Display device and method of driving the same

Abstract

To provide a display device that can reduce sensing problems occurring in high-resolution and high-frequency driving environments.SOLUTION: A display device can include a display panel including subpixels disposed in a display area and dummy subpixel lines disposed in an outer area of the display 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, and in response to a driving frequency of the display panel, increase or decrease a number of sensing target dummy subpixel lines among the dummy subpixel lines.SELECTED DRAWING: Figure 18

Description

Technical Field

[0001] This specification relates to a display device and a driving method thereof.

Background Art

[0002] With the development of information technology, the market for display devices, which are the connection medium between users and information, has been growing. As a result, the use of display devices such as Light Emitting Display Devices (LEDs), Quantum Dot Display Devices (QDDs), and Liquid Crystal Display Devices (LCDs) has been increasing.

[0003] The above-described display device includes a display panel including sub-pixels, a driving unit that outputs a driving signal for driving the display panel, and a power supply unit that generates a power supply to be supplied to the display panel or the driving unit.

[0004] In the above-described display device, when a driving signal, such as a scan signal and a data signal, is supplied to the sub-pixels formed on the display panel, the selected sub-pixels can display an image by transmitting light or directly emitting light.

[0005] However, as the resolution of the display device increases and the driving frequency increases, it may become difficult to ensure a sufficient sensing time to perform a compensation operation. For example, it may become difficult to sense during a short blank period while the display panel is being driven. Furthermore, there is a need to be able to detect the presence or absence of defects in the display panel based on different driving conditions.

Summary of the Invention

Problems to be Solved by the Invention

[0006] This specification solves the problem of ensuring sensing time that can be induced in a high-resolution and high-frequency driving environment (difficulty in sensing during a short blank period while driving a display panel). Also, this specification detects the presence or absence of defects in a display panel by increasing or decreasing the number of sensing target dummy sub-pixels corresponding to a change in the driving frequency when the display panel is driven in an orbit.

Means for Solving the Problem

[0007] This specification provides a display device including a display panel including sub-pixels arranged in a display area and a dummy sub-pixel line arranged in an outer peripheral area, and a circuit unit that outputs a data voltage for driving the display panel in a first period and acquires a sensing value from the display panel in a second period, wherein the circuit unit can increase or decrease the number of sensing target dummy sub-pixel lines among the dummy sub-pixel lines corresponding to the driving frequency of the display panel.

[0008] The circuit unit can increase the number of sensing target dummy sub-pixel lines as the driving frequency of the display panel becomes faster.

[0009] The circuit unit sets a reference driving frequency of the display panel, and can increase the number of sensing target dummy sub-pixel lines if it becomes faster than the reference driving frequency, and can decrease the number of sensing target dummy sub-pixel lines if it becomes slower than the reference driving frequency.

[0010] When the position of the image displayed on the display panel moves up, down, left, or right, the circuit unit can define a dummy sub-pixel line that displays black during the blank period of the display panel as a sensing target.

[0011] The circuit unit can determine the presence or absence of defects in the display panel based on the sensing value obtained from the sensing target dummy sub-pixel lines.

[0012] During the blank period of the display panel, the circuit unit can apply a sensing data voltage through a dummy data line connected to the dummy sub-pixel line, and obtain the sensing value through a reference line connected to the dummy sub-pixel line.

[0013] In another aspect, this specification provides a method for driving a display device, including a protection image display step of displaying a protection image based on sub-pixels arranged in a display area of a display panel and moving the position where the protection image is displayed, a black image display step of displaying a black image on at least one of dummy sub-pixel lines arranged in an outer peripheral area of the display panel and moving the position of the black image each time the display position of the protection image moves, and a sensing step of defining, as a sensing target, a dummy sub-pixel line that displays black among the dummy sub-pixel lines when the position of the image represented on the display panel moves up, down, left, or right, varying the number of the sensing target dummy sub-pixel lines corresponding to the driving frequency of the display panel, and performing sensing.

[0014] In the sensing step, the number of the sensing target dummy sub-pixel lines can be increased as the driving frequency of the display panel increases. The method may further include a defect determination step of determining whether there is a defect in the display panel based on the sensing value obtained from the sensing target dummy sub-pixel lines.

[0015] The sensing step can be performed while the display panel is in the blank period.

Advantages of the Invention

[0016] According to this specification, there is an effect that it is possible to solve the sensing time securing problem (difficulty in sensing during a short blank period during driving of a display panel) that can be induced in a high-resolution and high-frequency driving environment. Further, this specification has an effect that it is possible to solve the sensing time securing problem by increasing or decreasing the number of sensing target dummy sub-pixels in response to a change in the driving frequency during the orbit driving of the display panel. Further, this specification has an effect that it is possible to detect the presence or absence of a defect in the display panel by increasing or decreasing the number of dummy sub-pixels.

Brief Description of Drawings

[0017]

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Mode for Carrying Out the Invention

[0018] The advantages, features, and methods for achieving them of this specification will become apparent by referring to the embodiments described in detail together with the accompanying drawings. However, this specification is not limited to the embodiments described below and can be implemented in different forms. The embodiments are provided only to fully disclose the present disclosure and completely convey the scope of the present disclosure to those skilled in the art. This specification is defined only by the disclosed claims.

[0019] In order to explain the embodiments of the present disclosure, the shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings are merely exemplary, so the present disclosure is not limited to what is illustrated. The same reference numerals indicate the same components throughout the specification. Further, in the description of the present disclosure, when it is determined that the detailed description of related known technologies may unnecessarily obscure the gist of the present disclosure, the detailed description thereof is omitted.

[0020] In this specification, when terms such as "including", "having", "composed of", etc. are used, other parts can be added unless "only" is used. Also, when a component is expressed in the singular form, it shall include the plural form as well unless otherwise specified.

[0021] In the interpretation of components, even if there is no separate explicit description, it should be understood that the error range is included.

[0022] In the description of positional relationships, for example, when the positional relationship between two components is described as "above", "upper part", "lower part", "adjacent", etc., one or more other components may be located between the two components unless "immediately" or "directly" is used.

[0023] Although first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are only used to distinguish one component from another. Therefore, within the scope of the technical spirit of the present disclosure, the first component mentioned below may also be the second component.

[0024] The same reference numerals can refer to substantially the same elements throughout the present disclosure.

[0025] The following embodiments can be partially or wholly combined with each other, or can be combined with each other, and can be connected and operated in various technical ways. The embodiments can be implemented independently of or in relation to each other. Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0026] This specification can be composed of, but is not limited to, a television, an image player, a personal computer (PC), a home theater, automotive electrical devices, a smartphone, etc. This specification can be composed of a light-emitting display device (Light Emitting Display Device; LED), a quantum dot display device (Quantum Dot Display Device; QDD), a liquid crystal display device (Liquid Crystal Display Device; LCD), etc. However, hereinafter, for the sake of convenience of explanation, a light-emitting display device that directly emits light based on an inorganic light-emitting diode or an organic light-emitting diode will be taken as an example.

[0027] FIG. 1 is a block diagram schematically showing a light-emitting display device, FIG. 2 is a configuration diagram schematically showing the sub-pixels shown in FIG. 1, and FIG. 3 is an exemplary diagram of a pixel composed of sub-pixels.

[0028] As shown in FIGS. 1 to 3, the light-emitting display device may include a timing control unit 120, a gate driving unit 130, a data driving unit 140, a display panel 150, a power supply unit 180, and the like.

[0029] The image supply unit (set or host system) 110 can output various driving signals together with the image data signal supplied from the outside or the image data signal stored in the internal memory. The image supply unit 110 can supply the data signal and various driving signals to the timing control unit 120.

[0030] The timing control unit 120 can output a gate timing control signal GDC for controlling the operation timing of the gate driving unit 130, a data timing control signal DDC for controlling the operation timing of the data driving unit 140, and various synchronization signals. The timing control unit 120 can supply the data signal DATA supplied from the image supply unit 110 to the data driving unit 140 together with the data timing control signal DDC. The timing control unit 120 is formed in the form of an IC (Integrated Circuit) and can be mounted on a printed circuit board, but is not limited thereto.

[0031] The gate driving unit 130 can output a gate signal (or gate voltage) in response to the gate timing control signal GDC and the like supplied from the timing control unit 120. The gate driving unit 130 can supply the gate signal to the sub-pixels included in the display panel 150 via the gate lines GL1 to GLm. The gate driving unit 130 can be formed in the form of an IC or directly formed on the display panel 150 by the gate in panel method, but is not limited thereto.

[0032] The data driving unit 140 can sample and latch the data signal DATA in response to a data timing control signal DDC supplied from the timing control unit 120, etc., and convert the digital-form data signal into an analog-form data voltage based on the gamma reference voltage and output it. The data driving unit 140 can supply the data voltage to the sub-pixels included in the display panel 150 via the data lines DL1 to DLn. The data driving unit 140 can be formed in the form of an IC and mounted on the display panel 150 or on a printed circuit board, but is not limited thereto.

[0033] The power supply unit 180 can generate a first power supply at a high potential and a second power supply at a low potential based on an external input voltage supplied from the outside. The power supply unit 180 can output the first power supply via the first power supply line EVDD and output the second power supply via the second power supply line EVSS. The power supply unit 180 can generate or output not only the first power supply and the second power supply, but also voltages required for driving the gate driving unit 130 (e.g., scan high voltage and scan low voltage) and voltages required for driving the data driving unit 140 (drain voltage and half-drain voltage), etc.

[0034] The display panel 150 can display an image corresponding to a driving signal including a gate signal and a data voltage, a first power supply, a second power supply, etc. The sub-pixels of the display panel 150 can emit light directly. The display panel 150 can be manufactured based on a rigid or ductile substrate such as glass, silicon, polyimide, etc. For example, one sub-pixel SP can be connected to the first data line DL1, the first gate line GL1, the first power supply line EVDD, and the second power supply line EVSS, and can include a pixel circuit composed of a switching transistor, a driving transistor, a capacitor, an organic light emitting diode, etc.

[0035] Since the sub-pixel SP used in the light-emitting display device emits light directly, the circuit configuration is complex. In addition to the organic light-emitting diode that emits light, there are also various compensation circuits for compensating for the deterioration (such as threshold voltage and mobility) of the driving transistor that supplies the driving current required for driving the organic light-emitting diode. Therefore, reference is made to simply showing the sub-pixel SP in the form of a block.

[0036] The sub-pixels that emit light can be composed of pixels including red, green, and blue or pixels including red, green, blue, and white. For example, one pixel P may include a red sub-pixel SPR connected to the first data line DL1, a white sub-pixel SPW connected to the second data line DL2, a green sub-pixel SPG connected to the third data line DL3, and a blue sub-pixel connected to the fourth data line DL4. 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 the first reference line VREF1. The first reference line VREF1 can be used to sense the deterioration of the element(s) 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.

[0037] On the other hand, in the above description, the timing control unit 120, the gate driving unit 130, the data driving unit 140, etc. have been described as individual configurations. However, depending on the configuration method of the light-emitting display device, one or more of the timing control unit 120, the gate driving unit 130, and the data driving unit 140 can be integrated into one IC. In addition, the timing control unit 120, the gate driving unit 130, the data driving unit 140, the power supply unit 180, and the display panel 150 can be defined as a display module as an assembly for displaying an image.

[0038] In addition, in the above description, pixel P arranged in the order of red sub-pixel SPR, white sub-pixel SPF, green sub-pixel SPG, and blue sub-pixel SPB was shown as an example. However, the arrangement order and direction of the sub-pixels can vary depending on the configuration method of the light-emitting display device.

[0039] FIGS. 4 and 5 are diagrams for explaining the configuration of a gate driving unit of the gate-in-panel method, and FIG. 6 is a diagram showing an arrangement example of the gate driving unit of the gate-in-panel method.

[0040] As shown in FIG. 4, the gate driving unit of the gate-in-panel method may include a shift register 131 and a level shifter 135. The level shifter 135 can generate a driving clock signal Clks, a start signal Vst, etc. based on signals and voltages output from the timing control unit 120 and the power supply unit 180.

[0041] The shift register 131 operates based on signals Clks, Vst, etc. output from the level shifter 135, and can output gate signals Gate[1] to Gate[m] for turning on or off transistors formed on the display panel. The shift register 131 can be formed in a thin film form on the display panel by the gate-in-panel method.

[0042] As shown in FIGS. 4 and 5, unlike the shift register 131, the level shifter 135 can be formed independently in an IC form or included inside the power supply unit 180. However, this is only one example and is not limited thereto.

[0043] As shown in FIG. 6, shift registers 131a and 131b that output gate signals in the gate driving unit of the gate-in-panel method can be arranged in the non-display area NA of the display panel 150. The shift registers 131a and 131b are shown as an example arranged in the left and right non-display areas NA of the display panel 150, but they may be arranged in the upper and lower non-display areas NA of the display panel 150 or within the display area AA of the display panel 150.

[0044] FIG. 7 is an exemplary diagram schematically showing a sub-pixel and a data driving unit according to the first example of the embodiment, FIG. 8 is a diagram schematically showing a sub-pixel and a data driving unit according to the second example of the embodiment, and FIG. 9 is a waveform diagram for explaining a sensing period and a display period according to the embodiment.

[0045] As shown in FIG. 7, according to the first example, one 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. The driving transistor DT may have its gate electrode connected to the first electrode of the capacitor CST, its first electrode connected to the first power line EVDD, and its second electrode connected to the anode electrode of the organic light emitting diode OLED. The capacitor CST may have its first electrode connected to the gate electrode of the driving transistor DT and its second electrode connected to the anode electrode of the organic light emitting diode OLED. The organic light emitting diode OLED may have its anode electrode connected to the second electrode of the driving transistor DT and its cathode electrode connected to the second power line EVSS.

[0046] The switching transistor SW may have its gate electrode connected to the first scan line Gate1 included in the first gate line GL1, its first electrode connected to the first data line DL1, and its second electrode connected to the gate electrode of the driving transistor DT.

[0047] The sensing transistor ST may have its gate electrode connected to the second scan line Gate2 included in the first gate line GL1, its first electrode connected to the first reference line VREF1, and its second electrode connected to the anode electrode of the organic light emitting diode OLED.

[0048] The sensing transistor ST is a type of compensation circuit added to compensate for the degradation of the driving transistor DT or the organic light-emitting diode OLED. The sensing transistor ST can enable physical threshold voltage sensing based on the source follower operation of the driving transistor DT. The sensing transistor ST operates to obtain a sensing voltage Vsen via a sensing node defined between the driving transistor DT and the organic light-emitting diode OLED.

[0049] According to an embodiment, the data driving unit 140 may include a driving circuit unit 141 for driving the sub-pixel SP and a sensing circuit unit 145 for sensing the sub-pixel SP. The driving circuit unit 141 may be connected to the first data line DL1 via the first data channel DCH1. The driving circuit unit 141 may output a data voltage Vdata or the like for driving the sub-pixel SP via the first data channel DCH1.

[0050] The sensing circuit unit 145 may be connected to the first reference line VREF1 via the first sensing channel SCH1. The sensing circuit unit 145 may obtain a sensing voltage Vsen sensed from the sub-pixel SP via the first sensing channel SCH1. The sensing circuit unit 145 may obtain the sensing voltage Vsen based on a current sensing or voltage sensing method or the like.

[0051] As shown in FIG. 8, according to a second example, the first gate line GL1 may be integrated into one. That is, unlike the first example, the first gate line GL1 may not be divided into a first scan line and a second scan line, and wiring and space can be reduced. In this case, since the switching transistor SW and the sensing transistor ST are commonly connected to the first gate line GL1, they can be turned on or off simultaneously.

[0052] As shown in FIG. 9, the light-emitting display device according to the embodiment may adopt a driving method that is respectively divided corresponding to a first driving period PWR_ON, a second driving period DISPLAY, and a third driving period PWR_OFF during operation for driving the display panel.

[0053] The first driving period PWR_ON corresponds to a driving start period in which power is applied to the display panel. After power is applied to the display panel during the second driving period DISPLAY, for example, in response to a user input such as turning off the power of the display device, it corresponds to a panel driving period in which driving such as displaying an image is performed. For example, in response to a user input such as turning off the power of the display device, the third driving period PWR_OFF may correspond to a driving end period in which the power applied to the display panel is cut off. On the other hand, the third driving period PWR_OFF is a period in which driving is performed for a certain time while displaying black so that the sensing operation of the display panel is performed. That is, during the third driving period PWR_OFF, the power applied to the display panel and the like is not completely cut off. In other words, even after receiving an input from the user to turn off the power of the display device, the display device can display black so as to appear off (for example, giving the user an illusion that the device turns off the power immediately), but until the power is finally turned off, the power can be kept on to execute the sensing operation.

[0054] The light-emitting display device according to the embodiment may 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. Taking the second driving period DISPLAY as an example, the blank period BLK included in the vertical synchronization signal Vsync may be defined as the sensing period PSP, and the active period ACT included in the vertical synchronization signal Vsync may be defined as the display period DSP.

[0055] FIG. 10 is an exemplary diagram showing in more detail a part of the configuration included in the data driving unit according to the embodiment, and FIGS. 11 and 12 are diagrams showing the method of sensing the display panel according to the embodiment. Hereinafter, the sub-pixel SP will be described taking the structure illustrated in FIG. 7 as an example.

[0056] As in the embodiment shown in FIG. 10, the driving circuit unit 141 may include a digital-to-analog conversion unit DAC or the like to output a sensing data voltage, a black data voltage, or a display data voltage via the first data line DL1. The sensing circuit unit 145 may include a first voltage circuit unit SPRE, a second voltage circuit unit RPRE, a sampling circuit unit SAM, an analog-to-digital conversion unit ADC, etc. to output a voltage via the first reference line VREF1 for sensing.

[0057] The first voltage circuit unit SPRE and the second voltage circuit unit RPRE output voltages for initializing the nodes and circuits included in the sub-pixel SP or charging them with a voltage at a specific level. The first voltage circuit unit SPRE and the second voltage circuit unit RPRE may each include a first reference voltage source VPRES and a second reference voltage source VPRER. The first voltage circuit unit SPRE outputs a first reference voltage based on the first reference voltage source VPRES, and the second voltage circuit unit RPRE may output a second reference voltage (for example, VPRES < VPRER) based on the second reference voltage source VPRER.

[0058] The first reference voltage may be set to a voltage lower than the second reference voltage. The sampling circuit unit SAM may perform a sampling operation for acquiring a sensing voltage via the first reference line VREF1. For example, the sampling circuit unit SAM may acquire the sensing voltage from the sensing capacitor PCAP formed on the first reference line VREF1 based on the sensing capacitor PCAP.

[0059] The analog-to-digital conversion unit ADC can convert the sensed voltage in analog form acquired by the sampling circuit unit SAM into a sensed voltage in digital form and output it. For example, the analog-to-digital conversion unit ADC can convert the sensed voltage in analog form charged in the sensing capacitor PCAP into a sensed voltage in digital form and output it.

[0060] The timing control unit 120 may include a compensation unit that performs a compensation operation based on the sensed voltage (sensing data value) supplied from the sensing circuit unit 145. The compensation unit included in the timing control unit 120 can determine the presence or absence of deterioration of the driving transistor DT or the organic light-emitting diode OLED included in the sub-pixel SP based on the sensed voltage and can compensate for the deterioration.

[0061] As shown in FIG. 11, according to the first example, the light-emitting display device performs a sequential sensing method of sensing from the first gate line GL1 to the M-th gate line GLm of the display panel 150. For example, for the entire screen, sequential sensing can be performed one row at a time. In FIG. 11, as an example, sensing is sequentially performed from the first gate line GL1 at the upper stage of the display panel 150, but the sensing may start from the M-th gate line GLm at the lower stage of the display panel 150.

[0062] As shown in FIG. 12, according to the second example, the light-emitting display device can perform a random sensing method of sensing only the I-th gate line GLi of the display panel 150. In FIG. 12, as an example, only the I-th gate line GLi, which is one of the specific gate lines, is shown and described, but the sensing target may be two or more gate lines.

[0063] FIG. 13 is a diagram showing a dummy pixel group included in the display panel of the light-emitting display device according to an embodiment, and FIGS. 14 to 16 are diagrams for explaining the orbit driving method of the display panel according to the embodiment.

[0064] As shown in FIG. 13, the display panel 150 according to the embodiment may include dummy pixel groups DPG1 to DPG4 disposed in an outer peripheral region (or bezel region) of the display region. The dummy pixel groups DPG1 to DPG4 may include a first dummy pixel group DPG1, a second dummy pixel group DPG2, a third dummy pixel group DPG3, and a fourth dummy pixel group DPG4.

[0065] The first dummy pixel group DPG1 may be located in the left outer peripheral region of the display panel 150. The second dummy pixel group DPG2 may be located in the right outer peripheral region of the display panel 150. The third dummy pixel group DPG3 may be located in the upper outer peripheral region of the display panel 150. The fourth dummy pixel group DPG4 may be located in the lower outer peripheral region of the display panel 150.

[0066] The first dummy pixel group DPG1 may be connected to the first dummy data line DDL1 to the Jth dummy data line DDLj and may include a plurality of dummy sub-pixels DP arranged along the vertical direction. Here, j may be an integer of 2 or more. Although not shown, the first dummy pixel group DPG1 may be connected to a dummy gate line or the like so as to perform the same operation as the sub-pixels disposed in the display region of the display panel 150. In addition, the second dummy pixel group DPG2 located in the outer peripheral region opposite to the first dummy pixel group DPG1 may also have a structure similar to that of the first dummy pixel group DPG1.

[0067] The third dummy pixel group DPG3 may be connected to the first dummy gate line DGL1 to the J-th dummy gate line DGLj, and may include a number of dummy sub-pixels DP arranged along the horizontal direction. Here, j may be an integer of 2 or more. Although not shown in the figure, the third dummy pixel group DPG3 may be connected to a dummy data line or the like so as to perform the same operation as the sub-pixels arranged in the display area of the display panel 150. In addition, a fourth dummy pixel group DPG4 located in the outer peripheral region on the opposite side of the third dummy pixel group DPG3 may also be arranged in the same form as the third dummy pixel group DPG3.

[0068] On the other hand, FIG. 13 schematically shows that a dummy pixel group composed of a number of dummy sub-pixels is arranged in each outer peripheral region of the display panel 150 according to an embodiment.

[0069] As shown in FIGS. 14 to 16, the display panel 150 according to the embodiment can display a specific image (for example, a screen saver image) instead of a general display image. 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 screen saver image is displayed by dummy pixels and can rotate around the boundary of the screen in an orbital drive manner. The screen saver image can be displayed around the boundary in a clockwise rotation mode or a counterclockwise rotation mode.

[0070] FIG. 15 is a diagram showing that the position of the display image has moved from Y2 to Y1 in the vertical direction of the display panel 150. As shown in FIG. 15, when the position of the display image moves from the upper side to the lower side, the third dummy pixel group DPG3 located in the upper outer peripheral region of the display panel 150 may display a black image BLK. In the opposite case, the fourth dummy pixel group DPG4 shown in FIG. 13 will display a black image.

[0071] FIG. 16 shows an example in which the position of the display image moves from X2 to X1 in the horizontal direction of the display panel 150. As shown in FIG. 16, when the position of the display image moves from the right side to the left side, the second dummy pixel group DPG2 located in the right outer region of the display panel 150 may display a black image BLK. In the opposite case, the first dummy pixel group DPG1 shown in FIG. 13 will display a black image.

[0072] As described above, when a specific image (hereinafter, a protected image) is displayed, by using an orbiting driving method that moves the position where the protected image is displayed, it is possible to delay the degradation phenomenon caused by the sub-pixels included in the display panel 150 continuously displaying the same image. Further, if the dummy pixel group arranged in the outer region is displayed in black (black) as the position of the protected image moves, it is possible to prevent the problem that the movement of the position of the protected image is visually recognized on the screen, and to improve problems such as luminance difference problems caused by the movement of the position of the protected image. In addition, a rest period during which black is displayed can be added to the pixels near the boundary of the screen, which can delay the degradation phenomenon and the burn-in problem, so that the life of the device can be extended and the image quality can be improved. In particular, since static information such as logos and banners is often displayed at the boundaries or edges of the screen, such effects can be expected.

[0073] The light-emitting display device according to the embodiment may employ an adaptive sensing method in response to the phenomenon that the sensing time for acquiring the sensing voltage becomes longer or shorter due to a change in frequency. For this purpose, in the embodiment, the dummy pixels (or dummy sub-pixels) included in the dummy pixel groups DPG1 to DPG4 may be used. Hereinafter, as an example, the case where the position of the protected image displayed on the display panel 150 moves from the upper side to the lower side as shown in FIG. 15 will be used to explain the embodiment.

[0074] FIGS. 17 to 20 are diagrams for explaining a method of sensing one dummy sub-pixel included in a display panel at a first frequency according to an embodiment, and FIGS. 21 to 24 are diagrams for explaining a method of sensing a plurality of dummy sub-pixels included in a display panel at a second frequency according to an embodiment. Hereinafter, with reference to the internal configuration of the sensing circuit unit 145 illustrated in FIG. 10, a sensing method according to an embodiment will be described.

[0075] As shown in FIGS. 10 and 17 to 20, a light-emitting display device according to an embodiment can display a specific image (e.g., a screen saver image) that is not a general image on the display panel 150. When the position of the display image moves from the upper side Y2 to the lower side 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 with a screen saver image in the boundary region of the screen. For example, the screen saver image can include an intermediate or low gray scale value or a predetermined pattern in order to equalize the voltage and help the region of the screen rest, but the embodiment is not limited thereto.

[0076] When the light-emitting display device according to the embodiment is driven at a first frequency (e.g., 60 Hz), the first dummy sub-pixel DP1 can be specified as a sensing target line SL1 in the third dummy pixel group DPG3 that displays a black image BLK by orbit driving. The first dummy sub-pixel DP1 specified for the sensing target line SL1 can operate in the order of a first period P1 to a fourth period P4 defined by a first sensing time ST1 as follows.

[0077] During the first period P1 to the third period P3, a first scan signal and a first sensing 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 dummy sub-pixel DP1. The first scan signal and the first sensing signal (Scan & Sense) are applied at a high voltage during the first period P1 to the third period P3 and can be changed to a low voltage (off voltage) thereafter in the fourth period.

[0078] During the first period P1 and the second period P2, a sensing data voltage Sdata can be applied to the Jth data line DLj of the first dummy sub-pixel DP1. During the first period P1 and the second period P2, the first voltage circuit control signal VpreS can be changed to a low voltage (off voltage) after a high voltage (on voltage) is applied.

[0079] During the fourth period P4, the sampling circuit unit SAM connected to the Ith reference line VREFi of the first dummy sub-pixel DP1 can be turned on in response to a sampling control signal Sam. The sampling control signal Sam can be applied at a high voltage (on voltage) only during the fourth period P4.

[0080] During the first period P1, the sensing node of the driving transistor DT included in the first dummy sub-pixel DP1 can be initialized by a first reference voltage. During the second period P2, the driving transistor DT of the first dummy sub-pixel DP1 can operate for a certain time with a constant current source by the sensing data voltage Sdata. During the third period P3, the first dummy sub-pixel DP1 can operate in a current tracking state by source following of the driving transistor DT. During the fourth period P4, the voltage applied to the sensing node of the first dummy sub-pixel DP1 can be obtained as a sensing voltage Vsen by the sampling circuit unit SAM connected to the Ith reference line VREFi.

[0081] In summary of the above description, when the driving frequency of the light-emitting display device according to the embodiment is not fast enough to ensure sufficient sensing time, or when the driving frequency is slow enough to ensure sufficient sensing time (for example, 60 Hz), only one dummy pixel can be designated as the sensing target and sensed alone.

[0082] As shown in FIGS. 10 and 21 to 24, the light-emitting display device according to the embodiment can display a specific image (for example, a screen saver image) that is not a general image on the display panel 150. When the position of the displayed image moves from the upper side Y2 to the lower side Y1, the third dummy pixel group DPG3 located in the upper outer region of the display panel 150 can display a black image BLK. That is, when the fourth dummy pixel group DPG4 located in the lower outer region of the display panel 150 is displaying a screen saver image, the third dummy pixel group DPG3 located in the upper outer region of the display panel 150 can display a black image BLK, and sensing can be performed on one or more sub-pixels including the third dummy pixel group DPG3.

[0083] When the light-emitting display device according to the embodiment is driven at a second frequency (for example, a high frequency such as 240 Hz), the first to Jth dummy sub-pixels DP1 to DPj in the third dummy pixel group DPG3 that displays a black image BLK by orbital driving can be designated as sensing target lines SL1 to SLj. The first to Jth dummy sub-pixels DP1 to DPj designated for the sensing target lines SL1 to SLj can operate in the order of the first period P1 to the fourth period P4 defined by the second sensing time ST2 as follows. Here, it is referred to that the second sensing time ST2 corresponds to a time shorter than the first sensing time ST1 (ST2 < ST1). For example, when the light-emitting display device is driven at a high frequency, the time for displaying the black image BLK is short (for example, the sensing period of the PSP is short), so the first to Jth dummy sub-pixel groups DP1 to DPj designated as the sensing target lines SL1 to SLj can be sensed simultaneously in a lump.

[0084] During the first period P1 to the third period P3, a first scan signal and a first sensing 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 to J dummy sub-pixels DP1 to DPj. The first scan signal and the first sensing signal (Scan & Sense) are applied at a high voltage during the first period P1 to the third period P3 and can be changed to a low voltage (off voltage) thereafter.

[0085] During the fourth period P4, the sampling circuit unit SAM connected to the I-th reference line VREFi of the first to J dummy sub-pixels DP1 to DPj can be turned on in response to the sampling control signal Sam. The sampling control signal Sam can be applied at a high voltage (on voltage) only during the fourth period P4.

[0086] During the first period P1, the sensing nodes of the driving transistors DT included in the first to J dummy sub-pixels DP1 to DPj can be initialized by the first reference voltage. During the second period P2, the driving transistors DT of the first to J dummy sub-pixels DP1 to DPj can operate for a certain time with a constant current source by the sensing data voltage Sdata. During the third period P3, the first to J dummy sub-pixels DP1 to DPj can operate in a current tracking state by source following of the driving transistor DT. During the fourth period P4, the voltage applied to the sensing nodes of the first to J dummy sub-pixels DP1 to DPj can be integrated by the sampling circuit unit SAM connected to the I-th reference line VREFi and can be obtained as the sensing voltage Vsen. That is, the first to J dummy sub-pixels DP1 to DPj can be sensed simultaneously as a group.

[0087] In summary of the above description, when the driving frequency of the light-emitting display device according to the embodiment is so fast that sufficient sensing time cannot be ensured, a large number of dummy sub-pixels can be designated as sensing targets and sensed simultaneously. That is, when the light-emitting display device is driven at a high frequency, a dummy sub-pixel group can be detected simultaneously as a whole.

[0088] On the other hand, the light-emitting display device according to the embodiment can be configured to support various driving frequencies in addition to the above-described driving frequency. For example, when configured with UHD that can operate at 240 Hz, this can support not only the 240 Hz driving mode and the 60 Hz driving mode, but also the 120 Hz driving mode existing between them. Furthermore, recently manufactured and configured light-emitting display devices can support VRR (Variable Refresh Rate) operation so as to be adaptively used in various driving environments instead of a fixed driving frequency.

[0089] As can be seen from FIGS. 17 and 21, when the driving frequency for driving the display panel is fast (for example, a high frequency of 240 Hz), the time defining the blank period BLK included in the vertical synchronization signal Vsync may become short. To explain this separately, when the resolution of the display panel is high (high resolution) and the driving frequency for driving it is fast (high frequency), the sensing period PSP may become short. This also applies when the driving frequency for driving the display panel is fast and the resolution is high (high resolution).

[0090] Thus, if the blank period BLK becomes short, the sensing period PSP also becomes short. Therefore, it may be difficult to determine the significant difference as to whether the sensing voltage is acquired at a normal value or with an abnormal value.

[0091] In order to improve the significant difference determination ability, the light-emitting display device according to the embodiment can limit the sensing target to dummy sub-pixels while variably changing the current amount that can be obtained by sensing in accordance with the change in the driving frequency. Then, in order to variably change the current amount in accordance with the change in the driving frequency, the number of dummy sub-pixels to be sensed can be increased or decreased. That is, the light-emitting display device according to the embodiment can variably change the current amount obtained by increasing or decreasing the number of dummy sub-pixels to be sensed in accordance with the change in the driving frequency (which is the change in the blank period if described separately).

[0092] FIGS. 25 to 27 are diagrams for explaining the change in driving timing when an adaptive sensing method is employed in accordance with the change in frequency according to the embodiment.

[0093] As shown in FIGS. 25 and 26, when summing up the currents SUM obtained from a number of dummy sub-pixels DP1 to DPj rather than obtaining the current from one dummy sub-pixel DP1, the current amount may be increased. Further, assuming that the same target current amount is to be obtained, when summing up the currents SUM obtained from a number of dummy sub-pixels DP1 to DPj rather than obtaining the current from one dummy sub-pixel DP1, the sensing time Δt can be shortened.

[0094] As shown in FIG. 27, the light-emitting display device according to the embodiment can variably change the current amount obtained by increasing or decreasing the number of dummy sub-pixels to be sensed in accordance with the change in the driving frequency (which is the change in the blank period if described separately). For example, when the driving frequency is slower than 120 Hz, which is a reference driving frequency of low frequency such as 60 Hz, it is determined that the driving frequency can ensure sufficient sensing time, and only the first dummy sub-pixel DP1 can perform sensing. However, when the driving frequency is faster than 120 Hz, which is the reference driving frequency such as 240 Hz, it is determined that the driving frequency cannot ensure sufficient sensing time, and a number of dummy sub-pixels DP1 to DPj can perform sensing.

[0095] On the one hand, in the above example, the reference driving frequency of the light-emitting display device was set to 120 Hz as an example. However, the reference driving frequency can be set based on the minimum driving frequency and the maximum driving frequency of the configured light-emitting display device, or a driving frequency that induces insufficient sensing time can be set as the reference driving frequency.

[0096] As can be understood with reference to the illustrated example, according to the embodiment, the time for applying the sensing data voltage Sdata and the time for applying the first reference voltage (VpreS reference for permitting the application of the first reference voltage) can be fixed without fluctuation. However, the first scan signal Scan, the first sensing signal Sense, and the sampling control signal Sam that determine the sensing time can vary depending on the number of sensing target dummy sub-pixels. This can be confirmed by comparing when sensing one dummy sub-pixel DP1, when sensing the first to the I-th dummy sub-pixels DP1 to DPi, and when sensing the first to the J-th dummy sub-pixels DP1 to DPj.

[0097] In other words, since the faster the driving frequency, the shorter the sensing time, considering this, the number of sensing target dummy sub-pixels can be increased so that the amount of current that can be obtained during the limited time increases.

[0098] On the other hand, a method of varying the number of sensing target dummy sub-pixels corresponding to a change in the driving frequency while acquiring a sensing voltage using the dummy sub-pixels included in the display panel capable of performing orbit driving as in the embodiment can provide more advantageous benefits than a method of sensing the sub-pixels arranged in the display area of the display panel.

[0099] For example, if the driving frequency is faster than the aforementioned reference frequency (e.g., 120 Hz), the sensing time will be shortened. Therefore, it may be difficult to obtain a significant value of the sensing voltage from the sub-pixels arranged in the display area of the display panel within a limited time (blank period). However, the dummy sub-pixels included in the display panel display black for a certain period of time in response to the position movement of the protection image during orbit driving. Therefore, the number of dummy sub-pixels to be sensed can be selectively varied in response to the change in the driving frequency, and the sensing voltage can be obtained therefrom. In addition, during orbit driving, since a large number of dummy sub-pixels included in the display panel can be sensed at once, the sensing voltage can be obtained as a significant value compared to the sub-pixels arranged in the display area of the display panel. Furthermore, it can be utilized even when the sub-pixels arranged in the display area of the display panel cannot be sensed or when the sub-pixels arranged in the display area of the display panel are composed of non-sensing sub-pixels (sensing-less sub-pixels).

[0100] The light-emitting display device according to the embodiment can also obtain the sensing voltage from the dummy sub-pixels included in the display panel during orbit driving and detect the presence or absence of defects in the display panel based on this. The explanation is as follows.

[0101] FIG. 28 is a flowchart for explaining the driving method of the light-emitting display device according to the embodiment.

[0102] As shown in FIG. 28, the light-emitting display device according to the embodiment can determine whether the display panel is in orbit driving (S100). If the display panel is not in orbit driving (N), it is determined whether the power-off signal of the display panel is applied (S110). If the power-off signal of the display panel is applied (Y), the sub-pixels SP arranged in the display area of the display panel are sensed to obtain the sensing voltage, and a compensation operation for compensating for deterioration is performed based on this (S120). After the sensing and compensation operations of the sub-pixels SP are completed, the power of the display panel can be turned off.

[0103] In contrast, if the display panel is in orbit drive (Y), the drive frequency is analyzed (S130). If the current drive frequency is the first frequency (Y), the dummy sub-pixel DP of the display panel is sensed under the first condition to obtain a sensing voltage, and based on this, the presence or absence of a defect in the display panel is detected (S150). For example, the first frequency may be 60 Hz, and the first condition may be to sense one dummy sub-pixel to obtain a sensing voltage (for example, sensing one sub-pixel at a time).

[0104] If the current drive frequency is not the first frequency (N), it is determined whether it is the second frequency (S160). If the current drive frequency is the second frequency (Y), the dummy sub-pixel DP of the display panel is sensed under the second condition to obtain a sensing voltage, and based on this, the presence or absence of a defect in the display panel is detected (S170). For example, the second frequency is 120 Hz, and the second condition may be to sense a number of dummy sub-pixels that is more than the first condition but less than the third condition to obtain a sensing voltage.

[0105] If the current drive frequency is not the second frequency (N), it is determined whether it is the third frequency (S180). If the current drive frequency is the third frequency (Y), the dummy sub-pixel DP of the display panel is sensed under the third condition to obtain a sensing voltage, and based on this, the presence or absence of a defect in the display panel is detected (S190). For example, the third frequency is 240 Hz, and the third condition may be to sense a larger number of dummy sub-pixels than the second condition to obtain a sensing voltage (for example, sensing multiple rows or columns of sub-pixels simultaneously).

[0106] As described above, in the light-emitting display device according to the embodiment, when the display panel is in orbit drive, the drive frequency is analyzed, and the number of sensed dummy sub-pixels is selectively changed according to the current drive frequency to obtain a sensing voltage (sensing value), and based on this, it can be driven to detect the presence or absence of defects and the defect position (coordinates) of the display panel. In other words, the light-emitting display device can dynamically change how many sub-pixels to sense during one blank period BLK (for example, the sensing period PSP) based on the drive frequency. For example, when the light-emitting display device is driven at a low frequency (for example, 60 Hz), the light-emitting display device can sense one sub-pixel at a time, or sequentially sense one line at a time. Also, when the light-emitting display device is driven at an intermediate frequency (for example, 120 Hz), the light-emitting display device can perform simultaneous sensing of a group of sub-pixels at a time (for example, sense the sub-pixels of one line together). Furthermore, when the light-emitting display device is driven at a high frequency (for example, 240 Hz), the light-emitting display device can sense a larger group of sub-pixels simultaneously (for example, sense the sub-pixels of multiple rows or columns together). Also, when sensing multiple sub-pixels simultaneously, the sensed values can be summed, and the sum value can be compared with a predetermined value to determine the presence or absence of defects.

[0107] The defects of the display panel can be judged based on the sensing voltage, and include line defects due to defects in the data lines / gate lines included in the display panel (judgeable when a sensing value error occurs / when it is impossible to obtain a sensing value), power supply unit, power line or power supply failure output therefrom (judgeable when it is impossible to obtain a sensing value), short circuits between signal lines and power lines included in the display panel and the resulting overcurrent generation (burn-in due to overcurrent), etc.

[0108] As described above, this specification has the effect of solving the problem of ensuring sensing time that can be induced in a high-resolution and high-frequency driving environment (difficulty in sensing during a short blank period while driving the display panel). In addition, when the display panel is driven in an orbit, this specification has the effect of solving the problem of ensuring sensing time by increasing or decreasing the number of sensing target dummy sub-pixels corresponding to changes in the driving frequency. Further, this specification has the effect of detecting the presence or absence of defects in the display panel by increasing or decreasing the number of dummy sub-pixels.

Explanation of Reference Numerals

[0109] 120 Timing control unit 140 Data driving unit 150 Display panel 141 Driving circuit unit 145 Sensing circuit unit DPG1~DPG4 Dummy pixel groups SP Sub-pixel DP Dummy sub-pixel

Claims

1. A display panel including sub-pixels arranged in a display area and a dummy sub-pixel line arranged in an outer area of the display area, and a circuit unit that outputs a data voltage for driving the display panel during a first period and acquires a sensing value from the display panel during a second period. The circuit unit is a display device that increases or decreases the number of dummy sub-pixel lines to be sensed among the dummy sub-pixel lines detected during the second period in response to a change in a driving frequency of the display panel.

2. The display device according to claim 1, wherein the circuit unit increases the number of dummy sub-pixel lines to be sensed as the driving frequency of the display panel becomes faster.

3. The circuit unit sets a reference driving frequency of the display panel, and when the driving frequency is faster than the reference driving frequency, increases the number of dummy sub-pixel lines to be sensed, and when the driving frequency is slower than the reference driving frequency, decreases the number of dummy sub-pixel lines to be sensed. The display device according to claim 1.

4. The circuit unit selects, as a sensing target, a dummy sub-pixel line that displays black during a blank period when a position of an image displayed on the display panel moves up, down, left, or right. The display device according to claim 1.

5. The circuit unit determines a defect of the display panel based on the sensing value obtained from the number of dummy sub-pixel lines to be sensed. The display device according to claim 1.

6. The circuit unit applies a sensing data voltage via a dummy data line connected to at least one of the dummy sub-pixel lines during a blank period of the display panel, and acquires the sensing value via a reference line connected to at least one of the dummy sub-pixel lines. The display device according to claim 1.

7. A protection image display step of displaying a protection image based on sub-pixels arranged in a display area of a display panel and moving a position where the protection image is displayed, and a black image display step of displaying a black image on at least one of dummy sub-pixel lines arranged in an outer area of the display panel and moving a position of the black image each time the display position of the protection image moves. A driving method of a display device, including: when the position of an image displayed on the display panel moves up, down, left, or right, selecting, as a sensing target, at least one dummy sub-pixel line among the dummy sub-pixel lines that display a black image, and a sensing step of sensing the sensing target.

8. The driving method of the display device according to claim 7, further including a step of changing the number of at least one of the dummy sub-pixel lines sensed as the sensing target based on a change in the driving frequency of the display panel.

9. The sensing step of sensing the sensing target is The driving method of the display device according to claim 8, further including a step of increasing the number of at least one of the dummy sub-pixel lines to be sensed as the driving frequency of the display panel becomes faster.

10. The driving method of the display device according to claim 7, further including a step of determining a defect of the display panel based on a sensing value obtained from the sensing target.

11. The sensing step is performed during a blank period of the display panel. The driving method of the display device according to claim 7.

12. A display panel including a plurality of sub-pixels for displaying an image, the plurality of sub-pixels including a plurality of dummy sub-pixels arranged in a boundary region of the display panel, and A controller that, in response to driving the display panel at a first driving frequency, detects a voltage corresponding to one of the plurality of dummy sub-pixels during a blank period, and in response to driving the display panel at a second driving frequency higher than the first driving frequency, senses a voltage corresponding to a first number of the plurality of dummy sub-pixels during the blank period. A display device including.

13. The controller is In response to driving the display panel at a third driving frequency higher than the first and second driving frequencies, senses a voltage corresponding to a second number of the dummy sub-pixels during the blank period, The display device according to claim 12, wherein the second number of sub-pixels is larger than the first number of sub-pixels.

14. The display device according to claim 13, wherein the first driving frequency is 60 Hz, the second driving frequency is 120 Hz, and the third driving frequency is 240 Hz.

15. The plurality of dummy sub-pixels include a first dummy sub-pixel group arranged in the left outer region of the display panel, a second dummy sub-pixel group arranged in the right outer region of the display panel, a third dummy sub-pixel group arranged in the upper outer region of the display panel, and a fourth dummy sub-pixel group arranged in the lower outer region of the display panel. The display device according to claim 12, wherein the controller displays a protection image based on an orbital driving method using at least one of the first, second, third, and fourth dummy sub-pixel groups.

16. The controller In response to moving the protection image from the third dummy sub-pixel group to the fourth dummy sub-pixel group, the third dummy sub-pixel group performs black display during the blank period, senses a voltage corresponding to at least one dummy sub-pixel among the third dummy sub-pixel group during the blank period. The display device according to claim 15, wherein a compensation operation is executed based on the voltage corresponding to the at least one dummy sub-pixel among the third dummy sub-pixel group, or it is determined that there is a defect in the display panel.

17. The controller In response to driving the display panel at the first driving frequency, selecting a single dummy sub-pixel as the at least one dummy sub-pixel among the third dummy sub-pixel group sensed during the blank period. The display device according to claim 15, wherein in response to driving the display panel at the second driving frequency or the third driving frequency, one or a plurality of lines of a plurality of dummy sub-pixels are selected as the at least one dummy sub-pixel among the third dummy sub-pixel group sensed during the blank period.

18. The controller Adding voltage values corresponding to the one or a plurality of lines of a plurality of dummy sub-pixels to generate an addition value. The display device according to claim 17, wherein a compensation operation is executed based on the addition value, or it is determined that there is a defect in the display panel.

19. The controller is configured to: in response to moving the protection image from the second dummy sub-pixel group to the first dummy sub-pixel group, perform black display by the second dummy sub-pixel group during the blank period, sense a voltage corresponding to at least one dummy sub-pixel among the second dummy sub-pixel group during the blank period, execute a compensation operation or determine that there is a defect in the display panel based on the voltage corresponding to the at least one dummy sub-pixel among the second dummy sub-pixel group. The display device according to claim 15.

20. The controller is configured to: supply a sensing data voltage to a data line connected to one of the one dummy sub-pixel or the first number of dummy sub-pixels during the blank period, receive a detected value from a reference line connected to one of the one dummy sub-pixel or the first number of dummy sub-pixels during the blank period. The display device according to claim 12.

Images