Display device and its driving method

Abstract

To provide a display device that can reduce sensing problems in high-resolution and high-frequency driving environments. [Solution] According to one embodiment, a display device is provided which includes a display panel that includes subpixels arranged in a display area and dummy subpixel lines arranged in an outer area, and a circuit unit that outputs a data voltage for driving the display panel in a first period and acquires sensing values ​​from the display panel in a second period, wherein the circuit unit increases or decreases the number of dummy subpixel lines to be sensed among the dummy subpixel lines in accordance with the driving frequency of the display panel.

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 (LED), quantum dot display devices (QDD), and liquid crystal display devices (LCD) 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 secure a sufficient sensing time for performing 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 addresses the problem of ensuring sufficient sensing time (difficulty sensing during short blank periods while the display panel is in operation) that can be induced in high-resolution and high-frequency driving environments. Furthermore, this specification detects the presence or absence of defects in the display panel by increasing or decreasing the number of dummy subpixels to be sensed in response to changes in the driving frequency during the orbital driving of the display panel. [Means for solving the problem]

[0007] This specification provides a display device that includes a display panel having subpixels arranged in a display area and dummy subpixel lines arranged in an outer area, and a circuit unit that outputs a data voltage for driving the display panel in a first period and acquires sensing values ​​from the display panel in a second period, wherein the circuit unit increases or decreases the number of dummy subpixel lines to be sensed among the dummy subpixel lines in accordance with the driving frequency of the display panel.

[0008] The circuit unit can increase the number of dummy subpixel lines to be sensed as the driving frequency of the display panel increases.

[0009] The circuit unit sets a reference drive frequency for the display panel, and if the drive frequency is faster than the reference drive frequency, it increases the number of dummy subpixel lines to be sensed, and if the drive frequency is slower than the reference drive frequency, it decreases the number of dummy subpixel lines to be sensed.

[0010] The circuit unit may define a dummy subpixel line that displays black during the blank period of the display panel as a sensing target when the position of the image displayed on the display panel moves up, down, left, or right.

[0011] The circuit unit can determine whether or not there is a defect in the display panel based on the sensing value obtained from the dummy subpixel line to be sensed.

[0012] The circuit unit can apply a sensing data voltage via a dummy data line connected to the dummy subpixel line during the blanking period of the display panel, and acquire the sensing value via a reference line connected to the dummy subpixel line.

[0013] In other aspects, this specification provides a method for driving a display device, which includes: a protective image display step of displaying a protective image based on subpixels arranged in the display area of ​​a display panel and moving the position in which the protective image is displayed; a black image display step of displaying a black image on at least one of the dummy subpixel lines arranged in the outer area of ​​the display panel and moving the position of the black image each time the display position of the protective image moves; and a sensing step of defining the dummy subpixel lines that display black as sensing targets when the position of the image represented on the display panel moves up, down, left, or right, and varying the number of sensing target dummy subpixel lines in accordance with the driving frequency of the display panel and performing sensing.

[0014] In the sensing step, the number of dummy subpixel lines to be sensed can be increased as the driving frequency of the display panel increases. The system may further include a defect determination step that determines whether or not the display panel has defects based on the sensing values ​​obtained from the dummy subpixel lines to be sensed.

[0015] The sensing step may be performed while the display panel is blank. [Effects of the Invention]

[0016] According to the present 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, the present 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, the present 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 the Drawings

[0017] [Figure 1] It is a block diagram schematically showing a light-emitting display device. [Figure 2] It is a configuration diagram schematically showing the sub-pixels shown in FIG. 1. [Figure 3] It is an exemplary view of a pixel composed of sub-pixels. [Figure 4] It is a diagram for explaining the configuration of a gate driving unit of a gate-in-panel method. [Figure 5] It is a diagram for explaining the configuration of a gate driving unit of a gate-in-panel method. [Figure 6] It is a diagram showing an example of the arrangement of a gate driving unit of a gate-in-panel method. [Figure 7] It is a diagram briefly showing a sub-pixel and a data driving unit according to a first example of an embodiment. [Figure 8] It is a diagram briefly showing a sub-pixel and a data driving unit according to a second example of an embodiment. [Figure 9] It is a waveform diagram for explaining a sensing period and a display period according to an embodiment. [Figure 10] It is a diagram showing in more detail a part of the configuration included in a data driving unit according to an embodiment. [Figure 11] It is a diagram showing a method of sensing a display panel according to an embodiment. [Figure 12] It is a diagram showing a method of sensing a display panel according to an embodiment. [Figure 13]It is a diagram showing a dummy pixel group included in a display panel of a light-emitting display device according to an embodiment. [Figure 14] It is a diagram for explaining an over-driving method of a display panel according to an embodiment. [Figure 15] It is a diagram for explaining an over-driving method of a display panel according to an embodiment. [Figure 16] It is a diagram for explaining an over-driving method of a display panel according to an embodiment. [Figure 17] It is a diagram for explaining a method of sensing one dummy sub-pixel included in a display panel at a first frequency according to an embodiment. [Figure 18] It is a diagram for explaining a method of sensing one dummy sub-pixel included in a display panel at a first frequency according to an embodiment. [Figure 19] It is a diagram for explaining a method of sensing one dummy sub-pixel included in a display panel at a first frequency according to an embodiment. [Figure 20] It is a diagram for explaining a method of sensing one dummy sub-pixel included in a display panel at a first frequency according to an embodiment. [Figure 21] It is a diagram 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. [Figure 22] It is a diagram 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. [Figure 23] It is a diagram 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. [Figure 24] It is a diagram 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. [Figure 25] It is a diagram for explaining a change in driving timing by an adaptive sensing method corresponding to a change in frequency according to an embodiment. [Figure 26]This diagram illustrates the change in drive timing due to an adaptive sensing method in response to changes in frequency as shown in the embodiment. [Figure 27] This diagram illustrates the change in drive timing due to an adaptive sensing method in response to changes in frequency as shown in the embodiment. [Figure 28] This is a flowchart illustrating the driving method of the light-emitting display device according to the embodiment. [Modes for carrying out the invention]

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

[0019] The shapes, sizes, proportions, angles, numbers, etc., disclosed in the drawings to illustrate embodiments of this disclosure are illustrative only, and this disclosure is not limited to those shown. The same reference numerals indicate the same components throughout the specification. Furthermore, where a detailed description of the relevant prior art would unnecessarily obscure the essence of this disclosure, such detailed description is omitted.

[0020] In this specification, where "includes," "possesses," "consists of," etc., other parts may be added unless "only" is used. Also, where a component is expressed in the singular form, it is assumed to include the plural form unless otherwise specified.

[0021] In interpreting the constituent elements, it should be understood that a margin of error is included, even if there is no further explicit description.

[0022] In descriptions of positional relationships, for example, if the positional relationship between two parts is described as "above," "top," "bottom," "adjacent," etc., one or more other parts may be located between the two parts unless "immediately" or "directly" is used.

[0023] While terms such as "first," "second," etc., are used to describe various components, these components are not limited by these terms. These terms are used solely to distinguish one component from another. Therefore, within the scope of the technical spirit of this disclosure, the first component referred to below may also be the second component.

[0024] The same reference number may refer to substantially the same element throughout this disclosure.

[0025] The following embodiments can be combined or linked together in part or as a whole, and can be connected and operated in a variety of technical ways. The embodiments can be implemented independently or in association with each other. Various embodiments of this disclosure will be described in detail below with reference to the attached drawings.

[0026] This specification may consist of, but is not limited to, televisions, image players, personal computers (PCs), home theaters, automotive electrical systems, smartphones, etc. This specification may also consist of light-emitting display devices (LEDs), quantum dot display devices (QDDs), liquid crystal display devices (LCDs), etc. However, for the sake of explanation, a light-emitting display device that directly emits light based on inorganic or organic light-emitting diodes will be used as an example below.

[0027] Figure 1 is a schematic block diagram of a light-emitting display device, Figure 2 is a schematic configuration diagram of the subpixels shown in Figure 1, and Figure 3 is an example diagram of a pixel made up of subpixels.

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

[0029] The image supply unit (set or host system) 110 can output various drive signals along with image data signals supplied from an external source or image data signals stored in internal memory. The image supply unit 110 can supply data signals and various drive signals to the timing control unit 120.

[0030] The timing control unit 120 can output a gate timing control signal GDC for controlling the operating timing of the gate drive unit 130, a data timing control signal DDC for controlling the operating timing of the data drive 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 drive unit 140 along 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 to this.

[0031] The gate drive unit 130 can output a gate signal (or gate voltage) in response to a gate timing control signal GDC supplied from the timing control unit 120. The gate drive unit 130 can supply gate signals to subpixels included in the display panel 150 via gate lines GL1 to GLm. The gate drive unit 130 can be formed in the form of an IC or directly formed on the display panel 150 using a gate-in-panel (Gate In Panel) method, but is not limited to these.

[0032] The data drive 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, and convert the digital data signal into an analog data voltage based on a gamma reference voltage for output. The data drive unit 140 can supply data voltages to subpixels included in the display panel 150 via data lines DL1 to DLn. The data drive unit 140 can be formed in IC form and mounted on the display panel 150 or on a printed circuit board, but is not limited to this.

[0033] The power supply unit 180 can generate a high-potential first power supply and a low-potential second power supply based on an externally supplied external input voltage. The power supply unit 180 can output the first power supply via the first power supply line EVDD and the second power supply via the second power supply line EVSS. In addition to the first and second power supplies, the power supply unit 180 can generate or output voltages required to drive the gate drive unit 130 (e.g., scan high voltage and scan low voltage) and voltages required to drive the data drive unit 140 (drain voltage and half-drain voltage).

[0034] The display panel 150 can display an image in response to drive signals including gate signals and data voltages, a first power supply, and a second power supply. The subpixels of the display panel 150 can directly emit light. The display panel 150 can be fabricated from a rigid or ductile substrate such as glass, silicon, or polyimide. For example, one subpixel SP can be connected to a first data line DL1, a first gate line GL1, a first power supply line EVDD, and a second power supply line EVSS, and may include a pixel circuit consisting of a switching transistor, a drive transistor, a capacitor, an organic light-emitting diode, and the like.

[0035] Subpixel SPs used in light-emitting devices emit light directly, resulting in a complex circuit configuration. Furthermore, the compensation circuits for degradation (threshold voltage, mobility, etc.) of not only the light-emitting organic light-emitting diodes but also the drive transistors that supply the drive current necessary to drive the organic light-emitting diodes are diverse. Therefore, it is recommended to refer to a simplified representation of the subpixel SPs in block form.

[0036] Light-emitting subpixels may consist of pixels containing red, green, and blue light, or pixels containing red, green, blue, and white light. For example, a single pixel P may include a red subpixel SPR connected to the first data line DL1, a white subpixel SPW connected to the second data line DL2, a green subpixel SPG connected to the third data line DL3, and a blue subpixel connected to the fourth data line DL4. The red subpixel SPR, white subpixel SPW, green subpixel SPG, and blue subpixel SPB may all be connected to the first reference line VREF1. The first reference line VREF1 can be used to sense the degradation of one of the elements contained in the red subpixel SPR, white subpixel SPW, green subpixel SPG, and blue subpixel SPB, which will be explained below.

[0037] On the other hand, the above description described the timing control unit 120, gate drive unit 130, data drive unit 140, etc., as separate components. However, depending on the configuration of the light-emitting display device, one or more of the timing control unit 120, gate drive unit 130, and data drive unit 140 can be integrated into a single IC. Furthermore, the timing control unit 120, gate drive unit 130, data drive unit 140, power supply unit 180, and display panel 150 can be defined as a display module as an assembly for displaying an image.

[0038] In addition, the above explanation uses a pixel P arranged in the order of red subpixel SPR, white subpixel SPF, green subpixel SPG, and blue subpixel SPB as an example. However, the arrangement order and orientation of subpixels can vary depending on the configuration of the light-emitting display device.

[0039] Figures 4 and 5 are diagrams illustrating the configuration of the gate-in-panel type gate drive unit, and Figure 6 is a diagram showing an example of the arrangement of the gate-in-panel type gate drive unit.

[0040] As shown in Figure 4, the gate-in-panel gate drive unit may include a shift register 131 and a level shifter 135. The level shifter 135 can generate a drive clock signal Clks and 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 such as Clks and Vst output from the level shifter 135 and can output gate signals Gate[1] to Gate[m] to turn on or turn off transistors formed on the display panel. The shift register 131 can be formed on the display panel in the form of a thin film using a gate-in-panel method.

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

[0043] As shown in Figure 6, the shift registers 131a and 131b that output the gate signal in the gate-in-panel gate drive unit can be placed in the non-display area NA of the display panel 150. In this example, the shift registers 131a and 131b are shown placed in the left and right non-display areas NA of the display panel 150, but they may also be placed in the top and bottom non-display areas NA of the display panel 150, or within the display area AA of the display panel 150.

[0044] Figure 7 is an illustrative diagram showing a simplified representation of the subpixel and data drive unit according to the first embodiment, Figure 8 is a diagram showing a simplified representation of the subpixel and data drive unit according to the second embodiment, and Figure 9 is a waveform diagram illustrating the sensing period and display period according to the embodiment.

[0045] As shown in Figure 7, according to the first example, one subpixel 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 driver 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 driver 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 driver 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 drive 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 acquire a sensed voltage Vsen via a sensing node defined between the driving transistor DT and the organic light-emitting diode OLED.

[0049] According to the embodiment, the data driving unit 140 may include a driving circuit unit 141 for driving subpixels SP and a sensing circuit unit 145 for sensing subpixels SP. The driving circuit unit 141 may be connected to a first data line DL1 via a first data channel DCH1. The driving circuit unit 141 may output a data voltage Vdata or the like for driving subpixels 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 acquire the sensing voltage Vsen sensed from the subpixel SP via the first sensing channel SCH1. The sensing circuit unit 145 may acquire the sensing voltage Vsen based on a current sensing or voltage sensing method, etc.

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

[0052] As shown in Figure 9, the light-emitting display device according to the embodiment may employ a driving method that is divided into three periods for driving the display panel: a first driving period PWR_ON, a second driving period DISPLAY, and a third driving period PWR_OFF.

[0053] The first drive period, PWR_ON, corresponds to the start period when power is applied to the display panel. The second drive period, DISPLAY, corresponds to the panel drive period after power is applied to the display panel, when the display is driven, for example, in response to a user input such as turning off the power to the display device. The third drive period, PWR_OFF, may correspond to the end period when the power applied to the display panel is cut off, for example, in response to a user input such as turning off the power to the display device. On the other hand, the third drive period, PWR_OFF, is a period during which the display panel is driven for a certain amount of time while displaying black so that sensing operations can be performed. In other words, the power applied to the display panel is not completely cut off during the third drive period, PWR_OFF. To put it another way, even after receiving input from the user to turn off the power to the display device, the display device can display black to appear as if it is off (for example, giving the user the illusion that the device will turn off immediately), but it can keep the power on to perform sensing operations until it is finally turned off.

[0054] The light-emitting display device according to this embodiment can sense the display panel during at least one of the following periods: the first drive period PWR_ON, the second drive period DISPLAY, and the third drive period PWR_OFF. Taking the second drive period DISPLAY as an example, the blank 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.

[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 by 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 in order 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, or the like in order 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 nodes and circuits included in the sub-pixel SP or charging 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 obtaining a sensing voltage via the first reference line VREF1. For example, the sampling circuit unit SAM may obtain a sensing voltage from a sensing capacitor PCAP formed on the first reference line VREF1 based on the sensing capacitor PCAP.

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

[0060] The timing control unit 120 may include a compensation unit that performs compensation operations based on the sensing voltage (sensing data value) supplied from the sensing circuit unit 145. The compensation unit included in the timing control unit 120 can determine whether or not the driving transistor DT or organic light-emitting diode OLED included in the subpixel SP has deteriorated based on the sensing voltage, and can compensate for the deterioration.

[0061] As shown in Figure 11, according to the first example, the light-emitting display device uses a sequential sensing method that senses from the first gate line GL1 to the Mth gate line GLm of the display panel 150, and can sequentially sense the entire screen, one row at a time. In Figure 11, sensing is shown as an example to be performed sequentially from the first gate line GL1, which is the upper part of the display panel 150, but sensing may also be started from the Mth gate line GLm, which is the lower part of the display panel 150.

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

[0063] Figure 13 shows a dummy pixel group included in the display panel of a light-emitting device according to an embodiment, and Figures 14 to 16 are diagrams illustrating the orbit driving method of the display panel according to an embodiment.

[0064] As shown in Figure 13, the display panel 150 according to the embodiment may include dummy pixel groups DPG1 to DPG4 arranged in the outer region (or bezel region) of the display area. 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 region of the display panel 150. The second dummy pixel group DPG2 may be located in the right outer region of the display panel 150. The third dummy pixel group DPG3 may be located in the upper outer region of the display panel 150. The fourth dummy pixel group DPG4 may be located in the lower outer region of the display panel 150.

[0066] The first dummy pixel group DPG1 may include numerous dummy subpixels DP arranged vertically, connected to the first dummy data line DDL1 through the Jth dummy data line DDLj, where j can be an integer greater than or equal to 2. Although not shown in the diagram, each of the first dummy pixel groups DPG1 may be connected to dummy gate lines or the like so that they can perform the same operations as subpixels arranged in the display area of ​​the display panel 150. In addition, the second dummy pixel group DPG2, located in the outer region opposite to the first dummy pixel group DPG1, may also have a structure similar to the first dummy pixel group DPG1.

[0067] The third dummy pixel group DPG3 may include a number of dummy subpixels DP arranged horizontally, connected to the first dummy gate line DGL1 or the Jth dummy gate line DGLj, where j can be an integer greater than or equal to 2. Although not shown in the figures, the third dummy pixel group DPG3 may be connected to dummy data lines, etc., so that it can perform the same operations as the subpixels arranged in the display area of ​​the display panel 150. In addition, the fourth dummy pixel group DPG4, located in the outer region opposite the third dummy pixel group DPG3, may also be arranged in a similar manner to the third dummy pixel group DPG3.

[0068] On the other hand, Figure 13 simply shows that, according to the embodiment, dummy pixel groups consisting of numerous dummy subpixels are arranged in each outer region of the display panel 150.

[0069] As shown in Figures 14 to 16, the display panel 150 according to the embodiment may display a specific image (e.g., a screen protection image) rather than a general display image. In this case, the position of the display image may move horizontally (X1→X2 or X1←X2), vertically (Y2←Y1 or Y2→Y1), or both horizontally and vertically. For example, the screen protection image may be displayed by dummy pixels and rotate around the screen boundary in an orbital driving manner. The screen protection image may be displayed around the boundary in a clockwise or counterclockwise rotation manner.

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

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

[0072] As described above, when a specific image (hereinafter referred to as the "protected image") is displayed, using an orbit driving method that moves the position where the protected image is displayed can delay the degradation phenomenon caused by subpixels in the display panel 150 continuously displaying the same image. Furthermore, by displaying a dummy pixel group placed in the outer area in black along with the position movement of the protected image, the problem of the protective image's position movement being visible on the screen can be prevented, and problems such as brightness differences caused by the protective image's position movement can be improved. In addition, a rest period in which black is displayed can be added to pixels near the screen boundary, delaying degradation phenomena and burn-in problems, thereby extending the device's lifespan and improving image quality. This effect can be expected in particular for static information such as logos and banners, which are often displayed at the screen boundary or edges.

[0073] The light-emitting display device according to this embodiment can employ an adaptive sensing method to respond to the phenomenon where the sensing time for acquiring the sensing voltage becomes longer or shorter due to changes in frequency. For this purpose, the embodiment can utilize dummy pixels (or dummy subpixels) included in dummy pixel groups DPG1 to DPG4. Below, the embodiment will be described as an example in which the position of the protective image displayed on the display panel 150 moves from the top to the bottom, as shown in Figure 15.

[0074] Figures 17 to 20 illustrate a method for sensing a single dummy subpixel included in the display panel at a first frequency according to an embodiment, while Figures 21 to 24 illustrate a method for sensing multiple dummy subpixels included in the display panel at a second frequency according to an embodiment. Hereinafter, the sensing method according to the embodiment will be explained with reference to the internal configuration of the sensing circuit unit 145 shown in Figure 10.

[0075] As shown in Figures 10, 17-20, the light-emitting display device according to the embodiment may display a specific image (e.g., a screen protection image) on the display panel 150 that is not a general image. When the position of the display image moves from the upper Y2 to the lower Y1, the third dummy pixel group DPG3 located in the upper outer region of the display panel 150 may display a black image BLK. In other words, a portion of the actual input image data can be replaced with a screen protection image in the boundary region of the screen. For example, the screen protection image may include intermediate or low grayscale values ​​or a predetermined pattern to help equalize the voltage and allow that region of the screen to rest, but the embodiment is not limited thereto.

[0076] In the light-emitting display device according to the embodiment, when driven at a first frequency (e.g., 60Hz), the first dummy subpixel DP1 in the third dummy pixel group DPG3, which displays a black image BLK by orbit drive, can be designated as the sensing target line SL1. The first dummy 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 as follows.

[0077] During the first period P1 to the third period P3, a high-voltage (on-voltage) first scan signal and first sensing signal (Scan & Sense) may be applied to the first scan line Gate1 and second scan line Gate2 of the first dummy subpixel DP1. The first scan signal and first sensing signal (Scan & Sense) are applied at a high voltage during the first period P1 to the third period P3, and may 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 may be applied to the J data line DLj of the first dummy subpixel DP1. During the first period P1 and the second period P2, the first voltage circuit control signal VpreS may be changed from a high voltage (on voltage) to a low voltage (off voltage).

[0079] During the fourth period P4, the sampling circuit SAM connected to the first reference line VREFi of the first dummy subpixel DP1 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.

[0080] During the first period P1, the sensing node of the drive transistor DT contained in the first dummy subpixel DP1 may be initialized by a first reference voltage. During the second period P2, the drive transistor DT of the first dummy subpixel DP1 may operate for a constant time on a constant current source with a sensing data voltage Sdata. 。 During the third period P3, the first dummy subpixel DP1 may operate in a current-tracking state due to the source-following wing of the drive transistor DT. 。 During the fourth period P4, the voltage applied to the sensing node of the first dummy subpixel DP1 can be obtained as the sensing voltage Vsen by the sampling circuit SAM connected to the first reference line VREFi.

[0081] To summarize the above description, in the case where the driving frequency of the light-emitting display device according to the embodiment is not fast enough to ensure sufficient sensing time, or in the case where the driving frequency is slow enough to ensure sufficient sensing time (for example, 60 Hz), it can be designated as one dummy pixel 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 can be designated as sensing target lines SL1 to SLj in the third dummy pixel group DPG3 that displays a black image BLK by orbital driving. The first to Jth dummy sub-pixels DP1 to DPj designated as 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.

[0084] During the first period P1 to the third period P3, a high-voltage (on-voltage) first scan signal and first sensing signal (Scan & Sense) may be applied to the first scan line Gate1 and second scan line Gate2 of the first to J dummy subpixels DP1 to DPj. The first scan signal and first sensing signal (Scan & Sense) are applied at a high voltage during the first period P1 to the third period P3, and thereafter may be changed to a low voltage (off-voltage).

[0085] During the fourth period P4, the sampling circuit SAM connected to the I reference line VREFi of the first to J dummy subpixels DP1 to DPj may be turned on in response to the sampling control signal Sam. The sampling control signal Sam may 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 drive transistors DT included in the first to J dummy subpixels DP1 to DPj may be initialized by a first reference voltage. During the second period P2, the drive transistors DT of the first to J dummy subpixels DP1 to DPj may operate for a certain period of time on a constant current source with a sensing data voltage Sdata. 。 During the third period P3, the first to Jth dummy subpixels DP1 to DPj can operate in a current tracking state due to source following of the drive transistor DT. During the fourth period P4, the voltages applied to the sensing nodes of the first to Jth dummy subpixels DP1 to DPj are summed by the sampling circuit SAM connected to the Ith reference line VREFi and can be obtained as the sensing voltage Vsen. In other words, the first to Jth dummy subpixels DP1 to DPj can be sensed simultaneously as a group.

[0087] To summarize the above explanation, when the driving frequency of the light-emitting display device according to the embodiment is too high to ensure sufficient sensing time, a large number of dummy subpixels can be designated as sensing targets and sensed simultaneously. In other words, when the light-emitting display device is driven at a high frequency, groups of dummy subpixels can be detected simultaneously.

[0088] On the other hand, the light-emitting display device according to the embodiment can be configured to support a variety of drive frequencies in addition to the aforementioned drive frequencies. For example, if it is configured with a UHD capable of operating at 240Hz, it can support not only the 240Hz drive mode and the 60Hz drive mode, but also the 120Hz drive mode and other modes that lie between them. Furthermore, the light-emitting display device recently manufactured and configured can support VRR (Variable Refresh Rate) operation so that it can be adaptively used in a variety of drive environments, rather than being limited to a fixed drive frequency.

[0089] As can be seen in Figures 17 and 21, when the drive frequency for driving the display panel is high (e.g., a high frequency of 240 Hz), the time defining the blank period BLK included in the vertical synchronization signal Vsync may be shortened. To explain this separately, when the display panel has a high resolution and the drive frequency for driving it is high, the sensing period PSP may be shortened. This can also be true when the drive frequency for driving the display panel is high and the resolution is high.

[0090] Thus, as the blank period (BLK) shortens, the sensing period (PSP) also shortens, making it difficult to determine whether the sensing voltage is acquired at a normal value or at an abnormal value.

[0091] The light-emitting display device according to the embodiment can limit the sensing target to dummy subpixels while varying the amount of current that can be acquired by sensing in response to changes in the drive frequency, in order to improve the ability to judge significant differences. Furthermore, in order to vary the amount of current in response to changes in the drive frequency, the number of dummy subpixels to be sensed can be increased or decreased. In other words, the light-emitting display device according to the embodiment can vary the amount of current acquired by increasing or decreasing the number of dummy subpixels to be sensed in response to changes in the drive frequency (or, to be explained separately, changes in the blanking period), in order to improve the ability to judge significant differences.

[0092] Figures 25 to 27 illustrate the change in drive timing when an adaptive sensing method is adopted in response to changes in frequency according to the embodiment.

[0093] As shown in Figures 25 and 26, summing the currents obtained from multiple dummy subpixels DP1 to DPj may increase the total current compared to obtaining the current from a single dummy subpixel DP1. Furthermore, assuming the acquisition of the same target current, summing the currents obtained from multiple dummy subpixels DP1 to DPj may shorten the sensing time Δt compared to obtaining the current from a single dummy subpixel DP1.

[0094] As shown in Figure 27, the light-emitting display device according to the embodiment can vary the amount of current acquired by increasing or decreasing the number of dummy subpixels to be sensed in response to a change in the drive frequency (or, to put it another way, a change in the blanking period). For example, if the drive frequency is slower than the low-frequency reference drive frequency of 120Hz, such as 60Hz, it is determined that the drive frequency allows for sufficient sensing time, and only the first dummy subpixel DP1 can be sensed. However, if the drive frequency is faster than the reference drive frequency of 120Hz, such as 240Hz, it is determined that the drive frequency does not allow for sufficient sensing time, and a large number of dummy subpixels DP1 to DPj can be sensed.

[0095] On the other hand, in the example mentioned above, the reference drive frequency of the light-emitting display device was set to 120 Hz. However, the reference drive frequency may be set based on the lowest and highest drive frequencies of the configured light-emitting display device, or a drive frequency that induces insufficient sensing time may be set as the reference drive frequency.

[0096] As can be seen from 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 (see VpreS which permits the application of the first reference voltage) can be fixed without variation. However, the first scan signal Scan, the first sensing signal Sense, and the sampling control signal Sam, which determine the sensing time, can change depending on the number of dummy subpixels to be sensed. This can be confirmed by comparing the time when sensing one dummy subpixel DP1, when sensing the first to the Ith dummy subpixels DP1 to DPi, and when sensing the first to the Jth dummy subpixels DP1 to DPj.

[0097] Alternatively, since a faster drive frequency shortens the sensing time, the number of dummy subpixels to be sensed can be increased to increase the amount of current that can be acquired within the limited time, taking this into consideration.

[0098] On the other hand, as in the embodiment, a method that uses dummy subpixels included in a display panel capable of orbit driving to acquire a sensing voltage, while varying the number of dummy subpixels to be sensed in response to changes in the driving frequency, can offer even better advantages than a method that senses subpixels arranged in the display area of ​​the display panel.

[0099] For example, if the drive frequency becomes even faster than the aforementioned reference frequency (e.g., 120Hz), the sensing time will be shortened, making it potentially difficult to obtain a significant value of the sensing voltage from subpixels placed in the display area of ​​the display panel within a limited time (blank period). However, dummy subpixels included in the display panel display black for a certain period of time in response to the movement of the protected image during orbit driving. Therefore, the number of dummy subpixels to be sensed can be selectively varied in response to changes in the drive frequency, and the sensing voltage can be obtained from them. Furthermore, since a large number of dummy subpixels included in the display panel can be sensed at once during orbit driving, the sensing voltage relative to subpixels placed in the display area of ​​the display panel can be obtained at a significant value. Moreover, this method can be used even when it is not possible to sense subpixels placed in the display area of ​​the display panel, or when the subpixels placed in the display area of ​​the display panel consist of subpixels that cannot be sensed (sensingless subpixels).

[0100] The light-emitting display device according to this embodiment can also acquire a sensing voltage from a dummy subpixel included in the display panel during orbit driving and detect the presence or absence of defects in the display panel based on this, which can be explained as follows.

[0101] Figure 28 is a flowchart illustrating the driving method of a light-emitting display device according to an embodiment.

[0102] As shown in Figure 28, the light-emitting display device according to the embodiment can determine whether or not the display panel is in orbit drive mode (S100). If the display panel is not in orbit drive mode (N), it is determined whether or not a power-off signal has been applied to the display panel (S110). If a power-off signal has been applied to the display panel (Y), the subpixels SP arranged in the display area of ​​the display panel are sensed to obtain the sensing voltage, and a compensation operation is performed to compensate for degradation based on this (S120). Once the sensing and compensation operation of the subpixels SP is completed, the power to the display panel can be turned off.

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

[0104] If the current drive frequency is not the first frequency (N), it is determined whether or not it is the second frequency (S160). If the current drive frequency is the second frequency (Y), the dummy subpixels DP of the display panel are sensed under the second condition to obtain the sensing voltage, and based on this, the presence or absence of defects in the display panel is detected (S170). For example, if the second frequency is 120Hz, the second condition may involve sensing a number of dummy subpixels that are greater than those of the first condition but fewer than those of the third condition to obtain the sensing voltage.

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

[0106] As described above, the light-emitting display device according to the embodiment can analyze the drive frequency when the display panel is in orbit drive mode, selectively change the number of dummy subpixels to be sensed based on the current drive frequency to obtain a sensing voltage (sensing value), and based on this, drive to detect the presence and location (coordinates) of defects in the display panel. In other words, the light-emitting display device can dynamically change how many subpixels are sensed during one blank period BLK (e.g., sensing period PSP) based on the drive frequency. For example, when the light-emitting display device is driven at a low frequency (e.g., 60 Hz), it can sense one subpixel at a time, or sequentially sense one line at a time. When the light-emitting display device is driven at an intermediate frequency (e.g., 120 Hz), it can simultaneously sense a group of subpixels at once (e.g., sense a row of subpixels together). Furthermore, when the light-emitting display device is driven at a high frequency (e.g., 240 Hz), it can simultaneously sense larger groups of subpixels (e.g., sense subpixels in multiple rows or columns together). Furthermore, when multiple subpixels are detected simultaneously, the detected values ​​can be summed up and compared with a predetermined value to determine whether or not a defect exists.

[0107] A display panel defect is one that can be determined based on the sensing voltage and may include line defects due to defects in data lines / gate lines included in the display panel (determinable when sensing value errors occur / sensing value acquisition becomes impossible), power supply failures in the power supply unit, power lines, or power output therefrom (determinable when sensing value acquisition becomes impossible), and short circuits between signal lines or power lines included in the display panel and the resulting overcurrent (burn-in due to overcurrent).

[0108] In summary, this specification has the effect of resolving the sensing time management problem (difficulty sensing during short blank periods while the display panel is being driven) that can be induced in high-resolution and high-frequency driving environments. Furthermore, this specification has the effect of resolving the sensing time management problem by increasing or decreasing the number of dummy subpixels to be sensed in response to changes in the driving frequency when the display panel is orbiting. In addition, 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 subpixels. [Explanation of symbols]

[0109] 120 Timing Control Unit 140 Data-driven unit 150 Display Panels 141 Drive circuit section 145 Sensing Circuit Section DPG1~DPG4 Dummy Pixel Group SP Subpixel DP dummy subpixel

Claims

1. A display panel including subpixel lines placed in the display area and dummy subpixel lines placed in the hidden area, The system includes a circuit that outputs a data voltage to drive the dummy subpixel line during the first period and acquires sensing values ​​from the dummy subpixel line during the second period. The circuit unit is a display device that changes the starting point of the sensing period in accordance with the change in the driving frequency of the display panel.

2. The display device according to claim 1, wherein as the drive frequency of the display panel increases, the starting point of the sensing period approaches the starting point of the second period.

3. The aforementioned circuit section is Set the reference drive frequency of the display panel, If the drive frequency becomes higher than the reference drive frequency, the control is made to shorten the interval between the start point of the sensing period and the start point of the second period. The display device according to claim 1, wherein when the drive frequency becomes lower than the reference drive frequency, the device controls the interval between the start point of the sensing period and the start point of the second period to be lengthened.

4. The display device according to claim 1, wherein the circuit unit increases or decreases the number of dummy subpixel lines to be sensed among the dummy subpixel lines to be sensed during the second period.

5. The display device according to claim 4, wherein the circuit increases the number of dummy subpixel lines to be sensed when the drive frequency increases.

6. The aforementioned circuit section is Set the reference drive frequency of the display panel, If the drive frequency is faster than the reference drive frequency, the number of dummy subpixel lines to be sensed is increased. The display device according to claim 4, wherein the number of dummy subpixel lines to be sensed is reduced when the drive frequency is slower than the reference drive frequency.

7. The display device according to claim 4, wherein when the position of the image displayed on the display panel moves in any direction (up, down, left, or right), the circuit unit displays black on a dummy subpixel line corresponding to the position where the image is displayed, and selects the dummy subpixel line displaying black as the sensing target.

8. The display device according to claim 1, wherein the circuit unit determines a defect in the display panel based on the sensing value.

9. The aforementioned circuit section is During the second period of the display panel, a sensing data voltage is applied via a dummy data line connected to at least one of the dummy subpixel lines. The display device according to claim 1, wherein the sensing value is acquired via a reference line connected to at least one of the dummy subpixel lines.

10. A protective image display step involves displaying a protective image based on subpixels arranged in the display area of ​​a display panel, and moving the position in which the protective image is displayed. A black image display step involves displaying a black image on at least one of the dummy subpixel lines arranged in the outer region of the display panel, and moving the position of the black image each time the display position of the protective image moves. A sensing step in which, when the position of the image displayed on the display panel moves up, down, left, or right, at least one dummy subpixel line that displays a black image from among the dummy subpixel lines is selected as the sensing target, and the sensing target is sensed, A method for driving a display device, comprising an acquisition step of acquiring a sensed value from a selected dummy subpixel line by changing the starting point of the sensing period in accordance with a change in the driving frequency of the display panel.

11. The method for driving a display device according to claim 10, wherein when the driving frequency of the display panel increases, the starting point of the sensing period approaches the starting point of the second period.

12. A method for driving a display device according to claim 10, further comprising the step of changing the number of dummy subpixel lines to be sensed as sensing targets based on a change in the driving frequency of the display panel.

13. The method for driving a display device according to claim 12, wherein the number of dummy subpixel lines to be sensed increases as the driving frequency of the display panel increases.

14. A method for driving a display device according to claim 10, further comprising the step of determining a defect in the display panel based on the sensing value.

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