Light-emitting display device and method for driving the same

Abstract

To prevent the flickering of an organic light-emitting diode and damage by a high voltage difference.SOLUTION: The present disclosure provides a light-emitting display device including an organic light-emitting diode in which an anode electrode is connected to a first power supply line, a capacitor for storing a data voltage, and a drive transistor whose first electrode is connected to the cathode electrode of the organic light-emitting diode, whose gate electrode is connected to the first electrode of the capacitor, and whose second electrode is connected to the second electrode of the capacitor and a second power supply line, the drive transistor applying an initialization voltage to a node where the cathode electrode of the organic light-emitting diode and the first electrode of the drive transistor are connected.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a light-emitting display device and a driving method thereof. [Background technology]

[0002] With the development of information technology, the market for display devices, which are the connecting medium between users and information, is expanding. Therefore, the use of display devices such as Light Emitting Display Devices (LEDs), Quantum Dot Display Devices (QDDs), Liquid Crystal Display Devices (LCDs), etc. is increasing. Organic Light Emitting Diode (OLED) devices are also becoming more and more popular. In OLED devices, an electroluminescent layer made of organic compounds emits visible light. Therefore, no backlight is required. High image quality can be achieved while reducing the thickness and weight of the device.

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

[0004] In such display devices, when drive signals, such as scan signals and data signals, are provided to sub-pixels formed in a display panel, selected sub-pixels transmit light or directly emit light to display images. However, the sub-pixels from such display devices may suffer from problematic damage or flicker over time. Summary of the Invention [Problem to be solved by the invention]

[0005] The objective of the present disclosure is to solve the problem that organic light emitting diodes flicker or are damaged by high voltage difference when first driven. [Means for solving the problem]

[0006] The present disclosure provides a light emitting display device including an organic light emitting diode (OLED) having an anode electrode connected to a first power line, a capacitor for storing a data voltage, and a driving transistor having a first electrode connected to a cathode electrode of the OLED, a gate electrode connected to a first electrode of the capacitor, and a second electrode connected to a second power line and the driving transistor, wherein the driving transistor applies an initialization voltage to a node where the cathode electrode of the OLED and the first electrode of the driving transistor are connected.

[0007] The initialization voltage may be selected to cause the organic light emitting diode to not emit light.

[0008] The initialization voltage can be higher than the voltage applied to the first power line minus the threshold voltage of the organic light emitting diode. The threshold voltage of the organic light emitting diode is the voltage difference between the anode and cathode of the OLED, and when the voltage difference is exceeded, the OLED emits light (and therefore when the voltage difference is lowered, the OLED does not emit light). Here, the voltage applied to the first power line may be referred to as a first voltage or a high potential.

[0009] The initialization voltage can be lower than the sum of the voltage applied to the first power line and a breakdown voltage of the organic light emitting diode, the breakdown voltage being a negative bias voltage across the anode and cathode of the OLED, and exceeding the breakdown voltage can irreversibly damage the OLED.

[0010] In another aspect, the present disclosure provides a light emitting display device including: a display panel including a subpixel having an organic light emitting diode having an anode electrode connected to a first power line, a capacitor storing a data voltage, and a driving transistor having a first electrode connected to a cathode electrode of the organic light emitting diode, a gate electrode connected to a first electrode of the capacitor, and a second electrode connected to a second electrode of the capacitor and a second power line; and a driving unit driving the display panel, wherein the display panel has an initialization period in which an initialization voltage is applied to a node to which the cathode electrode of the organic light emitting diode and the first electrode of the driving transistor are connected.

[0011] The initialization period may be performed at least once during initial driving of the display panel.

[0012] The initialization voltage may be higher than a voltage applied to the first power line minus a threshold voltage of the organic light emitting diode, and may be lower than a voltage obtained by adding the voltage applied to the first power line and a breakdown voltage of the organic light emitting diode.

[0013] The initialization voltage may be transmitted via the second power line and applied to a node connecting the cathode electrode of the organic light emitting diode and the first electrode of the driving transistor via a second electrode of the driving transistor.

[0014] In yet another aspect, the present disclosure provides a method for driving a light emitting display device including a display panel including a subpixel having an organic light emitting diode having an anode electrode connected to a first power line, a capacitor storing a data voltage, and a driving transistor having a first electrode connected to a cathode electrode of the organic light emitting diode, a gate electrode connected to a first electrode of the capacitor, and a second electrode connected to a second electrode of the capacitor and a second power line, and a driving unit for driving the display panel, the method including the steps of: applying an initialization voltage to the second power line; and turning on the driving transistor so that the initialization voltage is applied to a node to which the cathode electrode of the organic light emitting diode and the first electrode of the driving transistor are connected via a second electrode of the driving transistor.

[0015] The initialization voltage may be higher than a voltage applied to the first power line minus a threshold voltage of the organic light emitting diode, and may have a voltage level lower than a voltage obtained by adding the voltage applied to the first power line and a breakdown voltage of the organic light emitting diode. Effect of the Invention

[0016] The present disclosure has an advantage that it is possible to solve the problem of an organic light emitting diode flickering or being damaged by a high voltage difference when initially driven by applying a voltage level that can initialize the drain node of a subpixel while making the organic light emitting diode non-emitting. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram illustrating a light emitting display device. [Diagram 2] FIG. 2 is a diagram illustrating a configuration of the sub-pixel illustrated in FIG. [Diagram 3] 11 is a diagram for explaining a configuration of a gate-in-panel type scan driver; FIG. [Figure 4]11 is a diagram for explaining a configuration of a gate-in-panel type scan driver; FIG. [Figure 5a] FIG. 13 is a diagram showing an example of the arrangement of a gate-in-panel type scan driver; [Figure 5b] FIG. 13 is a diagram showing an example of the arrangement of a gate-in-panel type scan driver; [Figure 6] FIG. 2 is a circuit configuration diagram of a subpixel according to a first embodiment of the present disclosure. [Figure 7] FIG. 10 is a diagram for briefly explaining a method for initializing a drain node of a subpixel according to a first embodiment of the present disclosure. [Figure 8] FIG. 10 is a diagram for briefly explaining a method for initializing a drain node of a subpixel according to a first embodiment of the present disclosure. [Figure 9] 11 is a diagram illustrating a method for initializing sub-pixels included in an entire display panel according to a second embodiment of the present disclosure. [Figure 10] 11 is a diagram illustrating a method for initializing sub-pixels included in an entire display panel according to a second embodiment of the present disclosure. [Figure 11] FIG. 11 is a diagram for explaining in detail a method for initializing a sub-pixel node according to a second embodiment of the present disclosure. [Figure 12] FIG. 11 is a diagram for explaining in detail a method for initializing a sub-pixel node according to a second embodiment of the present disclosure. [Figure 13] FIG. 11 is a diagram for explaining in detail a method for initializing a sub-pixel node according to a second embodiment of the present disclosure. [Figure 14] FIG. 11 is a diagram for explaining in detail a method for initializing a sub-pixel node according to a second embodiment of the present disclosure. [Figure 15] FIG. 11 is a diagram for explaining in detail a method for initializing a sub-pixel node according to a second embodiment of the present disclosure. [Figure 16] FIG. 11 is a diagram for explaining in detail a method for initializing a sub-pixel node according to a second embodiment of the present disclosure. [Figure 17] FIG. 13 is a diagram for explaining advantages of the embodiment over the comparative example. [Figure 18] FIG. 13 is a diagram for explaining advantages of the embodiment over the comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Display devices according to the present disclosure can be configured in, but are not limited to, televisions, video players, personal computers (PCs), home theaters, automotive electronics, smartphones, and the like.

[0019] In addition, the subpixel described below includes an n-type thin film transistor as an example, but it can also be configured as a p-type thin film transistor or a form in which n-type and p-type exist together. A thin film transistor is a three-electrode element including a gate, a source, and a drain. The source is an electrode that supplies carriers to the transistor. In a thin film transistor, carriers start to flow from the source. The drain is an electrode in a thin film transistor from which carriers exit to the outside. That is, in a thin film transistor, carriers flow from the source to the drain.

[0020] In the case of a p-type thin film transistor, the carriers are holes, so the source voltage is higher than the drain voltage so that holes flow from the source to the drain. In the p-type thin film transistor, holes flow from the source to the drain, so current flows from the source to the drain. In contrast, in the case of an n-type thin film transistor, the carriers are electrons, so the source voltage is lower than the drain voltage so that electrons flow from the source to the drain. In the n-type thin film transistor, electrons flow from the source to the drain, so current flows from the drain to the source. However, the source and drain of a thin film transistor can be changed by an applied voltage. Reflecting this, in the following description, one of the source and drain will be described as a first electrode, and the other of the source and drain will be described as a second electrode.

[0021] FIG. 1 is a block diagram illustrating a light emitting display device, and FIG. 2 is a diagram illustrating a configuration of a sub-pixel illustrated in FIG.

[0022] As shown in FIGS. 1 and 2, the light emitting display device may include an image supplier 110, a timing controller 120, a gate driver 130, a data driver 140, a display panel 150, a power supplier 180, and the like.

[0023] The image supply unit (set or host system) 110 can output various driving signals together with an image data signal supplied from the outside or an image data signal stored in an internal memory. The image supply unit 110 can supply the data signal and various driving signals to the timing control unit 120.

[0024] The timing controller 120 may output a gate timing control signal GDC for controlling the operation timing of the gate driver 130, a data timing control signal DDC for controlling the operation timing of the data driver 140, and various synchronous signals (vertical synchronous signal Vsync, horizontal synchronous signal Hsync), etc. The timing controller 120 may supply a data signal DATA supplied from the image supplier 110 to the data driver 140 together with the data timing control signal DDC. The timing controller 120 may be formed in the form of an IC (Integrated Circuit) and mounted on a printed circuit board, but is not limited thereto.

[0025] The gate driver 130 may output a gate signal (or a scan signal) in response to a gate timing control signal GDC provided from the timing controller 120. The gate driver 130 may provide gate signals to sub-pixels included in the display panel 150 via gate lines GL1 to GLm. The gate driver 130 may be formed in an IC form or directly on the display panel 150 in a gate in panel manner, but is not limited thereto.

[0026] The data driver 140 may sample and latch the data signal DATA in response to a data timing control signal DDC etc. provided from the timing controller 120, and may convert the digital data signal into an analog data voltage based on a gamma reference voltage and output the analog data voltage. The data driver 140 may provide data voltages to sub-pixels included in the display panel 150 via the data lines DL1 to DLn. The data driver 140 may be formed in an IC form and mounted on the display panel 150 or on a printed circuit board, but is not limited thereto.

[0027] The power supply unit 180 may generate a first voltage of high potential and a second voltage of low potential based on an external input voltage supplied from the outside, and output the first voltage and the second voltage via a first power line EVDD and a second power line EVSS. The power supply unit 180 may generate and output not only the first power supply and the second power supply, but also voltages required for driving the gate driver 130 (e.g., gate voltages including a gate high voltage and a gate low voltage) and voltages required for driving the data driver 140 (drain voltages including a drain voltage and a half drain voltage).

[0028] The display panel 150 can display an image in response to driving signals including gate signals and data voltages, a first power supply, and a second power supply. Sub-pixels of the display panel 150 directly emit light. The display panel 150 can be manufactured from a rigid or flexible substrate such as glass, silicon, or polyimide. The sub-pixels that emit light can include pixels including red, green, and blue, or pixels including red, green, blue, and white.

[0029] For example, one subpixel SP may be connected to a first data line DL1, a first gate line GL1, a first power line EVDD, and a second power line EVSS, and may include a pixel circuit including a switching transistor, a driving transistor, a capacitor, an organic light emitting diode, etc. The subpixel SP used in the light emitting display directly emits light, and therefore has a complex circuit configuration. In addition, there are various compensation circuits for compensating for deterioration of the organic light emitting diode that emits light, as well as the driving transistor that supplies a driving current to the organic light emitting diode, etc. Therefore, it should be noted that the subpixel SP is illustrated simply in the form of a block.

[0030] Meanwhile, in the above description, the timing controller 120, the gate driver 130, the data driver 140, etc. are described as being separate components, but depending on the configuration of the light emitting display device, one or more of the timing controller 120, the gate driver 130, and the data driver 140 may be integrated into a single IC.

[0031] 3 and 4 are diagrams for explaining the configuration of a gate-in-panel type gate driver, and FIG. 5 is a diagram showing an example of the arrangement of the gate-in-panel type gate driver.

[0032] 3, the gate driver of the gate-in-panel type may include a shift register 131 and a level shifter 135. The level shifter 135 may generate a clock signal Clks and a start signal Vst based on signals and voltages output from the timing controller 120 and the power supplier 180. The clock signal Clks may be generated in the form of K phases (K is an integer equal to or greater than 2) having different phases, such as 2 phases, 4 phases, or 8 phases.

[0033] The shift register 131 operates in response to signals Clks, Vst, etc. output from the level shifter 135, and can output gate signals Gate[1] to Gate[m] that can turn on or off transistors formed in the display panel. The shift register 131 can be formed as a thin film on the display panel in a gate-in-panel manner.

[0034] 3 and 4, the level shifter 135, unlike the shift register 131, may be formed independently in an IC form or may be included within the power supply unit 180. However, this is merely an example and is not limiting.

[0035] As shown in Figures 5a and 5b, in the gate-in-panel type gate driver, shift registers 131a and 131b for outputting gate signals may be disposed in a non-display area NA of a display panel 150. The shift registers 131a and 131b may be disposed in the non-display areas NA on the left and right sides of the display panel 150 as in Figure 5a, or may be disposed in the non-display areas NA on the top and bottom sides of the display panel 150 as in Figure 5b. Meanwhile, in Figures 5a and 5b, the shift registers 131a and 131b are illustrated and described as being disposed in the non-display area NA as an example, but the present invention is not limited thereto.

[0036] FIG. 6 is a circuit diagram of a subpixel according to a first embodiment of the present disclosure, and FIGS. 7 and 8 are diagrams for briefly explaining a method for initializing a drain node of a subpixel according to the first embodiment of the present disclosure.

[0037] As shown in FIG. 6, according to the first embodiment of the present disclosure, a sub-pixel may include a switching transistor SW, a driving transistor DT, a capacitor CST, and an organic light-emitting diode OLED.

[0038] The switching transistor SW may have a gate electrode connected to the first gate line GL1, a first electrode connected to the first data line DL1, and a second electrode connected to the gate electrode of the driving transistor DT and a first electrode of the capacitor CST, and may serve to transfer a data voltage applied via the first data line DL1 to the first electrode of the capacitor CST.

[0039] The driving transistor DT may have a gate electrode connected to a second electrode of the switching transistor SW and a first electrode of the capacitor CST, a first electrode connected to a cathode electrode of the organic light emitting diode OLED, and a second electrode connected to the second electrode of the capacitor CST and a second power line EVSS. The driving transistor DT may generate a driving current in response to a data voltage stored in the capacitor CST.

[0040] The capacitor CST may have a first electrode connected to the second electrode of the switching transistor SW and the gate electrode of the driving transistor DT, and a second electrode connected to the second electrode of the driving transistor DT and the second power line EVSS, and may serve to store a data voltage for driving the driving transistor DT.

[0041] The organic light emitting diode OLED may have an anode electrode connected to the first power line EVDD and a cathode electrode connected to the first electrode of the driving transistor DT. The organic light emitting diode OLED may emit light in response to the operation (driving current) of the driving transistor DT.

[0042] As shown in FIG. 7, around the driving transistor DT, a gate node Vg, a source node Vs, and a drain node Vd can be defined. The drain node Vd of the driving transistor DT can be initialized to a specific initialization voltage such as "Vd = Vini". For this reason, the conditions of the voltages applied through the gate node Vg, the source node Vs, and the drain node Vd can have conditions different from those of general display driving.

[0043] If the drain node Vd of the driving transistor DT is initialized, the voltage between the anode electrode and the cathode electrode of the organic light-emitting diode OLED can be made below the threshold voltage (OLED Vth) of the organic light-emitting diode, such as "Anode~Cathode < OLED Vth". Here, the threshold voltage of the OLED may be the voltage difference between the cathode and the anode of the OLED at which the OLED emits light when the voltage difference is exceeded (and the potential difference at which the OLED does not emit light when the voltage difference is below).

[0044] As shown in FIG. 8, if the drain node Vd of the driving transistor DT is initialized, the voltage across the organic light-emitting diode OLED can be maintained below the threshold voltage (OLED Vth) of the organic light-emitting diode until before general display driving.

[0045] FIGS. 9 and 10 are diagrams for explaining a method of initializing sub-pixels included in the entire display panel according to the second embodiment of the present disclosure.

[0046] As shown in FIG. 9, the light-emitting display device according to the second embodiment of the present disclosure can include a display panel 150, a flexible substrate 145 on which a data driving unit 140 is mounted, and a printed circuit board 143, etc. The first gate line GL1 of the display panel 150 can be an area where the data driving unit 140 is mounted, and the Mth gate line GLm can be on the opposite side of the area where the data driving unit 140 is mounted.

[0047] As shown in FIGS. 9 and 10, the light emitting display panel 150 may include an initialization period, which initializes the sub-pixels SP included in the entire display panel 150, and a display period, which displays an image using the sub-pixels SP included in the entire display panel 150.

[0048] The initialization period may be performed at least once when a voltage is applied (PW_ON) to the light emitting display device and the display panel 150 is initially driven. This is because after the initialization, the display panel 150 is driven in a predetermined driving manner so that the drain nodes of the sub-pixels are not maintained at an unspecified voltage.

[0049] During the initialization period (Initial Period), an initialization voltage may be simultaneously applied to all sub-pixels SP included in the display panel 150. To this end, a gate signal of a gate high voltage (H) may be simultaneously applied to the first gate line GL1 to the Mth gate line GLm. The gate signal of the gate high voltage (H) means a voltage that can turn on a switching transistor included in a sub-pixel, and the gate signal of the gate low voltage (L) means a voltage that can turn off a switching transistor included in a sub-pixel.

[0050] During a display period after the initialization period, a gate signal of a high gate voltage (H) may be sequentially applied to the first gate line GL1 to the M-th gate line GLm.

[0051] 11 to 16 are diagrams for explaining in detail a method for initializing a node of a sub-pixel according to the second embodiment of the present disclosure.

[0052] 11, the switching transistor SW and the driving transistor DT may have a turned-off state, where no signal or voltage is applied to the first data line DL1 and the first gate line GL1, and the first power line EVDD and the second power line EVSS may be applied with a first voltage of high potential and a second voltage of low potential for driving the subpixels, or may not be applied with these voltages.

[0053] 12, during the second initialization period, the switching transistor SW may be turned on. Here, a gate signal of a high gate voltage may be applied to the first gate line GL1, and a high data voltage High may be applied to the first data line DL1. A voltage of 0V may be applied to the first power line EVDD, and a ground voltage GND may be applied to the second power line EVSS. As a result, a high data voltage High may be applied to the gate node Vg, a ground voltage GND may be applied to the source node Vs, and a voltage of 0V may be applied to the drain node Vd.

[0054] Meanwhile, the first power line EVDD is applied with a voltage of 0V as an example, but this can be any voltage level lower than the threshold voltage of the organic light emitting diode (OLED Vth), and the high data voltage High can be any voltage that can turn on the driving transistor DT.

[0055] During the third initialization period shown in Fig. 13, the switching transistor SW may have a turned-off state, and the driving transistor DT may have a turned-on state by the high data voltage High. Here, a gate signal of a gate low voltage may be applied to the first gate line GL1, and a low data voltage Low may be applied to the first data line DL1. The first power line EVDD may be maintained at 0V, and the second power line EVSS may be switched from the ground voltage GND to the initialization voltage Vini and applied thereto. As a result, the high data voltage High may be applied to the gate node Vg, and the initialization voltage Vini may be applied to the source node Vs and the drain node Vd.

[0056] The initialization voltage Vini may have a voltage level higher than the first high potential voltage minus the threshold voltage of the organic light emitting diode (OLED Vth). Also, the initialization voltage Vini may have a voltage level lower than the first high potential voltage plus the breakdown voltage of the organic light emitting diode (OLED Breakdown = about 50 V). That is, the initialization voltage Vini can be any voltage level that can initialize the drain node Vd while making the organic light emitting diode OLED non-emitting.

[0057] During the fourth initialization period shown in Fig. 14, the switching transistor SW may have a turned-off state, and the driving transistor DT may have a turned-on state by the high data voltage High. Here, a gate signal of a gate low voltage may be applied to the first gate line GL1, and a low data voltage Low may be applied to the first data line DL1. Also, the first power line EVDD may be changed from 0V to a high potential first voltage (22V) and applied thereto, and the second power line EVSS may be maintained at the initialization voltage Vini. As a result, the high data voltage High may be applied to the gate node Vg, and the initialization voltage Vini may be applied to the source node Vs and the drain node Vd.

[0058] During the fifth initialization period shown in FIG. 15, the switching transistor SW may have a turned-on state, and the driving transistor DT may have a turned-off state by the low data voltage Low. Here, the first gate line GL1 may have a state in which a gate signal of a gate high voltage is applied, and the first data line DL1 may have a state in which the low data voltage Low is applied. The first power line EVDD may have a high potential first voltage (22V) maintained, and the second power line EVSS may have a state in which the initialization voltage Vini is maintained. Thus, the low data voltage Low is applied to the gate node Vg, and the initialization voltage Vini is maintained at the source node Vs and the drain node Vd. The low data voltage Low may be any voltage that can turn off the driving transistor DT.

[0059] During the sixth initialization period shown in FIG. 16, the switching transistor SW and the driving transistor DT may be turned off. Here, the first gate line GL1 may be applied with a gate signal of a gate low voltage, and the first data line DL1 may be applied with a low data voltage Low. The first power line EVDD may be maintained at a high potential first voltage of 22V, and the second power line EVSS may be switched from the initialization voltage Vini to the ground voltage GND and applied thereto. As a result, the gate node Vg may be applied with a low data voltage Low, the source node Vs may be applied with a ground voltage GND, and the drain node Vd may be maintained with the initialization voltage Vini.

[0060] 17 and 18 are diagrams for explaining advantages of the embodiment over the comparative example.

[0061] In FIG. 18, EVDD is a first voltage of high potential, Vd is a drain node Vd voltage of the subpixel, Gate1 is a gate signal, and Ioled is a current flowing through the organic light emitting diode OLED.

[0062] The comparative example shown in FIG. 17 is different from the above-mentioned embodiment in that no initialization voltage is applied to the drain node Vd of the subpixel during initial driving. When a high potential first voltage (22V) is applied to the subpixel of the comparative example shown in FIG. 17 for initial driving, a large potential difference may occur across the organic light emitting diode OLED regardless of whether the driving transistor DT is on or off. This can be seen by referring to PT in FIG. 18(a). When a large potential difference occurs across the organic light emitting diode OLED as in PT in FIG. 18(a), a momentary current may be generated as in FIG. 18(b). In this case, the organic light emitting diode OLED may cause flickering due to current leakage, and the large potential difference may cause breakdown or damage to the organic light emitting diode OLED.

[0063] However, in the embodiment of the present disclosure, when a voltage level (e.g., Vini>EVDD-OLED Vth) that can initialize the drain node Vd of the subpixel while making the organic light emitting diode OLED non-emitting is applied for initialization, the problem that may occur in the comparative example can be solved.

[0064] As described above, the present disclosure has an advantage that it is possible to solve the problem of an organic light emitting diode flickering or being damaged by a high voltage difference when initially driven by applying a voltage level that can initialize the drain node of a subpixel while causing the organic light emitting diode to not emit light.

[0065] The disclosure of this embodiment includes the following configuration. (Configuration 1) an organic light emitting diode having an anode electrode connected to a first power line; a capacitor for storing a data voltage; a driving transistor having a first electrode connected to a cathode electrode of the organic light emitting diode, a gate electrode connected to a first electrode of the capacitor, and a second electrode connected to a second electrode of the capacitor and a second power line; The light emitting display device, wherein the driving transistor applies an initialization voltage to a node where a cathode electrode of the organic light emitting diode and a first electrode of the driving transistor are connected. (Configuration 2) 2. The light-emitting display device according to configuration 1, wherein the initialization voltage has a voltage level that causes the organic light-emitting diode to not emit light. (Configuration 3) 3. The light-emitting display device according to configuration 1 or 2, wherein the initialization voltage has a voltage level higher than a voltage obtained by subtracting a threshold voltage of the organic light-emitting diode from a first voltage of high potential applied to the first power line. (Configuration 4) 4. The light emitting display device according to configuration 3, wherein the initialization voltage has a voltage level lower than a voltage obtained by adding up a first voltage of a high potential applied to the first power line and a breakdown voltage of the organic light emitting diode. (Configuration 5) a display panel including a sub-pixel having an organic light emitting diode having an anode electrode connected to a first power line, a capacitor for storing a data voltage, and a driving transistor having a first electrode connected to a cathode electrode of the organic light emitting diode, a gate electrode connected to a first electrode of the capacitor, and a second electrode connected to a second electrode of the capacitor and a second power line; a drive unit that drives the display panel, The display panel has an initialization period in which an initialization voltage is applied to a node to which a cathode electrode of the organic light emitting diode and a first electrode of the driving transistor are connected. (Configuration 6) 6. The light emitting display device according to configuration 5, wherein the initialization period is performed at least once during a first driving of the display panel. (Configuration 7) The light-emitting display device of configuration 5 or 6, wherein the initialization voltage has a voltage level higher than a voltage obtained by subtracting a threshold voltage of the organic light-emitting diode from a high-potential first voltage applied to the first power line, and has a voltage level lower than a voltage obtained by adding the high-potential first voltage and a breakdown voltage of the organic light-emitting diode. (Configuration 8) An light-emitting display device described in any one of configurations 5 to 7, wherein the initialization voltage is transmitted via the second power line and applied to a node connecting the cathode electrode of the organic light-emitting diode and the first electrode of the driving transistor via the second electrode of the driving transistor. (Configuration 9) A method for driving a light emitting display device, comprising: a display panel including sub-pixels each having an organic light emitting diode having an anode electrode connected to a first power line, a capacitor for storing a data voltage, and a driving transistor having a first electrode connected to a cathode electrode of the organic light emitting diode, a gate electrode connected to a first electrode of the capacitor, and a second electrode connected to a second electrode of the capacitor and a second power line; and a driving unit for driving the display panel, applying an initialization voltage to the second power line; turning on the driving transistor so that the initialization voltage is applied to a node connecting a cathode electrode of the organic light emitting diode and a first electrode of the driving transistor via a second electrode of the driving transistor. (Configuration 10) A method for driving a light-emitting display device according to configuration 9, wherein the initialization voltage has a voltage level higher than a voltage obtained by subtracting a threshold voltage of the organic light-emitting diode from a high-potential first voltage applied to the first power line, and has a voltage level lower than a voltage obtained by adding the high-potential first voltage and a breakdown voltage of the organic light-emitting diode. [Explanation of symbols]

[0066] 130 Gate driver 140 Data Drive Unit 150 Display Panel 180 Power supply section SW Switching transistor DT Drive Transistor CST Capacitor OLED Organic Light Emitting Diode

Claims

1. an organic light emitting diode (OLED) having an anode electrode connected to a first power line (EVDD); a capacitor (CST) for storing a data voltage; a driving transistor (DT) having a first electrode (Vd) connected to a cathode electrode of the organic light emitting diode, a gate electrode (Vg) connected to a first electrode of the capacitor, and a second electrode (Vs) connected to a second electrode of the capacitor and a second power line (EVSS); The driving transistor is turned on to apply a voltage applied to the second power line to a node to which the cathode electrode and the first electrode (Vd) are connected as an initialization voltage (Vini), The initialization voltage is applied to all the sub-pixels simultaneously; the initialization voltage is lower than a voltage obtained by adding a voltage applied to the first power line and a breakdown voltage of the organic light emitting diode; The initialization voltage is applied throughout a first initialization period to a sixth initialization period, In the first initialization period, the switching transistor and the driving transistor are turned off; In the second initialization period, the switching transistor is turned on and a high data voltage is applied to the gate electrode of the driving transistor; In the third initialization period, the initialization voltage is applied to the node through the driving transistor that is turned on, In the fourth initialization period, the voltage of the first power line is converted to a first voltage higher than 0V, In the fifth initialization period, the driving transistor is turned off by applying a low data voltage through the switching transistor; In the sixth initialization period, the voltage of the second power line is switched from the initialization voltage to a ground voltage.

2. The light emitting display device of claim 1 , wherein the initialization voltage is selected to cause the organic light emitting diode to not emit light.

3. The light emitting display device of claim 1 , wherein the initialization voltage is selected such that a voltage difference between the anode electrode and the cathode electrode of the organic light emitting diode is lower than a threshold voltage of the organic light emitting diode.

4. The light emitting display device of claim 1 , wherein the initialization voltage is higher than a voltage applied to the first power line minus a threshold voltage (Vth) of the organic light emitting diode.

5. a display panel including a sub-pixel having an organic light emitting diode having an anode electrode connected to a first power line, a capacitor for storing a data voltage, and a driving transistor having a first electrode connected to a cathode electrode of the organic light emitting diode, a gate electrode connected to a first electrode of the capacitor, and a second electrode connected to a second electrode of the capacitor and a second power line; a drive unit that drives the display panel, the display panel has an initialization period in which an initialization voltage is applied to a node to which a cathode electrode of the organic light emitting diode and a first electrode of the driving transistor are connected, The driving transistor is turned on to apply a voltage applied to the second power line to a node to which the cathode electrode and the first electrode (Vd) of the driving transistor are connected as an initialization voltage (Vini); The initialization voltage is applied to all the sub-pixels simultaneously; the initialization voltage is lower than a voltage obtained by adding a voltage applied to the first power line and a breakdown voltage of the organic light emitting diode; The initialization voltage is applied throughout a first initialization period to a sixth initialization period, In the first initialization period, the switching transistor and the driving transistor are turned off; In the second initialization period, the switching transistor is turned on and a high data voltage is applied to the gate electrode of the driving transistor; In the third initialization period, the initialization voltage is applied to the node through the driving transistor that is turned on, In the fourth initialization period, the voltage of the first power line is converted to a first voltage higher than 0V, In the fifth initialization period, the driving transistor is turned off by applying a low data voltage through the switching transistor; In the sixth initialization period, the voltage of the second power line is switched from the initialization voltage to a ground voltage.

6. The light emitting display device of claim 5 , wherein the initialization period is performed at least once during a first driving of the display panel.

7. 7. The light-emitting display device according to claim 5, wherein the initialization voltage is transmitted through the second power line and applied to a node connecting the cathode electrode of the organic light-emitting diode and the first electrode of the driving transistor through a second electrode of the driving transistor.

8. A method for driving a light emitting display device, comprising: a display panel including a sub-pixel (SP) having an organic light emitting diode (OLED) having an anode electrode connected to a first power supply line (EVDD), a capacitor (CST) for storing a data voltage, and a driving transistor (DT) having a first electrode (Vd) connected to a cathode electrode of the organic light emitting diode, a gate electrode (Vg) connected to a first electrode of the capacitor, and a second electrode connected to a second electrode (Vs) of the capacitor and a second power supply line (EVSS), applying an initialization voltage (Vini) to the second power line; turning on the driving transistor so that the initialization voltage is applied to a node to which a cathode electrode of the organic light emitting diode and a first electrode of the driving transistor are connected via a second electrode of the driving transistor; The initialization voltage is applied to all the sub-pixels simultaneously; the initialization voltage is lower than a voltage obtained by adding a voltage applied to the first power line and a breakdown voltage of the organic light emitting diode; The initialization voltage is applied throughout a first initialization period to a sixth initialization period, In the first initialization period, the switching transistor and the driving transistor are turned off; In the second initialization period, the switching transistor is turned on and a high data voltage is applied to the gate electrode of the driving transistor; In the third initialization period, the initialization voltage is applied to the node through the driving transistor that is turned on, In the fourth initialization period, the voltage of the first power line is converted to a first voltage higher than 0V, In the fifth initialization period, the driving transistor is turned off by applying a low data voltage through the switching transistor; In the sixth initialization period, the voltage of the second power line is switched from the initialization voltage to a ground voltage.

9. The method of claim 8 , wherein the driving transistor is turned on after the initialization voltage is applied to the second power line.

10. 9. The method of claim 8, wherein the first power line increases to a high potential after the initialization voltage is applied to the node, the high potential corresponding to a threshold voltage of the organic light emitting diode.

11. 11. The method of claim 10, further comprising turning off the driving transistor and maintaining the second power line at a ground voltage after increasing the first power line to the high potential.

12. The method of claim 8 , wherein the initialization voltage is selected such that a voltage difference between the anode electrode and the cathode electrode of the organic light emitting diode is lower than a threshold voltage of the organic light emitting diode.

13. 9. The method for driving a light-emitting display device according to claim 8, wherein the initialization voltage is higher than a voltage applied to the first power line minus a threshold voltage of the organic light-emitting diode, and / or the initialization voltage is lower than a voltage obtained by adding the voltage and a breakdown voltage of the organic light-emitting diode.

14. 14. The method of claim 8, wherein the initialization voltage is supplied to the second power line during an initialization period preceding a display period during which an image is displayed by the display panel.

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