KR100846948B1 - Organic Light Emitting Display - Google Patents

Abstract

The present invention relates to an organic light emitting display device and a pixel circuit thereof.

The technical problem to be solved is to minimize the deterioration (degradation) of the organic light emitting device to improve the lifetime and uniformity of the organic light emitting display device.

 To this end, the present invention comprises a first switching element for transmitting a data signal from the data signal line in response to the scan signal of the scan signal line; A driving transistor connected to the first switching element to control a driving current from a first power supply voltage line; A capacitive element connected between the control electrode of the driving transistor and the first power voltage line; An organic electroluminescent element connected to the second power supply voltage line and displaying an image with a driving current controlled by the driving transistor; An initialization switching element connected between the capacitive element and an initialization power supply voltage line to initialize the capacitive element; An organic electroluminescent display including a reverse bias application switching element connected between the organic electroluminescent element and the initialization power supply voltage line and a control electrode connected to an emission reverse control signal line to apply a reverse bias voltage to the organic electroluminescent element. Start the device.

AMOLED, organic electroluminescent display, degradation, reverse bias voltage applied

Description

Organic Light Emitting Display

1 is a schematic diagram showing the basic structure of a conventional organic electroluminescent device.

2 is a schematic diagram illustrating a basic pixel circuit of a voltage driving method.

FIG. 3 is a driving timing diagram of the pixel circuit shown in FIG. 2.

4 is a basic structural block diagram of an organic light emitting display device according to an exemplary embodiment of the present invention.

5 is a circuit diagram illustrating a pixel circuit of an organic light emitting display device according to an exemplary embodiment of the present invention.

FIG. 6 is a driving timing diagram of the pixel circuit shown in FIG. 5.

FIG. 7 illustrates the current flow during the initialization period T1 in the pixel circuit shown in FIG. 5.

FIG. 8 illustrates a current flow during the data voltage and the threshold voltage storage period T2 of the driving transistor in the pixel circuit shown in FIG. 5.

FIG. 9 shows the current flow during the light emission period T3 in the pixel circuit shown in FIG.

10 is a circuit diagram illustrating a pixel circuit of an organic light emitting display device according to another exemplary embodiment of the present invention.

11 is a circuit diagram illustrating a pixel circuit of an organic light emitting display device according to another exemplary embodiment of the present invention.

12 is a driving timing diagram of the pixel circuit shown in FIG. 11.

<Description of the reference numerals for the main parts of the drawings>

100; Flat panel display device according to the present invention

110; A scan signal driver 120; Data signal driver

130; A light emission control signal driver 140; Organic electroluminescent display panel

P; Pixel circuit 150; First power supply voltage

D [M]; Data signal line 160; Second power supply

S [N]; Scan signal line 170; Initialization power voltage supply

S [N-1]; Previous scan signal line C; Capacitive element

EM [N]; Light emission control signal line EMB [N]; Luminescent station control signal line

VDD; A first power supply voltage line VSS; Second power supply voltage line

SW_TR1; First switching element SW_TR2; Second switching element

SW_TR3; Third switching element SW_TR4; Fourth switching element

SW_TR5; Initialization switching element SW_TR6; Reverse bias switching element

DR_TR; Driving transistor

Vinit; Power supply voltage line

Organic light emitting diode (OLED); Organic electroluminescent element

The present invention relates to an organic light emitting display device and a pixel circuit thereof, and more particularly, to an organic light emitting diode (OLED) in a pixel circuit of an organic light emitting display device.

The present invention relates to an organic light emitting display device and a pixel circuit thereof capable of minimizing degradation.

Recently, an organic light emitting display device has been spotlighted as a next-generation flat panel display due to advantages such as thin thickness, wide viewing angle, and fast response speed.

Such an organic light emitting display device controls the amount of current flowing through the organic light emitting diode OLED of each pixel, thereby controlling the brightness of each pixel and displaying an image.

In other words, a current corresponding to the data voltage is supplied to the organic EL device, and the organic EL device emits light corresponding to the supplied current. At this time, the applied data voltage has a multi-level value in a predetermined range in order to express the gray scale.

In the case of using a thin film transistor (TFT) using amorphous silicon (a-si) as a driving transistor, current driving capability is relatively low, but the display device has excellent uniformity and an advantage in a large area process.

However, in a general organic light emitting display device, current flows only in one direction from the anode of the organic light emitting element OLED to the cathode, and thus, between the hole transport layer HTL and the light emitting layer EML of the organic thin film or the electron transport layer ETL. And a space charge is stored between the light emitting layer EML. Due to the accumulation of space charges, the current I _OLED flowing in the organic light emitting diode OLED may be reduced. As a result, since the brightness of each pixel is reduced, there is a problem that the brightness of the organic light emitting display device employing the pixel circuit gradually decreases over time. In addition, the lifespan of the organic light emitting display device may be shortened.

Furthermore, there is a problem that the luminance of the entire organic electroluminescent display is uneven as a result of the difference in the degree of deterioration of the organic electroluminescent element for each pixel circuit.

The present invention is to overcome the above-mentioned conventional problems,

The main object of the present invention is to apply a reverse bias voltage to the organic electroluminescent device to reduce degradation of the organic electroluminescent device, and thereby to reduce the degradation of the organic electroluminescent device and to uniform the luminance of each pixel. The present invention provides an organic light emitting display device and a pixel circuit thereof capable of increasing uniformity.

Another object of the present invention is to compensate for nonuniformity and variation of threshold voltage of a semiconductor device having a threshold voltage by applying a threshold voltage Vth compensation circuit.

In order to realize the main object of the present invention, in detail, an image display period of one frame is divided into a first period T1, a second period T2, and a third period T3, and in the first period, An initialization power supply voltage line is connected to initialize the capacitive element and the control electrode of the driving transistor and simultaneously apply a reverse bias voltage to the organic electroluminescent element. In the second period, a voltage is stored in the capacitive element and a reverse bias voltage is applied to the organic electroluminescent element. In the third period, the organic electroluminescent device emits light as a current corresponding to the data voltage flows to the organic electroluminescent device, and the first, second, and third periods are sequentially performed to It is to reduce the deterioration phenomenon.

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In this case, the first period and the second period become the non-light emitting period, and the third period is the light emitting period. The non-light emitting period can be made relatively short compared to the light emitting period.

 In general, the organic light emitting display panel displays an image by voltage driving or current driving the NxM organic light emitting cells arranged in a matrix form.

Organic electroluminescent device with diode characteristics (generally called OLED)

As shown in FIG. 1, the anode is composed of an anode (ITO), an organic thin film (organic layer), and a cathode (Cathode; Metal). The organic thin film has a light emitting layer (EMitting Layer, EML), an electron transport layer (ETL) for transporting electrons, and a hole transport layer (Hole Transport Layer, HTL) for transporting holes in order to improve hole balance and improve luminous efficiency. It can be made of a multi-layer structure including. In addition, an electron injection layer (EIL) for injecting electrons to one side of the electron transport layer and a hole injection layer for injecting a hole into one side of the hole injection layer may be further formed. Can be.

In addition, in the case of a phosphorescent organic EL device, a hole blocking layer (HBL) may be selectively formed between the emission layer (EML) and the electron transport layer (ETL), and an electron blocking layer EBL may be selectively formed between the emission layer EML and the hole transport layer HTL.

In addition, the organic thin film (organic layer) may be formed in a slim organic light emitting device (Slim OLED) structure to reduce the thickness by mixing the two types of layers. For example, a hole injection transport layer (HITL) structure for simultaneously forming the hole injection layer (HIL) and the hole transport layer (HTL), and the electron injection layer (EIL) and the electron transport layer (ETL) An electron injection transport layer (EITL) structure that is formed at the same time may be selectively formed. The slim organic electroluminescent device as described above has an object of use for increasing luminous efficiency.

In addition, a buffer layer may be selectively formed between the anode and the light emitting layer EML. The buffer layer may be divided into an electron buffer layer that buffers electrons and a hole buffer layer that buffers holes. The electron buffer layer may be selectively formed between the cathode and the electron injection layer EIL, and may be formed in place of the function of the electron injection layer EIL. In this case, the laminated structure of the organic thin film may be an emission layer (EML) / electron transport layer (ETL) / electron buffer layer / cathode. In addition, the hole buffer layer may be selectively formed between the anode and the hole injection layer EIL, and may be formed in place of the function of the hole injection layer HIL. At this time, the laminated structure of the organic thin film may be an anode / hole buffer layer (Hole buffer layer) / hole transport layer (HTL) / light emitting layer (EML).

The possible laminated structure with respect to the above structure is described as follows.

a) Normal Stack Structure

1) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode

2) anode / hole buffer layer / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode

3) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / electron buffer layer / cathode

4) anode / hole buffer layer / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / electron buffer layer / cathode

5) Anode / hole injection layer / hole buffer layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode

6) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron buffer layer / electron injection layer / cathode

b) Normal Slim Structure

1) anode / hole injection transport layer / light emitting layer / electron transport layer / electron injection layer / cathode

2) anode / hole buffer layer / hole injection transport layer / light emitting layer / electron transport layer / electron injection layer / cathode

3) Anode / hole injection layer / hole transport layer / light emitting layer / electron injection transport layer / electron buffer layer / cathode

4) Anode / hole buffer layer / hole transport layer / light emitting layer / electron injection transport layer / electron buffer layer / cathode

5) Anode / hole injection transport layer / hole buffer layer / light emitting layer / electron transport layer / electron injection layer / cathode

6) Anode / hole injection layer / hole transport layer / light emitting layer / electron buffer layer / electron injection transport layer / cathode

c) Inverted Stack Structure

1) cathode / electron injection layer / electron transport layer / light emitting layer / hole transport layer / hole injection layer / anode

2) cathode / electron injection layer / electron transport layer / light emitting layer / hole transport layer / hole injection layer / hole buffer layer / anode

3) cathode / electron buffer layer / electron injection layer / electron transport layer / light emitting layer / hole transport layer / hole injection layer / anode

4) cathode / electron buffer layer / electron injection layer / electron transport layer / light emitting layer / hole transport layer / hole buffer layer / anode

5) cathode / electron injection layer / electron transport layer / light emitting layer / hole transport layer / hole buffer layer / hole injection layer / anode

6) cathode / electron injection layer / electron buffer layer / electron transport layer / light emitting layer / hole transport layer / hole injection layer / anode

d) Inverted Slim Structure

1) cathode / electron injection layer / electron transport layer / light emitting layer / hole injection layer / anode

2) cathode / electron injection layer / electron transport layer / light emitting layer / hole injection transport layer / hole buffer layer / anode

3) cathode / electron buffer layer / electron injection transport layer / light emitting layer / hole transport layer / hole injection layer / anode

4) cathode / electron buffer layer / electron injection transport layer / light emitting layer / hole transport layer / hole injection layer / anode

5) cathode / electron injection layer / electron transport layer / light emitting layer / hole buffer layer / hole injection transport layer / anode

6) Cathode / electron injection transport layer / electron buffer layer / light emitting layer / hole transport layer / hole injection layer / anode

Here, cathode means cathode and anode means anode.

As a driving method of such an organic EL device, a passive matrix method and an active matrix method are known. In the passive matrix method, the anode and the cathode are formed to be orthogonal and the lines are selected and driven, thereby simplifying the manufacturing process and reducing the investment cost. The active matrix method has the advantage of being able to expand to medium-large size by forming active elements such as thin film transistors and capacitive elements in each pixel, with low current consumption and excellent image quality and lifetime.

As described above, in the active matrix method, a pixel circuit configuration based on an organic light emitting device and a thin film transistor is essential. In this case, an amorphous silicon thin film transistor or a polycrystalline silicon thin film transistor is used as the thin film transistor. Referring to FIG. 2, a pixel circuit of an organic light emitting display device is shown.

Referring to FIG. 3, a driving timing diagram of the pixel circuit shown in FIG. 2 is shown.

This pixel circuit representatively shows one of the N x M pixels.

As shown in FIG. 2, the pixel circuit of the organic light emitting display device supplies a scan signal line S [N] for supplying a scan signal, a data signal line D [M] for supplying a data signal, and a first power supply voltage. The first power supply voltage line VDD, the second power supply voltage line VSS supplying the second power supply voltage, the driving transistor DR_TR, the switching element SW_TR, the capacitive element C, and the organic electroluminescent element OLED. It includes. Here, the first power supply voltage may be a voltage of a relatively higher level than the second power supply voltage.

An operation during one frame of the above-described pixel circuit will be described with reference to FIG.

As shown in Fig. 3, the scanning signal is supplied, and then the data signal is supplied with a slight time difference. The reason for the slight time difference is to secure a margin from the turn-on time of the switching element by the supply of the scan signal to the supply time of the data signal. Referring back to the pixel circuit of FIG. 2 according to the timing diagram of FIG.

When the scan signal is supplied from the scan signal line S [N], the switching element SW_TR is turned on. Therefore, the data signal (voltage) from the data line D [M] is supplied to the control electrode of the driving transistor DR_TR and the first electrode A of the capacitive element C.

Therefore, the first power supply voltage from the first power supply voltage line VDD is supplied to the organic light emitting diode OLED through the driving transistor DR_TR, so that the organic light emitting diode OLED is constant for one frame. It emits light with brightness. Of course, since the data voltage supplied from the data line D [M] is stored in the capacitive element C, even if the supply of the scan signal from the scan signal line S [N] is interrupted for one frame, The driving transistor DR_TR remains turned on.

In addition, as the frame continues, forward current continues to be applied from the anode to the cathode in the organic EL device.

If the current flows continuously from the anode to the cathode of the organic electroluminescent device (OLED) only between the hole transport layer (HTL) and the light emitting layer (EML) of the organic thin film or between the electron transport layer (ETL) and the light emitting layer (EML) Space charge is stored. Due to the accumulation of space charges, the current I _OLED flowing in the organic light emitting diode OLED may be reduced. As a result, since the brightness of each pixel is reduced, there is a problem that the brightness of the organic light emitting display device employing the pixel circuit gradually decreases over time. In addition, the lifespan of the organic light emitting display device may be shortened.

Furthermore, there is a problem that the luminance of the entire organic electroluminescent display is uneven as a result of the difference in the degree of deterioration of the organic electroluminescent element for each pixel circuit.

In order to solve the above problem, the organic light emitting display device according to the present invention includes a first switching device for transmitting a data signal applied from the data line in response to a scan signal applied from a scan signal line, and a first switching device. A driving transistor connected with a first electrode to control a driving current between the first power supply voltage line and the second power supply voltage line, a capacitive element connected between the control electrode of the driving transistor and the first power supply voltage line, and the second power supply An organic electroluminescent element connected to a voltage line and displaying an image with a driving current controlled by the driving transistor, an initialization switching element connected between the capacitive element and an initialization power supply voltage line to initialize the capacitive element; A control electrode is connected between the organic EL device and the initialization power voltage line. Is connected to the station control signal, a reverse bias for applying a reverse bias voltage to the organic light emitting device may include a switching element.

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The organic light emitting display device may include a second switching connected between the first power voltage line and the first switching element.

The organic light emitting diode display may include a third switching device connected between the driving transistor and the organic light emitting diode.

The organic light emitting display device may include a fourth switching device connected between a control electrode and a second electrode of the driving transistor, and a control electrode connected to the scan signal line.

In the first switching device, a control electrode may be connected to the scan signal line, a first electrode may be connected to the data line, and a second electrode may be connected to the first electrode of the driving transistor.

 The driving transistor may include a first electrode connected between the second electrode of the first switching element and the second electrode of the second switching element, and the second electrode of the first switching element and the third switching element of the fourth switching element. A control electrode may be connected between the second electrode of the fourth switching device and the first electrode of the capacitive device.

In the capacitive element, a first electrode may be connected between the first power supply voltage line and a second switching element, and a second electrode may be connected between the control electrode of the driving transistor and the second electrode of the fourth switching element.

The initialization switching device may have a control electrode connected to a previous scan signal line, and may be connected between the capacitive element and the initialization power supply voltage line.

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In addition, the reverse bias application switching element has a control electrode connected to the light emission reverse control signal line, the first electrode is the first electrode of the initialization switching element, the anode of the organic electroluminescent element and the third switching element of the third switching element. It may be connected between the two electrodes, the second electrode may be connected to the initialization power supply voltage line.

In the organic electroluminescent device, an anode may be connected to a reverse bias application switching device, and a cathode may be connected to a second power supply voltage line.

In the second switching device, a control electrode is connected to the emission control signal line, a first electrode is connected to the first power supply voltage line, and a second electrode is connected to the first electrode of the driving transistor and the second electrode of the first switching device. Can be connected between.

In the third switching device, a control electrode is connected to the emission control signal line, a first electrode is connected between the second electrode of the driving transistor and the first electrode of the fourth switching device, and the second electrode is the organic electroluminescent device. It may be connected between the anode of the first electrode of the switching element for reverse bias application.

In the organic electroluminescent device, a second power supply voltage line is connected to a cathode, and the second power supply voltage by the second power supply voltage line is greater than the initialization power supply voltage by the initialization power supply voltage line.

 In the organic light emitting display device, the initialization switching element and the reverse bias applying switching element are turned on during an image display period of one frame, and the first switching element, the fourth switching element, the second switching element, and the third switching element. When is turned off, the initialization power is applied from the initialization power supply voltage line to the second electrode of the capacitive element, and the second power supply voltage is applied from the second power supply voltage line toward the anode at the cathode of the organic electroluminescent element so that the initialization power supply is Can be transferred to a voltage line.

In the organic light emitting display device, the first switching element, the fourth switching element, and the reverse bias applying switching element are turned on during the image display period of one frame, and the second switching element, the third switching element, and the initialization switching element When turned off, a data signal from the data line is applied to the second electrode of the capacitive element, and the first power voltage from the first power voltage line is controlled by the first electrode of the capacitive element and the driving transistor. May be applied to the electrode.

In the organic light emitting display device, the second switching device and the third switching device are turned on during an image display period of one frame, and the first switching device, the fourth switching device, the initialization switching device, and the switching device for applying reverse bias are applied. When turned off, a current may be applied from the anode of the organic EL device to the cathode direction.

 The first switching element, the driving transistor, the initialization switching element, and the reverse bias application switching element may be an N-type channel transistor.

The first switching element, the driving transistor, the initialization switching element, and the reverse bias applying switching element may be a P-type channel transistor.

The second switching device, the third switching device, and the fourth switching device may be N-type channel transistors.

The second switching device, the third switching device, and the fourth switching device may be P-type channel transistors.

The organic electroluminescent device includes a light emitting layer, and the light emitting layer may be any one selected from fluorescent materials and phosphorescent materials, or a mixture thereof.

The light emitting layer may be any one selected from red light emitting material, green light emitting material, and blue light emitting material, or a mixture thereof.

The driving transistor may be any one selected from an amorphous silicon thin film transistor, a polysilicon thin film transistor, an organic thin film transistor, and a nano thin film semiconductor transistor.

The driving transistor may be a polysilicon transistor having any one selected from nickel (Ni), cadmium (Cd), cobalt (Co), titanium (Ti), palladium (Pd), and tungsten (W).

As described above, the organic light emitting display device and the pixel circuit thereof according to the present invention divide an image display period of one frame into a first period, a second period, and a third period, in which the initialization power supply voltage line has a capacitance. A reverse bias voltage is applied to the organic electroluminescent device from the second power supply voltage line toward the initialization power supply voltage line while initializing the voltage stored in the capacitive element and the control electrode of the driving transistor connected to the control electrode of the active element and the driving transistor. .

In the second period, a voltage is stored in the capacitive element and a reverse bias voltage is applied to the organic EL device similarly to the first period.

In the third period, the current corresponding to the data voltage flows through the organic EL device, thereby causing the organic EL device to emit light.

As described above, in the non-emission period of the organic EL device, that is, the first period and the second period, a reverse bias voltage is applied to the organic EL device, thereby preventing degradation of the organic EL device, and Ultimately, the lifespan of the organic light emitting display device may be increased, and further, the uniformity of each pixel may be improved.

In addition, as described above, the organic light emitting display device and the pixel circuit thereof according to the present invention can variously adjust the ratio between the light emission period and the non-light emission period in an image display period of one frame in a ratio of 1: 1 or otherwise.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

In order to clearly describe the present invention, parts not related to the present invention are omitted in the accompanying drawings. The same reference numerals are used to designate parts having similar configurations and operations throughout the specification.

Referring to FIG. 4, the configuration of the organic light emitting display device according to the present invention is shown as a block diagram.

As shown in FIG. 4, the organic light emitting display device 100 includes a scan signal driver 110, a data signal driver 120, a light emission control signal driver 130, and an organic light emitting display panel 140 (hereinafter, referred to as a panel). 140), a first power supply voltage supply unit 150, a second power supply voltage supply unit 160, and an initialization power supply voltage supply unit 170.

The scan signal driver 110 may sequentially supply scan signals to the panel 140 through a plurality of scan signal lines S [1] and S [N].

The data signal driver 120 may supply a data signal to the panel through a plurality of data signal lines D [1], ..... D [M].

The emission control signal driver 130 includes a plurality of emission control signal lines EM [1] .. EM [N].

And a light emission control signal and a light emission reverse control signal to the panel 140 through a plurality of light emission reverse control signal lines EMB [1] and ..EMB [N].

In addition, the panel 140 includes a plurality of scan signal lines S [1], S [N], emission control signal lines EM [1] .. EM [N], and light emission regions arranged in a column direction. Control signal lines EMB [1], ... EMB [N] and a plurality of data signal lines D [1], ... D [M] arranged in a row direction, and the scanning signal lines S [1], , S [N]), emission control signal lines EM [1] .. EM [N], emission emission control signal lines EMB [1], .EMB [N] and data signal lines D [1], Pixel circuit 142 defined by D [M]).

The pixel circuit 142 (Pixel) may be formed in the pixel area defined by the scan signal line and the data signal line. Of course, as described above, the scan signal may be supplied from the scan signal driver 110 to the scan signal lines S [1], S [N], and the data signal lines D [1], ... D [M]) may be supplied with a data signal from the data driver 120, and the emission control signal lines EM [1] .. EM [N] and the emission control signal lines EMB [1],. EMB [N]) may be supplied with the emission control signal and the emission emission control signal from the emission control signal driver 130.

In addition, the first power supply voltage supply unit 150, the second power supply voltage supply unit 160, and the initialization power supply voltage supply unit 170 are provided with a first power supply voltage and a first power supply to each pixel circuit 142 of the panel 140. 2 serves to supply the power supply voltage and the initialization power supply voltage.

Meanwhile, as shown in FIG. 4, the scan signal driver 110, the data signal driver 120, the emission control signal driver 130, the panel 140, the first power voltage supply unit 150, and the second power voltage. The supply unit 160 and the initialization power voltage supply unit 170 may be formed on one substrate 102.

In particular, the driving units and the power supply units 110, 120, 130, 150, 160 and 170 may include scan signal lines S [1], S [N], data signal lines D [1], D [M], and emission control signal lines EM. [1] .., EM [N]), the emission reverse control signal lines EMB [1], ..EMB [N] and the same layer as the layer forming the transistor (not shown) of the pixel circuit 142 It may be formed. Of course, the driving units and the power supply units 110, 120, 130, 150, 160, and 170 may be formed on another substrate (not shown) separately from the substrate 102, and may be connected to the substrate 102. In addition, the driving units and the power supply units 110, 120, 130, 150, 160, and 170 may include a tape carrier package (TCP), a flexible printed circuit (FPC), a tape automatic bonding (TAB), a chip on glass (COG), and the like, which are connected to the substrate 102. It may be formed in any one form of the equivalents, and in the present invention is not limited to the shape and position of the driving unit and the power supply (110, 120, 130, 150, 160, 170).

Referring to FIG. 5, a pixel circuit of an organic light emitting display device according to an embodiment of the present invention is illustrated. The pixel circuits described below all refer to one pixel circuit Pixel of the organic light emitting display device 100 illustrated in FIG. 4.

As shown in FIG. 5, a pixel of the organic light emitting display device according to the present invention.

The circuit includes scan signal lines S [N], previous scan signal lines S [N-1], data signal lines D [M], emission control signal lines EM [N], emission emission control signal lines [EMB [N]. ], The first power supply voltage line VDD, the second power supply voltage line VSS, the initialization power supply voltage line Vinit, the first switching element SW_TR1, the second switching element SW_TR2, the third switching element SW_TR3, The fourth switching element SW_TR4, the driving transistor DR_TR, the initialization switching element SW_TR5, the reverse bias applying switching element SW_TR6,

Capacitive element (C) may be included.

The scan signal line S [N] serves to supply a scan signal for selecting the organic light emitting diode OLED to be turned on to the control electrode of the first switching element SW_TR1.

The scan signal line S [N] supplies a scan signal to the control electrode of the fourth switching element SW_TR4 and turns on the gate and drain of the driving transistor DR_TR when the fourth switching element SW_TR4 is turned on. Is connected to the driving transistor DR_TR to make a diode connection. Of course, the scan signal line S [N] may be connected to the scan signal driver 110 (see FIG. 4) that generates the scan signal.

The previous scan signal line S [N-1] serves to supply the previous scan signal to the control electrode of the initialization switching element SW_TR5. The initialization switching element SW_TR5 is connected to the initialization power supply voltage line Vinit, the capacitive element C, and the control electrode of the driving transistor DR_TR to thereby connect the capacitive element C and the driving transistor DR_TR. Initialize the control electrode of (Initialization). Of course, the previous scan signal line S [N-1] may be connected to the scan signal driver 110 (refer to FIG. 4) that generates the scan signal.

The data signal line D [M] serves to supply a data signal (voltage) proportional to light emission luminance to the first electrode A and the driving transistor DR_TR of the capacitive element C. Of course, the data signal line D [M] may be connected to the data signal driver 120 (see FIG. 4) that generates the data signal.

The emission control signal line EM [N] is connected to the control electrodes of the second switching element SW_TR2 and the third switching element SW_TR3 to supply the emission control signal. When the second switching element SW_TR2 and the third switching element SW_TR3 are turned on by the emission control signal, the first power voltage line VDD corresponding to the data signal stored in the capacitive element C is turned on. A current of may be applied to the organic light emitting diode OLED through the driving transistor DR_TR. Accordingly, the organic EL device may emit light. Of course, the emission control signal line E [N] may be connected to the emission control signal driver 130 (see FIG. 4) that generates the emission control signal.

The emission reverse control signal line EMB [N] serves to supply a low level signal to the control electrode of the reverse bias application switching element SW_TR6 when the emission control signal is a high level signal. When the reverse bias application switching device SW_TR6 is turned on by the emission reverse control signal, a reverse bias voltage may be applied to the organic light emitting diode OLED. Of course, the emission control signal line EMB [N] may be connected to the emission control signal driver 130 (see FIG. 4) that generates the emission control signal. (In practice, such a light emission reverse control signal can be easily obtained by connecting an inverter to the previous stage of the output terminal of the light emission control signal driver for outputting the light emission control signal.)

The first power supply voltage line VDD allows the first power supply voltage to be supplied to the organic light emitting diode OLED. Of course, the first power supply voltage line VDD may be connected to the first power supply voltage supply unit 150 (see FIG. 4) that supplies the first power supply voltage.

The second power supply voltage line VSS allows the second power supply voltage to be supplied to the organic light emitting diode OLED. Of course, the second power supply voltage line VSS may be connected to the second power supply voltage supply unit 160 (see FIG. 4) that supplies the second power supply voltage. In this case, the first power supply voltage may be generally higher than the second power supply voltage.

In addition, the second power supply voltage may use a ground voltage.

The initialization power supply voltage line Vinit serves to initialize the control electrodes of the capacitive element C and the driving transistor DR_TR. Of course, the initialization power supply voltage line Vinit may be connected to an initialization power supply voltage supply unit 170 (see FIG. 4) that supplies an initialization power supply voltage.

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The first switching element SW_TR1 has a first electrode (source electrode or drain electrode) connected to the data signal line D [M], and a second electrode (drain electrode or source electrode) of the driving transistor DR_TR. It may be connected to a first electrode (source electrode or drain electrode), and a control electrode (gate electrode) may be connected to the scan signal line S [N]. The first switching element SW_TR1 may be a P-type channel transistor. When the low level scan signal is applied to a control electrode through the scan signal line S [N], the first switching element SW_TR1 is turned on to turn on the driving voltage at the data voltage. The value obtained by subtracting the threshold voltage Vth is supplied to the first electrode of the capacitive element C.

In the driving transistor DR_TR, a first electrode is connected to a second electrode of the first switching element SW_TR1, a second electrode is connected to a first electrode of the third switching element SW_TR3, and a control electrode is formed of a first electrode. The second electrode of the four switching element SW_TR4 and the first electrode A of the capacitive element C may be connected. The driving transistor DR_TR may be a P-type channel transistor. In operation, when a low level signal is applied through the control electrode, the signal is turned on to supply a predetermined amount of current from the first power voltage line VDD to the organic light emitting diode OLED. Of course, since the data signal is supplied to the first electrode of the capacitive element C to charge it, the charging voltage of the capacitive element C for a certain period even if the first switching element SW_TR1 is turned off. As a result, a low level signal is continuously applied to the control electrode of the driving transistor DR_TR.

The driving transistor DR_TR may be any one selected from an amorphous silicon thin film transistor, a polysilicon thin film transistor, an organic thin film transistor, a nano thin film transistor, and an equivalent thereof, but is not limited thereto.

In addition, when the driving transistor DR_TR is a polysilicon thin film transistor,

It may be formed by any one method selected from a laser crystallization method, a metal induced crystallization method, a high pressure crystallization method and an equivalent method thereof, but is not limited to the method of manufacturing the polysilicon thin film transistor in the present invention.

For reference, the laser crystallization method is a method for crystallizing amorphous silicon, for example by irradiating an excimer laser, the metal-induced crystallization method is crystallized from the metal by applying a predetermined temperature with a metal, for example, placed on the amorphous silicon It is a method for starting to be annealed, and the high-pressure crystallization method is a method of crystallizing amorphous silicon by applying a predetermined pressure, for example.

In addition, when the driving transistor DR_TR is manufactured by the metal induction crystallization method, the driving transistor DR_TR includes nickel (Ni), cadmium (Cd), and cobalt (Co).

Titanium (Ti), palladium (Pd), tungsten (W), aluminum (Al) and any one selected from the equivalents may be further included.

The organic electroluminescent device (OLED) is a switching device for applying a reverse bias of the anode

The first electrode of SW_TR6 and the second electrode of the third switching device SW_TR3 may be connected, and the cathode may be connected to the second power voltage line VSS. The organic light emitting diode OLED emits light at a predetermined brightness by a current controlled through the driving transistor DR_TR while the third switching device SW_TR3 is turned on.

The organic light emitting diode OLED may include a light emitting layer (not shown), and the light emitting layer may be any one selected from a fluorescent material, a phosphorescent material, a mixture thereof, and an equivalent thereof. However, the material or type of the light emitting layer is not limited thereto.

In addition, the light emitting layer may be any one selected from a red light emitting material, a green light emitting material, a blue light emitting material, a mixture thereof, and an equivalent thereof, but is not limited thereto.

In the second switching device SW_TR2, a first electrode is connected between the first power voltage line VDD and the second electrode of the capacitive device C, and the second electrode is connected to the first switching device SW_TR1. The second electrode and the first electrode of the driving transistor DR_TR may be connected, and a control electrode may be connected to the emission control signal line EM [N].

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The second switching element SW_TR2 may be a P-type channel transistor. When the low level signal is applied to the control electrode through the emission control signal line EM [N], the second switching element SW_TR2 is turned on from the first power voltage line VDD. Current flows to the organic electroluminescent device (OLED).

In the capacitive element C, a first electrode A is connected between the control electrode of the driving transistor DR_TR, the second electrode of the fourth switching element SW_TR4 and the second electrode of the initialization switching element SW_TR5. The second electrode may be connected to the first electrode of the second switching element SW_TR2 and the first power voltage line VDD.

The capacitive element C maintains the data signal voltage and the threshold voltage Vth of the driving transistor on the first electrode for a predetermined period of time, and the second switching element SW_TR2 and the light emitting control signal line EM [N] are held by the light emitting control signal line EM [N]. When a low level signal is applied to the control electrode of the third switching device SW_TR3 and turned on, a current proportional to the magnitude of the data signal flows from the first power supply voltage line VDD to the organic light emitting device OLED. The organic electroluminescent element OLED is allowed to emit light.

In the fourth switching device SW_TR4, a first electrode is connected to the second electrode of the driving transistor DR_TR, and the second electrode is formed of the control electrode of the driving transistor DR_TR and the capacitive element C. The electrode may be connected to one electrode, and a control electrode may be connected to the scan signal line S [N]. The fourth switching device SW_TR4 may be a P-type channel transistor, and is turned on when a low level scan signal is applied from the scan signal line S [N], thereby turning on the control electrode (gate electrode) of the driving transistor DR_TR. ) And the second electrode (drain electrode) are connected, resulting in a diode connection.

In the initialization switching device SW_TR5, a first electrode is connected to the second electrode of the initialization power supply voltage line Vinit and the reverse bias application switching device SW_TR6, and the second electrode is formed of the capacitive device C. It may be connected to one electrode A, and a control electrode may be connected to the previous scan signal line S [N-1]. The initialization switching device SW_TR5 may be a P-type channel transistor, and is turned on when a low level signal is applied from the previous scan signal line S [N-1], and the initialization voltage power line Vinit and the The first electrode of the capacitive element C and the control electrode of the driving transistor DR_TR are connected. Accordingly, the control electrodes of the capacitive element C and the driving transistor DR_TR are initialized.

In the third switching device SW_TR3, a first electrode is connected with a second electrode of the driving transistor DR_TR, a second electrode is connected with an anode of the organic light emitting diode OLED, and a control electrode is light-emitting. It may be connected to the control signal line EM [N]. The third switching element SW_TR3 may be a P-type channel transistor, and when a low level signal is applied from the emission control signal line EM [N], the third switching element SW_TR3 is turned on to turn on the organic electroluminescent element from the driving transistor DR_TR. OLED) to connect the current to flow.

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In the reverse bias applying switching element SW_TR6, a first electrode is connected to an anode of the organic light emitting diode OLED, a second electrode is connected to the initialization power voltage line Vinit, and a control electrode is connected to the light emitting reverse direction. It may be connected to the control signal line EMB [N]. The reverse bias application switching element SW_TR6 may be a P-type channel transistor, and when the low level signal is applied from the emission reverse control signal line EMB [N], the reverse bias application switching element SW_TR6 is turned on in the second power voltage line VSS. The reverse bias voltage may be applied to the organic light emitting diode OLED in the direction of the initialization power supply voltage line Vinit. In order to apply the reverse bias voltage, it is preferable that the voltage of the second power supply voltage line VSS is higher than the voltage of the initialization power supply voltage line Vinit. When the ground voltage is used as the voltage of the second power voltage line VSS, that is, the cathode voltage of the organic light emitting diode OLED, the voltage of the initialization power voltage line Vinit may preferably have a negative value. have.

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The first switching element SW_TR1, the driving transistor DR_TR, the second switching element SW_TR2, the third switching element SW_TR3, the fourth switching element SW_TR4, the initialization switching element SW_TR5, and reverse biasing The switching element SW_TR6 may be any one selected from a P-type channel transistor and an equivalent thereof, but the type of the transistor is not limited thereto.

Referring to FIG. 6, a driving timing diagram of the pixel circuit shown in FIG. 5 is illustrated. As illustrated in FIG. 6, one frame may be divided into a first period, a second period, and a third period in the pixel circuit of the organic light emitting display according to the present invention. More specifically, one frame may include an initialization period T1, a data voltage and a threshold voltage storage period T2 of the driving transistor, and a light emission period T3. The reverse bias voltage is applied to the organic light emitting diode OLED during the initialization period T1, the data voltage and the threshold voltage storage period T2 of the driving transistor. The initialization period T1 and the ratio of the data voltage and the threshold voltage storage period T2 of the driving transistor to the light emission period T3 may be variously formed. Preferably, the initialization period is compared with the light emission period T3. It is preferable that the period of T1 and the threshold voltage storage period T2 of the data voltage and the driving transistor is short.

Referring to FIG. 7, a current flow is shown during the initialization period T1 in the pixel circuit shown in FIG. 5. Here, the operation of the pixel circuit will be described with reference to the timing diagram of FIG. 6.

First, the low level scan signal is applied from the previous scan signal line S [N-1] to the control electrode of the initialization switching element SW_TR5, so that the initialization switching element SW_TR5 is turned on, and the reverse bias application switching element ( The low bias signal of the light emission reverse control signal line EMB [N] is applied to the control electrode of SW_TR6, so that the reverse bias application switching element SW_TR6 is turned on.

As the initialization switching device SW_TR5 is turned on, the initialization power supply voltage of the initialization power supply voltage line Vinit is applied to the node A to which the first electrode of the capacitive element C and the control electrode of the driving transistor DR_TR are connected. The storage voltage of the capacitive element C and the control electrode of the driving transistor DR_TR are initialized.

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At this time, the emission control signal line EM [N] is connected to the control electrode of the third switching element SW_TR3.

As the high level signal is applied, the third switching device SW_TR3 is turned off, so that the organic light emitting diode OLED does not emit light.

When the voltage of the second power supply voltage line VSS is higher than the voltage of the initialization power supply voltage line Vinit by using the non-emission period, a reverse bias voltage is applied to the organic light emitting diode OLED. It can prevent the degradation of OLED. In addition, the voltage of the second power supply voltage line VSS may use a ground voltage. In this case, a voltage of the initialization power supply voltage line Vinit may be reverse biased to the organic light emitting diode OLED when a negative voltage is applied. Voltage can be applied.

During this period, the first switching element SW_TR1, the fourth switching element SW_TR4, the second switching element SW_TR2, and the third switching element SW_TR3 are turned off as a high level signal is applied to each control electrode. Will be.

In other words, the initialization period T1 initializes the control electrodes of the capacitive element C and the driving transistor DR_TR and applies a reverse bias voltage using the non-emission period of the organic electroluminescent element OLED. do.

Referring to FIG. 8, the current flow during the data voltage and the threshold voltage storage period T2 of the driving transistor in the pixel circuit shown in FIG. 5 is illustrated. Here, the operation of the pixel circuit will be described with reference to the timing diagram of FIG. 6.

First, when the scan signal line S [N] is connected to the control electrode of the first switching element SW_TR1, and a low level scan signal is applied from the scan signal line S [N], the first switching element SW_TR1 is applied. Is turned on to apply a data signal from the data signal line D [M].

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In addition, a low level scan signal of the scan signal line S [N] is applied to the control electrode of the fourth switching element SW_TR4, and the fourth switching element SW_TR4 is turned on. The fourth switching device SW_TR4 is connected between the control electrode (gate electrode) and the second electrode (drain electrode) of the driving transistor DR_TR to form a diode connection.

The present invention including a diode connection also has a function of compensating the threshold voltage of the driving transistor. Hereinafter, the principle of compensating the threshold voltage of the driving transistor will be described with reference to Equation 1 below.

Under the diode connection, a first power supply voltage VDD is applied to the second electrode of the capacitive element, and a difference between the data voltage V _DATA and the threshold voltage Vth of the driving transistor is applied to the first electrode A. FIG. Voltage (V _DATA- | Vth |) is applied.

Referring to FIG. 9, the current flow of the light emission period T3 in the pixel circuit shown in FIG. 5 is illustrated, and will be described with reference to the driving timing diagram of FIG. 6.

At this time, the current I _OLED flowing through the organic light emitting diode _OLED is represented by Equation 1 below.

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Here, V _DD is a first power supply voltage of the first power supply voltage line, V _DATA is a data voltage applied through the data signal line, V _th is a threshold voltage of the driving transistor DR_TR, and β is a constant. As shown in Equation 1, the current I _OLED flowing through the organic light emitting diode OLED during the light emission period T3 is applied to the data voltage V _DATA regardless of the threshold voltage of the driving transistor DR_TR. Flows correspondingly. In other words, the threshold voltage Vth of the driving transistor DR_TR is compensated.

In addition, the light emission reverse control signal line EMB [N] is connected to a control electrode of the reverse bias application switching element SW_TR6 so that the reverse direction is caused by a low level signal of the light emission reverse control signal line EMB [N]. The bias application switching element SW_TR6 remains turned on.

During this period T2, as in the initialization period T1, a high level signal of the emission control signal line EM [N] is applied to the control electrode of the third switching element SW_TR3, so that the third switching element is applied. Since the SW_TR3 is still turned off, the organic light emitting diode OLED does not emit light. When the voltage of the second power supply voltage line VSS is higher than the voltage of the initialization power supply voltage line Vinit by using the non-emission period, a reverse bias voltage is applied to the organic light emitting diode OLED. The degradation of the OLED can be prevented. In addition, the voltage of the second power supply voltage line VSS may use a ground voltage. In this case, a voltage of the initialization power supply voltage line Vinit may be reverse biased to the organic light emitting diode OLED when a negative voltage is applied. Voltage can be applied.

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During this period, the initialization switching element SW_TR5, the second switching element SW_TR2, and the third switching element SW_TR3 are turned off as a high level signal is applied to each control electrode.

In other words, during the data voltage and the threshold voltage storage period T2 of the driving transistor, the data voltage is stored in the capacitive element C and at the same time, a reverse bias voltage is obtained by using the non-emission period of the organic light emitting diode OLED. Is authorized.

Referring to FIG. 9, the current flow during the light emission period T3 in the pixel circuit shown in FIG. 5 is illustrated. Here, the operation of the pixel circuit will be described with reference to the timing diagram of FIG. 6. First, when the emission control signal line EM [N] is connected to the control electrode of the second switching element SW_TR2 and a low level emission control signal is applied, the second switching element SW_TR2 is turned on and the first power source is turned on. The first power supply voltage may be supplied from the voltage line VDD to the driving transistor DR_TR.

Also, when the emission control signal line EM [N] is connected to the control electrode of the third switching element SW_TR3 and the emission control signal having a low level is applied, the third switching element SW_TR3 is turned on and the driving is performed. A driving current may flow through the transistor DR_TR to the organic light emitting diode OLED. Accordingly, the organic light emitting diode emits light corresponding to each data signal.

During this period, the first switching element SW_TR1, the fourth switching element SW_TR4, the initialization switching element SW_TR5, and the reverse bias applying switching element SW_TR6 are turned on as a high level signal is applied to each control electrode. It will be off.

In other words, in the light emission period T3, the data voltage stored in the capacitive element C and the threshold voltage of the driving transistor are applied through the driving transistor DR_TR to emit the organic light emitting diode OLED. . In this case, the reverse bias application switching element SW_TR7 is turned off so that the reverse bias voltage is not applied to the organic light emitting diode OLED.

Preferably, the initialization period T1, the data voltage and the threshold voltage storage period T2 of the driving transistor are shorter than the emission period T3 so that the organic EL device emits light. .

Referring to FIG. 10, a pixel circuit of a flat panel display according to another exemplary embodiment of the present invention is illustrated.

The pixel circuit shown in FIG. 10 is similar to the pixel circuit shown in FIG. However, in the pixel circuit shown in FIG. 10, the first electrode of the reverse bias application switching element SW_TR6 is connected to the first electrode of the initialization switching element SW_TR5.

In other words. The reverse bias applying switching element SW_TR6 is positioned between the second power supply voltage line VSS and the initialization power supply voltage line Vinit as in FIG. 5, but the reverse bias application in FIG. Unlike the first electrode of the switching element SW_TR6 is connected to the anode of the organic light emitting element OLED and the second electrode of the third switching element SW_TR3, in another embodiment of FIG. 10, a switching element for applying reverse bias is shown. The first electrode of SW_TR6 may be connected to the first electrode of the initialization switching device SW_TR5.

Referring to FIG. 11, a pixel circuit of an organic light emitting display device according to another embodiment of the present invention is illustrated.

The pixel circuit shown in FIG. 11 is also almost the same as the pixel circuit shown in FIG. In the pixel circuit shown in FIG. 5, all transistors are P-type channel transistors, but all transistors shown in FIG. 11 are N-type transistors. As a result, the connection relationship between the elements is slightly different from that shown in FIG.

For example, the upper and lower ends of the pixel circuit using the P-type channel transistor shown in FIG. 5 are shown upside down, and the direction of the organic light emitting diode OLED is the same as the direction shown in FIG. If the type channel transistor is replaced with the N type transistor, the pixel circuit using the N type channel transistor of FIG. 11 may be implemented. At this time, the positions of the first electrode (source electrode or drain electrode) and the second electrode (drain electrode or source electrode) are reversed in the P-type channel transistor and the N-type channel transistor.

FIG. 12 is a driving timing diagram of the pixel circuit using the N-type channel transistor shown in FIG. In the case of the N-type transistor, a high level signal is turned on when the control electrode is applied. The driving timing diagram shown in FIG. 12 is a low level signal when compared to the driving timing diagram of FIG. The low level signal is converted into a high level signal.

As described above, the organic light emitting display device and the pixel circuit thereof according to the present invention divide an image display period of one frame into a first period, a second period and a third period, and in the first period, the capacitive element and the driving transistor. In addition, the control electrode is initialized and a reverse bias voltage is applied to the organic EL device, thereby preventing deterioration of the organic EL device. Further, in the second period, the data voltage and the threshold voltage of the driving transistor are stored in the capacitive element, and a reverse bias voltage is applied to the organic electroluminescent element, thereby preventing deterioration of the organic electroluminescent element. . In addition, in the third period, the operation of applying the reverse bias voltage to the organic light emitting diode is stopped, and the current corresponding to the data voltage stored in the capacitive element and the threshold voltage of the driving transistor is supplied through the driving transistor. By flowing through the device, there is an effect that the like electroluminescent device emits light.

The prominent effect of the present invention is to prevent degradation of the organic electroluminescent device by applying a reverse bias voltage to the organic electroluminescent device using the non-emission period of the organic electroluminescent device. There is an effect of improving the life of the organic EL device and improving the nonuniformity of the luminance of each pixel due to the difference in the deterioration phenomenon of each pixel circuit.

What has been described above is only one embodiment for implementing the organic light emitting display device and the pixel circuit thereof according to the present invention, and is not limited to the above-described embodiment of the present invention, as claimed in the following claims. As described above, any person having ordinary knowledge in the field of the present invention without departing from the gist of the present invention will have the technical spirit of the present invention to the extent that various modifications can be made.

Claims (26)

A first switching element transferring a data signal applied from the data line in response to a scan signal applied from the scan signal line; A driving transistor connected to the first switching element to control a driving current between a first power supply voltage line and a second power supply voltage line; A capacitive element connected between the control electrode of the driving transistor and the first power voltage line; An organic electroluminescent element connected to the second power supply voltage line and displaying an image with a driving current controlled by the driving transistor; An initialization switching element connected between the capacitive element and an initialization power supply voltage line to initialize the capacitive element; And A reverse bias application switching element connected between the organic electroluminescent element and the initialization power supply voltage line, and a control electrode connected to the emission reverse control signal line to apply a reverse bias voltage to the organic electroluminescent element. Organic electroluminescent display. The method of claim 1, And a second switching element connected between the first power voltage line and the first switching element. The method of claim 1, And a third switching device connected between the driving transistor and the organic light emitting device. The method of claim 1, And a fourth switching element connected between the control electrode and the second electrode of the driving transistor, the control electrode being connected to the scan signal line. The method of claim 1, A second switching device is connected between the first power supply voltage line and the first switching device, and a third switching device is connected between the driving transistor and the organic light emitting device, and between the control electrode and the drain of the driving transistor. And a fourth switching device and a scan signal line connected to the control electrode of the fourth switching device. The method of claim 1, The first switching element of claim 1, wherein a control electrode is connected to the scan signal line, a first electrode is connected to the data line, and a second electrode is connected to the first electrode of the driving transistor. The method of claim 5, The driving transistor may include a first electrode connected between the second electrode of the first switching element and the second electrode of the second switching element, and the second electrode of the first switching element and the third switching element of the fourth switching element. And a control electrode connected between the second electrode of the fourth switching element and the first electrode of the capacitive element. The method of claim 5, The capacitive element may include a first electrode connected between the first power supply voltage line and the second switching element, and a second electrode connected between the control electrode of the driving transistor and the second electrode of the fourth switching element. An organic light emitting display device. The method of claim 1, And the control electrode is connected to a previous scan signal line and is connected between the capacitive element and the initialization power supply voltage line. delete The method of claim 3, wherein In the reverse bias application switching element, a control electrode is connected to the light emission reverse control signal line, and a first electrode is a first electrode of the initialization switching element, an anode of the organic electroluminescent element, and a second electrode of the third switching element. And a second electrode connected to the initialization power supply voltage line. The method of claim 1, And the anode is connected to the reverse bias applying switching element, and the cathode is connected to the second power voltage line. The method of claim 5, In the second switching device, a control electrode is connected to the emission control signal line, a first electrode is connected to the first power supply voltage line, and a second electrode is connected to the first electrode of the driving transistor and the second electrode of the first switching device. An organic light emitting display device, characterized in that connected between. The method of claim 5, In the third switching device, a control electrode is connected to the emission control signal line, a first electrode is connected between the second electrode of the driving transistor and the first electrode of the fourth switching device, and the second electrode is the organic electroluminescence. And an anode of the device and a first electrode of the switching device for applying reverse bias. The method of claim 5, And the second power voltage line is connected to a cathode, and the second power voltage by the second power voltage line is greater than the initialization power voltage by the initialization power voltage line. The method of claim 5, The initialization switching element and the reverse bias applying switching element are turned on during the image display period of one frame, and the first switching element, the fourth switching element, the second switching element, and the third switching element are turned off. When the initialization power voltage line is applied, initialization power is applied to the first electrode of the capacitive element, and a second power supply voltage is applied from the second power supply voltage line toward the anode at the cathode of the organic electroluminescent element, thereby providing the initialization power supply voltage line. The organic light emitting display device, characterized in that delivered to. The method of claim 5, When the first switching element, the fourth switching element and the reverse bias applying switching element are turned on during the image display period of one frame, and the second switching element, the third switching element and the initialization switching element are turned off. And a data signal from the data line is applied to the first electrode of the capacitive element, and a first power voltage from the first power voltage line is applied to the control electrode of the capacitive element and the driving transistor. Organic electroluminescent display. The method of claim 5, When the second switching element and the third switching element are turned on during the image display period of one frame, and the first switching element, the fourth switching element, the initialization switching element, and the reverse bias applying switching element are turned off. And a current is applied in an anode direction of the anode of the organic light emitting diode. The method of claim 1, And the first switching element, the driving transistor, the initialization switching element, and the reverse bias applying switching element are N-type channel transistors. The method of claim 1, And the first switching element, the driving transistor, the initialization switching element, and the reverse bias applying switching element are P-type channel transistors. The method of claim 5, And the second switching element, the third switching element, and the fourth switching element are N-type transistors. The method of claim 5, And the second switching element, the third switching element, and the fourth switching element are P-type transistors. The method of claim 1, The organic electroluminescent device has a light emitting layer, and the light emitting layer is any one selected from fluorescent materials and phosphorescent materials, or a mixture thereof. The method of claim 23, wherein And the light emitting layer is any one selected from a red light emitting material, a green light emitting material, and a blue light emitting material or a mixture thereof. The method of claim 1, And the driving transistor is one selected from an amorphous silicon thin film transistor, a polysilicon thin film transistor, an organic thin film transistor, and a nano thin film semiconductor transistor. The method of claim 1, The driving transistor is an organic electroluminescence, characterized in that the polysilicon transistor having any one selected from nickel (Ni), cadmium (Cd), cobalt (Co), titanium (Ti), palladium (Pd) and tungsten (W). Display device.

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