Display device and display device driving method

Abstract

This display device comprises: a display panel comprising a plurality of pixels; and a panel driver for driving the display panel at a variable frame frequency. In an active period of a frame period, the panel driver performs an active scan operation for initializing light-emitting elements of the plurality of pixels while providing data voltages to the plurality of pixels. In a blank period of the frame period, the panel driver performs an initialization scan operation for initializing the light-emitting elements without providing the data voltages to the plurality of pixels. The time interval from the starting time point of the frame period to the time point at which the initialization scan operation is performed in the blank period is different from the time length of the minimum frame period corresponding to the maximum frame frequency of the variable frame frequency. Accordingly, luminance variation caused by variation of the variable frame frequency may be improved.

Description

Display device and method of driving the display device

[0001] The present invention relates to a display device, and more specifically, to a display device that drives a display panel with a variable frame frequency, and a driving method of the display device.

[0002] Typically, a display device displays an image at a constant frame frequency (or constant refresh rate), such as about 60 Hz, about 120 Hz, or about 240 Hz. However, the frame frequency of rendering by a host processor (e.g., a GPU (Graphics Processing Unit), an AP (Application Processor), or a graphics card) that provides frame data to the display device may not match the frame frequency of the display device. For example, when the host processor provides frame data for a game image that performs complex rendering to the display device, this frame frequency mismatch may become aggravated, and the frame frequency mismatch may cause a tearing phenomenon, such as a border being created in the image displayed on the display device.

[0003] The information disclosed in this background art is intended to enhance understanding of the background of the present invention and does not constitute prior art.

[0004] One object of the present invention is to provide a display device capable of improving brightness deviation according to variation in variable frame frequency.

[0005] Another object of the present invention is to provide a driving method of a display device capable of improving brightness deviation according to variation in variable frame frequency.

[0006] However, the problem to be solved by the present invention is not limited to the problem mentioned above, and may be expanded in various ways without departing from the spirit and scope of the present invention.

[0007] To prevent tearing, variable frame modes (e.g., Free-Sync mode, G-Sync mode, etc.) have been developed, in which a host processor provides image data to a display device at a variable frame frequency by changing the time length of the blank interval for each frame interval. A display device supporting the variable frame mode can prevent tearing by displaying an image in synchronization with the variable frame frequency, i.e., by driving the display panel at the variable frame frequency.

[0008] In order to achieve one object of the present invention, a display device according to embodiments of the present invention includes a display panel including a plurality of pixels, and a panel driver for driving the display panel at a variable frame frequency. In an active period of a frame period, the panel driver performs an active scan operation for initializing light-emitting elements of the plurality of pixels while providing data voltages to the plurality of pixels. In a blank period of the frame period, the panel driver performs an initialization scan operation for initializing the light-emitting elements without providing the data voltages to the plurality of pixels. A time interval from a start time of the frame period to a time at which the initialization scan operation is performed is different from a time length of a minimum frame period corresponding to a maximum frame frequency of the variable frame frequency.

[0009] In one embodiment, the active interval may have a constant time length, and the blank interval may include a basic blank interval when the variable frame frequency is the maximum frame frequency, and may include the basic blank interval and an additional blank interval when the variable frame frequency is lower than the maximum frame frequency.

[0010] In one embodiment, if the variable frame frequency is lower than the maximum frame frequency, the panel driver may not perform the initialization scan operation at the start of the additional blank period.

[0011] In one embodiment, when the variable frame frequency is lower than the maximum frame frequency, the panel driver may perform the initialization scan operation a predetermined time after the start of the additional blank period.

[0012] In one embodiment, the period of the initialization scan operation within the blank interval may not be constant.

[0013] In one embodiment, the panel driver can determine blank initialization points at which the initialization scan operation is performed within the blank period so that a deviation in the number of times the light-emitting elements are initialized per unit time is reduced as the variable frame frequency changes.

[0014] In one embodiment, the maximum frame frequency is 360 Hz, and a first blank initialization point in time at which the initialization scan operation is performed first among the blank initialization points corresponds to a frame frequency between 230 Hz and 240 Hz, a second blank initialization point in time at which the initialization scan operation is performed second among the blank initialization points corresponds to a frame frequency between 140 Hz and 150 Hz, a third blank initialization point in time at which the initialization scan operation is performed third among the blank initialization points corresponds to a frame frequency between 110 Hz and 120 Hz, a fourth blank initialization point in time at which the initialization scan operation is performed fourth among the blank initialization points corresponds to a frame frequency between 80 Hz and 90 Hz, and a fifth blank initialization point in time at which the initialization scan operation is performed fifth among the blank initialization points corresponds to a frame frequency between 60 Hz and 70 Hz.

[0015] In one embodiment, the blank initialization points can be adjusted by measuring the luminance of the display panel.

[0016] In one embodiment, each of the plurality of pixels may include a corresponding light-emitting element among the light-emitting elements, the light-emitting element including a capacitor having a first electrode connected to a gate node and a second electrode connected to a source node, a first transistor having a gate connected to the gate node, a drain receiving a first power voltage, and a source connected to the source node, a second transistor transmitting a data voltage to the gate node in response to a scan signal, a third transistor transmitting an initialization voltage to the source node in response to an initialization signal, and an anode connected to the source node and a cathode receiving a second power voltage.

[0017] In one embodiment, the panel driver may provide the scan signal and the initialization signal to each of the plurality of pixels to perform the active scan operation in the active period, and may provide the initialization signal to each of the plurality of pixels without providing the scan signal to perform the initialization scan operation in the blank period.

[0018] In one embodiment, the panel driver may include a frame counter that counts the duration of the frame section, and a blank initialization storage unit that stores blank initialization points in time at which the initialization scan operation is performed within the blank section. The panel driver may perform the initialization scan operation when the duration of the frame section counted by the frame counter corresponds to the blank initialization points in time stored in the blank initialization point storage unit.

[0019] In one embodiment, the blank initialization storage unit further stores initialization voltage levels corresponding to the blank initialization points, respectively, and the panel driver unit can adjust the initialization voltage applied to the plurality of pixels based on the initialization voltage levels stored in the blank initialization storage unit when the duration of the frame section counted by the frame counter corresponds to the blank initialization points stored in the blank initialization point storage unit.

[0020] In order to achieve another object of the present invention, in a driving method of a display device that drives a display panel including a plurality of pixels according to embodiments of the present invention with a variable frame frequency, an active scan operation is performed to initialize light-emitting elements of the plurality of pixels while providing data voltages to the plurality of pixels in an active period of a frame period, and an initialization scan operation is performed to initialize the light-emitting elements of the plurality of pixels while not providing the data voltages to the plurality of pixels in a blank period of the frame period. An interval from a start time of the frame period to a time at which the initialization scan operation is performed is different from a time length of a minimum frame period corresponding to a maximum frame frequency of the variable frame frequency.

[0021] In one embodiment, the active interval has a constant time length, the blank interval may be a basic blank interval when the variable frame frequency is the maximum frame frequency, and may include the basic blank interval and an additional blank interval when the variable frame frequency is lower than the maximum frame frequency.

[0022] In one embodiment, when the variable frame frequency is lower than the maximum frame frequency, the initialization scan operation may not be performed at the start of the additional blank interval, but may be performed a certain amount of time after the start of the additional blank interval.

[0023] In one embodiment, the period of the initialization scan operation within the blank interval may not be constant.

[0024] In one embodiment, to perform the initialization scan operation in the blank period, the duration of the frame period is counted, and when the duration of the frame period is equal to the time length of the minimum frame period, the initialization scan operation is skipped, and when the duration of the frame period is equal to or greater than K times the time length of the minimum frame period (K is an integer greater than or equal to 2), the initialization scan operation can be performed.

[0025] In one embodiment, blank initialization points at which the initialization scan operation is performed within the blank interval can be determined so as to reduce a deviation in the number of times the light emitting elements are initialized per unit time as the variable frame frequency changes.

[0026] In one embodiment, the blank initialization timings can be adjusted by measuring the luminance of the display panel.

[0027] In one embodiment, the duration of the frame interval is counted to perform the initialization scan operation in the blank interval, and when the duration of the frame interval corresponds to the blank initialization time points, the initialization scan operation can be performed.

[0028] In order to achieve another object of the present invention, an electronic device according to embodiments of the present invention includes a processor for providing image data, and a display device for displaying an image based on the image data. The display device includes a display panel including a plurality of pixels, and a panel driver for driving the display panel at a variable frame frequency. In an active period of a frame section, the panel driver performs an active scan operation for initializing light-emitting elements of the plurality of pixels while providing data voltages to the plurality of pixels. In a blank period of the frame section, the panel driver performs an initialization scan operation for initializing the light-emitting elements without providing the data voltages to the plurality of pixels. A time interval from a start time of the frame section to a time at which the initialization scan operation is performed is different from a time length of a minimum frame section corresponding to a maximum frame frequency of the variable frame frequency.

[0029] In a display device and a driving method of the display device according to embodiments of the present invention, a display panel is driven at a variable frame frequency, an active scan operation is performed in an active section of a frame section, and an initialization scan operation is performed in a blank section of the frame section. A time interval from a start point of the frame section to a point at which the initialization scan operation is performed may be different from a time length of a minimum frame section corresponding to a maximum frame frequency of the variable frame frequency. Accordingly, a luminance deviation due to a change in the variable frame frequency can be improved.

[0030] However, the effects of the present invention are not limited to the above-mentioned effects, and may be expanded in various ways without departing from the spirit and scope of the present invention.

[0031] FIG. 1 is a block diagram showing a display device according to embodiments of the present invention.

[0032] FIG. 2 is a circuit diagram showing an example of a pixel included in a display device according to embodiments of the present invention.

[0033] FIG. 3a is a drawing showing an example of a minimum frame interval corresponding to a maximum frame frequency and a maximum frame interval corresponding to the minimum frame frequency, and FIG. 3b is a drawing showing an example of the brightness of a display panel at a minimum frame frequency and a maximum frame frequency in a case where an initialization scan operation is not performed.

[0034] FIG. 4a is a timing diagram for explaining an example in which an active scan operation is performed in an active period and an initialization scan operation is performed in a blank period, and FIG. 4b is a timing diagram for explaining an example in which brightness decreases according to a change in a variable frame frequency.

[0035] FIG. 5 is a timing diagram illustrating an example of an initialization scan operation in a blank interval according to one embodiment of the present invention.

[0036] FIG. 6 is a timing diagram illustrating an example of an initialization scan operation in a blank period according to another embodiment of the present invention.

[0037] Figure 7 is a flowchart showing a method for driving a display device according to one embodiment of the present invention.

[0038] Figure 8 is a table showing an example of the number of initialization scan operations in each frame section according to the variable frame frequency.

[0039] FIG. 9a is a table showing an example of the number of times a light-emitting element is initialized per unit time according to a variable frame frequency, and FIG. 9b is a graph showing an example of the number of times a light-emitting element is initialized per unit time according to a variable frame frequency.

[0040] Fig. 10a is a table showing an example of the brightness of a display panel according to a variable frame frequency, and Fig. 10b is a graph showing an example of the brightness of a display panel according to a variable frame frequency.

[0041] Figure 11 is a flowchart showing a method of driving a display device according to another embodiment of the present invention.

[0042] Figure 12 is a table showing an example of the number of initialization scan operations in each frame section according to the variable frame frequency.

[0043] Fig. 13a is a table showing an example of the number of times a light-emitting element is initialized per unit time according to a variable frame frequency, and Fig. 13b is a graph showing an example of the number of times a light-emitting element is initialized per unit time according to a variable frame frequency.

[0044] Fig. 14a is a table showing an example of the brightness of a display panel according to a variable frame frequency, and Fig. 14b is a graph showing an example of the brightness of a display panel according to a variable frame frequency.

[0045] FIG. 15 is a block diagram showing an electronic device including a display device according to embodiments of the present invention.

[0046] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings. Identical components in the drawings are designated by the same reference numerals, and redundant descriptions of identical components are omitted.

[0047] FIG. 1 is a block diagram showing a display device according to embodiments of the present invention, FIG. 2 is a circuit diagram showing an example of a pixel included in a display device according to embodiments of the present invention, FIG. 3a is a diagram showing an example of a minimum frame period corresponding to a maximum frame frequency and a maximum frame period corresponding to the minimum frame frequency, FIG. 3b is a diagram showing an example of the luminance of a display panel at the minimum frame frequency and the maximum frame frequency in a case where an initialization scan operation is not performed, FIG. 4a is a timing diagram for explaining an example of an active scan operation being performed in an active period and an initialization scan operation being performed in a blank period, FIG. 4b is a timing diagram for explaining an example of luminance reduction according to a change in a variable frame frequency, FIG. 5 is a timing diagram for explaining an example of an initialization scan operation in a blank period according to an embodiment of the present invention, and FIG. 6 is a timing diagram for explaining an example of an initialization scan operation in a blank period according to another embodiment of the present invention.

[0048] Referring to FIG. 1, a display device (100) according to embodiments of the present invention includes a display panel (110) including a plurality of pixels (PX), and a panel driver (120) that drives the display panel (110). In one embodiment, the panel driver (120) may include a data driver (130) that provides data voltages (VDAT) to the plurality of pixels (PX), a scan driver (140) that provides scan signals (SC) and initialization signals (SI) to the plurality of pixels (PX), a power management circuit (150) that generates voltages (ELVDD, ELVSS, VINT), and a controller (160) that controls the operation of the display device (100).

[0049] The display panel (110) may include a plurality of data lines, a plurality of initialization lines, and a plurality of pixels (PX) connected thereto. In one embodiment, each pixel (PX) includes a light-emitting element, and the display panel (110) may be a light-emitting display panel.

[0050] For example, as illustrated in FIG. 2, each pixel (PX) may have a 3T1C structure including a first transistor (T1), a second transistor (T2), a third transistor (T3), a capacitor (CST), and a light-emitting element (EL).

[0051] The capacitor (CST) can store the data voltage (VDAT) transmitted from the data line (DL) by the second transistor (T2). The capacitor (CST) may be referred to as a storage capacitor for storing the data voltage (VDAT), but is not limited thereto. In one embodiment, the capacitor (CST) may include a first electrode connected to a gate node (NG) and a second electrode connected to a source node (NS).

[0052] The first transistor (T1) can generate a driving current based on the data voltage (VDAT) stored in the capacitor (CST). The first transistor (T1) may be called a driving transistor for generating the driving current, but is not limited thereto. In one embodiment, the first transistor (T1) may include a gate connected to a gate node (NG), a drain receiving a first power voltage (ELVDD), and a source connected to a source node (NS).

[0053] The second transistor (T2) can transmit the data voltage (VDAT) of the data line (DL) to the gate node (NG) in response to the scan signal (SC). The second transistor (T2) may be called a scan transistor, but is not limited thereto. In one embodiment, the second transistor (T2) may include a gate that receives the scan signal (SC), a drain connected to the data line (DL), and a source connected to the gate node (NG).

[0054] The third transistor (T3) can connect the initialization line (IL) to the source node (NS) in response to the initialization signal (SI). Therefore, the third transistor (T3) can transmit the initialization voltage (VINT) to the source node (NS) in response to the initialization signal (SI). When the initialization voltage (VINT) is applied to the source node (NS), the light-emitting element (EL) (or the anode of the light-emitting element (EL)) can be initialized based on the initialization voltage (VINT). Meanwhile, when the light-emitting element (EL) is initialized, the light-emitting element (EL) can not emit light (or can be turned off). In one embodiment, the initialization line (IL) can be used as a sensing line for sensing the characteristics of the pixel (PX), but is not limited thereto. In addition, in one embodiment, the third transistor (T3) can include a gate that receives the initialization signal (SI), a drain connected to the source node (NS), and a source connected to the initialization line (IL).

[0055] The light emitting element (EL) can emit light in response to the driving current flowing from the line of the first power supply voltage (ELVDD) to the line of the second power supply voltage (ELVSS). In one embodiment, the light emitting element (EL) can include an anode connected to a source node (NS) and a cathode receiving the second power supply voltage (ELVSS). In one embodiment, the light emitting element (EL) can be an organic light emitting diode (OLED). In another embodiment, the light emitting element (EL) can be a nano light emitting diode (NED), a quantum dot (QD) light emitting diode, a micro light emitting diode, an inorganic light emitting diode, or any other suitable light emitting element.

[0056] In one embodiment, as illustrated in FIG. 2, the first to third transistors (T1, T2, T3) may be implemented as N-type Metal Oxide Semiconductor (NMOS) transistors, but are not limited thereto. In addition, although FIG. 2 illustrates an example of a pixel (PX) having a 3T1C structure, the pixel (PX) according to embodiments of the present invention is not limited to the example of FIG. 2. In addition, in another embodiment, the display panel (110) may be an LCD (Liquid Crystal Display) panel, or any other suitable display panel.

[0057] The data driver (130) may generate data voltages (VDAT) based on a data control signal (DCTRL) and output image data (ODAT) received from the controller (160), and provide the data voltages (VDAT) to the plurality of pixels (PX) through the plurality of data lines. In one embodiment, the data control signal (DCTRL) may include, but is not limited to, an output data enable signal, a horizontal start signal, and a load signal. In addition, in one embodiment, the data driver (130) may receive the output image data (ODAT) from the controller (160) at a variable frame frequency (VFF) (for example, about 60 Hz to about 360 Hz). In one embodiment, the data driver (130) and the controller (160) may be implemented as a single integrated circuit, and such an integrated circuit may be referred to as a timing controller embedded data driver (TED) integrated circuit. In another embodiment, the data driver (130) and the controller (160) may each be implemented as separate integrated circuits.

[0058] The scan driver (140) may generate scan signals (SC) and / or initialization signals (SI) based on a scan control signal (SCTRL) received from the controller (160), and sequentially provide the scan signals (SC) and / or initialization signals (SI) to a plurality of pixels (PX) in units of rows. In one embodiment, the scan control signal (SCTRL) may include, but is not limited to, a scan start signal and a scan clock signal. In one embodiment, the scan driver (140) may be integrated or formed in the display panel (110). In another embodiment, the scan driver (140) may be implemented with one or more integrated circuits.

[0059] The power management circuit (150) can generate voltages (ELVDD, ELVSS, VINT) required for the operation of the display device (100). In one embodiment, the power management circuit (150) can generate a first power voltage (ELVDD) (e.g., a high power voltage), a second power voltage (ELVSS) (e.g., a low power voltage), and an initialization voltage (VINT) provided to the display panel (110). In one embodiment, the power management circuit (150) can be implemented as an integrated circuit, and such an integrated circuit can be called a power management integrated circuit (PMIC). In another embodiment, the power management circuit (150) can be included in the controller (160) or the data driver (130).

[0060] The controller (160) (e.g., a timing controller (TCON)) may receive input image data (IDAT) and a control signal (CTRL) from an external host processor (e.g., a graphics processing unit (GPU), an application processor (AP), or a graphics card). In one embodiment, the input image data (IDAT) may be RGB image data including red image data, green image data, and blue image data. In addition, the control signal (CTRL) may include, but is not limited to, a vertical synchronization signal, a horizontal synchronization signal, an input data enable signal, a master clock signal, and the like. The controller (160) may generate output image data (ODAT), a data control signal (DCTRL), a scan control signal (SCTRL), and a power management signal (PCTRL) based on the input image data (IDAT) and the control signal (CTRL). The controller (160) controls the operation of the data driver (130) by providing output image data (ODAT) and a data control signal (DCTRL) to the data driver (130), controls the operation of the scan driver (140) by providing a scan control signal (SCTRL) to the scan driver (140), and controls the operation of the power management circuit (150) by controlling a power management signal (PCTRL) to the power management circuit (150).

[0061] In one embodiment, the controller (160) can receive input image data (IDAT) from the external host processor at a variable frame frequency (VFF). In one example, the variable frame frequency (VFF) can vary from a minimum frame frequency of about 60 Hz to a maximum frame frequency of about 360 Hz, but is not limited thereto. In addition, the controller (160) can provide output image data (ODAT) at the variable frame frequency (VFF) to the data driver (130) and provide the scan start signal at the variable frame frequency (VFF) to the scan driver (140). Accordingly, the panel driver (120) can drive the display panel (110) at the variable frame frequency (VFF). In one embodiment, a mode of the display device (100) that drives the display panel (110) at the variable frame frequency (VFF) (or variable refresh rate (VRR)) can be referred to as a variable frame mode. Meanwhile, these variable frame modes may include, but are not limited to, Free-Sync mode, G-Sync mode, etc.

[0062] In the variable frame mode, the active period of each frame interval has a constant (or substantially constant) time length, but the time length of the blank period of the frame interval can be changed. For example, as illustrated in FIG. 3A, regardless of the variable frame frequency (VFF), each frame interval (MIN_FP, MAX_FP) can have an active period (AP) with a constant time length. However, when the variable frame frequency (VFF) is a maximum frame frequency (MAX_FF) of about 360 Hz, the blank period (BP) of the minimum frame interval (MIN_FP) corresponding to the maximum frame frequency (MAX_FF) can be a basic blank period (DBP). Conversely, when the variable frame frequency (VFF) is a minimum frame frequency (MIN_FF) of about 60 Hz, the blank period (BP') of the maximum frame interval (MAX_FP) corresponding to the minimum frame frequency (MIN_FF) can have a time length that increases from the basic blank period (DBP). That is, the blank interval (BP') of the maximum frame interval (MAX_FP) may include not only the basic blank interval (DBP) but also an additional blank interval (△BP).

[0063] In the variable frame mode in which the display panel (110) is driven with a variable frame frequency (VFF), when the light emitting elements (EL) of a plurality of pixels (PX) are initialized in the active period (AP) but the light emitting elements (EL) are not initialized in the blank period (BP), the display panel (110) may have a luminance deviation according to the variable frame frequency (VFF). For example, as illustrated in FIG. 3B, during the same period of time (e.g., about 33 ms), each light emitting element (EL) of the display panel (110) driven with a minimum frame frequency (MIN_FF) of about 60 Hz may be initialized (or turned off) about twice, but each light emitting element (EL) of the display panel (110) driven with a maximum frame frequency (MAX_FF) of about 360 Hz may be initialized (or turned off) about 12 times. Accordingly, the average luminance (AVGLUM2) of the display panel (110) driven at a maximum frame frequency (MAX_FF) of about 360 Hz may be lower than the average luminance (AVGLUM1) of the display panel (110) driven at a minimum frame frequency (MIN_FF) of about 60 Hz.

[0064] In order to reduce this luminance deviation of the display panel (110) according to the variable frame frequency (VFF), the panel driver (120) may perform an active scan operation in the active section of the frame section, as well as an initialization scan operation in the blank section of the frame section when the variable frame frequency (VFF) is lower than the maximum frame frequency (MAX_FF). Here, the active scan operation may be an operation of initializing the light emitting elements (EL) of the plurality of pixels (PX) while providing data voltages (VDAT) to the plurality of pixels (PX), and the initialization scan operation may be an operation of initializing the light emitting elements (EL) without providing the data voltages (VDAT) to the plurality of pixels (PX). In one embodiment, since the initialization scan operation does not provide the data voltages (VDAT) to the plurality of pixels (PX), the initialization scan operation may be called a dummy scan operation.

[0065] For example, as illustrated in FIG. 4A, when the display panel includes N rows of pixels (PX) (N is an integer greater than or equal to 2), in each active period (AP1, AP2) of the first and second frame periods (FP1, FP2), the scan driver (140) may perform an active scan operation (ASCAN) that sequentially provides first to Nth scan signals (SC1, SC2, …, SCN) to the plurality of pixels (PX) in units of rows, and sequentially provides first to Nth initialization signals (SI1, SI2, …, SIN) to the plurality of pixels (PX) in units of rows. That is, in each active period (AP1, AP2), a scan signal (SC) and an initialization signal (SI) are provided to each pixel (PX), a data voltage (VDAT) is provided to each pixel (PX) in response to the scan signal (SC), and a light emitting element (EL) of each pixel (PX) may be initialized or turned off in response to the initialization signal (SI). Meanwhile, the blank period (BP1) of the first frame period (FP1) corresponding to the variable frame frequency (VFF) of the maximum frame frequency (MAX_FF) of about 360 Hz is a basic blank period (DBP), and an initialization scan operation (ISCAN) may not be performed in the blank period (BP1) of the first frame period (FP1). However, the blank period (BP2) of the second frame period (FP2) corresponding to the variable frame frequency (VFF) of about 180 Hz, which is lower than the maximum frame frequency (MAX_FF) of about 360 Hz, may include the basic blank period (DBP) and an additional blank period (△BP). Additionally, in the blank period (BP2) of the second frame period (FP2), the scan driver (140) may perform an initialization scan operation (ISCAN) that does not provide the first to Nth scan signals (SC1, SC2, …, SCN) to the plurality of pixels (PX), but sequentially provides the first to Nth initialization signals (SI1, SI2, …, SIN) to the plurality of pixels (PX) in units of rows.For example, as illustrated in FIG. 4A, the scan driver (140) may perform or initiate an initialization scan operation (ISCAN) at the start of an additional blank period (△BP). Accordingly, in the blank period (BP2) of the second frame period (FP2), only the initialization signal (SI) is provided to each pixel (PX), the data voltage (VDAT) is not provided to each pixel (PX), and the light emitting element (EL) of each pixel (PX) may be initialized or turned off in response to the initialization signal (SI).

[0066] However, even if the initialization scan operation (ISCAN) is performed in the blank period (BP2), if the panel driver (120) performs the initialization scan operation (ISCAN) for each minimum frame period (MIN_FP) corresponding to the maximum frame frequency (MAX_FF) in each frame period (FP2), the display panel (110) may still have a luminance deviation according to the variable frame frequency (VFF). For example, as illustrated in FIG. 4B, in the first, second, and fourth frame periods (FP1, FP2, FP4) corresponding to the variable frame frequency (VFF) which is 1 / M (M is an integer greater than or equal to 1) of the maximum frame frequency (MAX_FF) of about 360 Hz, that is, in the first, second, and fourth frame periods (FP1, FP2, FP4) which are M times the minimum frame period (MIN_FP) corresponding to the maximum frame frequency (MAX_FF), the display panel (110) may have substantially the same luminance. However, in the third frame period (FP3) that is not M times (i.e., an integer multiple) of the minimum frame period (MIN_FP), the luminance of the display panel (110) may be reduced by the initialization scan operation (ISCAN) compared to the luminance of the display panel (110) in the first, second, and fourth frame periods (FP1, FP2, FP4) that are M times the minimum frame period (MIN_FP). In other words, in the case where the variable frame frequency (VFF) is not 1 / M of the maximum frame frequency (MAX_FF), the number of initializations (or off-times) of the light-emitting element (EL) during a unit time (e.g., 1 second) may be increased compared to the number of initializations (or off-times) of the light-emitting element (EL) during the unit time in the case where the variable frame frequency (VFF) is 1 / M of the maximum frame frequency (MAX_FF), and thus the luminance of the display panel (110) may be reduced.

[0067] However, in the display device (100) according to the embodiments of the present invention, in order to reduce such luminance change in the case where the variable frame frequency (VFF) is not 1 / M of the maximum frame frequency (MAX_FF), the time interval from the start of the frame section to the time at which the initialization scan operation (ISCAN) is performed may be different from the time length of the minimum frame section (MIN_FP) corresponding to the maximum frame frequency (MAX_FF). That is, in the example of FIGS. 4A and 4B in which the panel driver (120) performs the initialization scan operation (ISCAN) for each minimum frame section (MIN_FP) corresponding to the maximum frame frequency (MAX_FF) in each frame section, the initialization scan operation (ISCAN) may be performed or initiated at the end of the basic blank section (DBP) or the start of the additional blank section (△BP). However, in the display device (100) according to the embodiments of the present invention, the initialization scan operation (ISCAN) may not be performed or initiated at the start of the additional blank section (△BP). For example, in a display device (100) according to embodiments of the present invention, when the variable frame frequency (VFF) is lower than the maximum frame frequency (MAX_FF), the initialization scan operation (ISCAN) may be performed a certain time after the start time of the additional blank period (△BP).

[0068] For example, as illustrated in FIG. 5, when the panel driver (120) performs an active scan operation (ASCAN) at the start of the frame period (FP), that is, the start of the active period (AP), and performs an initialization scan operation (ISCAN) for each minimum frame period (MIN_FP), an initialization signal (SI') may be applied to each pixel (PX) at the start of the active period (AP), and an initialization signal (SI') may be applied for each minimum frame period (MIN_FP). In this case, if the variable frame frequency (VFF) is not 1 / M of the maximum frame frequency (MAX_FF), the time interval from the last time the initialization signal (SI') is applied to each pixel (PX) within the frame period (FP) to the first time the initialization signal (SI') is applied to the pixel (PX) in the next frame period may be shorter than the time length of the minimum frame period (MIN_FP), and thus the luminance of the display panel (110) may be reduced in the frame period (FP).

[0069] However, in the display device (100) according to one embodiment of the present invention, in order to prevent (or substantially prevent) such a decrease in brightness, the initialization scan operation (ISCAN) may not be performed at the start time (TP0) of the additional blank period (△BP), and the first initialization scan operation (ISCAN1) may be performed after a certain period of time (for example, the time length of the minimum frame period (MIN_FP)) from the start time (TP0) of the additional blank period (△BP). That is, the time interval (TI) from the start time of the frame period (FP) to the time at which the first initialization scan operation (ISCAN1) is performed may be different from the time length of the minimum frame period (MIN_FP) corresponding to the maximum frame frequency (MAX_FF).

[0070] To perform these operations, the controller (160) of the panel driver (120) may include a frame counter (170) (or blank counter) that counts the duration of the frame section (FP). In addition, the panel driver (120) may skip the initialization scan operation (ISCAN) when the duration of the frame section (FP) becomes the time length of the minimum frame section (MIN_FP), and perform the initialization scan operation (ISCAN1, ISACN2) when the duration of the frame section (FP) becomes K times the time length of the minimum frame section (MIN_FP) (K is an integer greater than or equal to 2). For example, as illustrated in FIG. 5, the panel driver (120) may perform a first initialization scan operation (ISCAN1) at a first blank initialization time point (BITP1) when the duration of the frame period (FP) becomes twice the time length of the minimum frame period (MIN_FP), and may perform a second initialization scan operation (ISCAN2) at a second blank initialization time point (BITP2) when the duration of the frame period (FP) becomes three times the time length of the minimum frame period (MIN_FP). Accordingly, since the initialization scan operation (ISCAN) is skipped when the duration of the frame period (FP) becomes the time length of the minimum frame period (MIN_FP), a decrease in the luminance of the display panel (110) may be prevented.

[0071] In another embodiment, as illustrated in FIG. 6, the cycle of the initialization scan operations (ISCAN1, ISCAN2, ISCAN3, ISCAN4, ISCAN5) within the blank period (BP) may not be constant. That is, in the display device (100) according to another embodiment of the present invention, the blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5) are determined and stored, and the initialization scan operations (ISCAN1, ISCAN2, ISCAN3, ISCAN4, ISCAN5) may be performed when the duration of the frame period (FP) becomes the blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5).

[0072] To perform such an operation, the controller (160) of the panel driver (120) may include a frame counter (170) (or blank counter) that counts the duration of a frame period (FP), and a blank initialization storage unit (180) that stores blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5) at which initialization scan operations (ISCAN1, ISCAN2, ISCAN3, ISCAN4, ISCAN5) are performed within the blank period (BP). In one embodiment, the blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5) at which initialization scan operations (ISCAN1, ISCAN2, ISCAN3, ISCAN4, ISCAN5) are performed within the blank period (BP) may be determined such that a deviation in the number of times the light emitting elements (EL) are initialized per unit time (e.g., 1 second) is reduced or minimized as the variable frame frequency (VFF) is changed. For example, as shown in FIG. 6, when the maximum frame frequency (MAX_FF) is about 360 Hz, the first blank initialization time point (BITP1) at which the first initialization scan operation (ISCAN1) is performed is determined to correspond to a frame frequency between 230 Hz and 240 Hz, the second blank initialization time point (BITP2) at which the second initialization scan operation (ISCAN2) is performed is determined to correspond to a frame frequency between 140 Hz and 150 Hz, the third blank initialization time point (BITP3) at which the third initialization scan operation (ISCAN3) is performed is determined to correspond to a frame frequency between 110 Hz and 120 Hz, the fourth blank initialization time point (BITP4) at which the fourth initialization scan operation (ISCAN4) is performed is determined to correspond to a frame frequency between 80 Hz and 90 Hz, and the fifth blank initialization time point (BITP4) at which the fifth initialization scan operation (ISCAN5) is performed The point in time (BITP5) can be determined to correspond to a frame frequency between 60 Hz and 70 Hz.Additionally, in one embodiment, the blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5) can be adjusted (e.g., fine-tuned) by measuring the luminance of the display panel (110) while changing the variable frame frequency (VFF).

[0073] In addition, the panel driver (120) can perform an initialization scan operation (ISCAN1, ISCAN2, ISCAN3, ISCAN4, ISCAN5) when the duration of the frame period (FP) counted by the frame counter (170) corresponds to the blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5) stored in the blank initialization storage (180). For example, as illustrated in FIG. 6, the panel driver (120) can perform or initiate the first initialization scan operation (ISCAN1) at the first blank initialization point (BITP1) determined to correspond to a frame frequency between 230 Hz and 240 Hz. That is, the first time interval (TI1) from the start time of the frame period (FP) to the first blank initialization time point (BITP1) at which the first initialization scan operation (ISCAN1) is performed may have a time length of the frame period corresponding to a frame frequency between 230 Hz and 240 Hz. Accordingly, the first time interval (TI1) from the start time of the frame period (FP) to the first blank initialization time point (BITP1) at which the first initialization scan operation (ISCAN1) is performed may be different from the time length of the minimum frame period (MIN_FP) corresponding to the maximum frame frequency (MAX_FF). In addition, the panel driver (120) may perform or initiate the second initialization scan operation (ISCAN2) at the second blank initialization time point (BITP2) determined to correspond to a frame frequency between 140 Hz and 150 Hz. That is, the second time interval (TI2) from the start time of the frame period (FP) to the second blank initialization time point (BITP2) at which the second initialization scan operation (ISCAN2) is performed may have a time length of the frame period corresponding to a frame frequency between 140 Hz and 150 Hz.In addition, the panel driver (120) may perform or initiate a third initialization scan operation (ISCAN3) at a third blank initialization time point (BITP3) determined to correspond to a frame frequency between 110 Hz and 120 Hz. That is, a third time interval (TI3) from a start time of a frame section (FP) to the third blank initialization time point (BITP3) at which the third initialization scan operation (ISCAN3) is performed may have a time length of a frame section corresponding to a frame frequency between 110 Hz and 120 Hz. In addition, the panel driver (120) may perform or initiate a fourth initialization scan operation (ISCAN4) at a fourth blank initialization time point (BITP4) determined to correspond to a frame frequency between 80 Hz and 90 Hz. That is, the fourth time interval (TI4) from the start time of the frame period (FP) to the fourth blank initialization time point (BITP4) at which the fourth initialization scan operation (ISCAN4) is performed may have a time length of the frame period corresponding to a frame frequency between 80 Hz and 90 Hz. In addition, the panel driver (120) may perform or initiate the fifth initialization scan operation (ISCAN5) at the fifth blank initialization time point (BITP5) determined to correspond to a frame frequency between 60 Hz and 70 Hz. That is, the fifth time interval (TI5) from the start time of the frame period (FP) to the fifth blank initialization time point (BITP5) at which the fifth initialization scan operation (ISCAN5) is performed may have a time length of the frame period corresponding to a frame frequency between 60 Hz and 70 Hz. In this case, the deviation in the number of times the light emitting elements (EL) are initialized during the unit time as the variable frame frequency (VFF) changes can be reduced or minimized, and the brightness deviation of the display panel (110) as the variable frame frequency (VFF) changes can be reduced or minimized.

[0074] In one embodiment, the blank initialization storage unit (180) may further store initialization voltage levels corresponding to the blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5), respectively. In addition, the panel driver unit (120) may adjust the initialization voltage (VINT) applied to the plurality of pixels (PX) based on the initialization voltage levels stored in the blank initialization storage unit (180) when the duration of the frame period (FP) counted by the frame counter (170) corresponds to the blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5) stored in the blank initialization storage unit (180). Accordingly, the luminance deviation of the display panel (110) due to the change in the variable frame frequency (VFF) may be further reduced.

[0075] As described above, in the display device (100) according to the embodiments of the present invention, the display panel (110) may be driven with a variable frame frequency (VFF), an active scan operation (ASCAN) may be performed in an active period (AP) of a frame period (FP), and an initialization scan operation (ISCAN1, ISCAN2, ISCAN3, ISCAN4, ISCAN5) may be performed in a blank period (BP) of the frame period (FP). In addition, a time interval (TI, TI1) from a start time of the frame period (FP) to a time when the first initialization scan operation (ISCAN1) is performed may be different from a time length of a minimum frame period (MIN_FP) corresponding to a maximum frame frequency (MAX_FF) of the variable frame frequency (VFF). Accordingly, a luminance deviation of the display panel (110) due to a change in the variable frame frequency (VFF) may be improved.

[0076] FIG. 7 is a flowchart showing a method of driving a display device according to an embodiment of the present invention, FIG. 8 is a table showing an example of the number of times an initialization scan operation is performed in each frame section according to a variable frame frequency, FIG. 9a is a table showing an example of the number of times a light-emitting element is initialized per unit time according to a variable frame frequency, FIG. 9b is a graph showing an example of the number of times a light-emitting element is initialized per unit time according to a variable frame frequency, and FIG. 10a is a table showing an example of the luminance of a display panel according to a variable frame frequency, and FIG. 10b is a graph showing an example of the luminance of a display panel according to a variable frame frequency.

[0077] Referring to FIGS. 1 and 7, in a driving method of a display device (100) according to an embodiment of the present invention, a panel driver (120) can drive a display panel (110) including a plurality of pixels (PX) at a variable frame frequency (VFF). The panel driver (120) can perform an active scan operation in an active period (S310). For example, in the active period of a frame period, the panel driver (120) can perform the active scan operation of initializing light-emitting elements of the plurality of pixels (PX) while providing data voltages (VDAT) to the plurality of pixels (PX).

[0078] In addition, in the blank section of the frame section, the panel driver (120) can perform an initialization scan operation for initializing the light-emitting elements without providing data voltages (VDAT) to a plurality of pixels (PX) (S320, S330, S340, S350). In the driving method of the display device (100) according to embodiments of the present invention, the interval from the start time of the frame section to the time at which the initialization scan operation is performed may be different from the time length of the minimum frame section corresponding to the maximum frame frequency of the variable frame frequency (VFF).

[0079] In one embodiment, to perform the initialization scan operation in the blank section, the frame counter (170) of the panel driver (120) may count the duration of the frame section (S320) and compare the duration of the frame section with K times the time length of the minimum frame section (K is an integer greater than or equal to 1) (S330). When the duration of the frame section is equal to the time length of the minimum frame section (i.e., when K is 1) (S330: K=1), the panel driver (120) may skip the initialization scan operation (S340). Alternatively, when the duration of the frame section is 2 or more K times the time length of the minimum frame section (S330: K>1), the panel driver (120) may perform the initialization scan operation (S350). When the frame section has not ended (S360: NO), the initialization scan operation may be repeatedly performed. In contrast, if the above frame section is terminated (S360: YES), operations in the next frame section can be performed.

[0080] For example, in a comparison display device in which the initialization scan operation is performed when the duration of the frame section is equal to the time length of the minimum frame section, as illustrated in FIG. 8, the initialization scan operation may be performed 0 times in each frame section when the variable frame frequency (VFF) is about 360 Hz, 1 time when the variable frame frequency (VFF) is about 350 Hz to about 180 Hz, 2 times when the variable frame frequency (VFF) is about 170 Hz to about 120 Hz, 3 times when the variable frame frequency (VFF) is about 110 Hz to about 90 Hz, 4 times when the variable frame frequency (VFF) is about 80 Hz, and 5 times when the variable frame frequency (VFF) is about 70 Hz to about 60 Hz. However, in the driving method of the display device (100) according to one embodiment of the present invention, since the initialization scan operation is skipped when the duration of the frame section is equal to the time length of the minimum frame section, the initialization scan operation may be performed 0 times in each frame section when the variable frame frequency (VFF) is about 360 Hz to about 180 Hz, performed once when the variable frame frequency (VFF) is about 170 Hz to about 120 Hz, performed twice when the variable frame frequency (VFF) is about 110 Hz to about 90 Hz, performed four times when the variable frame frequency (VFF) is about 80 Hz, and performed four times when the variable frame frequency (VFF) is about 70 Hz to about 60 Hz.

[0081] In this case, as illustrated in FIGS. 9A and 9B, in the comparison display device (410), the light-emitting element of each pixel (PX) may be initialized about 360 times at a variable frame frequency (VFF) of about 360 Hz for a unit time of about 1 second, and about 700 times at a variable frame frequency (VFF) of about 350 Hz. That is, in the comparison display device (410), the number of times the light-emitting element is initialized for the unit time according to the variable frame frequency (VFF) may have a difference of about 340 times. However, in the driving method of the display device (100) according to one embodiment (430) of the present invention, the light-emitting element of each pixel (PX) may be initialized about 360 times at a variable frame frequency (VFF) of about 360 Hz for a unit time of about 1 second, and about 180 times at a variable frame frequency (VFF) of about 180 Hz. Accordingly, in the driving method of the display device (100) according to one embodiment (430) of the present invention, the number of initializations of the light-emitting element during the unit time according to the variable frame frequency (VFF) may have a difference of about 180 times. That is, in the driving method of the display device (100) according to one embodiment of the present invention, the deviation in the number of initializations of the light-emitting element during the unit time according to the variable frame frequency (VFF) may be reduced.

[0082] In addition, when the target luminance of the display panel (110) is about 100 nit and the luminance decreases by about 0.1 nit when the light emitting element is initialized, as shown in FIGS. 10A and 10B, in the comparative display device (460), the display panel (110) may have a luminance of about 100 nit at a variable frame frequency (VFF) of about 360 Hz, but may have a luminance of about 66 nit at a variable frame frequency (VFF) of about 350 Hz. That is, in the comparative display device (460), the display panel (110) may have a luminance difference of about 34 nit depending on the variable frame frequency (VFF). However, in the driving method of the display device (100) according to one embodiment of the present invention, the display panel (110) may have a luminance of about 100 nit at a variable frame frequency (VFF) of about 360 Hz, but may have a luminance of about 118 nit at a variable frame frequency (VFF) of about 180 Hz. Therefore, in the driving method of the display device (100) according to one embodiment of the present invention (480), the display panel (110) may have a luminance difference of about 18 nit depending on the variable frame frequency (VFF). That is, in the driving method of the display device (100) according to one embodiment of the present invention, the luminance deviation of the display panel (110) depending on the variable frame frequency (VFF) may be reduced.

[0083] As described above, in the driving method of the display device (100) according to one embodiment of the present invention, when the duration of the frame section becomes (or is equal to) the time length of the minimum frame section, the initialization scan operation can be skipped. Accordingly, the deviation in the number of initializations of the light-emitting element per unit time according to the variable frame frequency (VFF) can be reduced, and the deviation in the brightness of the display panel (110) according to the variable frame frequency (VFF) can be reduced.

[0084] FIG. 11 is a flowchart showing a driving method of a display device according to another embodiment of the present invention, FIG. 12 is a table showing an example of the number of times an initialization scan operation is performed in each frame section according to a variable frame frequency, FIG. 13a is a table showing an example of the number of times a light-emitting element is initialized per unit time according to a variable frame frequency, FIG. 13b is a graph showing an example of the number of times a light-emitting element is initialized per unit time according to a variable frame frequency, FIG. 14a is a table showing an example of the luminance of a display panel according to a variable frame frequency, and FIG. 14b is a graph showing an example of the luminance of a display panel according to a variable frame frequency.

[0085] Referring to FIGS. 1 and 11, in a driving method of a display device (100) according to another embodiment of the present invention, blank initialization points in which an initialization scan operation is performed within a blank period are determined so as to reduce or minimize a deviation in the number of initializations (S500), and the blank initialization storage unit (180) of the panel driver (120) can store the determined blank initialization points. In one embodiment, the blank initialization points can be determined so as to reduce or minimize a deviation in the number of times light-emitting elements of a plurality of pixels (PX) are initialized per unit time (e.g., 1 second) as a variable frame frequency (VFF) is changed.

[0086] For example, as shown in FIG. 6, when the maximum frame frequency of the variable frame frequency (VFF) is 360 Hz, the first blank initialization point (BITP1) at which the initialization scan operation is performed for the first time is determined to correspond to a frame frequency between 230 Hz and 240 Hz, the second blank initialization point (BITP2) at which the initialization scan operation is performed for the second time is determined to correspond to a frame frequency between 140 Hz and 150 Hz, the third blank initialization point (BITP3) at which the initialization scan operation is performed for the third time is determined to correspond to a frame frequency between 110 Hz and 120 Hz, the fourth blank initialization point (BITP4) at which the initialization scan operation is performed for the fourth time is determined to correspond to a frame frequency between 80 Hz and 90 Hz, and the fifth blank initialization point (BITP5) at which the initialization scan operation is performed for the fifth time is determined to correspond to a frame frequency between 60 Hz and 70 Hz. It can be determined to correspond to the frequency. In addition, in one embodiment, the blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5) can be finely adjusted by measuring the luminance of the display panel (110) while changing the variable frame frequency (VFF) (S510).

[0087] In the active section of the frame section, the panel driver (120) can perform an active scan operation to initialize the light-emitting elements of the plurality of pixels (PX) while providing data voltages (VDAT) to the plurality of pixels (PX) (S520).

[0088] In addition, in the blank section of the frame section, the panel driver (120) can perform the initialization scan operation for initializing the light-emitting elements without providing data voltages (VDAT) to the plurality of pixels (PX) (S530, S540, S550). In the driving method of the display device (100) according to embodiments of the present invention, the interval from the start time of the frame section to the time at which the initialization scan operation is performed may be different from the time length of the minimum frame section corresponding to the maximum frame frequency of the variable frame frequency (VFF).

[0089] In one embodiment, to perform the initialization scan operation in the blank section, the frame counter (170) of the panel driver (120) may count the duration of the frame section (S530) and compare the duration of the frame section with blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5) stored in the blank initialization storage (180) (S540). When the duration of the frame section is different from the blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5) (S540: NO), the duration of the frame section may be continuously counted (S530). When the duration of the frame section corresponds to the blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5), the panel driver (120) may perform the initialization scan operation (S550). If the above frame interval is not terminated (S560: NO), the initialization scan operation may be repeatedly performed. Conversely, if the above frame interval is terminated (S560: YES), the operation in the next frame interval may be performed.

[0090] As described above, in the driving method of the display device (100) according to another embodiment of the present invention, the blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5) can be determined so that the deviation in the number of initializations is minimized as the variable frame frequency (VFF) changes. Accordingly, in the driving method of the display device (100) according to another embodiment of the present invention, for example, as illustrated in FIG. 12, in each frame section, when the variable frame frequency (VFF) is about 360 Hz to about 240 Hz, the driving may be performed 0 times, when the variable frame frequency (VFF) is about 230 Hz to about 150 Hz, the driving may be performed 1 time, when the variable frame frequency (VFF) is about 140 Hz to about 120 Hz, the driving may be performed 2 times, when the variable frame frequency (VFF) is about 110 Hz to about 90 Hz, the driving may be performed 3 times, when the variable frame frequency (VFF) is about 80 Hz to about 70 Hz, the driving may be performed 4 times, and when the variable frame frequency (VFF) is about 60 Hz, the driving may be performed 5 times.

[0091] In this case, as illustrated in FIGS. 13a and 13b, in the comparison display device (610), the number of initializations of the light-emitting element during the unit time (e.g., about 1 second) according to the variable frame frequency (VFF) may have a difference of about 340 times. However, in the driving method of the display device (100) according to another embodiment (630) of the present invention, the light-emitting element of each pixel (PX) may be initialized about 360 times at a variable frame frequency (VFF) of about 360 Hz, about 240 times at a variable frame frequency (VFF) of about 240 Hz, and about 460 times at a variable frame frequency (VFF) of about 230 Hz, during a unit time of about 1 second. Accordingly, in the driving method of the display device (100) according to another embodiment (630) of the present invention, the number of initializations of the light emitting element during the unit time according to the variable frame frequency (VFF) may have a difference of about 120 times. That is, in the driving method of the display device (100) according to another embodiment of the present invention, the deviation in the number of initializations of the light emitting element during the unit time according to the variable frame frequency (VFF) may be reduced.

[0092] In addition, when the target luminance of the display panel (110) is about 100 nit and the luminance decreases by about 0.1 nit when the light emitting element is initialized, as shown in FIGS. 14A and 14B, in the comparative display device (660), the display panel (110) may have a luminance difference of about 34 nit depending on the variable frame frequency (VFF). However, in the driving method of the display device (100) according to another embodiment (680) of the present invention, the display panel (110) may have a luminance of about 100 nit at a variable frame frequency (VFF) of about 360 Hz, a luminance of about 112 nit at a variable frame frequency (VFF) of about 240 Hz, and a luminance of about 90 nit at a variable frame frequency (VFF) of about 230 Hz. Accordingly, in the driving method of the display device (100) according to another embodiment (680) of the present invention, the display panel (110) can have a luminance difference of about 22 nits depending on the variable frame frequency (VFF). That is, in the driving method of the display device (100) according to another embodiment of the present invention, the luminance deviation of the display panel (110) depending on the variable frame frequency (VFF) can be reduced.

[0093] As described above, in the driving method of the display device (100) according to another embodiment of the present invention, the blank initialization points (BITP1, BITP2, BITP3, BITP4, BITP5) can be determined so that the deviation in the number of initializations according to the change in the variable frame frequency (VFF) is reduced or minimized. Accordingly, the deviation in the number of initializations of the light-emitting element per unit time according to the variable frame frequency (VFF) can be reduced, and the deviation in the brightness of the display panel (110) according to the variable frame frequency (VFF) can be reduced.

[0094] FIG. 15 is a block diagram showing an electronic device including a display device according to embodiments of the present invention.

[0095] Referring to FIG. 15, the electronic device (1100) may include a processor (1110), a memory device (1120), a storage device (1130), an input / output device (1140), a power supply (1150), and a display device (1160). The electronic device (1100) may further include several ports that may communicate with a video card, a sound card, a memory card, a USB device, or the like, or may communicate with other systems.

[0096] The processor (1110) may perform specific calculations or tasks. Depending on the embodiment, the processor (1110) may be a microprocessor, a central processing unit (CPU), etc. The processor (1110) may be connected to other components via an address bus, a control bus, a data bus, etc. Depending on the embodiment, the processor (1110) may also be connected to an expansion bus, such as a Peripheral Component Interconnect (PCI) bus.

[0097] The memory device (1120) can store data necessary for the operation of the electronic device (1100). For example, the memory device (1120) can include non-volatile memory devices such as EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory, PRAM (Phase Change Random Access Memory), RRAM (Resistance Random Access Memory), NFGM (Nano Floating Gate Memory), PoRAM (Polymer Random Access Memory), MRAM (Magnetic Random Access Memory), FRAM (Ferroelectric Random Access Memory), etc., and / or volatile memory devices such as DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), mobile DRAM, etc.

[0098] The storage device (1130) may include a solid state drive (SSD), a hard disk drive (HDD), a CD-ROM, etc. The input / output device (1140) may include an input means such as a keyboard, a keypad, a touchpad, a touchscreen, a mouse, etc., and an output means such as a speaker, a printer, etc. The power supply (1150) may supply power required for the operation of the electronic device (1100). The display device (1160) may be connected to other components via the buses or other communication links.

[0099] In a display device (1160), a display panel may be driven at a variable frame frequency, an active scan operation may be performed in an active section of a frame section, and an initialization scan operation may be performed in a blank section of the frame section. In addition, in the display device (1160), a time interval from a start point of the frame section to a point at which the initialization scan operation is performed may be different from a time length of a minimum frame section corresponding to a maximum frame frequency of the variable frame frequency. Accordingly, in the display device (1160), a luminance deviation due to a change in the variable frame frequency may be improved.

[0100] According to an embodiment, the electronic device (1100) may be any electronic device including a display device (1160) such as a smart phone, a mobile phone, a tablet computer, a digital television, a 3D TV, a personal computer (PC), a home appliance, a laptop computer, a personal digital assistant (PDA), a portable multimedia player (PMP), a digital camera, a music player, a portable game console, a navigation system, etc.

[0101] The present invention can be applied to any display device and electronic devices including the same. For example, the present invention can be applied to smartphones, mobile phones, tablet computers, TVs, digital TVs, 3D TVs, PCs, home electronic devices, laptop computers, PDAs, PMPs, digital cameras, music players, portable game consoles, navigation systems, and the like.

[0102] Although the present invention has been described above with reference to embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. A display panel comprising a plurality of pixels; and It includes a panel driver for driving the display panel at a variable frame frequency, In the active section of the frame section, the panel driver performs an active scan operation to initialize the light-emitting elements of the plurality of pixels while providing data voltages to the plurality of pixels, In the blank section of the above frame section, the panel driver performs an initialization scan operation to initialize the light-emitting elements without providing the data voltages to the plurality of pixels, A display device characterized in that the time interval from the start point of the frame section to the point at which the initialization scan operation is performed is different from the time length of the minimum frame section corresponding to the maximum frame frequency of the variable frame frequency.

2. In paragraph 1, The above active period has a constant time length, A display device characterized in that the blank interval includes a basic blank interval when the variable frame frequency is the maximum frame frequency, and includes the basic blank interval and an additional blank interval when the variable frame frequency is lower than the maximum frame frequency.

3. A display device characterized in that, in the second paragraph, when the variable frame frequency is lower than the maximum frame frequency, the panel driver does not perform the initialization scan operation at the start point of the additional blank period.

4. A display device characterized in that, in the second paragraph, when the variable frame frequency is lower than the maximum frame frequency, the panel driver performs the initialization scan operation a certain time after the start time of the additional blank period.

5. A display device characterized in that, in the first paragraph, the cycle of the initialization scan operation within the blank section is not constant.

6. A display device according to claim 1, wherein the panel driving unit determines blank initialization points at which the initialization scan operation is performed within the blank period so that the deviation in the number of times the light-emitting elements are initialized per unit time is reduced as the variable frame frequency changes.

7. In the 6th paragraph, the maximum frame frequency is 360 Hz, Among the above blank initialization points, the first blank initialization point at which the initialization scan operation is performed first corresponds to a frame frequency between 230 Hz and 240 Hz, Among the above blank initialization points, the second blank initialization point at which the initialization scan operation is performed second corresponds to a frame frequency between 140 Hz and 150 Hz, Among the above blank initialization points, the third blank initialization point in which the initialization scan operation is performed third corresponds to a frame frequency between 110 Hz and 120 Hz, Among the above blank initialization points, the fourth blank initialization point in which the initialization scan operation is performed fourth corresponds to a frame frequency between 80 Hz and 90 Hz, A display device characterized in that a fifth blank initialization point in which the initialization scan operation is performed fifth among the blank initialization points corresponds to a frame frequency between 60 Hz and 70 Hz.

8. A display device according to claim 6, characterized in that the blank initialization points are adjusted by measuring the brightness of the display panel.

9. In the first paragraph, each of the plurality of pixels, A capacitor comprising a first electrode connected to a gate node and a second electrode connected to a source node; A first transistor including a gate connected to the gate node, a drain receiving a first power voltage, and a source connected to the source node; A second transistor that transmits a data voltage to the gate node in response to a scan signal; a third transistor for transmitting an initialization voltage to the source node in response to an initialization signal; and A display device characterized by including a corresponding light-emitting element among the light-emitting elements, the light-emitting element including an anode connected to the source node and a cathode receiving a second power supply voltage.

10. In the 9th paragraph, the panel driving unit, Providing the scan signal and the initialization signal to each of the plurality of pixels to perform the active scan operation in the active section, A display device characterized in that the initialization signal is provided to each of the plurality of pixels without providing the scan signal so as to perform the initialization scan operation in the blank period.

11. In the first paragraph, the panel driving unit, a frame counter that counts the duration of the above frame interval; and A blank initialization storage unit is included that stores blank initialization points at which the initialization scan operation is performed within the blank interval. A display device characterized in that the panel driving unit performs the initialization scan operation when the duration of the frame section counted by the frame counter corresponds to the blank initialization points stored in the blank initialization point storage unit.

12. In paragraph 11, The above blank initialization storage unit further stores initialization voltage levels corresponding to each of the blank initialization points, A display device characterized in that the panel driver adjusts the initialization voltage applied to the plurality of pixels based on the initialization voltage levels stored in the blank initialization point storage unit when the duration of the frame section counted by the frame counter corresponds to the blank initialization points stored in the blank initialization point storage unit.

13. A method for driving a display device that drives a display panel including a plurality of pixels at a variable frame frequency, A step of performing an active scan operation for initializing light-emitting elements of the plurality of pixels while providing data voltages to the plurality of pixels in an active section of a frame section; and A step of performing an initialization scan operation for initializing the light-emitting elements without providing the data voltages to the plurality of pixels in a blank section of the frame section, A method for driving a display device, characterized in that the interval from the start point of the frame section to the point at which the initialization scan operation is performed is different from the time length of the minimum frame section corresponding to the maximum frame frequency of the variable frame frequency.

14. In paragraph 13, The above active period has a constant time length, A method for driving a display device, characterized in that the blank interval is a basic blank interval when the variable frame frequency is the maximum frame frequency, and includes the basic blank interval and an additional blank interval when the variable frame frequency is lower than the maximum frame frequency.

15. A driving method of a display device, characterized in that in the 14th paragraph, when the variable frame frequency is lower than the maximum frame frequency, the initialization scan operation is not performed at the start time of the additional blank period, but is performed after a certain time from the start time of the additional blank period.

16. A driving method of a display device, characterized in that, in the 13th paragraph, the cycle of the initialization scan operation within the blank section is not constant.

17. In the 13th paragraph, the step of performing the initialization scan operation in the blank section is: A step of counting the duration of the above frame section; a step of skipping the initialization scan operation when the duration of the frame interval is equal to the time length of the minimum frame interval; and A driving method of a display device, characterized in that it comprises a step of performing the initialization scan operation when the duration of the frame section is equal to or greater than K times the time length of the minimum frame section (K is an integer greater than or equal to 2).

18. In paragraph 13, A driving method of a display device, characterized in that it further includes a step of determining blank initialization points at which the initialization scan operation is performed within the blank period so as to reduce a deviation in the number of times the light emitting elements are initialized per unit time as the variable frame frequency changes.

19. In paragraph 18, A driving method of a display device, characterized in that it further includes a step of measuring the brightness of the display panel and adjusting the blank initialization points.

20. In the 18th paragraph, the step of performing the initialization scan operation in the blank section is: a step of counting the duration of the above frame section; and A driving method of a display device, characterized in that it comprises a step of performing the initialization scan operation when the duration of the frame section corresponds to the blank initialization time points.

21. A processor providing image data; and A display device for displaying an image based on the image data is included, The above display device, a display panel comprising a plurality of pixels; and It includes a panel driver for driving the display panel at a variable frame frequency, In the active section of the frame section, the panel driver performs an active scan operation to initialize the light-emitting elements of the plurality of pixels while providing data voltages to the plurality of pixels, In the blank section of the above frame section, the panel driver performs an initialization scan operation to initialize the light-emitting elements without providing the data voltages to the plurality of pixels, An electronic device characterized in that the time interval from the start point of the frame section to the point at which the initialization scan operation is performed is different from the time length of the minimum frame section corresponding to the maximum frame frequency of the variable frame frequency.

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