the implementation method of the light-emitting display device, one or more of the timing controller 120, the gate driver 130, and the data driver 140 can be integrated into a single IC. In addition, the timing controller 120, the gate driver 130, the data driver 140, the power supply 180, and the display panel 150 are components for displaying an image, and can be defined as a display module.

[0052] In addition, as an example, a red sub-pixel SPR, a white sub-pixel SPW, a green sub-pixel SPG, and a blue sub-pixel SPB are shown arranged in sequence (such as Figure 3Pixels PX of the sub-pixels SP1, SP2, SP3, SP4) shown. However, the arrangement order and direction of the sub-pixels may vary according to the implementation method of the light-emitting display device.

[0053] Figure 4 and Figure 5 is a schematic diagram showing the configuration of an in-panel gate type gate driver, Figure 6 is a schematic diagram showing an example of the configuration of an in-panel gate type gate driver.

[0054] As Figure 4 shown, the in-panel gate type gate driver may include a shift register 131 and a level shifter 135. The level shifter 135 may generate driving clock signals Clks and a start signal Vst based on signals and voltages output from a timing controller 120 and a power supply 180.

[0055] The shift register 131 operates based on the signals Clks and Vst output from the level shifter 135, and may output gate signals Gate[1] to Gate[m] for turning on or off transistors formed in the display panel. In the in-panel gate structure, the shift register 131 may be formed in a film shape on the display panel.

[0056] As Figure 4 and Figure 5 shown, different from the shift register 131, the level shifter 135 may be independently formed in the form of an IC, or may be included in the power supply 180. However, this is merely an example and is not limited thereto.

[0057] As Figure 6 shown, in the in-panel gate type gate driver, shift registers 131a and 131b that output gate signals may be provided in a non-display area NA of the display panel 150. As an example, the shift registers 131a and 131b are provided in the left non-display area NA and the right non-display area NA of the display panel 150, but the shift registers 131a and 131b may also be provided in the upper non-display area NA and the lower non-display area NA of the display panel 150, or may be provided in a display area AA of the display panel 150.

[0058] Figure 7 is a schematic diagram schematically showing sub-pixels and a data driver according to a first embodiment, Figure 8 is a schematic diagram schematically showing sub-pixels and a data driver according to a second embodiment, and Figure 9 is a waveform diagram showing a sensing period and a display period.

[0059] As Figure 7As shown, according to the first embodiment, a sub-pixel SP may include a switching transistor SW, a driving transistor DT, a sensing transistor ST, a capacitor CST, and an organic light-emitting diode OLED.

[0060] The driving transistor DT may include a gate connected to a first electrode of the capacitor CST, a first electrode connected to a first power supply line EVDD, and a second electrode connected to an anode of the organic light-emitting diode OLED. The capacitor CST may have a first electrode connected to the gate of the driving transistor DT and a second electrode connected to the anode of the organic light-emitting diode OLED. The organic light-emitting diode OLED may have an anode connected to the second electrode of the driving transistor DT and a cathode connected to a second power supply line EVSS.

[0061] The switching transistor SW may include a gate connected to a first scan line Gate1 included in the first gate line GL1, a first electrode connected to a first data line DL1, and a second electrode connected to the gate of the driving transistor DT. The sensing transistor ST may include a gate connected to a second scan line Gate2 included in the first gate line GL1, a first electrode connected to a first reference line VREF1, and a second electrode connected to the anode of the organic light-emitting diode OLED.

[0062] The sensing transistor ST is a compensation circuit added to compensate for the deterioration of the driving transistor DT or the organic light-emitting diode OLED. The sensing transistor ST can implement physical threshold voltage sensing based on the source follower operation of the driving transistor DT. The sensing transistor ST can be used to obtain a sensing voltage Vsen through a sensing node defined between the driving transistor DT and the organic light-emitting diode OLED.

[0063] According to an embodiment, the data driver 140 may include a driving circuit 141 for driving the sub-pixel SP and a sensing circuit 145 for sensing the sub-pixel SP. The driving circuit 141 may be connected to the first data line DL1 through a first data channel DCH1. The driving circuit 141 may output a data voltage Vdata for driving the sub-pixel SP through the first data channel DCH1.

[0064] The sensing circuit 145 may be connected to the first reference line VREF1 through a first sensing channel SCH1. The sensing circuit 145 may obtain a sensing voltage Vsen sensed from the sub-pixel SP through the first sensing channel SCH1. The sensing circuit 145 may obtain the sensing voltage Vsen based on a current sensing or voltage sensing method.

[0065] As Figure 8As shown, according to the second embodiment, the first gate line GL1 can be integrated into one line. That is, different from the first embodiment, the first gate line GL1 may not be divided into the first scan line and the second scan line, which can reduce wiring and save space. In this case, the switching transistor SW and the sensing transistor ST are commonly connected to the first gate line GL1, and thus can be turned on or off simultaneously.

[0066] As Figure 9 shown, when driving the display panel, the light-emitting display device according to this embodiment can adopt driving modes corresponding to a first driving period PWR_ON, a second driving period DISPLAY, and a third driving period PWR_OFF, respectively.

[0067] The first driving period PWR_ON may correspond to a driving start period for supplying power to the display panel (e.g., in response to a user input for turning on the display device), the second driving period DISPLAY may correspond to a panel driving period for performing operations such as displaying an image after supplying power to the display panel, and the third driving period PWR_OFF may correspond to a driving end period for cutting off the power supplied to the display panel (e.g., in response to a user input for turning off the display device). At the same time, the third driving period PWR_OFF is a period during which the display panel is driven for a specific period while displaying black so that a sensing operation of the display panel can be performed. That is, note that during the third driving period PWR_OFF, the power applied to the display panel etc. is not completely cut off. In other words, even after receiving an input from the user to cut off the power of the display device, the display device can display black to indicate being turned off (e.g., giving the user an illusion that the device is immediately powered off), but remains powered on to perform the sensing operation until the final power-off.

[0068] The light-emitting display device according to this embodiment can sense the display panel in at least one of the first driving period PWR_ON, the second driving period DISPLAY, and the third driving period PWR_OFF. For example, in the second driving period display, the blanking period BLK included in the vertical synchronization signal Vsync can be defined as the sensing period PSP, and the active period ACT included in the vertical synchronization signal Vsync can be defined as the display period DSP.

[0069] Figure 10 is a schematic diagram more specifically showing some components included in a data driver according to an embodiment, and Figure 11 and Figure 12 is a schematic diagram showing a sensing method of the display panel according to this embodiment. Hereinafter, as an example, the structure of the sub-pixel SP shown Figure 7 will be described.

[0070] InFigure 10 In the illustrated embodiment, the driving circuit 141 may include a digital-to-analog converter (DAC) to output a sense data voltage, a black data voltage, or a display data voltage through the first data line DL1. The sensing circuit 145 may include a first voltage circuit SPRE, a second voltage circuit RPRE, a sampling circuit SAM, and an analog-to-digital converter (ADC) to output and sense a voltage through the first reference line VREF1.

[0071] The first voltage circuit SPRE and the second voltage circuit RPRE may perform a voltage output operation to initialize or charge a node or circuit included in the sub-pixel SP to a specific voltage level. The first voltage circuit SPRE and the second voltage circuit RPRE may respectively include a first reference voltage source VPRES and a second reference voltage source VPRER. The first voltage circuit SPRE may output a first reference voltage based on the first reference voltage source VPRES, and the second voltage circuit RPRE may output a second reference voltage based on the second reference voltage source VPRER. The voltage of the first reference voltage may be set to be lower than the second reference voltage (e.g., VPRES < VPRER).

[0072] The sampling circuit SAM may perform a sampling operation to obtain a detection voltage through the first reference line VREF1. For example, the sampling circuit SAM may obtain a sense voltage from a sense capacitor PCAP formed on the first reference line VREF1 based on the sense capacitor PCAP.

[0073] The analog-to-digital converter ADC may convert the analog sense voltage obtained by the sampling circuit SAM into a digital sense voltage and output the digital sense voltage. For example, the analog-to-digital converter ADC may convert the analog sense voltage charged in the sense capacitor PCAP into a digital sense voltage and output the digital sense voltage.

[0074] The timing controller 120 may include a compensator that performs a compensation operation based on the sense voltage (sense data value) provided by the sensing circuit 145. The compensator included in the timing controller 120 may determine whether a driving transistor DT or an organic light-emitting diode OLED included in the sub-pixel SP has deteriorated based on the sense voltage and compensate for the deterioration.

[0075] As Figure 11 shown, according to the first embodiment, the light-emitting display device may perform an in-sequence sensing method in which sensing is performed from the first gate line GL1 to the M-th gate line GLm of the display panel 150 (e.g., sensing may be sequentially performed line by line for the entire screen). Although Figure 11 an example of starting sensing sequentially from the first gate line GL1 at the top of the display panel 150 is shown, sensing may also start from the M-th gate line GLm at the bottom of the display panel 150.

[0076] As shown Figure 12 in FIG. 2, according to the second embodiment, the light-emitting display device may perform a random sensing method of sensing only the i-th gate line GLi of the display panel 150. Although Figure 12 an example of sensing only one specific gate line, i.e., the i-th gate line GLi, is shown, the sensing target may also be two or more gate lines.

[0077] Figure 13 FIG. 3 is a schematic diagram showing a pseudo-pixel group included in a display panel of a light-emitting display device according to an embodiment, and Figures 14 to 16 FIG. 4 is a schematic diagram showing a track driving method of a display panel according to an embodiment.

[0078] As shown Figure 13 in FIG. 4, the display panel 150 according to this embodiment may include pseudo-pixel groups DPG1 to DPG4 provided in an outer region (or a border region) of the display region. The pseudo-pixel groups DPG1 to DPG4 may include a first pseudo-pixel group DPG1, a second pseudo-pixel group DPG2, a third pseudo-pixel group DPG3, and a fourth pseudo-pixel group DPG4.

[0079] The first pseudo-pixel group DPG1 may be located in the left outer region of the display panel 150. The second pseudo-pixel group DPG2 may be located in the right outer region of the display panel 150. The third pseudo-pixel group DPG3 may be located in the upper outer region of the display panel 150. The fourth pseudo-pixel group DPG4 may be located in the lower outer region of the display panel 150.

[0080] The first pseudo-pixel group DPG1 may be connected to first to j-th pseudo-data lines DDL1 to DDLj and may include a plurality of pseudo-sub pixels DP provided in the vertical direction. Here, j may be an integer of 2 or greater. Although not shown, the first pseudo-pixel group DPG1 may be connected to a pseudo-gate line to perform the same operation as the sub pixels provided in the display region of the display panel 150. In addition, the second pseudo-pixel group DPG2 located in the outer region opposite to the first pseudo-pixel group DPG1 may also have the same structure as the first pseudo-pixel group DPG1.

[0081] The third pseudo-pixel group DPG3 may be connected to first to j-th pseudo-gate lines DGL1 to DGLj and may include a plurality of pseudo-sub pixels DP provided in the horizontal direction. Here, j may be an integer of 2 or greater. Although not shown, the third pseudo-pixel group DPG3 may be connected to a pseudo-data line to perform the same operation as the sub pixels provided in the display region of the display panel 150. In addition, the fourth pseudo-pixel group DPG4 located in the outer region opposite to the third pseudo-pixel group DPG3 may also be provided in the same form as the third pseudo-pixel group DPG3.

[0082] Meanwhile, note that Figure 13 Briefly shown is that a pseudo-pixel group including a plurality of pseudo sub-pixels is disposed in each outer region of the display panel 150 according to this embodiment.

[0083] As Figures 14 to 16 shown, the display panel 150 according to this embodiment can display a specific image (e.g., a screensaver image) instead of a general display image (e.g., actual image data). In this case, the position of the display image can move in the horizontal direction (X1→X2 or X1→X2), the vertical direction (Y2→Y1 or Y2→Y1), or both the horizontal and vertical directions. For example, the screensaver image can be displayed by virtual pixels and rotate around the boundary of the screen in an orbit drive manner. The screensaver image can be displayed around the boundary in a clockwise rotation manner or a counterclockwise rotation manner.

[0084] Figure 15 An example showing the position of the display image moving from Y2 to Y1 in the vertical direction of the display panel 150 is shown. As Figure 15 shown, when the position of the display image moves from the top to the bottom, the third pseudo-pixel group DPG3 located in the upper outer region of the display panel 150 can display a black image BLK. In the opposite case, Figure 13 the fourth pseudo-pixel group DPG4 shown displays a black image BLK.

[0085] Figure 16 An example showing the position of the display image moving from X2 to X1 in the horizontal direction of the display panel 150 is shown. As Figure 16 shown, when the position of the display image moves from the right to the left, the second pseudo-pixel group DPG2 located in the right outer region of the display panel 150 can display a black image BLK. In the opposite case, Figure 13 the first pseudo-pixel group DPG1 shown displays a black image.

[0086] When a specific image (hereinafter referred to as a protection image) is displayed as described above, if an orbit driving method is used to move the position where the protection image is displayed, the sub-pixels included in the display panel 150 continuously display the same image, so the deterioration phenomenon can be delayed. In addition, if, in addition to moving the display position of the protection image, the dummy pixel groups provided in the outer regions also display black, the problem that the movement of the position where the protection image can be seen on the screen can be prevented, or the problem of brightness difference caused by the movement of the position of the protection image can be improved. In addition, an additional rest period during which black is displayed can be provided for the pixels around the boundary of the screen, and the deterioration phenomenon and the burn-in problem can be delayed, thereby increasing the lifespan of the device and improving the image quality. This can be particularly useful because logos or static information such as banners are usually displayed around the boundary or edge of the screen.

[0087] In response to the sensing time for obtaining the sensing voltage increasing or decreasing according to the frequency change, the light-emitting display device according to this embodiment can adopt an adaptive sensing method. For this purpose, the dummy pixels (or dummy sub-pixels) included in the dummy pixel groups DPG1 to DPG4 can be used in this embodiment. Hereinafter, an example in which the display position of the protection image on the display panel 150 moves from the top to the bottom will be described in this embodiment, as Figure 15 shown.

[0088] Figures 17 to 20 is a schematic diagram showing a method of sensing one dummy sub-pixel included in the display panel at a first frequency according to this embodiment, and Figures 21 to 24 is a schematic diagram showing a method of sensing a plurality of dummy sub-pixels included in the display panel at a second frequency according to this embodiment. Hereinafter, with reference to Figure 10 the internal configuration of the sensing circuit 145 shown, the sensing method according to this embodiment will be described.

[0089] As Figure 10 and Figures 17 to 20 shown, the light-emitting display device according to this embodiment can display a specific image (e.g., a screen protection image) on the display panel 150 instead of a normal image. When the position of the displayed image moves from the top (Y2) to the bottom (Y1), the third dummy pixel group DPG3 located in the upper outer region of the display panel 150 can display a black image BLK. In other words, a part of the actual input image data can be replaced by the screen protection image in the boundary region of the screen. For example, the screen protection image may include intermediate or low gray values or a specific predefined pattern to help equalize the voltage and rest the area of the screen, but the embodiment is not limited thereto.

[0090] When driving the light-emitting display device according to this embodiment at a first frequency (e.g., 60 Hz), the first pseudo-subpixel DP1 can be designated as the sensing target line SL1 in the third pseudo-pixel group DPG3 that displays the black image BLK through rail driving. The first pseudo-subpixel DP1 designated as the sensing target line SL1 can operate in the order of the first period P1 to the fourth period P4 defined in the first sensing time ST1, and the operations are as follows.

[0091] During the first period P1 to the third period P3, a first scan signal and a first sense signal Scan&Sense of a high voltage (on voltage) can be applied to the first scan line Gate1 and the second scan line Gate2 of the first pseudo-subpixel DP1. The first scan signal and the first sense signal Scan&Sense of a high voltage can be applied during the first period P1 to the third period P3, and then changed to a low voltage (off voltage).

[0092] During the first period P1 and the second period P2, a sensed data voltage Sdata of a high voltage (on voltage) can be applied to the j-th data line DLj of the first pseudo-subpixel DP1. A first voltage circuit control signal Vpres of a high voltage (on voltage) can be applied during the first period P1 and the second period P2, and then changed to a low voltage (off voltage).

[0093] During the fourth period P4, in response to a sampling control signal Sam, a sampling circuit SAM connected to the i-th reference line VREFi of the first pseudo-subpixel DP1 is turned on. The sampling control signal Sam of a high voltage (on voltage) can be applied only during the fourth period P4.

[0094] During the first period P1, the sensing node of the driving transistor DT included in the first pseudo-subpixel DP1 can be initialized with a first reference voltage. During the second period P2, the driving transistor DT of the first pseudo-subpixel DP1 can be operated as a constant current source by the sensed data voltage Sdata within a specific period. During the third period P3, according to the source follower of the driving transistor DT, the first pseudo-subpixel DP1 can operate in a current-following state. The voltage applied to the sensing node of the first pseudo-subpixel DP1 during the fourth period P4 can be acquired as a sensed voltage Vsen by the sampling circuit SAM connected to the i-th reference line VREFi.

[0095] Summarizing the above description, the light-emitting display device according to this embodiment can designate only one pseudo-pixel as the sensing target and sense the pseudo-pixel independently when the driving frequency is not high, so that sufficient sensing time can be ensured (or sufficient sensing time can be ensured when the driving frequency is sufficiently low).

[0096] As Figure 10 andFigures 21 to 24 As shown, the light-emitting display device according to this embodiment can display a specific image (e.g., a screensaver image) on the display panel 150 instead of a normal image. When the position of the displayed image moves from the top (Y2) to the bottom (Y1), the third pseudo-pixel group DPG3 located in the upper outer region of the display panel 150 can display a black image BLK. In other words, when the fourth pseudo-pixel group DPG4 located in the lower outer region of the display panel 150 is displaying a screensaver image, the third pseudo-pixel group DPG3 located in the upper outer region of the display panel 150 can display a black image BLK, and one or more sub-pixels including the third pseudo-pixel group DPG3 can be sensed.

[0097] When driving the light-emitting display device according to this embodiment at a second frequency (e.g., a higher frequency such as 240 Hz), the first to j-th pseudo-sub-pixels DP1 to DPj can be designated as the sensing target lines SL1 to SLj in the third pseudo-pixel group DPG3 that displays the black image BLK through rail driving. The first to j-th pseudo-sub-pixels DP1 to DPj designated as the sensing target lines SL1 to SLj can operate in the first period P1 to the fourth period P4 defined in the second sensing time ST2 in the following order. Here, the second sensing time ST2 is shorter than the first sensing time ST1 (ST2 < ST1). For example, when driving the light-emitting display device at a higher frequency, since less time is spent displaying the black image BLK (e.g., the PSP sensing period is shorter), the group of the first to J-th pseudo-sub-pixels DP1 to DPj designated as the sensing target lines SL1 to SLj can be sensed together at the same time.

[0098] During the first period P1 to the third period P3, a first scan signal and a first sensing signal Scan&Sense of high voltage (on voltage) can be applied to the first scan line Gate1 and the second scan line Gate2 of the first pseudo-sub-pixel DP1 to the j-th pseudo-sub-pixel DPj. During the first period P1 to the third period P3, a first scan signal and a first sensing signal Scan&Sense of high voltage can be applied and then changed to low voltage (off voltage).

[0099] During the first period P1 and the second period P2, a sensing data voltage Sdata of high voltage (on voltage) can be applied to the j-th data line DLj of the first pseudo-sub-pixel DP1 to the j-th pseudo-sub-pixel DPj. During the first period P1 and the second period P2, a first voltage circuit control signal Vpres of high voltage (on voltage) can be applied and then changed to low voltage (off voltage).

[0100] During a fourth period P4, in response to a sampling control signal Sam, a sampling circuit SAM that conducts a first to a j-th dummy sub-pixel DP1 to DPj and is connected to an i-th reference line VREFi is turned on. The sampling control signal Sam, which can be a high voltage (turn-on voltage), can be applied only during the fourth period P4.

[0101] In a first period P1, sensing nodes of driving transistors DT included in a first dummy sub-pixel DP1 to a j-th dummy sub-pixel DPj can be initialized with a first reference voltage. During a second period P2, driving transistors DT of the first to the j-th dummy sub-pixels DP1 to DPj can be operated as constant current sources by a sensed data voltage Sdata for a specific period. During a third period P3, according to the source follower of the driving transistor DT, the first to the j-th dummy sub-pixels DP1 to DPj can be operated in a current-following state. During a fourth period P4, voltages applied to the sensing nodes of the first dummy sub-pixel DP1 to the j-th dummy sub-pixel DPj can be summed by the sampling circuit SAM connected to the i-th reference line VREFi and obtained as a sensed voltage Vsen. In other words, the first to the J virtual sub-pixels DP1 to DPj can be sensed together as a group at the same time.

[0102] Summarizing the above description, when the driving frequency of the light-emitting display device according to this embodiment is too high to ensure sufficient sensing time, a plurality of dummy sub-pixels can be designated as sensing targets and sensed simultaneously. In other words, when the light-emitting display device is driven at a higher frequency, a group of dummy sub-pixels can be sensed together at the same time.

[0103] Meanwhile, the light-emitting display device according to this embodiment can be implemented to support various driving frequencies in addition to the above driving frequency. For example, if the light-emitting display device is implemented as a UHD display device capable of operating at 240 Hz, it can support not only a 240 Hz driving mode and a 60 Hz driving mode, but also a 120 Hz driving mode. In addition, recently manufactured and implemented light-emitting display devices can support variable refresh rate (VRR) operation, such that they can be adaptively used in various driving environments rather than a fixed driving frequency environment.

[0104] By Figure 17 and Figure 21 it can be determined that when the driving frequency for driving the display panel is high (high frequency), the time defined as a blanking period BLK included in a vertical synchronization signal Vsync can be reduced. In other words, if the resolution of the display panel is high (high resolution) and the driving frequency for driving the display panel is high (high frequency), then the sensing period PSP can be shortened. Applications can also be made when the driving frequency for driving the display panel is high and the resolution is high (high resolution).

[0105] In this way, as the blanking period BLK decreases, the sensing period PSP also decreases, so it may be difficult to determine whether the acquired sensing voltage is a normal value or an abnormal value.

[0106] To improve the ability to determine significant differences, the light-emitting display device according to this embodiment can change the amount of current that can be acquired through sensing in response to a change in the driving frequency, and limit the sensing target to pseudo sub-pixels. Additionally, the number of pseudo sub-pixels that are the sensing target can be increased or decreased in order to change the amount of current in response to a change in the driving frequency. That is, the light-emitting display device according to this embodiment can change the amount of acquired current by increasing or decreasing the number of pseudo sub-pixels that are the sensing target in response to a change in the driving frequency (i.e., a change in the blanking period) in order to improve the ability to determine significant differences.

[0107] Figures 25 to 27 is a schematic diagram showing the change in driving timing when an adaptive sensing method is employed in response to a frequency change according to an embodiment.

[0108] As Figure 25 and Figure 26 shown, when summing the amounts of current acquired from a plurality of pseudo sub-pixels DP1 to DPj instead of acquiring current from a single pseudo sub-pixel DP1, the amount of current can be increased. Additionally, assuming the same target amount of current is acquired, when summing the amounts of current acquired from a plurality of pseudo sub-pixels DP1 to DPj instead of acquiring current from a single pseudo sub-pixel DP1, the sensing time Δt can be reduced.

[0109] As Figure 27 shown, the light-emitting display device according to this embodiment can change the amount of acquired current by increasing or decreasing the number of pseudo sub-pixels that are the sensing target in response to a change in the driving frequency (i.e., a change in the blanking period). For example, if the driving frequency is lower than a reference driving frequency of 120 Hz, such as 60 Hz, then when it is determined that the driving frequency is sufficient to ensure the sensing time, only the first pseudo sub-pixel DP1 can be sensed. However, if the driving frequency is higher than the reference driving frequency of 120 Hz, such as 240 Hz, then when it is determined that the driving frequency cannot ensure sufficient sensing time, a plurality of pseudo sub-pixels DP1 to DPj can be sensed.

[0110] An example of setting the reference driving frequency of the light-emitting display device to 120 Hz has been described above. However, the reference driving frequency can be set based on the lowest and highest driving frequencies of the implemented light-emitting display device, or the driving frequency that can cause insufficient sensing time can be set as the reference driving frequency.

[0111] As can be determined by referring to the illustrated examples, according to this embodiment, the time for applying the sensed data voltage Sdata and the time for applying the first reference voltage (referring to Vpres, which allows the application of the first reference voltage) can be fixed and unchanged. However, the first scan signal Scan, the first sense signal Sense, and the sampling control signal Sam for determining the sensing time can vary according to the number of target sensed pseudo-subpixels. This conclusion can be determined by comparing the cases of sensing one pseudo-subpixel DP1, sensing the first to the i-th pseudo-subpixels DP1 to DPi, and sensing the first to the j-th pseudo-subpixels DP1 to DPj.

[0112] In other words, the sensing time decreases as the driving frequency increases, whereby the number of target sensed pseudo-subpixels can be increased, such that the amount of current that can be obtained within a limited time increases.

[0113] Meanwhile, in this embodiment, the sensed voltage is obtained using the pseudo-subpixels included in the display panel capable of performing orbital driving and the number of target sensed pseudo-subpixels is changed in response to the change in the driving frequency, which can be more advantageous than sensing the subpixels provided in the display area of the display panel.

[0114] For example, if the driving frequency becomes higher than the above reference frequency (e.g., 120 Hz), the sensing time decreases, so it may be difficult to obtain the effective value of the sensed voltage from the subpixels provided in the display area of the display panel within a limited time (blanking period). However, during orbital driving, the pseudo-subpixels included in the display panel display black for a certain period in response to the movement of the position of the protection image, so the number of target sensed pseudo-subpixels can be selectively changed in response to the change in the driving frequency, and the sensed voltage can be obtained therefrom. In addition, since multiple pseudo-subpixels included in the display panel can be sensed at one time during orbital driving, the effective value of the sensed voltage can be obtained as compared with the case of obtaining the sensed voltage from the subpixels provided in the display area of the display panel. Furthermore, this method can also be used when the subpixels provided in the display area of the display panel cannot be sensed or the subpixels provided in the display area of the display panel are non-sensed subpixels (subpixels without sensing).

[0115] The light-emitting display device according to this embodiment can obtain the sensed voltage from the pseudo-subpixels included in the display panel during orbital driving and detect whether there are defects in the display panel based on the sensed voltage, which will be described below.

[0116] Figure 28 is a flowchart showing a driving method of a light-emitting display device according to an embodiment.

[0117] As Figure 28As shown, the light-emitting display device according to this embodiment can determine whether the display panel is performing orbit driving (S100). If the display panel is not performing orbit driving (N), it is determined whether a power-off signal is applied to the display panel (S110). If a power-off signal is applied to the display panel (Y), the sensing voltage can be obtained by sensing the sub-pixels SP provided in the display area of the display panel, and a compensation operation for compensating for deterioration can be performed based on the sensing voltage (S120). If the detection and compensation operation of the sub-pixels SP is completed, the display panel can be turned off.

[0118] On the other hand, if the display panel is performing orbit driving (Y), the driving frequency is analyzed (S130). If the current driving frequency is the first frequency (Y), the sensing voltage can be obtained by sensing the dummy sub-pixels DP of the display panel under the first condition, and it can be detected whether there are defects in the display panel based on the sensing voltage (S150). For example, the first frequency can be a low frequency, such as 60 Hz, and the first condition is to obtain the sensing voltage by sensing one dummy sub-pixel (for example, sensing one sub-pixel at a time).

[0119] If the current driving frequency is not the first frequency (N), it is determined whether the current driving frequency is the second frequency (S160). If the current driving frequency is the second frequency (Y), the sensing voltage can be obtained by sensing the dummy sub-pixels DP of the display panel under the second condition, and it can be detected whether there are defects in the display panel based on the sensing voltage (S170). For example, the second frequency can be a medium or intermediate frequency, such as 120 Hz, and the second condition is to obtain the sensing voltage by sensing more dummy sub-pixels than those under the first condition and less dummy sub-pixels than those under the third condition.

[0120] If the current driving frequency is not the second frequency (N), it can be determined whether the current driving frequency is the third frequency (S180). If the current driving frequency is the third frequency (Y), the sensing voltage can be obtained by sensing the dummy sub-pixels DP of the display panel under the third condition, and it can be detected whether there are defects in the display panel based on the sensing voltage (S190). For example, the third frequency can be a high driving frequency, such as 240 Hz, and the third condition can be the condition of obtaining the sensing voltage by sensing a larger number of dummy sub-pixels than those in the second condition (for example, sensing the sub-pixels of multiple lines or multiple rows simultaneously).

[0121] As described above, when the track driving of the display panel is being performed, the light-emitting display device according to this embodiment can analyze the driving frequency, selectively change the number of pseudo sub-pixels to be sensed in response to the current driving frequency, obtain a sensed voltage (sensed value) based on this, and detect whether there is a defect in the display panel and the position (coordinates) of the defect based on the sensed voltage. In other words, the light-emitting display device can dynamically change how many sub-pixels are to be sensed during one blanking period BLK (e.g., the sensing period PSP) based on the driving frequency. For example, when the light-emitting display device is driven at a low frequency (e.g., 60 Hz), the light-emitting display device can perform the sensing of one sub-pixel at a time, or sense one line sequentially at a time. In addition, when the light-emitting display device is driven at an intermediate frequency (e.g., 120 Hz), the light-emitting display device can simultaneously sense a group of sub-pixels at the same time (e.g., sense the sub-pixels of one row together). In addition, when the light-emitting display device is driven at a high frequency (e.g., 240 Hz), the light-emitting display device can perform simultaneous sensing of a larger group of sub-pixels at the same time (e.g., sense the sub-pixels of multiple rows or multiple lines together). In addition, when multiple sub-pixels are simultaneously sensed at the same time, the sensed values can be added together, and the sum can be compared with a predetermined value to determine whether there is a defect.

[0122] Defects in the display panel can be determined based on the sensed voltage, and the defects can include line defects caused by defects in data lines / gate lines included in the display panel (which can be determined when a sensing value error / cannot obtain a sensing value occurs), defects in power supplies and power lines or errors in their outputs (which can be determined when a sensing value cannot be obtained), short circuits between signal lines or power lines included in the display panel, overcurrent caused by the short circuit (due to aging of the overcurrent), etc.

[0123] As described above, the effect of the present invention is to solve the problem of difficulty in ensuring sensing time that may occur in a high-resolution and high-frequency driving environment (it is difficult to sense during a short blanking period when driving the display panel). In addition, the effect of the present invention is to increase or decrease the number of pseudo sub-pixels to be sensed in response to a change in the driving frequency during the track driving of the display panel, thereby solving the problem of difficulty in ensuring sensing time. In addition, the effect of the present invention is to detect whether there is a defect in the display panel by increasing or decreasing the number of pseudo sub-pixels.

[0124] It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the present invention. Therefore, the present invention is intended to cover modifications and variations of the present invention as long as they fall within the scope of the appended claims and their equivalents.

Claims

1. A display device, comprising: a display panel, the display panel including sub-pixels provided in a display area and dummy sub-pixels provided in an outer area; and a circuit configured to output a data voltage for driving the display panel in a first period and obtain a sensed value from the display panel in a second period, wherein the circuit increases or decreases the number of sensed target dummy sub-pixels among the dummy sub-pixels in response to a driving frequency of the display panel.

2. The display device according to claim 1, wherein, The circuit increases the number of sensed target dummy sub-pixels as the driving frequency increases.

3. The display device according to claim 1, wherein, The circuit sets a reference driving frequency of the display panel, increases the number of sensed target dummy sub-pixels when the driving frequency becomes higher than the reference driving frequency, and decreases the number of sensed target dummy sub-pixels when the driving frequency becomes lower than the reference driving frequency.

4. The display device according to claim 1, wherein, When a position of an image displayed on the display panel moves upward, downward, leftward, or rightward, the circuit defines a dummy sub-pixel line that displays black during a blanking period of the display panel as a sensed target.

5. The display device according to claim 1, wherein, The circuit determines whether the display panel has a defect based on a sensed value obtained from the sensed target dummy sub-pixel line.

6. The display device according to claim 1, wherein, During the blanking period of the display panel, the circuit applies a sensed data voltage through a dummy data line connected to the dummy sub-pixel line and obtains the sensed value through a reference line connected to the dummy sub-pixel line.

7. A method for driving a display device, comprising: displaying a protection image based on sub-pixels provided in a display area of a display panel and moving a position where the protection image is displayed; displaying a black image on at least one of the dummy sub-pixels provided in an outer area of the display panel and moving a position of the black image whenever a display position of the protection image is moved; and when a position of an image displayed on the display panel moves upward, downward, leftward, or rightward, defining a dummy sub-pixel line that displays black among the dummy sub-pixels as a sensed target and sensing the sensed target dummy sub-pixels while changing the number of sensed target dummy sub-pixels in response to a driving frequency of the display panel.

8. The method according to claim 7, wherein, Sensing the sensed target dummy sub-pixels includes: increasing the number of sensed target dummy sub-pixels as the driving frequency of the display panel increases.

9. The method according to claim 7 further comprises: Determining whether the display panel has a defect based on a sensed value obtained from the sensed target dummy sub-pixel line.

10. The method according to claim 7, wherein, Performing sensing of the sensed target dummy sub-pixels during a blanking period of the display panel.

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