Display device

Abstract

A display device according to an embodiment of the present disclosure is provided. The display device includes a light-emitting diode, a first transistor, and an initialization driver. The first transistor is connected between an initialization power supply and an anode of the light-emitting diode and has a gate electrode connected to an initialization line. The initialization driver is configured to supply an initialization signal to the initialization line. The initialization driver supplies the initialization signal for each frame when driven at a first frequency, and supplies the initialization signal for every two or more frames when driven at a second frequency different from the first frequency.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0172238, filed on December 20, 2019, in the Korean Intellectual Property Office (KIPO), the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of the present disclosure relate to a display device. Background Art

[0004] As information technology develops, the importance of display devices as a connection medium between users and information has attracted attention. In response to this, the use of display devices such as liquid crystal display devices, organic light emitting display devices, and other display devices is increasing.

[0005] The display device includes pixels positioned in a region divided by scan lines and data lines, a scan driver for driving the scan lines, and a data driver for driving the data lines.

[0006] The scan driver supplies scan signals to the scan lines, selecting pixels in units of horizontal lines. The data driver supplies data signals synchronized with the scan signals. The data signals are then supplied to the pixels selected by the scan signals. Pixels receiving the data signals emit light of a predetermined brightness while controlling the amount of current flowing from a first power source via a light-emitting diode to a second power source. Furthermore, the emission timing of the pixels is controlled by an emission control signal supplied from an emission control line.

[0007] On the other hand, in the display device, when a low grayscale (eg, black) data signal is supplied, an operation for discharging or initializing a parasitic capacitor of a light emitting diode may be performed every frame to improve black representation capability. Summary of the Invention

[0008] Recently, display devices are driven at a high frequency (or high scan rate) to provide high-quality images. When a display device is driven at a high frequency, the number of frames displayed per second increases so that the screen can be switched smoothly.

[0009] However, in a display device driven at a high frequency, when an operation for discharging a parasitic capacitor of a light emitting diode is performed per frame, deviations in brightness and color between pixels that may occur at low grayscales may increase according to dispersion of a display panel.

[0010] A feature of the present disclosure is to provide a display device capable of reducing deviations in luminance and color between pixels that may occur at low grayscales when the display device is driven at a high frequency.

[0011] According to an embodiment of the present disclosure, a display device may include a light emitting diode, a first transistor, and an initialization driver, wherein the first transistor is connected between an initialization power source and an anode of the light emitting diode and has a gate electrode connected to an initialization line, and the initialization driver is used to supply an initialization signal to the initialization line.

[0012] The initialization driver may supply the initialization signal in groups of two or more frames when driven at the first frequency.

[0013] The initialization driver may supply the initialization signal every frame while being driven at a second frequency different from the first frequency, and the first frequency may be higher than the second frequency.

[0014] The first frequency may be 120 Hz, and the second frequency may be 60 Hz.

[0015] A group can be two frames.

[0016] The display device according to an embodiment of the present disclosure may further include a scan driver, a data driver, an emission control driver and a timing controller, wherein the scan driver is used to supply a scan signal to the scan line, the data driver is used to supply a data signal to the data line, the emission control driver is used to supply an emission control signal to the emission control line, and the timing controller is used to control the scan driver, the data driver, the emission control driver and the initialization driver.

[0017] The scan driver may be driven at a first frequency and supply a scan signal per frame, and the emission control driver may be driven at a first frequency and supply an emission control signal per frame.

[0018] The display device according to an embodiment of the present disclosure may also include second to seventh transistors and a storage capacitor. The second transistor has a first electrode connected to the anode of the light-emitting diode and a gate electrode connected to the emission control line. The third transistor has a first electrode connected to the first power supply and a gate electrode connected to the emission control line. The fourth transistor has a first electrode connected to the second electrode of the third transistor, a second electrode connected to the second electrode of the second transistor, and a gate electrode connected to the first node. The fifth transistor is connected between the first node and the second electrode of the fourth transistor and has a gate electrode connected to the first scan line. The sixth transistor is connected between the first node and the initialization power supply and has a gate electrode connected to the second scan line. The seventh transistor is connected between the data line and the first electrode of the fourth transistor and has a gate electrode connected to the first scan line. The storage capacitor is connected between the first power supply and the first node.

[0019] The scan driver may supply the scan signal to the first scan line every frame to overlap with the emission control signal.

[0020] The initialization driver may supply the initialization signal in each group while being driven at the first frequency to overlap with the emission control signal.

[0021] The initialization signal may be supplied after the scan signal, and the initialization signal and the scan signal may not overlap with each other.

[0022] The initialization driver may supply the initialization signal every frame regardless of the emission control signal when driven at the second frequency.

[0023] According to an embodiment of the present disclosure, a method of driving a display device may include supplying an initialization signal in groups of two or more frames to apply an initialization voltage to an anode of a light emitting diode of one of a plurality of pixels when driving at a first frequency.

[0024] The method according to the embodiment of the present disclosure may further include supplying an initialization signal per frame to apply an initialization voltage to an anode of the light emitting diode when driving at a second frequency different from the first frequency.

[0025] The method according to an embodiment of the present disclosure may further include: setting the pixel to a non-luminous state before applying an initialization voltage to the anode of the light-emitting diode; and charging the pixel with a voltage corresponding to the data signal. The pixel may sequentially emit light in units of horizontal lines to correspond to the charging voltage.

[0026] The first frequency may be higher than the second frequency.

[0027] The first frequency may be 120 Hz, and the second frequency may be 60 Hz.

[0028] According to an embodiment of the present disclosure, a display device may include a scan driver, a data driver, an emission control driver, a first initialization driver, a second initialization driver, a timing controller and pixels, wherein the scan driver is used to supply scan signals to scan lines respectively, the data driver is used to supply data signals to data lines respectively, the emission control driver is used to supply emission control signals to emission control lines respectively, the first initialization driver is used to supply first initialization signals to odd-numbered initialization lines respectively, the second initialization driver is used to supply second initialization signals to even-numbered initialization lines respectively, the timing controller is used to control the scan driver, the data driver, the emission control driver and the first initialization driver and the second initialization driver, and the pixels are located at intersections of scan lines and data lines.

[0029] The scan driver, the emission control driver, and the first and second initialization drivers may be driven at a high frequency.

[0030] The high frequency can be 120Hz.

[0031] The scan driver may supply a scan signal every frame, the emission control driver may supply an emission control signal every frame, the first initialization driver may supply a first initialization signal every odd frame, and the second initialization driver may supply a second initialization signal every even frame.

[0032] The pixel positioned on the i-th horizontal line among the pixels may include a light-emitting diode, a first transistor, second to seventh transistors, and a storage capacitor, wherein the first transistor is connected between an initialization power supply and an anode of the light-emitting diode and has a gate electrode connected to the i-th initialization line. The second transistor has a first electrode connected to the anode of the light-emitting diode and a gate electrode connected to the i-th emission control line. The third transistor has a first electrode connected to the first power supply and a gate electrode connected to the i-th emission control line. The fourth transistor has a first electrode connected to the second electrode of the third transistor, a second electrode connected to the second electrode of the second transistor, and a gate electrode connected to the first node. The fifth transistor is connected between the first node and the second electrode of the fourth transistor and has a gate electrode connected to the first scan line. The sixth transistor is connected between the first node and the initialization power supply and has a gate electrode connected to the second scan line. The seventh transistor is connected between the data line and the first electrode of the fourth transistor and has a gate electrode connected to the first scan line. The storage capacitor is connected between the first power supply and the first node.

[0033] The first scan line may be an i-th scan line, and the second scan line may be an (i-1)-th scan line, where i is a natural number.

[0034] The scan driver may supply a scan signal to the first scan line in one frame period to overlap with the emission control signal supplied to the i-th emission control line, the first initialization driver may supply a first initialization signal to the odd-numbered initialization lines every odd frame to overlap with the emission control signal supplied to the i-th emission control line, and the second initialization driver may supply a second initialization signal to the even-numbered initialization lines every even frame to overlap with the emission control signal supplied to the i-th emission control line. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and other aspects of the present disclosure will become more apparent by describing in further detail embodiments of the present disclosure with reference to the accompanying drawings.

[0036] Figure 1 is a block diagram illustrating a display device according to an embodiment of the present disclosure.

[0037] Figure 2 It is shown that the Figure 1 A circuit diagram of an example of a pixel in a display device.

[0038] Figure 3A The driving method according to the embodiment of the present disclosure is shown in FIG. Figure 2 The waveform diagram of the pixel method is shown in FIG.

[0039] Figure 3B 1 is a diagram for explaining a case where the initialization driver is driven at a low frequency (for example, 60 Hz) similarly to the scan driver.

[0040] Figure 3C 1 is a diagram for explaining a problem in the case where the initialization driver is driven at a high frequency (for example, 120 Hz) similarly to the scan driver.

[0041] Figure 4 The driving method according to the embodiment of the present disclosure is shown in FIG. Figure 2 The waveform diagram of the pixel method is shown in FIG.

[0042] Figure 5 is a diagram for explaining the effect when the initialization driver supplies an initialization signal to the pixel unit every two frames.

[0043] Figure 6 The driving method according to the embodiment of the present disclosure is shown in FIG. Figure 2 The waveform diagram of the pixel method is shown in FIG.

[0044] Figure 7 is a block diagram illustrating a display device according to an embodiment of the present disclosure.

[0045] Figure 8 It shows Figure 7 A block diagram of an example of an initialization driver is shown in .

[0046] Figure 9 Is shown driving Figure 7 The waveform diagram of the pixel method is shown in FIG. DETAILED DESCRIPTION

[0047] Like reference numerals refer to like elements. In addition, in the drawings, the thickness, proportion and size of the elements are exaggerated to effectively explain the technical content. The wording "and / or" includes one or more combinations that can be defined by the associated configurations.

[0048] The terms "first," "second," etc. may be used to describe various elements, but these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of the present disclosure. Unless the context clearly indicates otherwise, a singular expression may include a plural expression.

[0049] The words "including," "having," and similar words are intended to specify the features, numbers, steps, operations, elements, components, or a combination of such features, numbers, steps, operations, elements, and components described in the present disclosure. It should be understood that this does not exclude the possibility of the existence or addition of one or more other features, numbers, steps, operations, elements, components, or a combination of such features, numbers, steps, operations, elements, and components.

[0050] In the following description, when a part is connected to another part, this includes not only a case where the parts are directly connected but also a case where another part is connected in between.

[0051] Figure 1 is a block diagram illustrating a display device according to an embodiment of the present disclosure.

[0052] Reference Figure 1 A display device according to an embodiment of the present disclosure may include a pixel unit 130 (or a pixel circuit) including a plurality of pixels 140 positioned at intersections of a plurality of scan lines S1 to Sn and a plurality of data lines D1 to Dm, a scan driver 110 for driving the plurality of scan lines S1 to Sn, a data driver 120 for driving the plurality of data lines D1 to Dm, an initialization driver 160 for driving the plurality of initialization lines GB1 to GBn, an emission control driver 170 for driving the plurality of emission control lines E1 to En, and a timing controller 150 for controlling the scan driver 110, the data driver 120, and the initialization driver 160.

[0053] The scan driver 110 may supply scan signals to the plurality of scan lines S1 to Sn under the control of the timing controller 150. For example, the scan driver 110 may sequentially supply scan signals to the plurality of scan lines S1 to Sn.

[0054] The emission control driver 170 may supply the emission control signal to the plurality of emission control lines E1 to En under the control of the timing controller 150. For example, the emission control driver 170 may sequentially supply the emission control signal to the plurality of emission control lines E1 to En.

[0055] Here, the scan signal may be supplied at the same time as the emission control signal is supplied. For example, the emission control signal may be supplied to overlap with at least two scan signals. The emission control signal may be set to a gate-off voltage (e.g., a high voltage) so that the transistor included in the pixel 140 may be turned off. In addition, the scan signal may be set to a gate-on voltage (e.g., a low voltage) so that the transistor included in the pixel 140 may be turned on.

[0056] The data driver 120 may supply data signals to the plurality of data lines D1 to Dm under the control of the timing controller 150. The data signals supplied to the plurality of data lines D1 to Dm may be supplied to the pixels 140 selected by the scan signal in units of horizontal lines.

[0057] The initialization driver 160 may supply an initialization signal to the plurality of initialization lines GB1 to GBn under the control of the timing controller 150. For example, the initialization driver 160 may sequentially supply the initialization signal to the plurality of initialization lines GB1 to GBn. In addition, the initialization signal may be set to a gate-on voltage so that the transistor included in the pixel 140 can be turned on.

[0058] The pixel unit 130 may include a plurality of scan lines S1 to Sn, a plurality of initialization lines GB1 to GBn, and a plurality of emission control lines E1 to En formed in a first direction (e.g., a horizontal direction), and pixels 140 positioned at intersections of a plurality of data lines D1 to Dm formed in a second direction (e.g., a vertical direction). The pixels 140 may be selected by a scan signal in units of horizontal lines and store data signals received from the plurality of data lines D1 to Dm. Thereafter, each of the plurality of pixels 140 may emit light having a predetermined brightness while controlling the amount of current flowing from the first power source ELVDD to the second power source ELVSS via the light emitting diode in response to the data signal.

[0059] The timing controller 150 may control the scan driver 110 , the data driver 120 , and the initialization driver 160 in response to signals supplied from the outside.

[0060] exist Figure 1 , each of the plurality of pixels 140 is shown as being connected to one scan line. However, depending on the structure of the pixel 140, the pixel 140 may be connected to more than one scan line. In this case, a dummy scan line may be additionally formed in the pixel unit 130.

[0061] Figure 2 It is shown that the Figure 1 A circuit diagram of an example of a pixel 140 in a display device of FIG. Figure 2 , the pixel 140 connected to the mth data line Dm and the i-th scan line Si will be described.

[0062] Reference Figure 2 , the pixel 140 according to an embodiment of the present disclosure may include a light emitting diode LED, a first transistor M1, a second transistor M2, a third transistor M3, a fourth transistor M4, a fifth transistor M5, a sixth transistor M6, and a seventh transistor M7, and a storage capacitor Cst.

[0063] The anode of the light emitting diode LED may be connected to the pixel circuit 142 , and the cathode of the light emitting diode LED may be connected to the second power source ELVSS. The light emitting diode LED may emit light having a predetermined brightness corresponding to the amount of current supplied from the pixel circuit 142 .

[0064] The pixel circuit 142 can control the amount of current flowing from the first power source ELVDD to the second power source ELVSS via the light-emitting diode LED in response to a data signal. For example, when a scan signal is supplied to the (i-1)th scan line Si-1, the pixel circuit 142 can initialize the gate electrode of the drive transistor and, when a scan signal is supplied to the i-th scan line Si, store the data signal received from the m-th data line Dm. Furthermore, when the supply of the emission control signal to the i-th emission control line Ei is stopped, the pixel circuit 142 can control the amount of current supplied to the light-emitting diode LED in response to the data signal.

[0065] The pixel circuit 142 may be implemented by various types of circuits known in the art. In addition, the first power source ELVDD may be set to a higher voltage than the second power source ELVSS so that current can flow to the light emitting diode LED.

[0066] The first transistor M1 may be connected between an initialization power source Vint and an anode of the light-emitting diode LED. A gate electrode of the first transistor M1 may be connected to an i-th initialization line GBi (or a control line). When an initialization signal is supplied to the i-th initialization line GBi to supply a voltage of the initialization power source Vint to the anode of the light-emitting diode LED, the first transistor M1 may be turned on. Here, the initialization power source Vint may be set to a voltage lower than that of the data signal.

[0067] The first transistor M1 can improve the black rendering capability of the pixel 140. In other words, when the first transistor M1 is turned on, the parasitic capacitor Coled of the light emitting diode LED can be discharged. Then, when black brightness is achieved, the light emitting diode LED does not emit light due to the leakage current supplied by the second transistor M2, and thus, the black rendering capability can be improved.

[0068] In detail, the parasitic capacitor Coled may be charged with a predetermined voltage corresponding to the current supplied during the previous frame period from the pixel circuit 142. When the parasitic capacitor Coled is charged, the light emitting diode LED can easily emit light even with a low current.

[0069] A low grayscale (e.g., black) data signal may be supplied to the pixel circuit 142 during the current frame period. Ideally, when a low grayscale (e.g., black) data signal is supplied, the pixel circuit 142 may not supply current to the light emitting diode LED. However, in the pixel circuit 142 composed of transistors, even when a low grayscale (e.g., black) data signal is supplied, a predetermined leakage current I leak It may also be supplied to the light emitting diode LED. In this case, when the parasitic capacitor Coled is charged, the light emitting diode LED may emit light weakly, and thus, the black expression capability may be reduced.

[0070] On the other hand, when the parasitic capacitor Coled is discharged by the voltage of the initialization power supply Vint, even when the leakage current I leak When the light emitting diode LED is turned off, the light emitting diode LED can also be set to a non-lighting state.

[0071] In addition, the initialization driver 160 may supply the initialization signal to the i-th initialization line GBi to overlap with the emission control signal supplied to the i-th emission control line Ei in at least some periods. A detailed description of supplying the initialization signal by the initialization driver 160 will be described later.

[0072] The second transistor M2 may be connected between the fourth transistor M4 and the anode of the light emitting diode LED. The gate electrode of the second transistor M2 may be connected to the i-th emission control line Ei. When the emission control signal is supplied to the i-th emission control line Ei, the second transistor M2 may be turned off, and may be turned on in other cases.

[0073] The third transistor M3 may be connected between the first power source ELVDD and the fourth transistor M4. A gate electrode of the third transistor M3 may be connected to the i-th emission control line Ei. When the emission control signal is supplied to the i-th emission control line Ei, the third transistor M3 may be turned off, and may be turned on in other cases.

[0074] A first electrode of a fourth transistor M4 (e.g., a driving transistor) may be connected to the first power source ELVDD via the third transistor M3, and a second electrode of the fourth transistor M4 may be connected to the anode of the light emitting diode LED via the second transistor M2. A gate electrode of the fourth transistor M4 may be connected to the first node N1. The fourth transistor M4 may control the amount of current flowing from the first power source ELVDD to the second power source ELVSS via the light emitting diode LED in response to the voltage of the first node N1.

[0075] The fifth transistor M5 may be connected between the second electrode of the fourth transistor M4 and the first node N1. The gate electrode of the fifth transistor M5 may be connected to the i-th scan line Si. When a scan signal is supplied to the i-th scan line Si, the fifth transistor M5 may be turned on to electrically connect the second electrode of the fourth transistor M4 to the first node N1. Therefore, when the fifth transistor M5 is turned on, the fourth transistor M4 may be connected in the form of a diode.

[0076] The sixth transistor M6 may be connected between the first node N1 and the initialization power supply Vint. A gate electrode of the sixth transistor M6 may be connected to the (i-1)th scan line Si-1. When a scan signal is supplied to the (i-1)th scan line Si-1, the sixth transistor M6 may be turned on to supply the voltage of the initialization power supply Vint to the first node N1.

[0077] The seventh transistor M7 may be connected between the mth data line Dm and the first electrode of the fourth transistor M4. A gate electrode of the seventh transistor M7 may be connected to the i-th scan line Si. When a scan signal is supplied to the i-th scan line Si, the seventh transistor M7 may be turned on to electrically connect the mth data line Dm to the first electrode of the fourth transistor M4.

[0078] The storage capacitor Cst may be connected between the first power source ELVDD and the first node N1 and may store a voltage corresponding to the data signal and a threshold voltage of the fourth transistor M4.

[0079] Figure 3A The driving method according to the embodiment of the present disclosure is shown in FIG. Figure 2 . In this case, as an example, the scan driver 110, the initialization driver 160, and the emission control driver 170 may be driven at a low frequency (such as 60 Hz per frame). However, for convenience of description, this driving frequency is described as an example, and other driving frequencies are used in other embodiments.

[0080] Reference Figure 1 、 Figure 2 and Figure 3A First, the emission control signal may be supplied to the i-th emission control line Ei during each of the multi-frames 1F and 2F. When the emission control signal is supplied to the i-th emission control line Ei, the second transistor M2 and the third transistor M3 may be turned off.

[0081] When the third transistor M3 is turned off, the first power source ELVDD and the first electrode of the fourth transistor M4 can be electrically separated from each other. When the second transistor M2 is turned off, the second electrode of the fourth transistor M4 and the anode of the light-emitting diode LED can be electrically separated from each other. Therefore, the pixel 140 can be set to a non-light-emitting state during the period when the emission control signal is supplied to the i-th emission control line Ei.

[0082] Thereafter, a scan signal may be supplied to the (i-1)th scan line Si-1. When the scan signal is supplied to the (i-1)th scan line Si-1, the sixth transistor M6 may be turned on. When the sixth transistor M6 is turned on, the voltage of the initialization power supply Vint may be supplied to the first node N1.

[0083] After the scan signal is supplied to the (i-1)th scan line Si-1, the scan signal may be supplied to the i-th scan line Si. When the scan signal is supplied to the i-th scan line Si, the fifth transistor M5 and the seventh transistor M7 may be turned on.

[0084] When the fifth transistor M5 is turned on, the first node N1 and the second electrode of the fourth transistor M4 may be electrically connected to each other. That is, when the fifth transistor M5 is turned on, the fourth transistor M4 may be connected in the form of a diode.

[0085] When the seventh transistor M7 is turned on, the data signal from the mth data line Dm can be supplied to the first electrode of the fourth transistor M4. In this case, since the first node N1 is initialized to the voltage of the initialization power supply Vint, the fourth transistor M4 can be turned on. When the fourth transistor M4 is turned on, a voltage obtained by subtracting the absolute value of the threshold voltage of the fourth transistor M4 from the voltage of the data signal can be supplied to the first node N1. In this case, the storage capacitor Cst can store a voltage corresponding to the data signal and the threshold voltage of the fourth transistor M4.

[0086] Afterwards, an initialization signal may be supplied to the i-th initialization line GBi. When the initialization signal is supplied to the i-th initialization line GBi, the first transistor M1 may be turned on. When the first transistor M1 is turned on, the voltage of the initialization power supply Vint may be supplied to the anode of the light emitting diode LED, and thus, the parasitic capacitor of the light emitting diode LED may be discharged.

[0087] After the initialization signal is supplied to the i-th initialization line GBi, the supply of the emission control signal to the i-th emission control line Ei may be stopped. When the supply of the emission control signal to the i-th emission control line Ei is stopped, the second transistor M2 and the third transistor M3 may be turned on. When the third transistor M3 is turned on, the first power source ELVDD and the first electrode of the fourth transistor M4 may be electrically connected to each other. When the second transistor M2 is turned on, the second electrode of the fourth transistor M4 and the anode of the light emitting diode LED may be electrically connected to each other.

[0088] In this case, the fourth transistor M4 may control the amount of current flowing from the first power source ELVDD to the second power source ELVSS via the light emitting diode LED in response to the voltage of the first node N1. Then, the light emitting diode LED may emit light having a predetermined brightness corresponding to the amount of current supplied from the fourth transistor M4.

[0089] Figure 3B 1 is a diagram for explaining a case where the initialization driver 160 is driven at a low frequency (for example, 60 Hz) similarly to the scan driver 110 . Figure 3C 1 is a diagram for explaining a problem in the case where the initialization driver 160 is driven at a high frequency (for example, 120 Hz) similarly to the scan driver 110 .

[0090] In this case, the time it takes for the parasitic capacitor Coled of the LED to charge varies depending on the emission color of the LED. This is because the operating points (or threshold voltages) differ when the LED has different emission colors. According to an embodiment of the present disclosure, the time it takes for the parasitic capacitor Coled of the LED to charge can increase in the order of blue, red, and green.

[0091] Reference Figure 3B and Figure 3C When both the scan driver 110 and the initialization driver 160 are driven at a high frequency (eg, 120 Hz), color deviation between pixels 140 at low grayscales may increase compared to a case of driving at a low frequency (eg, 60 Hz).

[0092] For example, Figure 3B As shown in FIG, when both the scan driver 110 and the initialization driver 160 are driven at a low frequency of 60 Hz per frame, the light emission time of the initialization driver 160 to initialize the light emitting diode LED can be sufficiently ensured.

[0093] That is, the light emitting diode LED emitting blue light B may be in a non-light emitting state during the first time t1 when the parasitic capacitor Coled is charged, and the light emitting diode LED emitting green light G may be in a non-light emitting state during the first time t1_1 when the parasitic capacitor Coled is charged. However, even when considering the dispersion between the pixels 140, the light emitting time of both the light emitting diode LED emitting blue light B and the light emitting diode LED emitting green light G can be sufficiently ensured until the second time t2 corresponding to one frame.

[0094] On the other hand, Figure 3C As shown in FIG, when both the scan driver 110 and the initialization driver 160 are driven at a high frequency of 120 Hz per frame, a light emission time for the initialization driver 160 to initialize the light emitting diode LED may not be sufficiently ensured.

[0095] That is, the light emitting diode LED emitting blue light B may be in a non-light emitting state during the first time t1 when the parasitic capacitor Coled is charged, and the light emitting diode LED emitting green light G may be in a non-light emitting state during the first time t1_1 when the parasitic capacitor Coled is charged.

[0096] Compared to the second time t2 when driven at a low frequency of 60 Hz, the second time t2′ corresponding to one frame is relatively short. Therefore, even when considering the dispersion between pixels 140, the light-emitting diode LED emitting blue light B can maintain a certain level of light emission time. However, since the light-emitting diode LED emitting green light G has a relatively short light emission time, the dispersion between pixels 140 may increase the deviation of brightness and color.

[0097] Hereinafter, as an embodiment of the present disclosure, when both the scan driver 110 and the initialization driver 160 are driven at a high frequency such as 120 Hz per frame, a driving method for sufficiently ensuring a light emitting time of the light emitting diode LED will be described.

[0098] Figure 4 The driving method according to the embodiment of the present disclosure is shown in FIG. Figure 2 In this case, it is assumed that the scan driver 110, the initialization driver 160, and the emission control driver 170 are all driven at a high frequency of 120 Hz per frame.

[0099] Reference Figure 1 、 Figure 2 and Figure 4The scan driver 110 may supply a scan signal to the pixel unit 130 every frame, and the emission control driver 170 may also supply an emission control signal to the pixel unit 130 every frame. On the other hand, the initialization driver 160 may supply an initialization signal to the pixel unit 130 every two frames.

[0100] First, the emission control signal may be supplied to the i-th emission control line Ei during the first frame 1 F. When the emission control signal is supplied to the i-th emission control line Ei, the second transistor M2 and the third transistor M3 may be turned off.

[0101] When the third transistor M3 is turned off, the first power source ELVDD and the first electrode of the fourth transistor M4 can be electrically separated from each other. When the second transistor M2 is turned off, the second electrode of the fourth transistor M4 and the anode of the light-emitting diode LED can be electrically separated from each other. Therefore, the pixel 140 can be set to a non-light-emitting state during the period when the emission control signal is supplied to the i-th emission control line Ei.

[0102] Thereafter, a scan signal may be supplied to the (i-1)th scan line Si-1. When the scan signal is supplied to the (i-1)th scan line Si-1, the sixth transistor M6 may be turned on. When the sixth transistor M6 is turned on, the voltage of the initialization power supply Vint may be supplied to the first node N1.

[0103] After the scan signal is supplied to the (i-1)th scan line Si-1, the scan signal may be supplied to the i-th scan line Si. When the scan signal is supplied to the i-th scan line Si, the fifth transistor M5 and the seventh transistor M7 may be turned on.

[0104] When the fifth transistor M5 is turned on, the first node N1 and the second electrode of the fourth transistor M4 may be electrically connected to each other. That is, when the fifth transistor M5 is turned on, the fourth transistor M4 may be connected in the form of a diode.

[0105] When the seventh transistor M7 is turned on, the data signal from the mth data line Dm can be supplied to the first electrode of the fourth transistor M4. In this case, since the first node N1 is initialized to the voltage of the initialization power supply Vint, the fourth transistor M4 can be turned on. When the fourth transistor M4 is turned on, a voltage obtained by subtracting the absolute value of the threshold voltage of the fourth transistor M4 from the voltage of the data signal can be supplied to the first node N1. In this case, the storage capacitor Cst can store a voltage corresponding to the data signal and the threshold voltage of the fourth transistor M4.

[0106] Afterwards, an initialization signal may be supplied to the i-th initialization line GBi. When the initialization signal is supplied to the i-th initialization line GBi, the first transistor M1 may be turned on. When the first transistor M1 is turned on, the voltage of the initialization power supply Vint may be supplied to the anode of the light emitting diode LED, and thus, the parasitic capacitor of the light emitting diode LED may be discharged.

[0107] After the initialization signal is supplied to the i-th initialization line GBi, the supply of the emission control signal to the i-th emission control line Ei may be stopped. When the supply of the emission control signal to the i-th emission control line Ei is stopped, the second transistor M2 and the third transistor M3 may be turned on. When the third transistor M3 is turned on, the first power source ELVDD and the first electrode of the fourth transistor M4 may be electrically connected to each other. When the second transistor M2 is turned on, the second electrode of the fourth transistor M4 and the anode of the light emitting diode LED may be electrically connected to each other.

[0108] In this case, the fourth transistor M4 may control the amount of current flowing from the first power source ELVDD to the second power source ELVSS via the light emitting diode LED in response to the voltage of the first node N1. Then, the light emitting diode LED may emit light having a predetermined brightness corresponding to the amount of current supplied from the fourth transistor M4.

[0109] At the same time, as in the first frame 1F, the emission control signal may be supplied to the i-th emission control line Ei during the second frame 2F. Thereafter, the scan signal may be supplied to the (i-1)-th scan line Si-1. In addition, after the scan signal is supplied to the (i-1)-th scan line Si-1, the scan signal may be supplied to the i-th scan line Si. However, after the scan signal is supplied to the i-th scan line Si, the initialization signal may not be supplied to the i-th initialization line GBi.

[0110] When the initialization signal is not supplied to the i-th initialization line GBi, the first transistor M1 may be turned off. When the first transistor M1 is turned off, the voltage of the initialization power supply Vint may not be supplied to the anode of the light emitting diode LED. Accordingly, the parasitic capacitor Coled of the light emitting diode LED may remain in a charged state.

[0111] Afterwards, the supply of the emission control signal to the i-th emission control line Ei may be stopped. When the supply of the emission control signal to the i-th emission control line Ei is stopped, the second transistor M2 and the third transistor M3 may be turned on. When the third transistor M3 is turned on, the first power source ELVDD and the first electrode of the fourth transistor M4 may be electrically connected to each other. When the second transistor M2 is turned on, the second electrode of the fourth transistor M4 and the anode of the light emitting diode LED may be electrically connected to each other.

[0112] In this case, the fourth transistor M4 can control the amount of current flowing from the first power source ELVDD to the second power source ELVSS via the light-emitting diode LED in response to the voltage of the first node N1. The light-emitting diode LED can then emit light having a predetermined brightness corresponding to the amount of current supplied from the fourth transistor M4. Basically, as the above process is repeated, the pixel 140 can emit light having a brightness corresponding to the data signal.

[0113] Figure 5 is a diagram for explaining an effect when the initialization driver 160 supplies an initialization signal to the pixel unit 130 every two frames.

[0114] Reference Figure 4 and Figure 5 , the scan driver 110 may supply the scan signal to the pixel unit 130 every frame, but the initialization driver 160 may supply the initialization signal to the pixel unit 130 every two frames. Therefore, the light emitting time of the light emitting diode LED in the second frame 2F can be sufficiently ensured.

[0115] That is, the light emitting diode LED emitting blue light B may be in a non-light emitting state during the first time t1' when the parasitic capacitor Coled is charged, and the light emitting diode LED emitting green light G may be in a non-light emitting state during the first time t1_1' when the parasitic capacitor Coled is charged. In this case, since the initialization driver 160 may not supply the initialization signal to the pixel unit 130 in the second frame 2F, the parasitic capacitor Coled of the light emitting diode LED may not be discharged. Therefore, the first time t1' and the first time t1_1' when the respective parasitic capacitors Coled are charged are comparable. Figure 3C The first time t1 and the first time t1_1 shown in FIG. 5 are relatively shorter.

[0116] Therefore, even in Figure 5 The second time t2′ corresponding to one frame in the case of driving at a high frequency (eg, 120 Hz) shown in FIG. 1 becomes longer than that in FIG. 1 . Figure 3A and Figure 3BThe second time t2 corresponding to one frame in the case of driving at a low frequency (for example, 60 Hz) shown in the figure is relatively shorter. Since the first time t1' and the first time t1_1' during which the respective parasitic capacitances Coled are charged are unnecessary, the light-emitting diodes LED emitting blue light B and the light-emitting diodes LED emitting green light G can be sufficiently ensured to emit light even when considering the dispersion between the pixels 140. In other words, the color deviation between the pixels 140 can be reduced, and the power consumption can be reduced. Hereinafter, other embodiments will be described. In the following embodiments, the description of the same configuration as the above embodiments will be omitted or simplified, and the differences will be mainly described.

[0117] Figure 6 The present invention shows another embodiment of the driving Figure 2 140 is a waveform diagram of the method shown in FIG.

[0118] Reference Figure 1 、 Figure 2 and Figure 6 , such as Figure 4 , the scan driver 110 and the emission control driver 170 may be driven at a high frequency such as 120 Hz per frame (eg, 1F and 2F), but the initialization driver 160 may be driven at a lower frequency such as 60 Hz per frame (eg, 1F').

[0119] Specifically, the emission control signal may be supplied to the i-th emission control line Ei during the first frame 1F driven at 120 Hz. Thereafter, the scan signal may be supplied to the (i-1)-th scan line Si-1. After the scan signal is supplied to the (i-1)-th scan line Si-1, the scan signal may be supplied to the i-th scan line Si.

[0120] As in the first frame 1F, the emission control signal may be supplied to the i-th emission control line Ei during the second frame 2F driven at 120 Hz. Thereafter, the scan signal may be supplied to the (i-1)-th scan line Si-1. After the scan signal is supplied to the (i-1)-th scan line Si-1, the scan signal may be supplied to the i-th scan line Si.

[0121] Meanwhile, after the scan signal is supplied to the first scan line S1, the initialization signal may be supplied to the first initialization line GB1. However, the initialization driver 160 may sequentially supply the initialization signal to the first to 2n initialization lines GB1 to GB2n during the first frame 1F' driven at 60 Hz.

[0122] During the first frame 1F of the scan driver 110 and the emission control driver 170, the initialization driver 160 may sequentially supply the initialization signal to the first to nth initialization lines GB1 to GBn. In addition, during the second frame 2F of the scan driver 110 and the emission control driver 170, the initialization driver 160 may sequentially supply the initialization signal to the (n+1)th to 2nth initialization lines GBn+1 to GB2n.

[0123] That is, one frame of the initialization driver 160 driven at 60 Hz may correspond to two frames of the scan driver 110 and the emission control driver 170 driven at 120 Hz. Therefore, the initialization driver 160 may sequentially supply the initialization signal to the first to 2n initialization lines GB1 to GB2n during the two frames of the scan driver 110 and the emission control driver 170. Figure 4 The embodiments shown in FIG. 1 have the same or similar effects.

[0124] Figure 7 is a block diagram illustrating a display device according to another embodiment of the present disclosure.

[0125] Reference Figure 7 ,and Figure 1 The embodiment shown in is different in that the display device may include not only the first initialization driver 161 located on one side of the pixel unit 130 but also the second initialization driver 162 located on the other side of the pixel unit 130 .

[0126] Specifically, the first initialization driver 161 may be connected to a plurality of odd-numbered initialization lines GB1, GB3, to GB2n-1. The second initialization driver 162 may be connected to a plurality of even-numbered initialization lines GB2, GB4, to GB2n. Thus, an initialization signal supplied from the outside and consisting of a combination of a gate-on voltage and a gate-off voltage may be applied to the first initialization line GB1 to the 2nth initialization line GB2n. The first initialization driver 161 and the second initialization driver 162 may be configured essentially as a shift register and may include a plurality of stages arranged in a line. Furthermore, the first initialization driver 161 and the second initialization driver 162 may be formed so as to be integrated in the same manufacturing process as the switching elements of the pixels 140. However, the first initialization driver 161 and the second initialization driver 162 may be implemented in the form of an integrated circuit.

[0127] Figure 8 It shows Figure 7 A block diagram of an example of an initialization driver is shown in .

[0128] Reference Figure 8, the first initialization driver 161 may supply initialization signals only to the odd-numbered initialization lines GB1, GB3 to GB2n-1. For example, the first initialization driver 161 may include a plurality of stages ST1, ST3, and ST5 independently connected to each other. The plurality of stages ST1, ST3, and ST5 may be connected to the corresponding odd-numbered initialization lines GB1, GB3, and GB5, respectively, to sequentially output initialization signals.

[0129] Each of the plurality of stages ST1, ST3, and ST5 may receive a first voltage VGL and a second voltage VGH having a higher level than the first voltage VGL. Furthermore, each of the plurality of stages ST1, ST3, and ST5 may receive at least one clock signal CLK. The at least one clock signal CLK may have the same period. According to an embodiment of the present disclosure, the first initialization driver 161 may sequentially output an initialization signal having an activation level at intervals of one cycle of the clock signal CLK.

[0130] The first stage ST1 can be driven by receiving a first start signal FLM1. In detail, the first stage ST1 can receive a first voltage VGL and a second voltage VGH, and provide an initialization signal to a first initialization line GB1 in response to the first start signal FLM1 and a clock signal CLK. The initialization signal can be provided to corresponding pixels 140 arranged in a row unit (refer to FIG. 1 ) through the first initialization line GB1. Figure 7 ).

[0131] A plurality of stages ST3 and ST5 other than the first stage ST1 may be connected independently of one another to be sequentially driven. For example, the third stage ST3 may receive an initialization signal output from the first stage ST1, which is the previous stage. The third stage ST3 may receive a first voltage VGL and a second voltage VGH, and supply an initialization signal to the third initialization line GB3 in response to the initialization signal and the clock signal CLK supplied via the first initialization line GB1. Since the other stage ST5 also operates in substantially the same manner, a detailed description thereof will be omitted.

[0132] The second initialization driver 162 may supply initialization signals only to the even-numbered initialization lines GB2, GB4 to GB2n. For example, the second initialization driver 162 may include a plurality of stages ST2, ST4, and ST6 connected independently of one another. The plurality of stages ST2, ST4, and ST6 may be connected to the corresponding even-numbered initialization lines GB2, GB4, and GB6, respectively, to sequentially output initialization signals.

[0133] Each of the plurality of stages ST2, ST4, and ST6 may receive a first voltage VGL and a second voltage VGH having a higher level than the first voltage VGL. Furthermore, each of the plurality of stages ST2, ST4, and ST6 may receive at least one clock signal CLK. The at least one clock signal CLK may have the same period. According to an embodiment of the present disclosure, the second initialization driver 162 may sequentially output an initialization signal having an activation level at intervals of one cycle of the clock signal CLK.

[0134] The second stage ST2 can be driven by receiving the second start signal FLM2. In detail, the second stage ST2 can receive the first voltage VGL and the second voltage VGH, and provide an initialization signal to the second initialization line GB2 in response to the second start signal FLM2 and the clock signal CLK. The initialization signal can be provided to the corresponding pixels 140 arranged in a row unit (refer to Figure 7 ).

[0135] The plurality of stages ST4 and ST6 other than the second stage ST2 may be connected independently of one another to be sequentially driven. For example, the fourth stage ST4 may receive an initialization signal output from the second stage ST2, which is the previous stage. The fourth stage ST4 may receive a first voltage VGL and a second voltage VGH, and supply the initialization signal to the fourth initialization line GB4 in response to the initialization signal and the clock signal CLK supplied through the second initialization line GB2. Since the other stage ST6 also operates in substantially the same manner, a detailed description of the operation will be omitted.

[0136] Figure 9 Is shown driving Figure 7 140 is a waveform diagram of the method shown in FIG.

[0137] Reference Figure 2 、 Figure 7 、 Figure 8 and Figure 9 , such as Figure 4 , the first initialization driver 161 may supply the initialization signal only to the odd-numbered initialization lines GB1, GB3 to GB2n-1 during odd frames. The second initialization driver 162 may supply the initialization signal only to the even-numbered initialization lines GB2, GB4 to GB2n during even frames.

[0138] In detail, the emission control signal may be supplied to the first emission control line E1 during the first frame 1F driven at 120 Hz. Thereafter, the scan signal may be supplied to the zeroth scan line S0. Thereafter, the scan signal may be supplied to the first scan line S1. After the scan signal is supplied to the first scan line S1, the initialization signal may be supplied to the first initialization line GB1.

[0139] Next, the emission control signal may be supplied to the second emission control line E2. Thereafter, the scan signal may be supplied to the first scan line S1. Thereafter, the scan signal may be supplied to the second scan line S2. However, after the scan signal is supplied to the second scan line S2, the initialization signal may not be supplied to the second initialization line GB2.

[0140] Next, the emission control signal may be supplied to the third emission control line E3. Thereafter, the scan signal may be supplied to the second scan line S2. Thereafter, the scan signal may be supplied to the third scan line S3. After the scan signal is supplied to the third scan line S3, the initialization signal may be supplied to the third initialization line GB3.

[0141] Next, the emission control signal may be supplied to the fourth emission control line E4. Thereafter, the scan signal may be supplied to the third scan line S3. Thereafter, the scan signal may be supplied to the fourth scan line S4. However, after the scan signal is supplied to the fourth scan line S4, the initialization signal may not be supplied to the fourth initialization line GB4.

[0142] That is, the first initialization driver 161 may supply the initialization signal only to the odd-numbered plurality of initialization lines GB1 , GB3 to GB2n−1 during the odd-numbered frames.

[0143] At the same time, the emission control signal may be supplied to the first emission control line E1 during the second frame 2F driven at 120 Hz. Thereafter, the scan signal may be supplied to the zeroth scan line S0. Thereafter, the scan signal may be supplied to the first scan line S1. However, after the scan signal is supplied to the first scan line S1, the initialization signal may not be supplied to the first initialization line GB1.

[0144] Next, the emission control signal may be supplied to the second emission control line E2. Thereafter, the scan signal may be supplied to the first scan line S1. Thereafter, the scan signal may be supplied to the second scan line S2. After the scan signal is supplied to the second scan line S2, the initialization signal may be supplied to the second initialization line GB2.

[0145] Next, the emission control signal may be supplied to the third emission control line E3. Thereafter, the scan signal may be supplied to the second scan line S2. Thereafter, the scan signal may be supplied to the third scan line S3. However, after the scan signal is supplied to the third scan line S3, the initialization signal may not be supplied to the third initialization line GB3.

[0146] Next, the emission control signal may be supplied to the fourth emission control line E4. Thereafter, the scan signal may be supplied to the third scan line S3. Thereafter, the scan signal may be supplied to the fourth scan line S4. After the scan signal is supplied to the fourth scan line S4, the initialization signal may be supplied to the fourth initialization line GB4.

[0147] That is, the second initialization driver 162 may supply the initialization signal only to the even-numbered plurality of initialization lines GB2 , GB2 to GB2 n during the even-numbered frames.

[0148] Thus, we obtain Figure 4 The embodiments shown in FIG. 1 have the same or similar effects.

[0149] When driven at a high frequency, the display device according to the embodiment of the present disclosure can discharge the parasitic capacitor of the light emitting diode every group of multiple frames, thereby reducing the occurrence of deviation in brightness and color between pixels at low grayscales.

[0150] In a display device according to an embodiment of the present disclosure, the driving frequency of the initialization driver can be set to be different from the driving frequencies of the scan driver and the light-emission control driver to discharge the parasitic capacitors of the light-emitting diodes. Therefore, the occurrence of brightness and color deviations between pixels at low grayscales can be reduced.

[0151] The technical concept of the present disclosure has been described in detail based on the above embodiments. However, it should be noted that the above embodiments are for illustrative purposes only and are not intended to limit the present disclosure. In addition, it will be understood by those skilled in the art that various modifications can be made within the scope of the technical concept of the present disclosure.

[0152] The scope of the present disclosure is not limited to the detailed description of the specification, but should be determined by the appended claims. In addition, it should be interpreted that the meaning and scope of the claims and all changes or modifications derived from equivalent concepts are included in the scope of the present disclosure.

Claims

1. A display device, comprising: light-emitting diodes; a first transistor connected between an initialization power source and an anode of the light emitting diode and having a gate electrode connected to an initialization line; a scan driver configured to supply a scan signal to the scan line; an emission control driver configured to supply an emission control signal to an emission control line; as well as an initialization driver for supplying an initialization signal to the initialization line, wherein the scan driver is driven at a first frequency and supplies the scan signal in each frame, wherein the emission control driver is driven at the first frequency and supplies the emission control signal in each frame; wherein the initialization driver supplies the initialization signal in groups of two or more frames when driving at the first frequency, wherein the display device is driven at frequencies including but not limited to the first frequency and the second frequency, and The first frequency is higher than the second frequency.

2. The display device according to claim 1, wherein The initialization driver supplies the initialization signal in each frame when driven at the second frequency.

3. The display device according to claim 2, wherein: The first frequency is 120 Hz, and the second frequency is 60 Hz.

4. The display device according to claim 1, further comprising: a data driver configured to supply a data signal to a data line; as well as A timing controller is configured to control the scan driver, the data driver, the emission control driver, and the initialization driver.

5. The display device according to claim 4, further comprising: a second transistor having a first electrode connected to the anode of the light emitting diode and a gate electrode connected to the emission control line; a third transistor having a first electrode connected to a first power source and a gate electrode connected to the emission control line; a fourth transistor having a first electrode connected to the second electrode of the third transistor, a second electrode connected to the second electrode of the second transistor, and a gate electrode connected to the first node; a fifth transistor connected between the first node and the second electrode of the fourth transistor and having a gate electrode connected to a first scan line; a sixth transistor connected between the first node and the initialization power source and having a gate electrode connected to a second scan line; a seventh transistor connected between the data line and the first electrode of the fourth transistor and having a gate electrode connected to the first scan line; as well as A storage capacitor is connected between the first power source and the first node.

6. The display device according to claim 5, wherein: The scan driver supplies the scan signal to the first scan line in each frame to overlap with the emission control signal.

7. The display device according to claim 6, wherein: The initialization driver supplies the initialization signal for each of the groups when driven at the first frequency so as to overlap with the emission control signal.

8. The display device according to claim 7, wherein: The initialization signal is supplied after the scan signal, and the initialization signal and the scan signal do not overlap with each other.

9. The display device according to claim 4, wherein: The initialization driver supplies the initialization signal in every frame when driven at the second frequency regardless of the emission control signal.

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