KR20190079827A - VDD-less Pixel Circuit and Organic Light Emitting display using the Pixel Circuit - Google Patents

Abstract

The present invention relates to a pixel circuit without a VDD line for image quality compensation, and to an organic light emitting display using the same. The pixel circuit used in the organic light emitting display proposed in the present invention includes a first scan line, a second scan line, an EM line, a data line, an initial voltage line, a driving TFT, and an organic light emitting diode. A high-potential voltage of a first scan signal is used as a driving voltage for driving the organic light emitting diode. According to the present invention, a design area is reduced and short between wirings is reduced by using a high voltage of a scan signal instead of an existing driving voltage (VDD) and removing a driving voltage line.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pixel circuit having no driving voltage line and an organic light emitting display using the pixel circuit.

The present invention relates to an organic light emitting display, and more particularly, to a VDD line-free pixel circuit for image quality compensation and an OLED display using the pixel circuit.

The organic light emitting display includes an organic light emitting diode (OLED) which emits light by itself, has a high response speed, and has a large luminous efficiency, luminance, and viewing angle.

The organic light emitting diode (OLED) includes an anode electrode, a cathode electrode, and organic compound layers (HIL, HTL, EML, ETL, EIL) formed therebetween. The organic compound layer includes a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer EIL). When a driving voltage is applied to the anode electrode and the cathode electrode, holes passing through the HTL and electrons passing through the ETL are transferred to the EML to form excitons, Thereby generating visible light.

The organic light emitting display device arranges the pixels each including the OLED in a matrix form and adjusts the brightness of the pixels according to the gradation of the video data. Each of the pixels includes a driving TFT (Thin Film Transistor) for controlling a driving current flowing in the OLED. In particular, the conventional pixel circuit uses a driving voltage (VDD) for OLED driving. The use of such a driving voltage causes a potential difference between the start point and the end point of the driving voltage line due to a voltage drop (IR Drop) Thus, there is a problem that luminance unevenness occurs between pixels.

Korean Patent Registration No. 10-1719481

An object of the present invention is to provide a pixel circuit which removes luminance unevenness by using an initial voltage instead of a driving voltage, and an organic light emitting display device using the pixel circuit.

According to an aspect of the present invention, there is provided a pixel circuit for use in an OLED display device including a first scan line, a second scan line, an EM line, a data line, an initial voltage line, a driving TFT and an organic light emitting diode A high potential voltage of the first scan signal may be used as a driving voltage for driving the organic light emitting diode.

Wherein the pixel circuit further includes first to seventh switching TFTs and a storage capacitor, the source and the drain of the first switching TFT are connected to the gate of the driving TFT, the second scanning line, and the drain of the driving TFT, respectively And a source and a gate of the second switching TFT are respectively connected to the data line, the second scan line, and the source of the driving TFT, The drain of the third switching TFT is connected to the drain of the second switching TFT and the source of the driving TFT, and the source, gate, and drain of the fourth switching TFT are connected to the EM line, Drain, the EM line, and one end of the OLED, and a source, a gate, and a drain of the fifth switching TFT are connected to the initial voltage line, the first scan line, Gate, and drain of the sixth switching TFT are connected to one end of the OLED, the second scan line, and the initial voltage line, respectively, and the source, gate, and drain of the seventh switching TFT are connected to the gate, Wherein the first node is connected to the first scan line, the EM line, and the first node, the storage capacitor is located between the first node and the gate of the drive TFT, The source of the third switching TFT, and the one end of the storage capacitor are connected.

A first scan signal is applied to the first scan line, a second scan signal is applied to the second scan line, a light emission signal is applied to the EM line, a data voltage is applied to the data line, An initial voltage is applied to the initial voltage line, and one frame period is divided into a first period to a fourth period in order to cause the organic light emitting diode to emit light. In the first period, the first scan signal is ON, The second scan signal and the light emission signal are in the OFF state. In the third period, the first scan signal and the second scan signal are in the OFF state. In the second period, the second scan signal is in the ON state. The scan signal and the light emission signal are both in the off state, and in the fourth section, the first scan signal and the second scan signal are in the off state and the light emission signal is in the on state.

In addition, in the first period, the fifth switching TFT is turned on by the first scan signal, and in the second period, the first switching TFT, the second switching TFT, The second switching TFT, and the sixth switching TFT are turned on, the initial voltage is applied to the first node, and in the fourth period, the third switching TFT, the fourth switching TFT, The seventh switching TFT may be turned on.

In addition, the pixel circuit further includes an eighth switching TFT, and a source, a gate, and a drain of the eighth switching TFT are respectively connected to the initial voltage line, the second scan line, and the first node, 8 switching TFT may be turned on by the second scan line during the second period to apply the initial voltage to the first node.

The driving TFT and the plurality of switching TFTs used in the pixel circuit may be PMOS or NMOS.

According to an aspect of the present invention, there is provided an organic light emitting display including a plurality of pixel circuits arranged in a lattice form in a display region, a first scan signal, a second scan signal, An EM line and an initial voltage line arranged to be spaced apart in a first direction to provide a signal, and an initial voltage, and a scan line, an EM line, and an initial voltage Wherein each pixel circuit of the plurality of pixel circuits includes a driving voltage for driving the organic light emitting diode and a voltage (high potential voltage) when the first scanning signal is off Can be used.

Here, in the plurality of pixel circuits in the n-th row in the second direction orthogonal to the first direction, the first scan signal may include a plurality of pixel circuits in the (n-1) And the second scan signal may be a scan signal for a plurality of pixel circuits in an nth row in the second direction and may further include a dummy scan line for a plurality of pixel circuits in a first row .

And a second initial voltage line and a switching TFT for providing a separate initial voltage to a plurality of pixel circuits in an nth row in a second direction orthogonal to the first direction, The initial voltage can be supplied only when the second scan signal is turned on by the switching TFT.

According to an aspect of the present invention, there is provided a method of driving an organic light emitting diode in a pixel circuit that receives a first scan signal, a second scan signal, and an emission signal and emits an organic light emitting diode using a driving TFT, A TFT initializing step of applying an initial voltage to the gate of the driving TFT by the first scan signal, a voltage initializing step of initializing a voltage formed in the organic light emitting diode to an initial voltage by the second scan signal, A sampling step of applying a voltage obtained by subtracting a threshold voltage to a data voltage, and applying an off-state voltage (high-potential voltage) of the first scan signal to the source of the driving TFT by the emission signal, A voltage to which the high potential voltage is added is applied to a voltage charged in the storage capacitor, It may comprise the step of generating a current for driving the diode.

According to the present invention, the high voltage of the scan signal is used in place of the conventional driving voltage (VDD) to eliminate the driving voltage line, thereby reducing the design area and reducing short-circuit short-circuit defects.

In addition, there is an effect of eliminating the difference in luminance difference between the pixels located above / below the display device due to the conventional driving voltage drop.

1 is a diagram illustrating an organic light emitting display including a pixel circuit without a driving voltage line according to an embodiment of the present invention.
2 is a circuit diagram showing a pixel of an OLED display according to an embodiment of the present invention.
3 is a diagram showing driving timings for a pixel circuit according to an embodiment of the present invention.
Figs. 4 to 6 are diagrams showing the operation of the pixel circuit according to the driving timing of Fig. 3. Fig.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between . Also, when a part is referred to as "including " an element, it does not exclude other elements unless specifically stated otherwise.

If any part is referred to as being "on" another part, it may be directly on the other part or may be accompanied by another part therebetween. In contrast, when a section is referred to as being "directly above" another section, no other section is involved.

The terms first, second and third, etc. are used to describe various portions, components, regions, layers and / or sections, but are not limited thereto. These terms are only used to distinguish any moiety, element, region, layer or section from another moiety, moiety, region, layer or section. Thus, a first portion, component, region, layer or section described below may be referred to as a second portion, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified and that the presence or absence of other features, regions, integers, steps, operations, elements, and / It does not exclude addition.

Terms indicating relative space such as "below "," above ", and the like may be used to more easily describe the relationship to other portions of a portion shown in the figures. These terms are intended to include other meanings or acts of the apparatus in use, as well as intended meanings in the drawings. For example, when inverting a device in the figures, certain portions that are described as being "below" other portions are described as being "above " other portions. Thus, an exemplary term "below" includes both up and down directions. The device can be rotated by 90 degrees or rotated at different angles, and terms indicating relative space are interpreted accordingly.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

1 is a diagram illustrating an organic light emitting display including a pixel circuit without a driving voltage line according to an embodiment of the present invention.

Referring to FIG. 1, an organic light emitting display according to an exemplary embodiment of the present invention includes pixel circuits 30 each including an OLED and having no driving voltage lines arranged in a matrix form, a GIP 10 for controlling the pixel circuits 30, A data driver 20 and a controller 40. [

The GIP 10 provides an EM signal and a scan signal to the pixel circuits. Some of the functions of the conventional scan driver are transferred to the controller 40 so as to remove the scan driver (or gate driver) from the conventional LCD or OLED drive circuit and contribute to the productivity improvement through the CI and process simplification, Function is performed by the GIP 10 in the panel, and is generally constituted by a shift register.

The EM signal and the scan signal generated by the GIP 10 are supplied to the pixels through the scan lines 61 to 64 arranged in the EM lines 51 to 54 and the scan lines 61 to 64 spaced apart from the EM lines, Lt; / RTI > circuits.

The scan signal supplied from the GIP 10 may be sequentially supplied to the pixel circuits at the bottom or to the top pixel circuits from the bottom pixel circuits starting from the pixel circuits at the top. In the case of a large screen, the pixel circuits included in the entire screen can be divided into several blocks and sequentially supplied in the block.

In particular, a scan signal supplied to the previous stage may be supplied to the pixel circuit shown in the present invention. In particular, for the first stage, a dummy scan signal may be additionally generated and supplied.

The data driver 20 supplies data voltages for gradation representation to data lines 71 to 74 arranged in a second direction which may be orthogonal to the EM lines 51 to 54 and the scan lines 61 to 64, To the pixel circuit (30).

The controller 40 provides a timing signal, a control signal, etc. so that the GIP 10 and the data driver 20 can generate control signals at appropriate timing. The controller 40 generates and supplies signals for controlling the operation timings of the GIP 10 and the data driver 20 based on timing signals such as a vertical synchronization signal, a horizontal synchronization signal, a clock signal, and a data enable signal .

Although not shown, the initial power supply line Vini may be disposed in the first direction away from the EM lines 51 to 54 and the scan lines 61 to 64.

2 is a circuit diagram showing a pixel of an OLED display according to an embodiment of the present invention. FIG. 2 shows one pixel of all the pixels of the organic light emitting diode display, and each pixel has the same configuration.

Referring to FIG. 2, the pixel circuit of the OLED display according to an embodiment of the present invention includes an n-th scan line 102 to which an n-th scan signal Scan (n) An EM line 104 to which an (n-1) th scan line 103, an nth light emitting signal EM (n) are input to which a signal Scan (n-1) An initial voltage line 106 to which an initial voltage Vini is input, a plurality of TFTs DT, T1 to T7, a storage capacitor Cst, and an OLED 110. [ In addition, a switching TFT T8 used for connecting an initial voltage Vini to pixel circuits sharing a scan line in a GIP (Gate in Panel) may be provided.

The nth scan line 102 and the (n-1) th scan line 103 are divided in the nth scan line and the (n-1) th scan line in the scan lines 61 to 64, respectively, A scan signal is applied from the GIP 10. The (n-1) th scan line 103 is for applying a scan signal to the pixel circuits of the immediately preceding row of the (n-1) th scan line 102, the (n-1) th scan signal is turned off and the n-th scan signal is turned on. the fifth switching TFT T5 is driven through the (n-1) th scan signal, and the first, second, sixth, and eighth switching TFTs are driven through the nth scan signal.

The EM line 104 is wired in the nth EM line among the EM lines 51 to 54 in Fig. 1, and a light emission (EM) signal is applied from the GIP 10. And drives the third, fourth, and seventh switching TFTs through the light emission signal.

The data line 105 is branched from one of the data lines 71 to 74 in FIG. 1 as a wiring for applying a data voltage (Vdata) for driving the driving TFT DT to the gate of the driving TFT.

The initial voltage line 106 is the wiring to which the initial voltage Vini is applied.

The plurality of TFTs DT, T1 to T8 may be divided into first to eighth switching TFTs T1 to T8 and a driving TFT DT. Hereinafter, the plurality of TFTs (DT, T1 to T8) will be described based on PMOS.

The source and gate of the fifth switching TFT T5 are respectively connected to the initial voltage line 106 and the (n-1) th scan line 103, and the drain of the fifth switching TFT T5 is connected to the driving TFT DT. 1) th scan signal Scan (n-1) applied to the (n-1) th scan line 103 and connected to the gate of the driving TFT DT Can be initialized to the initial voltage Vini.

The source and the gate of the first switching TFT T1 are connected to the gate of the driving TFT DT and the nth scanning line 102 respectively and the drain of the first switching TFT T1 is connected to the drain of the driving TFT DT .

The source and gate of the second switching TFT T2 are connected to the data line 105 and the nth scan line 102 respectively and the drain of the second switching TFT T2 is connected to the source of the driving TFT DT .

The first switching TFT T1 and the second switching TFT T2 may be turned on by the nth scan signal applied to the nth scan line 102 to be used to compensate the threshold voltage of the driver TFT DT have.

The source and the gate of the sixth switching TFT T6 are respectively connected to one end of the OLED 110 and the nth scan line 102 and the drain of the sixth switching TFT T6 is connected to the initial voltage line 106 the scan driver 100 may turn on the scan voltage of the OLED 100 during the previous frame period by the nth scan signal Scan (n) applied to the nth scan line 103 to initialize the voltage to the initial voltage Vini. have.

The source and the gate of the eighth switching TFT T8 are connected to the initial voltage Vini and the nth scan line 102 respectively and the drain of the eighth switching TFT T8 is connected to the first node Node A the nineteenth scan line 103 is turned on by the nth scan signal Scan (n) applied to the nth scan line 103 to apply the initial voltage Vini to one side of the storage capacitor Cst, To be charged in the storage capacitor Cst. At this time, although the eighth switching TFT T8 may be included in each pixel circuit, there may be only one for all the pixel circuits controlled by the nth scan line in Fig. 1, that is, for all the pixel circuits in the nth row, , And the eighth switching TFT T8 is provided in the GIP.

The source and the gate of the third switching TFT T3 are connected to the first node Node A and the EM line 104 respectively and the drain of the third switching TFT T3 is connected to the drain of the second switching TFT T2 And is connected together to the source of the driving TFT DT.

The source and gate of the seventh switching TFT T7 are respectively connected to the (n-1) th scan line 103 and the EM line 104, and the drain of the seventh switching TFT T7 is connected to the first node Node A .

The third switching TFT T3 and the seventh switching TFT T7 are turned on by the nth emission signal EM (n) applied to the EM line 104 to turn on the (n-1) th scan line 103 (N-1) th scan signal to the source of the driving TFT DT to be used as the driving voltage of the driving TFT DT.

The source and gate of the fourth switching TFT T4 are respectively connected to the drain and EM line 104 of the driving TFT DT and the drain of the seventh switching TFT T7 is connected to the OLED 110, Is turned on by the n-th emission signal EM (n) applied to the driving TFT 104 to supply a current generated by the driving TFT DT to the OLED 110 so that the OLED 110 can emit light give. Here, the other side of the OLED 110 may be connected to the low potential voltage VGL or the ground.

At this time, the intensity of the light emitted by the OLED 110 is proportional to the amount of current flowing through the OLED 110, and the amount of the current flowing through the OLED 110 corresponds to the amount of the data voltage Vdata applied to the gate of the driving TFT DT It is proportional to size. As a result, the organic light emitting display device can display various images by displaying different gradations by applying a data voltage (Vdata) of various sizes to each pixel region.

A storage capacitor Cst may be coupled between the gate of the first node Node A and the driver TFT DT and the storage capacitor Cst may be connected to the data voltage Vdata applied to the data line 105 for one frame, And the driving TFT DT so that the amount of current flowing through the OLED 110 can be kept constant and the gradation displayed by the OLED 110 can be kept constant.

FIG. 3 is a timing chart for driving a pixel circuit according to an embodiment of the present invention, and FIGS. 4 to 6 are diagrams illustrating operations of a pixel circuit according to the driving timing of FIG.

Referring to FIG. 3, the pixel circuit of the organic light emitting diode display divides one frame period into a plurality of periods to control the light emission of the OLED 110.

The first period 310 is a TFT initialization period and the light emission signal EM (n) and the nth scan signal Scan (n) of the EM line 104 are turned off, Only the fifth switching TFT T5 is turned on as shown in Fig. 4 and the gate of the driving TFT DT is turned on, The voltage is initialized to the initial voltage Vini. At this time, the initial voltage Vini may be 2 to 3V.

In the second period 320, the (n-1) th scan signal Scan (n-1) and the light emitting signal EM (n) are turned off in the OLED 110 initialization period and the sampling period, The scan signal Scan (n) is turned on to turn on the first, second, sixth, and eighth switching TFTs T1, T2, T6, and T8, as shown in FIG.

The voltage formed in the OLED 110 due to the turn-on of the sixth switching TFT T6 is discharged to the connected initial voltage Vini, and the voltage formed in the OLED 110 in the previous frame period becomes the initial voltage Vini).

The eighth switching TFT T8 is turned on so that the initial voltage Vini is applied to one side of the storage capacitor Cst.

The data voltage Vdata applied to the data line 105 is applied to the source of the driving TFT DT while the second switching TFT T2 is turned on and the base voltage of the driving TFT DT The driving TFT DT is turned on by the difference between the initial voltage Vini applied to the driving TFT DT and the data voltage Vdata applied to the source of the driving TFT DT and the voltage Vdata-Vth reduced by the threshold voltage Vth ) Appear in the drain of the driving TFT, and this voltage is caught by the gate of the driving TFT DT while the first switching TFT (T1) is turned on. Accordingly, Vdata-Vth is applied to the other side of the storage capacitor Cst, so that Vdata-Vth-Vini is stored in the storage capacitor.

The third section 330 is a section for holding the data voltage Vdata in a floating section and reinforcing the threshold voltage. (N) scan signal Scan (n-1) and the n-th scan signal Scan (n) are both turned off, DT is maintained and the threshold voltage Vth is compensated.

The fourth section 340 is a light emission section in which the nth emission signal EM (n) is applied to the EM line 104 to turn on the third, fourth, and seventh switching TFTs T3, T4, and T7 - Turn it on. (N-1) -th scan signal Scan (n-1) is off state in the fourth section 340 due to the turn-on of the seventh switching TFT, -1) is applied to the first node Node A and the third switching TFT T3 is turned on so that the source of the driving TFT DT is also supplied with the (n-1) th scan signal ( (VGH) of scan (n-1) and scan (n-1). Here, the high-potential voltage may be a voltage of 7 to 10V.

In this state, the gate voltage of the driving TFT DT is the sum of the voltages charged in the storage capacitor Cst to the voltage of the first node Node A, and thus becomes Vdata-Vth-Vini + VGH. Then, the current flowing through the OLED 110 can be obtained as shown in the following equation.

_{I OLED = K (Vsg-Vth} ) 2 = K (VGH- (Vdata-Vth-Vini + VGH) -Vth) 2 = K (Vini-Vdata) 2

That is, the current flowing in the OLED 110 is determined only by the initial voltage Vini and the data voltage Vdata. Here, Vsg represents the source-gate voltage of the driving TFT DT.

In order to supply the current for emitting the OLED during the light emission period, the wiring for providing the conventional driving voltage VDD is eliminated by using the high potential voltage VGH of the scan signal instead of the driving voltage VDD, Thereby reducing the overall design area and reducing the short circuit failure between wirings.

As shown in the above equation, the driving current of the OLED 110 depends on the initial voltage Vini. However, as in the case of the initial voltage (Vini) and the driving voltage (VDD), there is a possibility that a voltage drop occurs at a farther side than the nearest one as the length becomes longer. However, when the 16: 9 aspect ratio is used as a reference, the difference between the starting point and the ending point of the driving voltage VDD is 16, and the difference between the starting point and the end point of the initial voltage Vini is 4.5. It is very small at 0.28% of the voltage drop at the voltage VDD. Therefore, the luminance unevenness due to the voltage drop of the driving voltage VDD can be largely eliminated.

In the above description, the driving TFT and the switching TFTs are PMOS transistors. However, the plurality of TFTs according to the present invention include NMOS transistors. In addition, the OLED 110 includes both a top emission method and a bottom emission method in which light is emitted upward.

As described above, the present invention provides a device capable of compensating a threshold voltage in real time and an organic light emitting diode display including the device, thereby sensing a threshold voltage of a driving TFT in real time and compensating the threshold voltage. It is possible to prevent deterioration of image quality of the light emitting display device.

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 present invention as defined by the following claims and their equivalents. Only. It is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. .

10: Gate In Panel (GIP)
20: Data driver
30: a pixel circuit
40: controller
51 to 54: EM line
61 to 64: scan line
71 to 74: Data line
102: nth scan line
103: (n-1) th scan line
104: EM line
105: Data line
106: Initial voltage line
110: OLED
Cst: storage capacitor
DT: driving TFT
T1 to T8: switching TFT

Claims (11)

A pixel circuit for use in an organic light emitting display,
A first scan line, a second scan line, an EM line, a data line, an initial voltage line, a driving TFT and an organic light emitting diode,
And a high potential voltage of the first scan signal is used as a driving voltage for driving the organic light emitting diode.
Pixel circuit. The method according to claim 1,
Further comprising first to seventh switching TFTs and a storage capacitor,
The source and the drain of the first switching TFT are respectively connected to the gate of the driving TFT, the second scanning line, and the drain of the driving TFT,
A source, a gate, and a drain of the second switching TFT are respectively connected to the source of the data line, the second scan line, and the driving TFT,
A source and a gate of the third switching TFT are respectively connected to a first node and the EM line, a drain of the third switching TFT is connected together to a drain of the second switching TFT and a source of the driving TFT,
The source, the gate, and the drain of the fourth switching TFT are respectively connected to the drain of the driving TFT, the EM line, and one end of the organic light emitting diode,
The source, the gate, and the drain of the fifth switching TFT are respectively connected to the gates of the initial voltage line, the first scan line, and the driving TFT,
A source, a gate, and a drain of the sixth switching TFT are respectively connected to one end of the organic light emitting diode, the second scan line, and the initial voltage line,
Source, gate and drain of the seventh switching TFT are connected to the first scan line, the EM line, and the first node, respectively,
The storage capacitor being located between the gate of the first node and the driving TFT,
Wherein the first node is a point where a drain of the seventh switching TFT, a source of the third switching TFT, and one end of the storage capacitor are connected,
Pixel circuit. 3. The method of claim 2,
A first scan signal is applied to the first scan line,
A second scan signal is applied to the second scan line,
A light emission signal is applied to the EM line,
A data voltage is applied to the data line,
An initial voltage is applied to the initial voltage line,
The organic light emitting diodes are divided into a first period to a fourth period to emit light,
In the first period, the first scan signal is in an ON state, the second scan signal and an emission signal are in an OFF state,
In the second period, the second scan signal is in the on state, the first scan signal and the light emission signal are in the off state,
In the third period, the first scan signal, the second scan signal,
In the fourth period, the first scan signal and the second scan signal are in the off state and the light emission signal is in the on state.
Pixel circuit. The method of claim 3,
In the first period, the fifth switching TFT is turned on by the first scan signal,
In the second period, the first switching TFT, the second switching TFT, and the sixth switching TFT are turned on by the second scan signal, the initial voltage is applied to the first node,
And the third switching TFT, the fourth switching TFT, and the seventh switching TFT are turned on by the light emitting signal in the fourth period,
Pixel circuit. 5. The method of claim 4,
Further comprising an eighth switching TFT,
A source, a gate, and a drain of the eighth switching TFT are connected to the initial voltage line, the second scan line, and the first node, respectively,
And the eighth switching TFT is turned on by the second scan line during the second period to apply the initial voltage to the first node,
Pixel circuit. The method according to claim 1,
The driving TFT is a PMOS or NMOS,
Pixel circuit. An organic light emitting display device,
A plurality of pixel circuits arranged in a lattice form in a display region;
A scan line, an EM line, and an initial voltage line arranged in a first direction to provide a first scan signal, a second scan signal, a light emission signal, and an initial voltage to each pixel circuit of the plurality of pixel circuits; And
A data line arranged orthogonal to the scan line, the EM line, and the initial voltage line to provide a data voltage to the plurality of pixel circuits; / RTI >
Wherein each pixel circuit of the plurality of pixel circuits uses a voltage (high-potential voltage) when the first scan signal is turned off as a driving voltage for driving the organic light emitting diode,
Organic light emitting display. 8. The method of claim 7,
In a plurality of pixel circuits in an nth row in a second direction orthogonal to the first direction,
The first scan signal is a scan signal for a plurality of pixel circuits in the (n-1) th row in the second direction,
Wherein the second scan signal is a scan signal for a plurality of pixel circuits in an n-th row in the second direction,
Organic light emitting display. 9. The method of claim 8,
A dummy scan line,
Wherein the dummy scan line provides the first scan signal for a plurality of pixel circuits in a first row in a second direction orthogonal to the first direction,
Organic light emitting display. 8. The method of claim 7,
For a plurality of pixel circuits in an n-th row in a second direction orthogonal to the first direction,
A second initial voltage line for providing a separate initial voltage, and a switching TFT,
Wherein the second initial voltage line is supplied with the initial voltage only when the second scan signal is turned on by the switching TFT,
Organic light emitting display. A method for driving an organic light emitting diode (OLED) in a pixel circuit that receives a first scan signal, a second scan signal, and an emission signal and emits an organic light emitting diode using a driving TFT,
A TFT initializing step of applying an initial voltage to the gate of the driving TFT by the first scan signal;
Sampling a voltage formed in the organic light emitting diode by the second scan signal to an initial voltage and applying a voltage obtained by subtracting a threshold voltage from an initial voltage and a data voltage to both ends of the storage capacitor; And
(High-potential voltage) of the first scan signal is applied to the source of the driving TFT by the emission signal, and the high-potential voltage is added to the voltage charged in the storage capacitor at the gate of the driving TFT And generating a current for driving the organic light emitting diode by applying a voltage to the organic light emitting diode.
A method for emitting an organic light emitting diode.

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