Display device and driving method thereof

Abstract

The present invention relates to a display device and a driving method thereof, wherein the display device comprises: a display panel, comprising a plurality of data lines, a plurality of scan lines and a plurality of pixel circuits, wherein each pixel circuit comprises an organic light emitting diode, a first transistor and a second transistor, wherein the first transistor is connected to an anode electrode of the organic light emitting diode, and the second transistor is connected to the scan line, the data line and the first transistor; a data driving unit, which provides a reference voltage to the plurality of data lines during a first interval of a frame when a driving mode is converted from a low-power driving mode to a normal driving mode; a scan driving unit, which simultaneously provides a scan signal of a turn-on voltage for turning on the second transistor to the plurality of scan lines; and a voltage generating unit, which applies a high-level second power supply voltage for turning off the organic light emitting diode to a cathode electrode of the organic light emitting diode during the first interval of the frame.

Description

Technical Field

[0001] The present invention relates to a display device and a driving method thereof, and more particularly to a display device and a driving method thereof for improving instantaneous afterimage. Background Art

[0002] Generally, a display device includes a display panel and a display panel driving unit. The display panel includes a plurality of pixels, a plurality of scan lines, a plurality of data lines, and a plurality of light-emitting control lines. The display panel driving unit includes: a scan driving unit that provides scan signals to the plurality of scan lines; a data driving unit that provides data voltages to the data lines; a light-emitting driving unit that provides light-emitting control signals to the light-emitting control lines; and a timing control unit that generates control signals for controlling the scan driving unit, the data driving unit, and the light-emitting driving unit.

[0003] Recently, research is being conducted on a method of reducing power consumption by low-frequency driving when an image displayed on the display panel is a still image or the display panel is in an always on display (AOD) mode. Summary of the invention

[0004] An object of the present invention is to provide a display device for removing a momentary afterimage when switching from a low-power driving mode to a normal driving mode.

[0005] Another object of the present invention is to provide a driving method of the display device.

[0006] In order to achieve the above-mentioned purpose, a display device according to an embodiment of the present invention includes: a display panel, including multiple data lines, multiple scan lines and multiple pixel circuits, and each pixel circuit includes an organic light emitting diode, a first transistor and a second transistor, the first transistor is connected to the anode electrode of the organic light emitting diode, and the second transistor is connected to the scan line, the data line and the first transistor; a data driving unit, when the driving mode is converted from a low-power driving mode to a normal driving mode, provides a reference voltage to the multiple data lines during a first interval of a frame; a scan driving unit, simultaneously providing a scan signal of a turn-on voltage for turning on the second transistor to the multiple scan lines; and a voltage generating unit, during the first interval of the frame, applying a high-level second power supply voltage for making the organic light emitting diode non-emitting to the cathode electrode of the organic light emitting diode.

[0007] In one embodiment, the display panel further includes a plurality of light emitting lines, and the pixel circuit further includes a third transistor connected to the light emitting lines and the first transistor.

[0008] In one embodiment, in the first interval of the frame, the light emitting driving section simultaneously provides a light emitting control signal of a turn-on voltage for turning on the third transistor to the plurality of light emitting lines.

[0009] In one embodiment, during the active interval of the frame, the voltage generating unit provides the high-level second power voltage to the cathode electrode of the organic light emitting diode.

[0010] In one embodiment, during the second interval of the frame, the voltage generating unit provides a second power supply voltage having a level lower than the first power supply voltage to the cathode electrode of the organic light emitting diode, and the light emitting driving unit simultaneously provides a light emitting control signal of a turn-on voltage to the plurality of light emitting lines, wherein the first power supply voltage is generated by the voltage generating unit, and the first power supply voltage and the second power supply voltage are used to drive the organic light emitting diode.

[0011] In one embodiment, the first interval of the frame is located before the activation interval, and the second interval is located after the activation interval.

[0012] In one embodiment, when the driving mode is converted from the low-power driving mode to the normal driving mode, a frame including the first interval, the activation interval, and the second interval is repeated during a preset time.

[0013] In one embodiment, when the driving mode is converted from the low-power driving mode to the normal driving mode, one of an odd-numbered frame and an even-numbered frame includes the first interval, the active interval, and the second interval.

[0014] In one embodiment, the first transistor and the third transistor are P-type transistors, and the second transistor is an N-type transistor.

[0015] In one embodiment, the display panel further includes a plurality of sensing lines, and the pixel circuit further includes a fourth transistor connected to the sensing lines, the anode electrode of the organic light emitting diode, and the scan line.

[0016] In one embodiment, the fourth transistor is an N-type transistor.

[0017] In one embodiment, the display device further includes: a sensing unit connected to the sensing line and configured to perform analog-to-digital conversion on a sensing signal transmitted from the sensing line to generate sensing data.

[0018] In order to achieve the above-mentioned purpose, in a driving method of a display device according to an embodiment of the present invention, the display device includes multiple scan lines and multiple pixel circuits, and each pixel circuit includes an organic light-emitting diode, a first transistor and a second transistor, the first transistor is connected to the anode electrode of the organic light-emitting diode, and the second transistor is connected to the scan line, the data line and the first transistor, wherein the driving method of the display device includes the following steps: when the driving mode is converted from a low-power driving mode to a normal driving mode, a reference voltage is provided to the multiple data lines during a first interval of a frame; a scan signal of a turn-on voltage for turning on the second transistor is provided to the multiple scan lines at the same time; and during the first interval of the frame, a high-level second power supply voltage for making the organic light-emitting diode non-emitting is applied to the cathode electrode of the organic light-emitting diode.

[0019] In one embodiment, the display device further includes a plurality of light-emitting lines, and the pixel circuit further includes a third transistor connected to the light-emitting lines and the first transistor, and the driving method of the display device further includes the following steps: in the first interval of the frame, a light-emitting control signal of a turn-on voltage for turning on the third transistor is simultaneously provided to the plurality of light-emitting lines.

[0020] In one embodiment, the driving method of the display device further includes the following step: during an active interval of the frame, providing the high-level second power supply voltage to a cathode electrode of the organic light emitting diode.

[0021] In one embodiment, during the second interval of the frame, a second power supply voltage with a level lower than the first power supply voltage is provided to the cathode electrode of the organic light emitting diode; and a light emitting control signal of a turn-on voltage is provided to the multiple light emitting lines at the same time, wherein the first power supply voltage is generated by the voltage generating unit, and the first power supply voltage and the second power supply voltage are used to drive the organic light emitting diode.

[0022] In one embodiment, the first interval of the frame is located before the activation interval, and the second interval is located after the activation interval.

[0023] In one embodiment, when the driving mode is converted from the low-power driving mode to the normal driving mode, a frame including the first interval, the activation interval, and the second interval is repeated during a preset time.

[0024] In one embodiment, when the driving mode is converted from the low-power driving mode to the normal driving mode, one of an odd-numbered frame and an even-numbered frame includes the first interval, the active interval, and the second interval.

[0025] In one embodiment, the first transistor and the third transistor are P-type transistors, and the second transistor is an N-type transistor.

[0026] According to the display device and the driving method thereof according to the embodiment of the present invention, when the driving mode is switched from the low-power driving mode to the normal driving mode, the threshold voltage is initialized and the simultaneous light emission method is adopted, thereby eliminating the momentary afterimage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a block diagram of a display device according to an embodiment of the present invention.

[0028] Figure 2 is included in the diagram Figure 1 Equivalent circuit diagram of the pixel circuit in a pixel.

[0029] Figure 3 is a flowchart for illustrating a method for driving a display device according to an embodiment of the present invention.

[0030] Figures 4a to 4c It is used to illustrate Figure 3 Waveform diagram of the driving method.

[0031] Figure 5 is a flowchart for illustrating a method for driving a display device according to an embodiment of the present invention.

[0032] Figure 6a and Figure 6b It is used to illustrate Figure 5 Waveform diagram of the driving method. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0034] Figure 1 is a block diagram of a display device according to an embodiment of the present invention.

[0035] Reference Figure 1 The display device 1000 includes a display panel 110 , a timing control unit 120 , a voltage generating unit 130 , a data driving unit 141 , a sensing unit 145 , a scan driving unit 150 and a light emitting driving unit 160 .

[0036] The display panel 110 includes a plurality of pixels P, a plurality of data lines DL, a plurality of sensing lines SSL, a plurality of scan lines SL, and a plurality of light emitting control lines EL. The pixels P may be arranged in a matrix including a plurality of pixel rows and a plurality of pixel columns. Each pixel P includes an organic light emitting diode and a plurality of transistors and at least one capacitor for driving the organic light emitting diode. The pixels P are connected to the data lines DL, the sensing lines SSL, the scan lines SL, and the light emitting control lines EL.

[0037] According to an embodiment, the pixel P may include a first type of transistor and a second type of transistor different from the first type. For example, the first type of transistor may be a polysilicon thin film transistor. For example, the first type of transistor may be a low temperature polysilicon (LTPS) thin film transistor. For example, the second type of transistor may be an oxide thin film transistor. For example, the first type of transistor may be a P-type transistor, and the second type of transistor may be an N-type transistor.

[0038] The data line DL is connected to the data driving unit 141 to transmit a data voltage to the pixel P.

[0039] The sensing line SSL is connected to the sensing unit 145 and transfers a sensing signal sensed from the pixel P to the sensing unit 145 .

[0040] The scan lines SL are connected to the scan driving unit 150 to transmit scan signals to the pixels P.

[0041] The light emitting control line EL is connected to the light emitting driving unit 160 to transmit a light emitting control signal to the pixel P.

[0042] The timing control unit 120 can control the overall driving mode of the display device 1000. The timing control unit 120 receives an image signal DATA and a control signal CONT from an external device. The image signal DATA may include red, green, and blue data. The control signal CONT may include a horizontal synchronization signal, a vertical synchronization signal, a main clock signal, etc.

[0043] The timing control unit 120 converts the image signal DATA according to the specifications such as the pixel structure and resolution of the display panel 110 , and outputs the image data DATA1 obtained by correcting the image signal DATA using various correction algorithms.

[0044] The timing control part 120 generates a first control signal CONT1 for driving the data driving part 141 , a second control signal CONT2 for driving the scan driving part 150 , and a third control signal CONT3 for driving the light emitting driving part 160 based on the control signal CONT.

[0045] The voltage generating unit 130 generates a plurality of driving voltages using an external voltage. The plurality of driving voltages include a scanning driving voltage SDV provided to the scanning driving unit 150, a light-emitting driving voltage EDV provided to the light-emitting driving unit 160, and a plurality of power supply voltages ELVDD and ELVSS provided to the display panel 110. The scanning driving voltage SDV may include a scanning on voltage and a scanning off voltage. The light-emitting driving voltage EDV may include a light-emitting on voltage and a light-emitting off voltage. The plurality of power supply voltages may include a first power supply voltage ELVDD and a second power supply voltage ELVSS for driving an organic light-emitting diode of the display panel 110.

[0046] According to an embodiment, the plurality of power supply voltages may further include a second power supply voltage ELVSS_H of a high level.

[0047] The data driving part 141 converts the image data DATA1 into a data voltage in response to the first control signal CONT1 and outputs the data voltage to the data line DL.

[0048] The sensing unit 145 may provide sensing data, which is sensing data obtained by analog-to-digital conversion of a sensing signal SENS sensed from the pixel P in a set sensing interval, to the timing control unit 120 . The timing control unit 120 may correct the image data DATA1 using the sensing data.

[0049] The scan driving part 150 generates a plurality of scan signals in response to the second control signal CONT2. The second control signal CONT2 may include a scan start signal and at least one clock signal.

[0050] The light emitting driving unit 160 generates a plurality of light emitting control signals in response to the third control signal CONT3. The third control signal CONT3 may include a light emitting start signal and at least one clock signal.

[0051] According to an embodiment, the display device 1000 can be driven in a normal driving mode, a low power driving mode, and an afterimage removal mode.

[0052] In the normal driving mode, for example, a normal image is displayed on the display panel 110 at a panel driving frequency of 120 Hz.

[0053] In the low power driving mode, when the image displayed on the display panel 110 is a still image or the display panel 110 operates in an always-on mode, the display panel 110 displays frame images at a low frequency in order to reduce power consumption.

[0054] In the afterimage removal mode, when the driving mode is switched from the low-power driving mode to the normal driving mode, the display panel 110 is driven to remove a momentary afterimage corresponding to a still image in the low-power driving mode.

[0055] The frame interval of the afterimage removal mode may include an initialization interval for initializing a threshold voltage, an activation interval for writing a normal image into the display panel 110 , and a simultaneous light emitting interval for making a plurality of horizontal lines of the display panel 110 emit light simultaneously.

[0056] Figure 2 is included in the diagram Figure 1 Equivalent circuit diagram of the pixel circuit in a pixel.

[0057] Reference Figure 1 and Figure 2 , the pixel P includes a pixel circuit.

[0058] The pixel circuit includes: a first transistor T1, a second transistor T2, a third transistor T3, a storage capacitor Cst, an organic light emitting diode OLED and a fourth transistor T4.

[0059] The first transistor T1 may be a polysilicon thin film transistor. The first transistor T1 may be a P-type thin film transistor. The first transistor T1 includes a control electrode connected to the first node N1, a first electrode connected to the third transistor T3, and a second electrode connected to the second node N2.

[0060] The second transistor T2 may be an oxide thin film transistor. The second transistor T2 may be an N-type thin film transistor. The second transistor T2 includes a control electrode connected to the scan line SL, a first electrode connected to the data line DL, and a second electrode connected to the first node N1.

[0061] The third transistor T3 may be a polysilicon thin film transistor. The third transistor T3 may be a P-type thin film transistor. The third transistor T3 includes a control electrode connected to the light emitting control line EL, a first electrode receiving a first power supply voltage ELVDD, and a second electrode connected to the first electrode of the first transistor T1.

[0062] The storage capacitor Cst includes a first electrode connected to the first node N1 and a second electrode receiving the first power voltage ELVDD.

[0063] The organic light emitting diode OLED includes a first electrode connected to the second electrode of the first transistor T1 and a second electrode receiving a second power voltage ELVSS.

[0064] The fourth transistor T4 may be an oxide thin film transistor. The fourth transistor T4 may be an N-type thin film transistor. The fourth transistor T4 includes a control electrode connected to the scan line SL, a first electrode connected to the second node N2, and a second electrode connected to the sensing line SSL.

[0065] Referring to the image display method of the pixel circuit, when the data voltage Vdata is applied to the data line DL and the on-voltage of the scan signal S is applied to the control electrode of the second transistor T2, the second transistor T2 is turned on and the data voltage Vdata is applied to the first node N1. The second transistor T2 is an N-type transistor, so a high level can become a turn-on voltage. The data voltage Vdata applied to the first node N1 is applied to the storage capacitor Cst.

[0066] The data voltage Vdata applied to the first node N1 is applied to the control electrode of the first transistor T1.

[0067] Next, when the turn-on voltage of the light emitting control signal EM is applied to the third transistor T3, the third transistor T3 is turned on and a current is formed between the first power voltage ELVDD and the second power voltage ELVSS. The third transistor T3 is a P-type transistor, so a low level can become a turn-on voltage.

[0068] The first transistor T1 is turned on based on the data voltage Vdata stored in the storage capacitor Cst, and a driving current based on the gate / source voltage of the first transistor T1 flows toward the anode electrode of the organic light emitting diode OLED.

[0069] Therefore, according to the driving current corresponding to the data voltage Vdata, the organic light emitting diode OLED may generate light of a gray scale corresponding to the data voltage Vdata.

[0070] In addition, if the sensing method of the pixel circuit is observed, the pixel circuit forms a sensing signal in a set sensing interval, and transmits the sensing signal to the sensing unit 145 through the sensing line SSL.

[0071] The sensing interval may be set in a power-off interval of the display device or a vertical blank interval of an image display interval.

[0072] In the sensing section, a reference voltage for forming a sensing signal is applied to the data line DL, and a turn-on voltage of the scanning signal is applied to the second transistor T2 and the fourth transistor T4 .

[0073] The second transistor T2 and the fourth transistor T4 are N-type transistors and thus have a high-level turn-on voltage.

[0074] The second transistor T2 is turned on, and the reference voltage is applied to the first node N1, and the first transistor T1 is turned on based on the reference voltage. A driving current based on the gate / source voltage of the first transistor T1 is applied to the anode electrode of the organic light emitting diode OLED, that is, the second node N2. The fourth transistor T4 is turned on, and the sensing signal applied to the anode electrode of the organic light emitting diode OLED is transmitted to the sensing portion 145 disposed outside the display panel 110 through the sensing line SSL.

[0075] Figure 3 is a flowchart for illustrating a method for driving a display device according to an embodiment of the present invention. Figures 4a to 4c It is used to illustrate Figure 3 Waveform diagram of the driving method.

[0076] Reference Figure 1 , Figure 2 , Figure 3 and Figure 4a The timing control unit 120 drives the data driving unit 141, the scanning driving unit 150 and the light emitting driving unit 160 at the panel driving frequency in the normal driving mode, so as to display a normal image to the display panel 110 (step S110). The case where the panel driving frequency is 120 Hz is taken as an example for description.

[0077] The frame interval of the normal driving mode includes an active interval ACT in which a data voltage is supplied to the display panel 110 and at least one vertical blank interval VB1 and VB2 in which a data voltage is not supplied to the display panel 110 .

[0078] The data driving unit 141 outputs data voltages D1, D2, D3, . . . , DN for horizontal lines in a horizontal period during the active interval ACT, and does not output data voltages during the vertical blank intervals VB1 and VB2 (here, N represents the number of horizontal lines of the display panel).

[0079] The scan driving unit 150 outputs the following scan signals S1, S2, S3, ...: corresponding to the horizontal interval 1H in which the data voltage of the horizontal line is output by the data driving unit 141, the on-voltage HL is provided, and the off-voltage LL is provided in the remaining intervals of the frame. The on-voltage HL of the scan signal is a voltage for turning on the second transistor T2 and the fourth transistor T4, which are N-type transistors of the pixel circuit, and has a high level. The on-interval of the scan signal having the on-voltage HL may be equal to or less than the horizontal interval 1H.

[0080] The light driving unit 160 outputs the following light control signals EM1, EM2, EM3, ...: corresponding to the horizontal interval 1H in which the data voltage of the horizontal line is output by the data driving unit 141, the light control signals EM1, EM2, EM3, ... have a cut-off voltage HL and a turn-on voltage LL in the remaining intervals of the frame. For the turn-on voltage LL of the light control signal, the turn-on voltage for turning on the third transistor T3 as the P-type transistor of the pixel circuit has a low level, and the turn-off voltage for turning off the third transistor T3 has a high level. The turn-on interval of the light control signal having the turn-on voltage LL may be longer than the horizontal interval 1H.

[0081] like Figure 4a As shown, in the first horizontal interval H1, the data voltage D1 of the first horizontal line is output, and the on-voltage HL of the first scan signal S1 corresponding to the first horizontal line is output, and the off-voltage HL of the first light emitting control signal EM1 is output. Accordingly, the pixel circuit applies the data voltage to the control electrode of the first transistor T1. Thereafter, when the on-voltage LL of the first light emitting control signal EM1 is output, the first transistor T1 is turned on based on the data voltage, and a driving current is applied to the organic light emitting diode OLED. Therefore, the first horizontal line emits light.

[0082] Next, in the second horizontal interval H2, the data voltage D2 of the second horizontal line is output, and the on-voltage HL of the second scan signal S2 corresponding to the second horizontal line is output, and the off-voltage HL of the second light emitting control signal EM2 is output. Accordingly, the pixel circuit applies the data voltage to the control electrode of the first transistor T1. Thereafter, when the on-voltage LL of the second light emitting control signal EM2 is output, the first transistor T1 is turned on based on the data voltage, and a driving current is applied to the organic light emitting diode OLED. Therefore, the second horizontal line emits light.

[0083] As described above, in the normal driving mode, the plurality of horizontal lines of the display panel 110 may display a normal image by sequentially emitting light.

[0084] In addition, when the driving mode of the display device is switched to a low-power driving mode for reducing power consumption (step S120), the display device displays a standby image on the display panel 110 (step S130). The standby image includes a still image that hardly changes with time, a clock image, a weather image, and the like.

[0085] Reference Figure 4b In the low power driving mode, in the first frame interval (1st Frame) at a panel driving frequency, for example, 120 Hz, the data driving unit 141, the scanning driving unit 150 and the light emitting driving unit 160 sequentially emit light to display a standby image to the display panel 110.

[0086] For example, in the first frame interval (1st Frame), the data driving unit 141 outputs data voltages D1, D2, D3, . . . , DN of horizontal lines in the active interval ACT with a horizontal period, and does not output data voltages in the vertical blank intervals VB1 and VB2.

[0087] The scan driving unit 150 outputs the scan signals S1 , S2 , S3 , . . . having an on voltage HL in a horizontal section 1H in which the data driving unit 141 outputs the data voltage of the horizontal line and having an off voltage LL in the remaining sections of the frame.

[0088] The light driving unit 160 outputs the following light control signals EM1, EM2, EM3, . . . : having a cut-off voltage HL in a horizontal section 1H corresponding to the data voltage of the horizontal line output by the data driving unit 141 and having a conduction voltage LL in the remaining sections of the frame.

[0089] In the first frame period (1st Frame), the plurality of horizontal lines of the display panel 110 may sequentially display the standby image by sequentially emitting light.

[0090] During the second frame interval to the 120th frame interval (2nd~120thFrame, approximately one second) at a panel driving frequency, such as 120Hz, the timing control unit 120 drives the data driving unit 141, the scanning driving unit 150 and the light emitting driving unit 160 to maintain the standby image displayed on the display panel 110.

[0091] For example, the data driving unit 141 does not output the data voltage, the scan driving unit 150 outputs the off voltage LL of the scan signal, and the light emitting driving unit 160 outputs the on voltage LL of the light emitting control signal. Accordingly, the pixel circuit can use the data voltage stored in the storage capacitor Cst in the first frame interval (1st Frame) to maintain the standby image displayed on the display panel 110 during the second frame interval to the 120th frame interval (2nd to 120th Frame) at 120Hz.

[0092] As a result, the display panel 110 can have the effect of being driven at a panel frequency of 1 Hz to display a standby image of one frame per second. In the low power driving mode, the power consumption of the display device can be reduced.

[0093] In addition, according to a mode conversion signal such as a user's selection, when the driving mode is converted from the low-power driving mode to the normal driving mode (step S140), the timing control unit 120 drives the data driving unit 141, the scanning driving unit 150 and the light-emitting driving unit 160 in an afterimage removal mode during a preset time (step S150).

[0094] The preset time can be set by experimental value using the time when the afterimage can be seen when the low-power driving mode is switched to the normal driving mode. For example, when the afterimage can be seen for 10 seconds, the preset time can be set to about 6 to 8 seconds.

[0095] Reference Figure 4c In the afterimage removal mode, the panel driving frequency, for example, a frame interval of 120 Hz includes an initialization interval INP, an activation interval ACT, and a simultaneous light emitting interval SEP.

[0096] In the initialization interval INP, the data driving unit 141 outputs a reference voltage (bias voltage) Vref for initializing the threshold voltage of the first transistor T1 of the pixel circuit to the data line. The reference voltage Vref may be a data voltage of the lowest level among the data voltages. For example, the reference voltage Vref may be a data voltage of a white grayscale.

[0097] The scan driving unit 150 simultaneously outputs the on-voltage HL of the scan signal to the plurality of scan lines during the initialization interval INP in which the data driving unit 140 outputs the reference voltage Vref.

[0098] The light emitting driving unit 160 outputs a conduction voltage LL of a light emitting control signal to a plurality of light emitting lines.

[0099] Accordingly, in the initialization interval INP, the threshold voltage of the first transistor T1 of the pixel circuit may be initialized by the reference voltage Vref. The first transistor T1 may initialize the threshold voltage shifted by displaying a still image for a long time in the low power driving mode.

[0100] According to an embodiment, in the initialization interval INP, a high-level second power voltage ELVSS_H is applied to the display panel 110. The high-level second power voltage ELVSS_H may be set to a level that prevents current from flowing through the organic light emitting diode OLED and prevents it from emitting light.

[0101] Therefore, even if the third transistor T3 is turned on, the high level second power voltage ELVSS_H can be used to prevent current from flowing to the organic light emitting diode OLED. Since the organic light emitting diode OLED is not applied with a driving current, it does not emit light.

[0102] In the active interval ACT, the data driving unit 141 outputs data voltages D1, D2, D3, . . . , DN of horizontal lines in a horizontal period.

[0103] The scan driving unit 150 outputs the following scan signals S1, S2, S3, ... having a turn-on voltage HL corresponding to the horizontal interval 1H in which the data voltage of the horizontal line is output by the data driving unit 141. The second transistor T2 of the pixel circuit is turned on, so that the data voltage can be applied to the control electrode of the first transistor T1.

[0104] According to an embodiment, in the active interval ACT, a high-level second power voltage ELVSS_H is applied to the display panel 110. The high-level second power voltage ELVSS_H may be set to a level that prevents current from flowing through the organic light emitting diode OLED and prevents it from emitting light.

[0105] Accordingly, even if the third transistor T3 is turned on, current will not flow to the organic light emitting diode OLED due to the high level of the second power voltage ELVSS_H, and thus no light will be emitted.

[0106] In the simultaneous light emitting period SEP, the data driving unit 141 does not output the data voltage.

[0107] The scan driving unit 150 simultaneously outputs a cut-off voltage LL of a scan signal to a plurality of scan lines.

[0108] The light driving unit 160 outputs a turn-on voltage LL of a light emitting control signal to a plurality of light emitting lines.

[0109] According to an embodiment, during the simultaneous light emitting period SEP, the display panel 110 is applied with a second power voltage ELVSS lower than the first power voltage ELVDD.

[0110] Accordingly, the third transistor T3 is turned on by applying the turn-on voltage LL of the light emitting control signal, and forms a current between the first power voltage ELVDD and the second power voltage ELVSS. The first transistor T1 is turned on based on the data voltage, and a driving current based on the gate / source voltage of the first transistor T1 flows to the anode electrode of the organic light emitting diode OLED.

[0111] Accordingly, the display panel 110 can display a normal image in a normal driving mode in a simultaneous light-emitting manner in which a plurality of horizontal lines emit light simultaneously.

[0112] The display device is driven to the afterimage removal mode during a preset time, for example, 6 seconds to 8 seconds, and then, Figure 4a As shown, a normal image is displayed in a normal driving mode in which a frame interval includes an activation interval and at least one vertical blank interval VB1, VB2 (step S160).

[0113] According to this embodiment, the frame interval of the afterimage removal mode may include a threshold voltage initialization interval, an activation interval for writing data of a normal image into the display panel, and a simultaneous light-emitting interval for making a plurality of horizontal lines emit light simultaneously. When the low-power driving mode for displaying a still image is converted to the normal driving mode for displaying a normal image, the display device is driven in the afterimage removal mode during a preset time, so that the momentary afterimage corresponding to the standby image can be removed.

[0114] Hereinafter, the same reference numerals are given to the same components as those in the above embodiment, and duplicate descriptions are omitted.

[0115] Figure 5 is a flowchart for illustrating a method for driving a display device according to an embodiment of the present invention. Figure 6a and Figure 6b It is used to illustrate Figure 5 Waveform diagram of the driving method.

[0116] Reference Figure 1 , Figure 2 , Figure 5 and Figure 4a The timing control unit 120 drives the data driving unit 141, the scanning driving unit 150 and the light emitting driving unit 160 at the panel driving frequency in the normal driving mode, so that a normal image is displayed on the display panel 110 (step S110). The case where the panel driving frequency is 120 Hz is taken as an example for description.

[0117] The frame interval includes an active interval ACT and at least one vertical blank interval VB1, VB2.

[0118] The data driving unit 141 outputs data voltages D1, D2, D3, . . . , DN for horizontal lines in a horizontal period during the active interval ACT, and does not output data voltages during the vertical blank intervals VB1 and VB2 (here, N represents the number of horizontal lines of the display panel).

[0119] The scan driving unit 150 outputs the scan signals S1 , S2 , S3 , . . . having an on voltage HL in a horizontal section 1H in which the data driving unit 141 outputs the data voltage of the horizontal line and having an off voltage LL in the remaining sections of the frame.

[0120] The light driving unit 160 outputs the following light control signals EM1, EM2, EM3, . . . : having a cut-off voltage HL in a horizontal section 1H corresponding to the data voltage of the horizontal line output by the data driving unit 141 and having a conduction voltage LL in the remaining sections of the frame.

[0121] like Figure 4a As shown, in the normal driving mode, a plurality of horizontal lines of the display panel 110 can be made to emit light in sequence, thereby displaying a normal image.

[0122] In addition, when the driving mode of the display device is changed to the low-power driving mode (step S120 ), the display device displays a standby image on the display panel 110 (step S130 ).

[0123] Reference Figure 4b In the low power driving mode, in the first frame interval (1st Frame) of 120 Hz, the data driving unit 141, the scanning driving unit 150 and the light emitting driving unit 160 display a standby image on the display panel 110 in a sequential light emitting manner.

[0124] During the period from the second frame interval to the 120 Hz frame interval (2nd to 120th Frame), the timing control unit 120 drives the data driving unit 141, the scanning driving unit 150, and the light driving unit 160 to maintain the standby image displayed on the display panel 110. For example, the data driving unit 141 does not output the data voltage, the scanning driving unit 150 outputs the cut-off voltage LL of the scanning signal, and the light driving unit 160 outputs the on voltage LL of the light control signal. Accordingly, the pixel circuit can use the data voltage stored in the storage capacitor Cst in the first frame interval (1st Frame) to maintain the standby image displayed on the display panel 110 during the period from the second frame interval to the 120th frame interval (2nd to 120th Frame).

[0125] The display panel 110 may have an effect of displaying a standby image of one frame per second by driving the display panel 110 at a panel driving frequency of 1 Hz. In the low power driving mode, power consumption of the display device may be reduced.

[0126] In addition, when the driving mode is converted from the low-power driving mode to the normal driving mode (step S140), the timing control unit 120 drives the data driving unit 141, the scanning driving unit 150 and the light-emitting driving unit 160 by rotating the normal driving mode and the afterimage removal mode in frames during a preset time (steps S251 and S253).

[0127] Reference Figure 6a In an odd-numbered frame interval Odd_FRAME of the panel driving frequency, the timing control unit 120 displays a normal image on the display panel 110 in a normal image mode.

[0128] For example, the odd-numbered frame intervals of 120 Hz include an active interval ACT and at least one vertical blank interval VB1, VB2.

[0129] The data driving unit 141 outputs data voltages D1, D2, D3, ..., DN in a horizontal period in the activation interval ACT, and does not output data voltages in the vertical blank intervals VB1 and VB2. The scanning driving unit 150 outputs the following scanning signals S1, S2, S3, ...: corresponding to the horizontal interval 1H in which the data voltage of the horizontal line is output by the data driving unit 141, it has a turn-on voltage HL and has a turn-off voltage LL in the remaining intervals of the frame. The light driving unit 160 outputs the following light control signals EM1, EM2, EM3, ...: corresponding to the horizontal interval 1H in which the data voltage of the horizontal line is output by the data driving unit 141, it has a turn-off voltage HL and has a turn-on voltage LL in the remaining intervals of the frame. In the odd-numbered frame interval, the multiple horizontal lines of the display panel 110 can display a normal image in a sequential light-emitting manner (step S251).

[0130] Reference Figure 6b , the timing control unit 120 drives a normal image on the display panel 110 in an afterimage removal mode in an even-numbered frame interval Even_FRAME at the panel driving frequency.

[0131] For example, the even-numbered frame interval at 120 Hz includes an initialization interval INP, an activation interval ACT, and a simultaneous light-emitting interval SEP.

[0132] In the initialization interval INP, the data driving unit 141 outputs a reference voltage (bias voltage) Vref for initializing a threshold voltage to the data line. The scanning driving unit 150 outputs a conduction voltage HL of a scanning signal to a plurality of scanning lines at the same time. The light emitting driving unit 160 outputs a conduction voltage LL of a light emitting control signal to a plurality of light emitting lines. A high-level second power supply voltage ELVSS_H is applied to the display panel 110. The high-level second power supply voltage ELVSS_H can be set to a level that prevents current from flowing in the organic light emitting diode OLED and prevents it from emitting light.

[0133] Accordingly, in the initialization interval INP, the threshold voltage of the first transistor T1 of the pixel circuit is initialized by the reference voltage Vref, and the organic light emitting laser OLED does not emit light.

[0134] In the activation interval ACT, the data driving unit 141 outputs data voltages D1, D2, D3, ..., DN for horizontal lines in a horizontal period. The scan driving unit 150 outputs the following scan signals S1, S2, S3, ...: corresponding to the horizontal interval 1H in which the data voltages for the horizontal lines are output by the data driving unit 141 and have a turn-on voltage HL. A high-level second power supply voltage ELVSS_H is applied to the display panel 110. The high-level second power supply voltage ELVSS_H can be set to a level that prevents current from flowing in the organic light emitting diode OLED and prevents it from emitting light. The second transistor T2 of the pixel circuit is turned on, so that the data voltage is applied to the control electrode of the first transistor T1, and the organic light emitting diode OLED does not emit light.

[0135] In the simultaneous light emitting period SEP, the data driving unit 141 does not output the data voltage. The scan driving unit 150 simultaneously outputs the off voltage LL of the scan signal to the plurality of scan lines. The light emitting driving unit 160 outputs the on voltage LL of the light emitting control signal to the plurality of light emitting lines.

[0136] Accordingly, the third transistor T3 is turned on, the first transistor T1 is turned on based on the data voltage, and a driving current based on the gate / source voltage of the first transistor T1 flows to the anode electrode of the organic light emitting diode OLED. Accordingly, in the even-numbered frame interval, in the display panel 110, a plurality of horizontal lines can emit light simultaneously, thereby displaying a normal image (step S253).

[0137] Thus, the display device can be driven in the normal driving mode in the odd-numbered frame interval during a preset time, for example, 6 seconds to 8 seconds, and can be driven in the afterimage removal mode in the even-numbered frame interval, thereby removing momentary afterimages.

[0138] After the preset time, if Figure 4a As shown, the operation is performed in a normal driving mode in which a frame interval includes an activation interval and at least one vertical blank interval VB1 and VB2 (step S160).

[0139] According to the above embodiments, when the driving mode is switched from the low-power driving mode to the normal driving mode, the threshold voltage is initialized and a simultaneous light emission method is adopted, thereby being able to eliminate momentary afterimages.

[0140] Industrial Applicability

[0141] The present invention can be applied to display devices and various devices and systems including display devices. Therefore, the present invention can be usefully used in various electronic devices such as mobile phones, smart phones, PDAs, PMPs, digital cameras, video cameras, PCs, server computers, workstations, notebook computers, digital televisions, set-top boxes, music players, portable game consoles, navigation systems, smart cards, printers, etc.

[0142] The present invention has been described above with reference to preferred embodiments, however it will be appreciated that those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the invention as set forth in the claims.

Claims

1. A display device, wherein: include: A display panel, comprising a plurality of data lines, a plurality of scan lines and a plurality of pixel circuits, wherein each pixel circuit comprises an organic light emitting diode, a first transistor and a second transistor, wherein the first transistor is connected to an anode electrode of the organic light emitting diode, and the second transistor is connected to the scan line, the data line and the first transistor; a data driving unit that provides a reference voltage to the plurality of data lines during a first interval of a frame when the driving mode is switched from the low-power driving mode to the normal driving mode; a scan driving unit, which provides a scan signal of a turn-on voltage for turning on the second transistor to the plurality of scan lines simultaneously during a first interval of the frame; as well as a voltage generating unit, which applies a high-level second power supply voltage to the cathode electrode of the organic light emitting diode during the first interval of the frame so as to prevent the organic light emitting diode from emitting light; The display device further comprises a plurality of light-emitting lines, During the active interval of the frame, the voltage generating unit provides the high-level second power supply voltage to the cathode electrode of the organic light emitting diode, During a second interval of the frame, the voltage generating unit provides a second power voltage having a level lower than the first power voltage to a cathode electrode of the organic light emitting diode, The light-emitting driving unit provides a light-emitting control signal of a conduction voltage to the plurality of light-emitting lines at the same time, and the light-emitting driving unit provides a light-emitting control signal to the plurality of light-emitting lines, The first power supply voltage is generated by the voltage generating unit, and the first power supply voltage and the second power supply voltage are used to drive the organic light emitting diode.

2. The display device according to claim 1, wherein: The pixel circuit further includes a third transistor connected to the light emitting line and the first transistor.

3. The display device according to claim 2, wherein: In a first section of the frame, the light emitting driving section simultaneously supplies a light emitting control signal of a conduction voltage for turning on the third transistor to the plurality of light emitting lines.

4. The display device according to claim 1, wherein: The first interval of the frame is located before the activation interval, and the second interval is located after the activation interval.

5. The display device according to claim 4, characterized in that When the driving mode is converted from the low-power driving mode to the normal driving mode, a frame including the first interval, the activation interval, and the second interval is repeated during a preset time.

6. The display device according to claim 4, characterized in that When the driving mode is converted from the low-power driving mode to the normal driving mode, one of the odd-numbered frame and the even-numbered frame includes the first interval, the active interval, and the second interval.

7. The display device according to claim 2, wherein: The first transistor and the third transistor are P-type transistors, and the second transistor is an N-type transistor.

8. The display device according to claim 2, wherein: The display panel further includes a plurality of sensing lines. The pixel circuit further includes a fourth transistor connected to the sensing line, the anode electrode of the organic light emitting diode, and the scan line.

9. The display device according to claim 8, wherein: The fourth transistor is an N-type transistor.

10. The display device according to claim 8, wherein: Also includes: The sensing unit is connected to the sensing line and performs analog-to-digital conversion on the sensing signal transmitted from the sensing line to generate sensing data.

11. A method for driving a display device, the display device comprising a plurality of data lines, a plurality of scan lines and a plurality of pixel circuits, each pixel circuit comprising an organic light emitting diode, a first transistor and a second transistor, the first transistor being connected to an anode electrode of the organic light emitting diode, the second transistor being connected to the scan lines, the data lines and the first transistor, wherein: The driving method of the display device comprises the following steps: When the driving mode is converted from the low-power driving mode to the normal driving mode, providing a reference voltage to the plurality of data lines during a first interval of a frame; During a first interval of the frame, simultaneously providing a scanning signal of a turn-on voltage for turning on the second transistor to the plurality of scanning lines; During a first interval of the frame, applying a second power supply voltage of a high level for making the organic light emitting diode not emit light to a cathode electrode of the organic light emitting diode; as well as During the active interval of the frame, the high-level second power supply voltage is provided to the cathode electrode of the organic light emitting diode, The display device further comprises a plurality of light-emitting lines, During a second interval of the frame, providing a second power supply voltage having a level lower than the first power supply voltage to a cathode electrode of the organic light emitting diode; as well as simultaneously providing a light-emitting control signal of a conduction voltage to the plurality of light-emitting lines, The first power supply voltage and the second power supply voltage are used to drive the organic light emitting diode.

12. The method for driving a display device according to claim 11, wherein: The pixel circuit further includes a third transistor connected to the light emitting line and the first transistor. The driving method of the display device further comprises the following steps: In a first section of the frame, a light emission control signal having a turn-on voltage for turning on the third transistor is simultaneously provided to the plurality of light emission lines.

13. The method for driving a display device according to claim 11, wherein: The first interval of the frame is located before the activation interval, and the second interval is located after the activation interval.

14. The method for driving a display device according to claim 11, wherein: When the driving mode is converted from the low-power driving mode to the normal driving mode, a frame including the first interval, the activation interval, and the second interval is repeated during a preset time.

15. The method for driving a display device according to claim 11, wherein: When the driving mode is converted from the low-power driving mode to the normal driving mode, one of the odd-numbered frame and the even-numbered frame includes the first interval, the active interval, and the second interval.

16. The method for driving a display device according to claim 12, wherein: The first transistor and the third transistor are P-type transistors, and the second transistor is an N-type transistor.

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