Display device and driving method thereof

Abstract

The present application relates to a display device and a driving method thereof. The display device includes a display unit including a plurality of pixels and a sensing unit disposed outside the display unit, wherein the sensing unit senses deterioration information of a driving transistor in each of the plurality of pixels through a plurality of sensing lines and compensates for deterioration of the driving transistor. The sensing unit senses the deterioration information during a first sensing period, and the first sensing period is included in each of a power-off period in which a power supply for the display device to display an image is not supplied, a power-on period in which the display device is turned on, and an image display period in which an image is continuously displayed after the display device is turned on.

Description

[0001] This application claims priority to and all benefits derived from Korean Patent Application No. 10-2020-0031997, filed on March 16, 2020, which is hereby incorporated by reference in its entirety. Technical Field

[0002] The present disclosure relates to a display device and a method of driving the display device. Background Art

[0003] A display device, such as a conventional smartphone, may include at least one display area. The display area may be defined by a data output portion, and input data may be displayed on the display area. Furthermore, the display area may be provided with a touch sensor and may operate as a touch screen. Such a display area may be employed on the front face of the display device to display various information.

[0004] Recently, flat panel display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), or organic light emitting display devices are widely used as display devices. Summary of the Invention

[0005] In an organic light-emitting display device, a pixel typically includes multiple transistors, a storage capacitor, and an organic light-emitting diode (OLED). Luminance differences between pixels can occur due to variations between pixels (e.g., the distribution of threshold voltages of drive transistors), and these differences can be detected as smear. Consequently, research is underway into various smear compensation algorithms to correct for smear.

[0006] An embodiment of the present disclosure provides a display device in which the length of a period for sensing and compensating for degradation of a driving transistor is minimized.

[0007] Another embodiment of the present disclosure provides a display device and a method of driving the same, in which degradation of a driving transistor is sensed or compensated even in a period in which the display device is turned on or displays an image.

[0008] According to an embodiment of a display device of the present disclosure, the display device includes a display unit including a plurality of pixels and a sensing unit disposed outside the display unit, wherein the sensing unit senses degradation information of a driving transistor in each of the plurality of pixels via a plurality of sensing lines and compensates for the degradation of the driving transistor. In such an embodiment, the sensing unit senses the degradation information during a first sensing period, and the first sensing period is included in each of a power-off period during which power is not supplied for displaying an image by the display device, a power-on period during which the display device is turned on, and an image display period during which an image is continuously displayed after the display device is turned on.

[0009] In an embodiment, the length of the first sensing period may be in the range of about 10 microseconds (μs) to about 100 μs.

[0010] In an embodiment, the display device may further include: a first scan driver, which provides a scan signal to each of a plurality of pixels through a scan line; a second scan driver, which provides a sensing scan signal to each of a plurality of pixels through a sensing scan line; and a data driver, which provides a data voltage to each of a plurality of pixels through a data line.

[0011] In an embodiment, each of the plurality of pixels may include: a first transistor serving as a driving transistor; a second transistor connected between a data line and a gate electrode of the first transistor; wherein the second transistor can be turned on or off based on a scan signal; and a third transistor connected between an electrode of the first transistor and a corresponding one of the plurality of sensing lines; wherein the third transistor can be turned on or off based on a sensing scan signal, and the second transistor and the third transistor can be turned on or off simultaneously in a first sensing period.

[0012] In an embodiment, the sensing unit may include: a multiplexer unit including a plurality of multiplexers including input terminals connected to a plurality of sensing lines; and an analog-to-digital converter performing analog-to-digital conversion on sensing signals received from the plurality of sensing lines to generate sensing data as digital signals.

[0013] In an embodiment, the sensing unit may further include an operational amplifier unit including a plurality of operational amplifiers connected between the multiplexer unit and the analog-to-digital converter.

[0014] In an embodiment, the number of the plurality of operational amplifiers included in the operational amplifier unit may be equal to or smaller than the number of the plurality of sensing lines.

[0015] In an embodiment, the operational amplifier unit may include: a first operational amplifier and a second operational amplifier, each of the first operational amplifier and the second operational amplifier integrating, sampling, and scaling a current flowing through a plurality of sensing lines, and differentially amplifying an output at one output terminal of each of a plurality of multiplexers; and a third operational amplifier including: an inverting input terminal connected to the other output terminal of each of the plurality of multiplexers and a non-inverting input terminal supplied with an initialization voltage.

[0016] In an embodiment, signals of two adjacent odd-numbered sensing lines or two adjacent even-numbered sensing lines may be input to a first operational amplifier and a second operational amplifier, and a signal of a sensing line between two adjacent odd-numbered sensing lines or two adjacent even-numbered sensing lines may be input to a third operational amplifier.

[0017] In an embodiment, the display device may sense degradation information of the driving transistor during a second sensing period included in the power-off period, and a length of the second sensing period may be longer than a length of the first sensing period.

[0018] In an embodiment, the length of the second sensing period may be approximately 30 milliseconds (ms) or longer.

[0019] In an embodiment, the first compensation period, the second compensation period, and the third compensation period may be included in the power-off period, the power-on period, and the image display period, respectively, and the degradation of the driving transistor may be compensated during the first compensation period, the second compensation period, and the third compensation period based on the sensing data value sensed in the second sensing period.

[0020] In an embodiment, degradation of the driving transistor may be further compensated during a fourth compensation period based on a first sensing data value sensed in a first sensing period included in the power-off period and a second sensing data value sensed in a first sensing period included in the power-on period.

[0021] In an embodiment, degradation of the driving transistor may be compensated during the fifth compensation period based on the first sensing data value sensed in the first sensing period included in the power-off period and the third sensing data value sensed in the first sensing period included in the image display period.

[0022] In an embodiment, the fifth compensation period may be included a plurality of times in the image display period, and in each of the plurality of fifth compensation periods, the threshold voltage of the driving transistor may be compensated in a stepwise manner.

[0023] In an embodiment, the first sensing period included in the image display period may be included in a vertical blanking period in which image display is stopped.

[0024] An embodiment of a method for driving a display device includes a power-off period during which power is not supplied for displaying an image, a power-on period during which the display device is turned on, and an image display period during which an image is continuously displayed after the display device is turned on. The method includes: sensing degradation information of a drive transistor in a pixel of the display device during a first sensing period included in each of the power-off period, the power-on period, and the image display period; and compensating for degradation of the drive transistor based on a first sensed data value sensed in the first sensing period included in the power-off period and a second sensed data value sensed in the first sensing period included in the power-on period. In such an embodiment, the length of the first sensing period is in a range of approximately 10 μs to approximately 100 μs.

[0025] In an embodiment, the method may further include sensing degradation information of the driving transistor during a second sensing period included in the power-off period, wherein the second sensing period is longer than the first sensing period and may be about 30 ms or longer.

[0026] In an embodiment, the method may further include compensating for degradation of the driving transistor during each of the power-off period, the power-on period, and the image display period based on the sensing data value sensed in the second sensing period.

[0027] In an embodiment, the method may further include compensating for degradation of the driving transistor based on a first sensing data value sensed in a first sensing period included in the power-off period and a third sensing data value sensed in a first sensing period included in the image display period.

[0028] According to an embodiment of the present disclosure, a display device can minimize the length of a period during which degradation of a driving transistor is compensated.

[0029] In such an embodiment, even if degradation of the driving transistor is sensed and compensated during a period in which the display device displays an image, recognition by the user can be minimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other features of the present invention will become more apparent by describing in further detail embodiments of the present invention with reference to the accompanying drawings, in which:

[0031] Figure 1 is a block diagram of a display device according to an embodiment of the present disclosure;

[0032] Figure 2 It shows Figure 1 A circuit diagram showing a schematic connection relationship between pixels, data drivers, and sensing units;

[0033] Figure 3is a timing diagram illustrating a method of driving a display device according to an embodiment of the present disclosure;

[0034] Figure 4 is a block diagram schematically illustrating a portion of a sensing unit according to an embodiment of the present disclosure;

[0035] Figure 5 yes Figure 4 A circuit diagram of a sensing unit;

[0036] Figure 6 It is shown in the figure Figure 5 A conceptual diagram of a schematic flow of signals during a sensing period of odd-numbered sensing lines in a circuit diagram of FIG.

[0037] Figure 7 It is shown in the figure Figure 5 A conceptual diagram of a schematic flow of signals during a sensing period of an even-numbered sensing line in a circuit diagram of FIG.

[0038] Figure 8 is a graph schematically illustrating a threshold voltage compensation value of a driving transistor in a pixel circuit according to an embodiment of the present disclosure versus time in a first sensing period;

[0039] Figure 9 is a graph relating to a sensed data value according to a gate-source voltage of a driving transistor in a first sensing period according to an embodiment of the present disclosure;

[0040] Figure 10 is a conceptual diagram related to a method of compensating for a threshold voltage of a driving transistor in a pixel circuit according to an embodiment of the present disclosure;

[0041] Figure 11 is a graph illustrating that a threshold voltage of a driving transistor is compensated in an image display period according to an embodiment of the present disclosure; and

[0042] Figure 12 is a graph illustrating a concept of a first sensing period according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0043] The present invention will now be described more fully hereinafter with reference to the accompanying drawings showing various embodiments. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. Throughout the text, like reference numerals refer to like elements.

[0044] It will be understood that although the terms "first," "second," "third," etc. may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below could be referred to as a second element, component, region, layer, or section without departing from the teachings herein.

[0045] The terms used herein are only for the purpose of describing specific embodiments and are not intended to be limiting. As used herein, "one", "the" and "at least one" do not represent a limitation on quantity and are intended to include both the singular and the plural, unless the context clearly indicates otherwise. For example, "an element" has the same meaning as "at least one element" unless the context clearly indicates otherwise. "At least one" is not to be interpreted as being limited to "one". "Or" means "and / or". As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will be further understood that, when used in this specification, the term "include" or "comprising" specifies the presence of the features, regions, integers, steps, operations, elements and / or parts, but does not exclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, parts and / or groups thereof.

[0046] As used herein, "about" or "approximately" is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, taking into account the measurements in question and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations or within ±30%, 20%, 10%, or 5% of the stated value.

[0047] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0048] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the accompanying drawings, the same or similar reference numerals are used to indicate the same or similar components.

[0049] Display devices may include organic light-emitting display devices, quantum dot light-emitting display devices, micro-LED display devices, etc. Hereinafter, for ease of description, an embodiment in which the display device is an organic light-emitting display device will be described in detail. However, the present disclosure is not limited thereto, and the spirit of the present disclosure may be applied to other display devices as long as the spirit of the present disclosure is not changed.

[0050] Figure 1 is a block diagram of a display device according to an embodiment of the present disclosure. Figure 2 It shows Figure 1 A circuit diagram showing a schematic connection relationship between pixels, data drivers and sensing units.

[0051] Reference Figure 1 and Figure 2 , an embodiment of the display device 100 includes a display unit 110 , a timing controller 120 , a data driver 131 , a sensing unit 133 , a first scan driver 141 , a second scan driver 143 , an initialization voltage determining unit 150 , and a voltage generator 160 .

[0052] The display unit 110 includes a plurality of pixels PX, a plurality of scan lines SL1, SL2, ..., SLN, a plurality of sensing scan lines SSL1, SSL2, ..., SSLn, a plurality of data lines DL1, DL2, ..., DLM, and a plurality of sensing lines SDL1, SDL2, ..., SDLm (here, n, N, m, and M are natural numbers).

[0053] The pixels PX may be arranged in a matrix including a plurality of pixel rows and a plurality of pixel columns. The pixel rows may correspond to a horizontal direction relative to the display unit 110, and the pixel columns may correspond to a vertical direction.

[0054] Each pixel PX includes a pixel circuit, and the pixel circuit includes a plurality of transistors and an organic light emitting diode driven by the plurality of transistors.

[0055] In one embodiment, for example, the pixel circuit includes a data line DLj, a sensing line SDLj, a scan line SLi, a sensing scan line SSLi, a first transistor T1, a light emitting element LD, a second transistor T2, a storage capacitor Cst, and a third transistor T3 (here, j is a natural number equal to or greater than 1 and equal to or less than m and M, and i is a natural number equal to or greater than 1 and equal to or less than n and N).

[0056] The data line DLj is connected to an output terminal of the data driver 131 and transmits a data voltage Vdata or a data signal DATA[m] to the pixel circuit.

[0057] The sensing line SDLj is connected to the sensing unit 133. The sensing line SDLj may transmit the initialization voltage VINT to the pixel circuit in the image display period, and transmit the sensing signal generated in the pixel circuit to the sensing unit 133 in the sensing period. The line capacitor C LINE Can be connected between the ground terminal and the sensing line SDLj.

[0058] The scan lines SL1, SL2, ..., SLN are connected to the output terminal of the first scan driver 141 and transmit the scan signal SCAN[n] generated by the first scan driver 141 to the pixel circuit. The scan signal SCAN[n] includes a period for turning on the second transistor T2.

[0059] , SSLn may be connected to an output terminal of the second scan driver 143 and transmit a sensing scan signal SENSE[n] generated by the second scan driver 143 to the pixel circuit. The sensing scan signal SENSE[n] includes a period for turning on the third transistor T3.

[0060] The first transistor T1 includes a gate electrode connected to the storage capacitor Cst, a first electrode receiving the first power voltage ELVDD, and a second electrode connected to the anode of the light emitting element LED. The first transistor T1 may be referred to as a driving transistor.

[0061] The light emitting element LD includes an anode connected to the second electrode of the first transistor T1 and a cathode receiving the second power voltage ELVSS.

[0062] The second transistor T2 includes a gate electrode connected to the scan line SLi, a first electrode connected to the data line DLj, and a second electrode connected to the gate electrode of the first transistor T1. The second transistor T2 can provide a data voltage Vdata to the gate electrode of the first transistor T1 under the control of the scan signal SCAN[n]. In such an embodiment, the second transistor T2 can be arranged between the data line DLj and the gate electrode of the first transistor T1 and can be turned on or off in response to the scan signal SCAN[n].

[0063] The storage capacitor Cst includes a first electrode connected to the gate electrode of the first transistor T1 and a second electrode connected to the anode of the light emitting element LD (the second electrode of the first transistor T1 ).

[0064] The third transistor T3 includes a gate electrode connected to the sensing scan line SSLi, a first electrode connected to the second electrode of the first transistor T1, and a second electrode connected to the sensing line SDLj. The third transistor T3 can provide information about the current flowing through the driving transistor or information about the voltage of the anode to the sensing unit 133 through the sensing line SDLj in response to the sensing scan signal SENSE[n]. The third transistor T3 can be connected between the second electrode of the driving transistor and the sensing line SDLj and can be turned on or off in response to the sensing scan signal SENSE[n].

[0065] The timing controller 120 receives a control signal CONT and image data DATA from the outside (eg, an external graphic device), and generates a plurality of control signals based on the control signal CONT.

[0066] The plurality of control signals may include a first control signal CONT1 controlling the data driver 131 , a second control signal CONT2 controlling the first scan driver 141 , a third control signal CONT3 controlling the second scan driver 143 , and a fourth control signal CONT4 controlling the initialization voltage determination unit 150 .

[0067] The data driver 131 performs digital-to-analog conversion on the corrected image data DATAc provided from the timing controller 120 based on the first control signal CONT1 to generate a data voltage Vdata, and outputs the data voltage Vdata to the plurality of data lines DL1 , DL2 , . . . , DLM.

[0068] The data driver 131 may include an amplifier AMP. The data driver 131 may output the data voltage Vdata to the data lines DL1, DL2, . . . , DLM through the amplifier.

[0069] In an embodiment, the data driver 131 may output a data voltage Vdata for sensing a threshold voltage of the first transistor T1 in the corresponding pixel PX to the data lines DL1 , DL2 , . . . , DLM.

[0070] The sensing unit 133 performs analog-to-digital conversion on the sensing signals received from the plurality of sensing lines SDL1 , SDL2 , . . . , SDLm to generate sensing data SD as digital signals. The sensing unit 133 may provide the sensing data SD to the timing controller 120 .

[0071] In an embodiment, the sensing unit 133 may be located outside the display unit 110. In an embodiment, for example, the sensing unit 133 may be provided in the display device 100 together with the data driver 131 in the form of a driver integrated circuit (IC).

[0072] The sensing unit 133 may include an operational amplifier unit 220 including a first input terminal receiving a sensing signal and a second input terminal receiving an initialization voltage VINT, and outputting an analog signal to an output terminal.

[0073] The operational amplifier unit 220 may include an initialization capacitor C connected between the first input terminal and the output terminal. INT . Output capacitor C O It may be connected between the ground terminal and the output terminal of the operational amplifier unit 220 .

[0074] The sensing unit 133 may include an analog-to-digital converter (also referred to as ADC) 240, which converts the sensing signal through analog-to-digital conversion and outputs the sensing data to the output terminal ADC_OUT. The sensing unit 133 may include a switch member 230 (a switch matrix to be described later) connected between the output terminal of the operational amplifier unit 220 and the analog-to-digital converter 240. The sensing signal received from the sensing line SDLj may be output as sensing data that sequentially passes through the operational amplifier unit 220, the switch matrix 230, and the analog-to-digital converter 240.

[0075] Although not shown in the drawings, the sensing unit 133 may further include a multiplexer, which will be referred to later. Figure 4 etc. describe the multiplexer in detail.

[0076] According to an embodiment, the timing controller 120 calculates a correction value (eg, a threshold voltage compensation value of a driving transistor) based on the sensing data to compensate for degradation of a pixel circuit, and generates corrected image data DATAc based on the correction value.

[0077] According to an embodiment, the timing controller 120 may control the initialization voltage determination unit 150 to correct the level of the initialization voltage VINT based on the correction value.

[0078] The first scan driver 141 may generate a plurality of scan signals SCAN[n] based on the second control signal CONT2 and may sequentially output the plurality of scan signals SCAN[n] to the plurality of scan lines SL1 , SL2 , . . . , SLN.

[0079] The second scan driver 143 may generate a plurality of sensing scan signals SENSE[n] based on the third control signal CONT3 and may sequentially output the plurality of sensing scan signals SENSE[n] to the plurality of sensing scan lines SSL1 , SSL2 , . . . , SSLn.

[0080] In an embodiment, the first scan driver 141 and the second scan driver 143 may be separate units. In an alternative embodiment, the scan driver may be provided in the display device in the form of a single scan driver including sub-scan drivers that perform the functions of each of the first scan driver 141 and the second scan driver 143.

[0081] According to an embodiment, a period during which the third transistor T3 is turned on by the sensing scan signal SENSE[n] applied to the pixel circuit may overlap with a period during which the second transistor T2 is turned on by the scan signal SCAN[n].

[0082] The initialization voltage determination unit 150 divides the image data DATA of a frame into a plurality of blocks and calculates a plurality of block brightness values ​​corresponding to the plurality of blocks.

[0083] The initialization voltage determination unit 150 extracts the maximum and minimum luminance values ​​among a plurality of block luminance values ​​and calculates a luminance difference value between the maximum and minimum luminance values. The initialization voltage determination unit 150 determines the level of the initialization voltage VINT for each frame based on the luminance difference value.

[0084] The voltage generator 160 generates a plurality of driving voltages using an external power voltage for driving the display unit 110. The plurality of driving voltages may include a first power voltage ELVDD, a second power voltage ELVSS, and a plurality of initialization voltages VINT.

[0085] According to an embodiment, the voltage generator 160 generates the initialization voltage VINT for each frame corresponding to the level of the initialization voltage VINT determined by the initialization voltage determination unit 150. The voltage generator 160 may output the initialization voltage VINT for each frame to the sensing unit 133.

[0086] Figure 3 is a timing diagram illustrating a method of driving a display device according to an embodiment of the present disclosure.

[0087] Also refer to Figure 3 In an embodiment of a method for driving a display device, the display device may have a power-off period in which power for displaying an image is not supplied, a power-on period in which the display device 100 is turned on by a user, and an image display period in which an image is continuously displayed after the display device 100 is turned on. Figure 3 An example is shown in which the sensing period is included in the power-on period among the above-mentioned periods.

[0088] In an embodiment, the display device 100 may include a first sensing period SSP1 in at least one selected from a power-off period, a power-on period, and an image display period. In an embodiment, one or more first sensing periods SSP1 may be included in each of at least one selected from a power-off period, a power-on period, and an image display period. In an embodiment, the first sensing period SSP1 may be included multiple times in the power-on period and / or the image display period.

[0089] In an embodiment, during the first sensing period SSP1, the data driver 131 may maintain the potential of the anode of the light-emitting element LD at a constant voltage through an amplifier, and the first scan driver 141 and the second scan driver 143 may supply a gate-on level scan signal SCAN[n] and a sensing scan signal SENSE[n] to the pixel circuit, respectively, to simultaneously turn on the second transistor T2 and the third transistor T3. At this time, the sensing unit 133 may sense the current through constant current driving. Here, the first sensing period SSP1 may be defined as a period for sensing degradation information of the drive transistor in the pixel circuit.

[0090] Because the first sensing period SSP1 is relatively short, even if the first sensing period SSP1 is included in at least one of the power-on period and the image display period, the threshold voltage of the driving transistor can be determined by the sensed current. The first sensing period SSP1 may be referred to as a fast current sensing (fast U sensing (FUSEN)) period.

[0091] In an embodiment, during the first sensing period SSP1, the scan signal and the sensing signal can be controlled to be identical to each other. Therefore, compared with a conventional scan driver, the circuit configuration of the first scan driver 141 and the second scan driver 143 can be simplified, and therefore, various aspects such as size and reliability are desirable. In such an embodiment, because the sensing unit 133 includes an operational amplifier, the length of the first sensing period SSP1 can be shortened compared to the length of the sensing time (second sensing period) performed during a conventional power-off period. In an embodiment, the length of the first sensing period SSP1 can be in a range of approximately 10 microseconds (μs) to approximately 100 μs. Therefore, in an embodiment of the method of driving the display device 100, the display device 100 can sense degradation of the first transistor during the power-on period or image display period and the power-off period.

[0092] According to an embodiment, by determining the threshold voltage of the driving transistor in the first sensing period SSP1, the threshold voltage characteristics can be improved by changing the level of the initialization voltage VINT in the power-off period. In the power-on period or the image display period, the display quality of the image recognized by the user can be improved by threshold voltage characteristic improvement (degradation compensation) by changing the level of the initialization voltage based on the brightness characteristics of the image for each frame. The threshold voltage of the driving transistor can be improved by the characteristics of the initialization voltage supplied to the driving transistor, and the period during which such an operation is performed can be defined as a compensation period. In an embodiment, the compensation period may be a period substantially equal to the first sensing period SSP1 (or the second sensing period), but is not limited thereto. In an alternative embodiment, the compensation period may be a period after the first sensing period SSP1 (or the second sensing period). Reference will be made later to Figure 10 The compensation period is described in more detail.

[0093] According to an embodiment, the display device 100 may include a second sensing period during the power-off period. The second sensing period corresponds to a period during which current is sensed by causing the drive transistor to be in a source-follower mode. In one embodiment, for example, during the second sensing period and the compensation period following the second sensing period, a process of inputting a black data voltage to the pixel PX, initializing, sensing, and then re-inputting the black data voltage may be performed. During the second sensing period, degradation information of the drive transistor may be sensed similarly to the first sensing period SSP1. The second sensing period may be longer than the first sensing period. In an embodiment, when considering saturation time, the second sensing period may be approximately 30 milliseconds (ms) or longer per pixel. In one embodiment, for example, when the display device 100 has an ultra-high-definition (UHD) resolution, the total length of the second sensing period for determining the threshold voltages of the drive transistors of all pixels PX may be in the range of approximately 5 minutes to approximately 10 minutes.

[0094] Hereinafter, the configuration of an embodiment of the sensing unit 133 for fast current sensing will be described.

[0095] Figure 4 is a block diagram schematically illustrating a portion of a sensing unit according to an embodiment of the present disclosure. Figure 5 yes Figure 4 Circuit diagram of the sensing unit. Figure 6 It is shown in the figure Figure 5 A conceptual diagram of a schematic flow of signals during a sensing period of odd-numbered sensing lines in a circuit diagram of FIG. Figure 7 It is shown in the figure Figure 5 A conceptual diagram of a schematic flow of signals during a sensing period of even-numbered sensing lines in a circuit diagram of FIG.

[0096] Figures 4 to 7 A portion of the sensing unit 133 is shown, illustrating elements directly related to four sensing lines SDL[2n-1], SDL[2n], SDL[2n+1], and SDL[2n+2] arranged adjacently. Figure 6 and Figure 7 A flow for describing the concept of signals performed in the first sensing period SSP1 is shown.

[0097] Reference Figures 4 to 7 , an embodiment of the sensing unit 133 may include a multiplexer unit 210 , an operational amplifier unit 220 , a switch matrix 230 , and an analog-to-digital converter 240 .

[0098] According to an embodiment, the sensing unit 133 may include an input terminal electrically connected to a ground terminal 207 to which a ground potential GND is applied, an input terminal electrically connected to an initialization terminal 206 to which an initialization voltage VINT is applied, and an input terminal electrically connected to an external terminal 205 to which an arbitrary voltage VCAL_EXT is supplied for measuring a sensing line. The sensing unit 133 may further include a plurality of switches SW_VCAL, SW_PANEL_DISP, SW_PANEL, SW_VINT, and SW_GND to control application of voltages (e.g., the ground potential GND, the initialization voltage VINT, and the arbitrary voltage VCAL_EXT) to the sensing unit 133.

[0099] The multiplexer unit 210 may include a plurality of multiplexers 211 and 212. An input terminal of each of the plurality of multiplexers 211 and 212 is connected to at least one sensing line. An output terminal of each of the multiplexers 211 and 212 may be connected to one input terminal of operational amplifiers (also referred to as OP-AMPs) 221, 222, and 223.

[0100] In an embodiment, the input terminal of each of the multiplexers 211 and 212 can be connected to adjacent odd-numbered sensing lines SDL[2n-1] and SDL[2n+1] and even-numbered sensing lines SDL[2n] and SDL[2n+2]. In the first sensing period SSP1, the sensing operation can be performed by dividing the first sensing period SSP1 into a first period (odd-numbered sensing line sensing period) and a second period (even-numbered sensing line sensing period) to differentially amplify the sensing values ​​of the sensing lines. For ease of description, Figures 5 to 7Multiplexers 211 and 212 are shown connected to first through fourth sensing lines SDL1, SDL2, SDL3, and SDL4. In one embodiment, for example, input terminals 201 and 202 of the first multiplexer 211 may be connected to the first sensing line SDL1, which is an odd-numbered sensing line (e.g., SDL[2n-1]), and the second sensing line SDL2, which is an even-numbered sensing line (e.g., SDL[2n]). Input terminals 203 and 204 of the second multiplexer 212 may be connected to the third sensing line SDL3, which is another odd-numbered sensing line (e.g., SDL[2n+1]), and the fourth sensing line SDL4, which is another even-numbered sensing line (e.g., SDL[2n+2]).

[0101] In an embodiment, each of the multiplexers 211 and 212 may have a 2-to-1 multiplexer (2:1 MUX) structure. Each of the multiplexers 211 and 212 may include a plurality of switching elements SW_CH_EVEN, SW_CH_ODD, SW_PANEL_DISP, and SW_CH_DUM. The plurality of switching elements SW_CH_EVEN, SW_CH_ODD, SW_PANEL_DISP, and SW_CH_DUM may include: a switching element SW_CH_ODD that is turned on to sense the odd-numbered sensing lines SDL[2n-1] and SDL[2n+1] in a first period, a switching element SW_CH_EVEN that is turned on to sense the even-numbered sensing lines SDL[2n] and SDL[2n+2] in a second period, and a dummy switching element SW_CH_DUM. According to an alternative embodiment, the dummy switching element SW_CH_DUM may be omitted.

[0102] In an embodiment, the multiplexer unit 210 can implement a virtual switch matrix with every two sensing lines (e.g., SDL1 and SDL2 and SDL3 and SDL4) as a unit to connect the sensing lines SDL1, SDL2, SDL3, and SDL4 with the operational amplifier unit 220 and to implement a 2:1 MUX structure.

[0103] The operational amplifier unit 220 may include a first operational amplifier 221 and a second operational amplifier 222, which integrate, sample, and scale the current flowing through the sensing lines SDL1, SDL2, SDL3, and SDL4, and differentially amplify the output of one output terminal of the multiplexers 221 and 212. The operational amplifier unit 220 may further include a third operational amplifier 223, through which the output of the other output terminal of the multiplexers 211 and 212 is input. Each of the first to third operational amplifiers 221, 222, and 223 may include an amplifier, a switch SW_ITG_SIG, SW_ITG_RST, or SW_ITG_REF, and a capacitor C F ,like Figure 5 As shown in .

[0104] The third operational amplifier 223 can integrate, sample, scale, and differentially amplify the current flowing through the reference sensing line. Here, the reference sensing line can be determined as the even-numbered sensing lines SDL[2n] and SDL[2n+2] during the first period for sensing the odd-numbered sensing lines SDL[2n-1] and SDL[2n+1], and can be determined as the odd-numbered sensing lines SDL[2n-1] and SDL[2n+1] during the second period for sensing the even-numbered sensing lines SDL[2n] and SDL[2n+2]. In one embodiment, for example, the reference sensing line during the first period can be set to the second sensing line SDL2, and the reference sensing line during the second period can be set to the third sensing line SDL3.

[0105] The third operational amplifier 223 may be a differential amplifier. An inverting input terminal of the differential amplifier may be connected to another output terminal of the multiplexer through a switch element, and an initialization voltage VINT* may be provided to a non-inverting input terminal.

[0106] The third operational amplifier 223 can receive a signal from the reference sense line. The third operational amplifier 223 can be configured identically or similarly to the first operational amplifier 221 and the second operational amplifier 222, and thus, the third operational amplifier 223 can generate a reference signal REF that is equal to the noise generated in the first operational amplifier 221 and the second operational amplifier 222. In an embodiment, a signal at a virtual ground voltage level can be provided to the reference sense line. The reference signal REF generated from the third operational amplifier 223 can be transmitted to the switch matrix 230 to cancel the noise included in the output terminal of the first operational amplifier 221 and the output terminal of the second operational amplifier 222.

[0107] In an embodiment, a differential signal may be transmitted to a reference sense line and each of the even-numbered sense lines SDL[2n] and SDL[2n+2] or the odd-numbered sense lines SDL[2n-1] and SDL[2n+1] adjacent to the reference sense line. The differential signal may be a signal transmitted using a transmission mode such as double data rate triple synchronous dynamic random access memory (DRAM) (DDR3), low power double data rate synchronous DRAM (LPDDR2), low voltage differential signaling (LVDS), serial advanced technology configuration (S-ATA), and mobile industry processor interface (MiPi).

[0108] In an embodiment, the number of operational amplifiers 221, 222, and 223 included in the operational amplifier unit 220 may be equal to or less than the number of sensing lines SDL1, SDL2, SDL3, and SDL4. The display device 100 may include a smaller number of operational amplifiers 221, 222, and 223 than the number of sensing lines SDL1, SDL2, SDL3, and SDL4 by disposing a multiplexer unit 210 between the plurality of operational amplifiers 221, 222, and 223 and the plurality of sensing lines SDL1, SDL2, SDL3, and SDL4.

[0109] The switch matrix 230 may selectively provide the signal SIG output from the operational amplifier unit 220 to the analog-to-digital converter 240 as voltages ADC+ and ADC− through the switch SW_AFE_SPL and the capacitor Cs.

[0110] In the first period (see Figure 6 In Figure 133a), the current flowing through the source electrode of the driving transistor can be detected through the odd-numbered sensing lines SDL[2n-1] and SDL[2n+1] by applying the sensing data voltage Vdata to the pixels connected to the odd-numbered sensing lines SDL[2n-1] and SDL[2n+1]. The current flowing through the source electrode of the driving transistor can be detected through the even-numbered sensing lines SDL[2n] and SDL[2n+2] by applying the sensing data voltage Vdata for turning off the driving transistor to the pixels connected to the even-numbered sensing lines SDL[2n] and SDL[2n+2]. The value detected as described above can be differentially amplified and can be converted into a digital sensing value.

[0111] In the second period (see Figure 8In Figure 133b), the current flowing through the source electrode of the driving transistor can be detected through the even-numbered sensing lines SDL[2n] and SDL[2n+2] by applying the sensing data voltage Vdata to the pixels connected to the even-numbered sensing lines SDL[2n] and SDL[2n+2]. The current flowing through the source electrode of the driving transistor can be detected through the odd-numbered sensing lines SDL[2n-1] and SDL[2n+1] by applying the sensing data voltage Vdata for turning off the driving transistor to the pixels connected to the odd-numbered sensing lines SDL[2n-1] and SDL[2n+1]. The value detected as described above can be differentially amplified and can be converted into a digital sensing value.

[0112] In an embodiment, the analog-to-digital converter 240 may include a single analog-to-digital converter and a capacitor C nS ,like Figure 5 However, the present disclosure is not limited to Figure 5 In an embodiment, when the sensing signals received from the plurality of sensing lines SDL1, SDL2, ..., SDLm are provided by the operational amplifier unit 220 and the switch matrix 230, the analog-to-digital converter 240 may perform analog-to-digital conversion on the sensing signals to generate sensing information data as digital signals. The sensing unit 133 may provide the sensing information data outputted through the output terminals 241 and 242 of the analog-to-digital converter 240 to the timing controller 120. In an embodiment, for example, the sensing information data outputted through the output terminals 241 and 242 of the analog-to-digital converter 240 may have opposite bits V ON and V OP The timing controller 120 may extract the sensing data SD based on the sensing information data.

[0113] Figure 8 is a graph schematically illustrating a threshold voltage compensation value of a driving transistor in a pixel circuit according to an embodiment of the present disclosure and time in a first sensing period.

[0114] exist Figure 8 In FIG, since the X axis is a period in which the first sensing period SSP1 and the compensation period are substantially the same as each other, the X axis is represented as time within the first sensing period SSP1. Figure 8 In FIG, the threshold voltage of the driving transistor is represented as VTH.

[0115] Reference Figure 8 According to an embodiment, when the threshold voltage of the driving transistor is compensated (e.g., after VTH compensation), compensation can be performed relatively accurately compared to the threshold voltage (e.g., before VTH compensation) or the threshold voltage of the driving transistor where error compensation is performed (e.g., VTH error compensation).

[0116] When sensing data (e.g., see Figure 9 When sensing data obtained under the same sensing conditions (same external conditions, same sensing voltage, and same sensing time) is obtained, the obtained sensing data can be the same as when the threshold voltage of the drive transistor does not change. When a change in sensing conditions occurs, this is caused by a change in the threshold voltage, and therefore, an inverse operation can be performed on the threshold voltage to be compensated. While the same sensing conditions are maintained, the threshold voltage to be compensated can be calculated by comparing the sensing data sensed at different time points, and the threshold voltage of the drive transistor can be compensated based on the calculated value.

[0117] For example, when the amount of degradation of the driving transistor according to the duration of the power-on state of the display device 100 cannot be reflected and compensation is performed based on sensing data measured in a power-off period of the display device 100, erroneous compensation may occur. Alternatively, for example, when compensation is performed based on sensing data measured in a power-off state, in the case where the display device 100 continues the power-off state for several periods, the fact that the threshold voltage characteristics recover by themselves according to time without external compensation may not be reflected, and thus, erroneous compensation may occur.

[0118] Figure 9 is a graph relating to a sensed data value according to a gate-source voltage of a driving transistor in a first sensing period according to an embodiment of the present disclosure. Figure 10 is a conceptual diagram related to a method of compensating a threshold voltage of a driving transistor in a pixel circuit according to an embodiment of the present disclosure.

[0119] Reference Figure 9 , the first sensing data value FU1 is a value measured in the first sensing period SSP1 in the power-off state, the second sensing data value FU2(1) is a value measured in the first sensing period SSP1 after the power-off state continues, and the third sensing data value FU2(2) corresponds to a value measured in the first sensing period SSP1 after a certain time has passed in the image display period.

[0120] In the graph illustrating the first sensing data value FU1 in the power-off state, since the threshold voltage compensation of the driving transistor is completed, the gate-source voltage of the driving transistor may exceed 0 volts (V). After continuing the power-off state, in the graph illustrating the second sensing data value FU2 (1), the value of the offset threshold voltage may be reduced to be less than the threshold voltage compensation value due to recovery, etc. Therefore, the gate-source voltage of the driving transistor may be increased in the negative direction (in the negative direction). Figure 9In the graph illustrating the third sensing data value FU2(2) after a certain time has passed in the image display period, the value of the threshold voltage shifted by the additional degradation process becomes greater than the threshold voltage compensation value, and therefore, the gate-source voltage of the driving transistor can be shifted in the positive direction ( Figure 9 +Shift in the Shift key) exceeds 0V.

[0121] When a constant reference voltage Vref is applied to the driving transistor during the first sensing period SSP1 and current is sensed, the measured sensed value may be changed because the threshold voltage of the driving transistor varies according to environmental changes of the display device 100. In an embodiment, when a threshold voltage compensation value is applied by calculating the amount of change in the threshold voltage using the sensed value of another first sensing period SSP1, the display device 100 can respond to subtle changes in the threshold voltage in real time to compensate for such changes in the measured sensed value. Therefore, the display device 100 can compensate for the threshold voltage of the driving transistor.

[0122] Reference Figure 10 In an embodiment, the power-off period may include a second sensing period, a first compensation period for compensating for the threshold voltage of the drive transistor based on the sensed value VSEN1, and a first sensing period SSP1. Depending on the embodiment, the first sensing period SSP1 of the power-off period may be included in the power-off state and / or while the power-off state continues. The first sense data value FU1 may be sensed in the first sensing period SSP1 during the power-off period.

[0123] According to an embodiment, the power-on period may include a second compensation period for compensating for the threshold voltage of the drive transistor in the power-on period based on the sensed data value VSEN1 in the second sense period of the power-off period. In addition, the power-on period may further include a first sensing period SSP1 for measuring the second sensed data value FU2(1). As described above, the power-on period may not include the second sensing period.

[0124] According to an embodiment, the image display period may include a third compensation period for compensating the threshold voltage of the driving transistor in the image display period based on the sensed data value VSEN1 in the second sensing period of the power-off period. As described above, the image display period may not include the second sensing period.

[0125] In an embodiment, the power-on period may include a fourth compensation period for calculating a compensation value and compensating the threshold voltage to compensate for changes in the threshold voltage according to recovery and / or environmental changes. In the fourth compensation period, the compensation value may be calculated based on the first sensing data value FU1 and the second sensing data value FU2(1). According to an embodiment, the power-on period may include at least one fourth compensation period.

[0126] In an embodiment, the image display period may include a fifth compensation period for calculating a compensation value and compensating the threshold voltage to compensate for a change in the threshold voltage according to degradation. In the fifth compensation period, the compensation value may be calculated using the first sensing data value FU1 and the third sensing data value FU2(2). According to an embodiment, the image display period may include at least one fifth compensation period.

[0127] In an embodiment, the first sensed data value FU1 may be calculated based on the following Equation 1. In such an embodiment, the second sensed data value FU2(1) and the third sensed data value FU2(2) may be calculated based on the following Equation 2.

[0128] [Equation 1]

[0129] FU1=k*a*(Vref-Vth)gamma

[0130] [Equation 2]

[0131] FU2=k*a*(Vref-Vth+b)gamma

[0132] In [Equation 1] and [Equation 2], k represents a constant reflecting the characteristics of the display device 100, a represents a mobility component, Vref represents the gate-source voltage of the driving transistor in the first sensing period SSP1, Vth represents the threshold voltage of the driving transistor, gamma represents the voltage-current conversion relationship, and b represents the additional change amount of the threshold voltage. FU2 described in [Equation 2] represents any one of the second sensing data value FU2(1) and the third sensing data value FU2(2). In one embodiment, for example, k, a, and gamma may have the same value between pixels PX. In the case of FU1, since the first sensing period SSP1 of the power-off period is performed after the second sensing period, Vth may be 0V.

[0133] The change value of the threshold voltage in the fourth compensation period and the fifth compensation period may be calculated by [Equation 1] and [Equation 2] as shown in the following [Equation 3].

[0134] [Equation 3]

[0135]

[0136] FU1 and FU2 can be obtained using the first sensing data value FU1, the second sensing data value FU2, and the third sensing data value FU2(2), and gamma can be obtained using the IV curve of the driving transistor. Therefore, b can be a constant and corresponds to the value of the threshold voltage shifted as described above.

[0137] When a certain time has passed, the compensation value calculated based on the sensed data value sensed in the second sensing period of the power-off period may be compensated in the form of overcompensation or non-compensation. However, the value of the threshold voltage offset by the second sensed data value FU2(1) and the third sensed data value FU2(2) sensed in real time may be calculated, and the value of the threshold voltage may be added to the threshold voltage compensation value. Therefore, the display device 100 can be converted into a structure in which the display device 100 can be compensated in real time.

[0138] In an embodiment, the real-time current variation can be sensed in the first sensing period SSP1 in the middle of the image display period by the operational amplifier unit 220 of the sensing unit 133. In such an embodiment, the value of the shifted threshold voltage can be calculated to compensate for the threshold voltage of the driving transistor in real time.

[0139] Figure 11 is a graph illustrating that a threshold voltage of a driving transistor is compensated in an image display period according to an embodiment of the present disclosure.

[0140] Reference Figure 11 , the image display period may include a plurality of first sensing periods SSP1. The threshold voltage compensation value according to the value 'b' of the offset threshold voltage may be applied in a step unit or in a step manner. That is, the image display period may include a plurality of first sensing periods SSP1 and a fifth compensation period according to each of the first sensing periods SSP1 to compensate for the threshold voltage in a step unit.

[0141] When the threshold voltage is compensated in steps, the compensation performance can be improved so that the compensation performed in the fifth compensation period during the image display period is natural. That is, even if the threshold voltage of the driving transistor is compensated in the fifth compensation period, the user's recognition can be minimized.

[0142] In one embodiment, for example, when the threshold voltage compensation value is set to B (target) according to the value 'b' of the threshold voltage shifted during the predetermined first sensing period SSP1 in the image display period, the predetermined first period CASE1 may have a plurality of fifth compensation periods so that the threshold voltage reaches B (target) in step units. When the threshold voltage compensation value is set to B' (new) according to the value 'b' of the threshold voltage shifted during the predetermined first sensing period SSP1 during the predetermined second period CASE2 after the predetermined first period CASE1, the predetermined second period CASE2 may have a plurality of fifth compensation periods so that the threshold voltage reaches B' (new) in step units.

[0143] Figure 12 is a graph illustrating a concept of a first sensing period according to an embodiment of the present disclosure.

[0144] Reference Figure 12 In an embodiment, since the first sensing period is a relatively short time, the display device 100 can simultaneously sense pixels PX connected to a plurality of sensing lines in the first sensing period. The first sensing period in the image display period may be included in a vertical blanking period in which actual image display is stopped.

[0145] In one embodiment, for example, when the sensing unit 133 of the display device 100 is Figure 12 When simultaneously sensing pixels PX connected to three sensing lines as shown in , sensing data obtained by sensing pixels PX connected to the same sensing line over three consecutive frames can be obtained. The sensing unit 133 of the display device 100 can obtain sensing data corresponding to the number of frames including the first sensing period SSP1 with respect to the pixels PX connected to the same sensing line. In one embodiment, for example, when sensing data is obtained over three consecutive frames, the number of sensing data obtained is three.

[0146] In an embodiment, the display device 100 may compensate the threshold voltage based on the average value of the sensing data obtained for each of the pixels PX connected to the same sensing line. Therefore, erroneous compensation due to noise and sudden environmental changes outside the pixel PX may be minimized.

[0147] Figure 12 The graph shown in is merely exemplary, and the number of sensing lines sensed in one vertical blanking period and the number of times sensing is repeated for each frame may be selectively preset or modified for each display device 100 according to the environment of the display device 100. Such setting values ​​may be stored in a memory (not shown) in the display device 100.

[0148] The present invention should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the present invention to those skilled in the art.

[0149] While the invention has been particularly shown and described with reference to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit or scope of the invention as defined by the following claims.

Claims

1. A display device, comprising: a display unit comprising a plurality of pixels; as well as a sensing unit disposed outside the display unit, wherein the sensing unit senses degradation information of a driving transistor in each of the plurality of pixels through a plurality of sensing lines and compensates for degradation of the driving transistor, wherein the sensing unit senses the degradation information during a first sensing period, the first sensing period is included in each of a power-off period in which power for the display device to display an image is not supplied, a power-on period in which the display device is turned on, and an image display period in which the image is continuously displayed after the display device is turned on, the display device sensing the degradation information of the driving transistor during a second sensing period included in the power-off period, The first sensing period included in the power-off period is subsequent to the second sensing period included in the power-off period, The second sensing period is longer than the first sensing period. A first compensation period, a second compensation period, and a third compensation period are included in the power-off period, the power-on period, and the image display period, respectively, and The degradation of the driving transistor is compensated during the first compensation period, the second compensation period, and the third compensation period based on a sensing data value sensed in the second sensing period.

2. The display device according to claim 1, wherein The length of the first sensing period is in the range of 10 μs to 100 μs.

3. The display device according to claim 1, further comprising: a first scan driver that provides a scan signal to each of the plurality of pixels through a scan line; a second scan driver that provides a sensing scan signal to each of the plurality of pixels through a sensing scan line; as well as A data driver supplies a data voltage to each of the plurality of pixels through a data line.

4. The display device according to claim 3, wherein Each pixel of the plurality of pixels comprises: a first transistor serving as the driving transistor; a second transistor connected between the data line and a gate electrode of the first transistor, wherein the second transistor is turned on or off based on the scan signal; and a third transistor connected between one electrode of the first transistor and a corresponding one of the plurality of sensing lines, wherein the third transistor is turned on or off based on the sensing scan signal, and The second transistor and the third transistor are simultaneously turned on or turned off in the first sensing period.

5. The display device according to claim 1, wherein The sensing unit includes: a multiplexer unit including a plurality of multiplexers including input terminals connected to the plurality of sensing lines; and An analog-to-digital converter performs analog-to-digital conversion on the sensing signals received from the plurality of sensing lines to generate sensing data as digital signals. The display device according to claim 5 , wherein: The sensing unit further includes an operational amplifier unit including a plurality of operational amplifiers connected between the multiplexer unit and the analog-to-digital converter.

7. The display device according to claim 6, wherein: The number of the plurality of operational amplifiers included in the operational amplifier unit is equal to or smaller than the number of the plurality of sensing lines.

8. The display device according to claim 6, wherein: The operational amplifier unit comprises: a first operational amplifier and a second operational amplifier, each of the first operational amplifier and the second operational amplifier integrating, sampling, and scaling currents flowing through the plurality of sensing lines and differentially amplifying an output at one output terminal of each of the plurality of multiplexers; and a third operational amplifier including an inverting input terminal connected to the other output terminal of each of the plurality of multiplexers and a non-inverting input terminal supplied with an initialization voltage.

9. The display device according to claim 8, wherein Signals of two adjacent odd-numbered sensing lines or two adjacent even-numbered sensing lines are input to the first operational amplifier and the second operational amplifier, and A signal of the sensing line between the two adjacent odd-numbered sensing lines or the two adjacent even-numbered sensing lines is input to the third operational amplifier.

10. The display device according to claim 1, wherein The length of the second sensing period is 30 ms or longer.

11. The display device according to claim 1, wherein The degradation of the driving transistor is compensated during a fourth compensation period based on a first sensing data value sensed in the first sensing period included in the power-off period and a second sensing data value sensed in the first sensing period included in the power-on period.

12. The display device according to claim 11, wherein The degradation of the driving transistor is compensated during a fifth compensation period based on the first sensing data value sensed in the first sensing period included in the power-off period and a third sensing data value sensed in the first sensing period included in the image display period.

13. The display device according to claim 12, wherein: The fifth compensation period is included a plurality of times in the image display period, and In each of the plurality of fifth compensation periods, the threshold voltage of the driving transistor is compensated in a step-by-step manner.

14. The display device according to claim 1, wherein The first sensing period included in the image display period is included in a vertical blanking period in which image display is stopped.

15. A method of driving a display device, the display device having a power-off period in which power for displaying an image is not supplied, a power-on period in which the display device is turned on, and an image display period in which the image is continuously displayed after the display device is turned on, the method comprising: sensing degradation information of a driving transistor in a pixel of the display device during a first sensing period included in each of the power-off period, the power-on period, and the image display period; compensating for degradation of the driving transistor based on a first sensing data value sensed in the first sensing period included in the power-off period and a second sensing data value sensed in the first sensing period included in the power-on period; sensing the degradation information of the driving transistor during a second sensing period included in the power-off period; as well as compensating for the degradation of the driving transistor during a first compensation period included in the power-off period, a second compensation period included in the power-on period, and a third compensation period included in the image display period based on a sensing data value sensed in the second sensing period, The length of the first sensing period is in the range of 10 μs to 100 μs. wherein the first sensing period included in the power-off period is after the second sensing period included in the power-off period, and The second sensing period is longer than the first sensing period.

16. The method according to claim 15, wherein The length of the second sensing period is 30 ms or longer.

17. The method according to claim 15, further comprising: The degradation of the driving transistor is compensated based on the first sensing data value sensed in the first sensing period included in the power-off period and a third sensing data value sensed in the first sensing period included in the image display period.

Images