KR20150104241A - Display device and method for driving the same - Google Patents

Abstract

Provided is a driving method of a display device, which comprises a step of data recording and compensation and a step of applying a third power containing a charging pulse to an anode of an organic light emitting diode, regarding a driving method of a display device comprising a plurality of pixels, an organic light emitting diode connected between a first power and a second power, a first transistor for transmitting a driving current, a second transistor for connecting the first transistor to a data line, a third transistor for diode connecting the first transistor, a fourth transistor for transmitting a voltage of a third power to the first transistor, a fifth transistor for controlling light emission of the organic light emitting diode, a sixth transistor for connecting the third power to the organic light emitting diode, and a storage capacitor connected between the first transistors.

Description

DISPLAY APPARATUS AND METHOD FOR DRIVING THE SAME

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pixel and an organic light emitting display using the same, and more particularly, to a pixel control driving method for improving a response speed of a pixel.

Recently, various flat panel display devices capable of reducing the weight and volume, which are disadvantages of cathode ray tubes (CRTs), have been developed. Examples of the flat panel display include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), and an organic light emitting display (OLED) ).

Among the flat panel display devices, organic light emitting display devices display images using an organic light emitting diode that emits light by recombination of electrons and holes. The organic light emitting display device has a fast response speed, is driven at low power consumption, It has attracted attention because of its excellent viewing angle.

2. Description of the Related Art Conventionally, an organic light emitting diode (OLED) is classified into a passive matrix type OLED (PMOLED) and an active matrix type OLED (AMOLED) according to a method of driving an organic light emitting diode.

Of these, an active matrix type OLED (AMOLED) which is selected and turned on for each unit pixel in view of resolution, contrast, and operation speed has become mainstream.

One pixel of the active matrix type OLED includes an organic light emitting diode, a first transistor for controlling the amount of current supplied to the organic light emitting diode, and a switching transistor for transmitting a data signal for controlling the light emitting amount of the organic light emitting diode to the first transistor.

However, in the case of an active matrix type organic light emitting diode display, response speeds are different due to characteristic deviations of organic light emitting diodes that emit light according to respective colors, which makes it difficult to accurately display gradations. Particularly, the problem of response speed delay in a green organic light emitting diode deteriorates the image quality of a moving image.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a driving method for improving the response speed of a pixel for excellent moving picture display. To this end, an example of the present invention is to propose a driving method for improving an initial response speed by precharging a capacitor using a charging pulse capable of charging a capacitor of each organic light emitting diode in an initialization period of the organic light emitting diode.

According to an embodiment of the present invention, an organic light emitting diode includes a plurality of pixels, the pixel including an organic light emitting diode connected between a first power source and a second power source, a first transistor for transmitting a driving current according to a data signal to the organic light emitting diode, A second transistor for connecting an electrode of the first transistor and a data line corresponding to the scan signal, a third transistor for diode-connecting the first transistor corresponding to the first scan signal, a second transistor for connecting the gate of the first transistor, A fourth transistor for transmitting the voltage of the third power source to the electrode, a fifth transistor for controlling the light emission of the organic light emitting diode in response to the emission control signal, a fifth transistor for controlling the light emission of the organic light emitting diode, A sixth transistor for connecting the first transistor and the second transistor; And a storage capacitor coupled between the first power source and the first transistor, the method comprising: a data write and compensation step of applying a data signal through a data line in synchronization with a first scan signal and storing the data signal in a capacitor ; And applying a third power source including a charge pulse to the anode of the organic light emitting diode while the sixth transistor is turned on.

According to an embodiment of the present invention, the maximum difference voltage between the third power source and the second power source is less than or equal to a threshold voltage of the organic light emitting diode.

According to an embodiment of the present invention, a third power source including a charge pulse may be applied to some pixels among a plurality of pixels.

According to one example of the present invention, some pixels are green pixels.

According to an embodiment of the present invention, the charging pulse of the third power source may be applied at least once every image frame.

According to an embodiment of the present invention, the display device may apply the charge pulse to the third power source in the non-emission period.

According to an embodiment of the present invention, there is provided a method of driving a liquid crystal display device including an initialization step of turning on a fourth transistor by a second scan signal to connect a storage capacitor and a third power source, .

According to an embodiment of the present invention, the charge pulse of the third power source is superimposed on at least one of the first scan signal, the second scan signal, and the third scan signal.

According to an embodiment of the present invention, a display device includes a scan driver for sequentially supplying a scan signal to scan lines, a scan driver for supplying an emission control signal to the emission control lines formed in parallel with the scan lines, And a plurality of pixels disposed at intersections of the data driver, the scan lines, the emission control lines, and the data lines, the plurality of pixels being supplied with a first power source, which is a high potential pixel power source, and a second power source, Each of the pixels includes an organic light emitting diode connected between a first power source and a second power source; A first transistor for transmitting a driving current according to a data signal to the organic light emitting diode and having a gate electrode connected to a first node; A second transistor connected between the first electrode of the first transistor connected to the first power source and the data electrode and having a gate electrode connected to the first scanning line; A fourth transistor having a gate electrode connected to the second scanning line, and connecting the first node to the third power source; A sixth transistor for connecting the anode electrode of the organic light emitting diode and the third power source; A fifth transistor for controlling emission of the organic light emitting diode in response to the light emission control signal; And a storage capacitor coupled between the first power source and the gate electrode of the first transistor, wherein the power source unit supplies a third power source including a first power source, a second power source, and a charge pulse to the pixel unit.

According to an embodiment of the present invention, an initialization voltage for initializing the first node from the third power source in the non-emission period is output.

According to an embodiment of the present invention, the third power supply includes a charge pulse of a voltage higher than the initialization voltage.

According to an embodiment of the present invention, the charge pulse has a narrower pulse width than the turn-on gate signal of the sixth transistor.

According to an embodiment of the present invention, the difference between the maximum value of the charge pulse and the second power supply voltage is equal to or less than the threshold voltage of the organic light emitting diode.

The organic light emitting diode display according to the technical idea of the present invention is characterized in that a charge pulse for precharging a capacitor formed in an organic light emitting diode is applied during an initialization period of a non-light emitting period, thereby improving delay.

The response speed of the organic light emitting display device can be improved even with a simple circuit configuration by applying the voltage of the initialization power source while varying the precharge pulse pulse.

The organic light emitting display according to the technical idea of the present invention analyzes a display position and an image shape of an image received from the outside in a block unit composed of a plurality of cells and corrects the image data based thereon, Can be improved.

However, the effects of the present invention are not limited thereto, and various modifications may be made without departing from the spirit and scope of the present invention.

1 is a block diagram schematically showing a display device according to an embodiment of the present invention.
2 is a circuit diagram showing the pixel circuit structure of the display device shown in Fig.
3 is a timing chart for explaining pixel operation in the prior art.
4 is an explanatory view for explaining the initialization step.
5 is an explanatory view for explaining the operation of the data write and compensation step.
6 is an explanatory view for explaining the operation of the black improvement step.
7 is an explanatory view for explaining the operation of the light emitting section.
8 (a) and 8 (b) are schematic diagrams illustrating light output of a display device to which a conventional driving method is applied.
9 is a waveform diagram of an organic light emitting diode according to an embodiment of the present invention.
10 is an explanatory diagram of a charge pulse operation according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Thus, in some embodiments, well known process steps, well known device structures, and well-known techniques are not specifically described to avoid an undesirable interpretation of the present invention. Like reference numerals refer to like elements throughout the specification.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. When a part is "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. It is noted that the terms "comprises" and / or "comprising" used in the specification are intended to be inclusive in a manner similar to the components, steps, operations, and / Or additions.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically showing a display device according to an embodiment of the present invention.

1, a display device 100 according to an embodiment of the present invention includes a display unit 10 including a plurality of pixels, a scan driver 20, a data driver 30, a light emitting driver 40, 50), and a power supply unit 60 for supplying an external voltage to the display device.

Each of the plurality of pixels is connected to two of the plurality of scanning lines S0 to Sn transmitted to the display unit 10. [

In FIG. 1, the pixel is connected to the scanning line corresponding to the pixel line and the scanning line of the previous line, but is not necessarily limited thereto.

Each of the plurality of pixels includes one of a plurality of data lines D1 to Dm transmitted to the display unit 10 and one of the plurality of emission control lines EM1 to EMn transmitted to the display unit 10. [ Line.

The scan driver 20 generates and transmits two corresponding scan signals to each pixel through the plurality of scan lines S0 to Sn. That is, the scan driver 20 transmits the first scan signal through the scan line corresponding to the pixel line including each pixel, and transmits the second scan signal through the scan line corresponding to the previous pixel line of the pixel line.

1, the pixel 70, which is one of the plurality of pixels included in the n-th pixel line, is connected to the scan line Sn corresponding to the n-th pixel line and the (n-1) And is connected to the corresponding scanning line Sn-1, respectively.

The pixel 70 receives the first scan signal through the scan line Sn and simultaneously receives the second scan signal through the scan line Sn-1.

The data driver 30 transmits a data signal to each pixel through a plurality of data lines D1 to Dm.

The light emission driving unit 40 generates and transmits a light emission control signal to each pixel through the plurality of light emission control lines EM1 to EMn.

The controller 50 converts a plurality of video signals R, G and B transmitted from the outside into a plurality of video data signals DR, DG and DB and transmits them to the data driver 30. The control unit 50 receives the vertical synchronizing signal Vsync, the horizontal synchronizing signal Hsync and the clock signal MCLK and drives the scan driving unit 20, the data driving unit 30, and the light emitting driving unit 40 And transmits the generated control signals to the respective control signals. That is, the control unit 50 includes a scan driving control signal SCS for controlling the scan driving unit 20, a data driving control signal DCS for controlling the data driving unit 30, And generates and transmits control signals ECS.

 The display section 10 also includes a plurality of pixels located at the intersections of the plurality of scan lines S0 to Sn, the plurality of data lines D1 to Dm, and the plurality of emission control lines EM1 to EMn.

 The plurality of pixels are supplied with an external voltage such as a first power ELVDD, a second power ELVSS, and a third power VINT from the power supply unit 60. The first power ELVDD has a higher voltage level than the second power ELVSS. The third power source VINT may be an initialization voltage for initializing the voltage of the gate electrode of the first transistor. The first power source ELVDD may have a voltage in the range of 3 to 6V and the second power source ELVSS may have a voltage in the range of -7 to 0V. Of course, the voltage range of the first power ELVDD and the second power ELVSS is only an example and may have various voltage ranges capable of driving the display device.

The display unit 10 includes a plurality of pixels arranged in a substantially matrix form. Although not particularly limited, a plurality of scanning lines S0 to Sn extend in a substantially row direction in the arrangement of the pixels and are substantially parallel to each other, and the plurality of data lines D1 to Dm extend in a substantially column direction, It is almost parallel.

Each of the plurality of pixels emits light of a predetermined luminance by a driving current supplied to the organic light emitting diode according to a corresponding data signal transmitted through the plurality of data lines (D1 to Dm).

Hereinafter, the circuit structure of the pixel 70 of the display device 100 according to the embodiment of the present invention will be described with reference to FIG.

2 is a circuit diagram showing the pixel circuit structure of the display device shown in Fig.

2, the pixel 70 is connected to the n-th scan line Sn and the (n-1) -th scan line Sn-1 of the plurality of pixels included in the display unit 10 of the display device 100 of FIG. 1 . The pixel 70 is also connected to the mth data line Dm and the nth emission control line EMn. For convenience of explanation, the scanning line Sn is referred to as a first scanning line, and the scanning line Sn-1 is referred to as a second scanning line.

The pixel 70 according to the exemplary embodiment of the present invention may include a first scan line for transmitting a first scan signal for activating a pixel 70 to transmit a data signal, And a second scan line for transferring a second scan signal for controlling the first transistor Tl to maintain an operation voltage (On bias) or a threshold voltage (Vth).

Each transistor includes a gate electrode, a first electrode, and a second electrode. The first electrode may be a source electrode, and the second electrode may be a drain electrode. In the following description, the first electrode is referred to as a source electrode and the second electrode is referred to as a drain electrode for convenience of explanation.

The pixel 70 shown in FIG. 2 includes an organic light emitting diode (OLED), a first transistor T1, a second transistor T2, a third transistor T3, a fourth transistor T4, A fifth transistor T5, a sixth transistor T6, a seventh transistor T7, and a capacitor Cst.

The first transistor T1 includes a gate electrode connected to the first node N1, a source electrode connected to the third node N3 connected to the drain electrode of the fifth transistor T5, and a source electrode connected to the second node N2 Drain electrode.

The first transistor T1 is connected to the third node N3 through which the source electrode of the first transistor T1 is connected through the mth data line Dm and the second transistor T2, [m]) and transmits the generated driving current I1 to the organic light emitting diode OLED through the drain electrode. The driving current I1 is a current corresponding to a voltage difference Vgs between a source electrode and a gate electrode of the first transistor T1 and is a current corresponding to a data voltage according to a data signal applied to the source electrode. I1).

For convenience of explanation, the voltage difference between the source electrode and the gate electrode of the first transistor T1 is referred to as a gate-source voltage. The gate-source voltage Vgs is referred to as an on bias voltage when the gate-source voltage Vgs is a voltage that turns on the first transistor T1, And is referred to as an off bias voltage when the voltage is lower than the threshold voltage of the transistor T1 and the first transistor T1 is turned off.

The second transistor T2 includes a gate electrode connected to the nth scan line Sn and a source electrode connected to the mth data line Dm and a source electrode of the first transistor T1 and a drain electrode of the fifth transistor T5. And a drain electrode connected to the third node N3 connected in common.

The second transistor T2 activates driving of the pixel 70 in response to a corresponding scan signal S [n] transmitted through the nth scan line Sn. In other words, the second transistor T2 responds to the scan signal S [n] and supplies the data voltage corresponding to the data signal D [m] transferred through the mth data line Dm to the third node N3, .

The third transistor T3 includes a gate electrode connected to the nth scan line Sn and both electrodes connected to the gate electrode and the drain electrode of the first transistor T1.

The third transistor T3 operates in response to a corresponding scan signal S [n] transmitted through the nth scan line Sn. By connecting the gate electrode and the drain electrode of the first transistor T1, The transistor T1 is diode-connected to compensate the threshold voltage of the first transistor T1.

That is, when the first transistor T1 is diode-connected, a voltage lowered by the threshold voltage of the first transistor T1 from the data voltage applied to the source electrode of the first transistor T1 is applied to the gate of the first transistor T1 Electrode.

The Vth sign is given to the threshold voltage of the first transistor T1 and the data voltage applied to the source electrode of the first transistor T1 is given a Vdata sign. And the voltage Vdata-Vth is applied to the voltage applied to the gate electrode of the first transistor T1 according to the connection.

Since the gate electrode of the first transistor T1 is connected to one electrode of the capacitor Cst, the voltage Vdata-Vth of the gate electrode of the first transistor T1 is held by the capacitor Cst. Since the voltage Vdata-Vth reflecting the threshold voltage Vth of the first transistor T1 is applied and held at the gate electrode, the driving current I1 flowing through the first transistor T1 is maintained at It is not affected by the threshold voltage Vth.

The fifth transistor T5 includes a gate electrode connected to the nth emission control line EMn, a source electrode connected to the supply line of the first power source ELVDD, and a drain electrode connected to the third node N3.

The sixth transistor T6 is connected to the gate electrode connected to the nth emission control line EMn, the source electrode connected to the second node N2 and the fourth node N4 connected to the anode electrode of the organic light emitting diode OLED And connected drain electrodes.

The fifth transistor T5 and the sixth transistor T6 operate in response to the nth emission control signal EM [n] transmitted through the nth emission control line EMn. That is, when the fifth transistor T5 and the sixth transistor T6 are turned on in response to the nth emission control signal EM [n], the direction of the organic light emitting diode OLED from the first power source ELVDD, So that the organic light emitting diode emits light in accordance with the light emission current I2 corresponding to the drive current I1 to display an image of the data signal.

The fourth transistor T4 includes a gate electrode connected to the (n-1) th scan line Sn-1, a source electrode connected to the third power supply VINT supply line, a gate electrode of the first transistor T1, And a drain electrode connected to the first node N1, to which one electrode of the first electrode N1 is commonly connected.

The fourth transistor T4 is turned on in response to the (n-1) th scanning signal S [n-1] transmitted through the n-1th scanning line Sn- 3 power supply (VINT) to the first node (N1).

The fourth transistor T4 is connected to the (n-1) th scan signal S [n-1] previously transmitted to the (n-1) th scan line corresponding to the previous pixel row of the nth pixel row including the pixel 70 The voltage of the third power source VINT can be transmitted to the first node N1 as the initialization voltage before the pixel driver is activated.

At this time, although the voltage of the third power source (VINT) is not limited, it can be set to have a low level voltage so that the gate electrode voltage of the first transistor (T1) can be sufficiently lowered and initialized. That is, during a period in which the (n-1) th scanning signal S [n-1] is transferred to the gate electrode of the fourth transistor T4 at the gate- VINT). For example, the initialization voltage may range from -5V to 0V.

The capacitor Cst includes one electrode connected to the first node N1 and the other electrode connected to the supply line of the first power source ELVDD. Since the capacitor Cst is connected between the gate electrode of the first transistor T1 and the supply line of the first power source ELVDD as described above, the voltage applied to the gate electrode of the first transistor T1 can be maintained .

The seventh transistor T7 has a source electrode connected to the drain electrode of the sixth transistor T6 and a fourth node N4 connected to the anode electrode of the organic light emitting diode OLED, A gate electrode connected to the (n-1) th scan line Sn-1, and a drain electrode connected to the power supply line of the third power source VINT.

The bypass current I3 flows through the seventh transistor T7 in the OFF state by the set voltage of the third power source VINT. At this time, the set voltage of the third power source VINT is not particularly limited, and may be equal to or smaller than the second power source ELVSS, which is the cathode voltage of the organic light emitting diode OLED. If the organic light emitting diode OLED emits light even when the minimum current of the transistor for displaying the black image flows through the driving current I1, the black current is not properly displayed, And can be dispersed into a current path outside the current path of the organic light emitting diode. Here, the minimum current of the transistor means a current under a condition that the transistor is turned off because the gate-source voltage of the transistor is smaller than the threshold voltage. Thus, the minimum driving current (for example, a current of 10 pA or less) under the condition of turning off the transistor is transmitted to the organic light emitting diode and expressed as an image of black luminance.

When a minimum driving current for displaying a black image flows, the effect of bypass transfer of the bypass current I3 is large, whereas when a large driving current for displaying an image such as a general image or a white image flows, the bypass current I3 It is hardly influenced by the effect of Therefore, when the drive current for displaying the black image flows, the light emission current I2 of the organic light emitting diode, which is reduced by the amount of the bypass current I3 branched from the drive current I1, So that it has a minimum amount of current.

3 is a timing chart for explaining pixel operation in the prior art.

A timing chart for performing the initializing drive operation of the conventional pixel will be described with reference to FIG. On the other hand, the first scanning line means the current scanning line, and the second scanning line means the previous scanning line. Th scan line S [n + 1] is used as a signal for controlling the seventh transistor T7, it is also possible to drive by using the second scan line S [n-1]. In this case, although not separately shown, a circuit in which the gate of the seventh transistor T7 and the gate of the fourth transistor T4 are constituted as a common node is used.

Referring to FIG. 3, the first period t1 to the third period t3 correspond to the initialization period, and the fourth period t4 corresponds to the light emission period. The emission control signal EM [n] of the third period t3 in the first period t1 is supplied to the fifth transistor T5 and the sixth transistor T6 to electrically isolate the driving power source ELVDD from the organic light emitting diode Off signal High. The circuit configuration of the embodiment is constituted by a P-channel transistor, and the transistor is turned on when the gate signal of the transistor is in the Low state.

The operation of each drive waveform will be described with reference to Figs. 3 to 6. Fig.

4 is an explanatory view for explaining the initialization step.

The initialization step corresponds to the first period t1, and the scan signal is supplied to the second scan line Sn-1 so that the fourth transistor T4 is turned on. When the fourth transistor is turned on, the voltage of the third power source VINT is transferred to the first node N1.

The third power supply VINT is set to have a voltage value sufficiently low enough to initialize the first node N1.

5 is an explanatory view for explaining the operation of the data write and compensation step.

The data writing and compensating step corresponds to the second period t2 and the scan signals are supplied to the first scan line Sn so that the second and third transistors T2 and T3 are turned on, One transistor is diode-connected by the third transistor.

The data signal is supplied to the data line DM during the second period t2 and the data signal is supplied to the first transistor T1 via the first transistor T1 and the third transistor T3, And is transmitted to the node N1. At this time, since the first transistor T1 is diode-connected, the data signal voltage is transmitted to the first node N1 with a difference of the threshold voltage of the first transistor T1.

That is, the second period t2 is a data write and a threshold voltage (Vth) compensation period in which a voltage corresponding to the data signal and the threshold voltage of the first transistor T1 is applied to the first node N1 , And the voltage delivered to the first node N1 in the second period t2 is stored in the storage capacitor Cst.

6 is an explanatory view for explaining the operation of the black improvement step.

The black developing step corresponds to the third period t3 and the scan signal is applied to the third scan line Sn + 1 to turn on the seventh transistor T7.

The minimum current of the transistor for displaying the black image flows to the driving current I1 so that the organic light emitting diode OLED is prevented from emitting light, and a part of the current is bypassed by the seventh transistor T7, do.

7 is an explanatory view for explaining the operation of the light emitting section.

The fourth period t4 of the light emitting period is a period during which the organic light emitting diode emits light. A current path is formed from the first power source ELVDD to the organic light emitting diode via the fifth transistor T5, the first transistor T1 and the sixth transistor T6.

8 (a) and 8 (b) are schematic diagrams illustrating light output of a display device to which a conventional driving method is applied.

8 (a) shows a screen in which a gray gradient pattern is scrolled upward in the panel. The gradation pattern means a pattern having a gradual high gradation from black to white. When the gradient pattern is moved from the bottom to the top of the screen, the color pixels (red, blue, and green) of the area representing black should be changed simultaneously from the turn-off state to the turn-on state. At this time, if the response speed varies according to the organic light emitting diode of the hue displayed by each pixel, deterioration of image quality occurs in the low gradation region, so that the user can easily recognize the response.

8 (b) is a graph of light emission luminance of a pixel on a boundary surface turned on in black on the screen of Fig. 8 (a).

Organic light emitting diodes have different characteristics for each color. Particularly in the case of a green light emitting diode (Coled), a capacitor is formed larger than that of blue or red. Therefore, when switching from the turn-off state to the turn-on state, a larger current is required to charge the capacitor.

Fig. 8 (b) is a graph of the output light on the low gray scale boundary surface when the gradation screen of Fig. 8 (a) is scrolled. Referring to the graph, it can be seen that the green light output has a luminance output delay in the initial frame as compared with the blue and red light outputs.

This is because light is not outputted in the turn-on initial frame N because a sufficient current is not provided to charge the capacitor of the green organic light emitting diode.

On the other hand, since the blue and red organic light emitting diodes have a small capacitance, normal light output is possible from the turn-on initial frame (N). Due to such a difference in light output response speed, white (gray) can not be expressed in the first half of the frame N, and a phenomenon occurs in which blue and red are expressed as purple, which is a mixed color. As a result, a purple color band is visible in the low gradation region of the gradation scroll.

9 is a waveform diagram of an organic light emitting diode according to an embodiment of the present invention.

10 is an explanatory diagram of a charge pulse operation according to an embodiment of the present invention.

9 to 10, a pulse wave or an AC power is applied to the third power source VINT. The third power supply VINT has a sufficiently low voltage that can initialize the node 1 N1 in the first period t1 as a reference voltage and at least the third transistor T7 is turned on in the third period, Times voltage pulse VINT2.

The charging pulse VINT2 is precharged to the organic light emitting diode capacitor Coled in the third period t3 so that the organic light emitting diode capacitor Coled is initially charged in the fourth period t4, . This allows the green organic light emitting diode to emit light at a fast response rate.

Although the charge pulse VINT2 can be individually applied only to the green pixel having a slow response speed, in this case, there is a disadvantage that the structure of the panel and the circuit to the power supply portion must be added. It is more preferable to apply it to all the pixels of the panel without adding a separate circuit device.

The charging pulse VINT2 may be applied during the first period or the second period other than the third period. It is possible to simplify the design of the controller of the power supply section by generating the repeated charge pulse VINT2 by applying the pulse in the first period and the second period. Even if the charging pulse VINT2 is applied in the first period or the second period, since the charging operation of the organic light emitting diode capacitor Coled occurs only in the third period, no circuit change such as generating a separate control signal is required .

The maximum voltage of the charge pulse VINT2 prevents the difference voltage from the ground power ELVSS from exceeding the organic light emitting diode threshold voltage ELVth. When the difference voltage between the charging pulse VINT2 and the ground power ELVSS is higher than the threshold voltage ELVth of the organic light emitting diode, the organic light emitting diode emits light in the non-light emitting period, and the contrast of the display device is deteriorated.

The charge pulse VINT2 is applied in the first period t1 to the third period t3 which are the non-emission period and overlaps with the scan signals Sn-1, Sn, Sn + 1 used as the pixel transistor gate signal Respectively. However, it has a narrower pulse width than the scanning signal.

While the technical spirit of the present invention has been described in detail with reference to the above embodiments, it is to be noted that the embodiments are illustrative and not restrictive. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

100: display device
10: Display section 20:
30: Data driver 40:
50: control unit 60: power supply unit
70: pixel

Claims (13)

A plurality of pixels, each pixel including an organic light emitting diode connected between a first power source and a second power source, a first transistor for transmitting a driving current according to a data signal to the organic light emitting diode, A second transistor for connecting an electrode of the first transistor and a data line, a third transistor for diode-connecting the first transistor corresponding to the first scan signal, a third transistor for connecting the gate electrode of the first transistor, A fifth transistor for controlling the emission of the organic light emitting diode in response to the emission control signal, a second transistor for controlling the anode voltage of the organic light emitting diode to be connected to the third power supply in response to the third scan signal, A sixth transistor connected to the first power supply; And a storage capacitor coupled between the first power source and the first transistor, the method comprising:
A data write and compensation step in which a data signal is applied through the data line in synchronization with the first scan signal and is stored in the capacitor; And
And applying the third power source including a charge pulse to the anode of the organic light emitting diode while the sixth transistor is turned on. The method according to claim 1,
Wherein the maximum difference voltage between the third power source and the second power source is less than or equal to a threshold voltage of the organic light emitting diode. 3. The method of claim 2,
And applies the third power source including the charge pulse to some pixels among the plurality of pixels. The method of claim 3,
And the pixels are green pixels. 3. The method according to any one of claims 1 to 2,
A driving method of a display device for applying a charging pulse of the third power source at least once every video frame 3. The method according to any one of claims 1 to 2,
A driving method of a display device for applying a third power source including a charging pulse in a non-emission period of a display device The method according to claim 6,
An initialization step of turning on the fourth transistor by the second scan signal to connect the storage capacitor and the third power source;
And turning on the sixth transistor by the third scan signal. 8. The method of claim 7,
Wherein a charge pulse of the third power source is superimposed on at least one of the first scan signal, the second scan signal, and the third scan signal. A scan driver for sequentially supplying scan signals to the scan lines and supplying emission control signals to the emission control lines formed in parallel with the scan lines,
A data driver for supplying a data signal to the data lines,
And a plurality of pixels disposed at intersections of the scan lines, the emission control lines, and the data lines, the plurality of pixels being supplied with a first power source, which is a high-potential pixel power source, and a second power source,
Each of the pixels
An organic light emitting diode connected between the first power source and the second power source;
A first transistor for transmitting a driving current according to a data signal to the organic light emitting diode and having a gate electrode connected to a first node;
A second transistor connected between the first electrode of the first transistor connected to the first power source and the data electrode and having a gate electrode connected to the first scanning line;
A fourth transistor having a gate electrode connected to the second scanning line, and connecting the first node to the third power source;
A sixth transistor connected between the anode of the organic light emitting diode and the third power source;
A fifth transistor for controlling emission of the organic light emitting diode in response to the light emission control signal; And a storage capacitor coupled between the first power source and the gate electrode of the first transistor,
And a power supply unit for supplying a third power source including a first power source, a second power source, and a charge pulse to the pixel unit. 10. The method of claim 9,
Wherein the power supply unit outputs an initialization voltage for initializing the first node to a third power supply in a non-emission period. 11. The method of claim 10,
And the third power source includes a charge pulse having a voltage higher than the initialization voltage. 10. The method of claim 9,
Wherein the charge pulse has a narrower pulse width than the turn-on gate signal of the sixth transistor. 10. The method of claim 9,
Wherein a difference between a maximum value of the charging pulse of the third power source and the second power source voltage is equal to or less than a threshold voltage of the organic light emitting diode.

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