Gate driver, organic light emitting diode display device and driving method thereof

Abstract

Disclosed is a gate driver, an organic light emitting diode display device and a driving method thereof, capable of preventing a driving transistor from affecting a light emitting diode when power is applied and when impedance is measured. The organic light emitting diode display device includes an organic light emitting diode including an organic compound layer formed between an anode electrode and a cathode electrode; a gate driver including a first scan driver for providing a first scan signal, a second scan driver for providing a second scan signal, and a light emitting control driver for providing a light emitting control signal; and a level shifter for providing an operating voltage to the light emitting control driver.

Description

[0001] This application is a divisional application of the invention patent application entitled “Gate driver, organic light-emitting diode display device and driving method thereof” with application number 201911206498.6 filed on November 29, 2019.

[0002] This application claims the benefit of Korean Patent Application No. 10-2018-0161539, filed on December 14, 2018, which is hereby incorporated by reference as if fully set forth herein. Technical Field

[0003] The present invention relates to an organic light emitting diode display device, and more particularly, to an organic light emitting diode display device capable of preventing a driving transistor from affecting a light emitting diode when power is applied and when impedance is measured. Background Art

[0004] Recently, various flat panel displays (FPDs) have been developed at an accelerated pace. In particular, organic light emitting diode (OLED) displays use self-luminous elements that emit light by themselves, and thus have fast response speed, high luminous efficiency, high brightness, and a wide viewing angle.

[0005] An organic light-emitting diode display device has an organic light-emitting diode in each pixel. The organic light-emitting diode includes an organic compound layer formed between an anode electrode and a cathode electrode. The organic compound layer includes a hole injection layer (HIL), a hole transport layer (HTL), an emissive 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 hole transport layer (HTL) and electrons passing through the electron transport layer (ETL) move to the emissive layer (EML) to form excitons, resulting in the emissive layer (EML) generating visible light.

[0006] In an organic light-emitting diode display device, pixels, each including an organic light-emitting diode, are arranged in a matrix, and the brightness of the pixels is controlled by the grayscale of video data. In an organic light-emitting diode display device, a TFT, which is an active element, is selectively turned on to select a pixel, and the pixel's light emission is maintained by the voltage stored in a storage capacitor.

[0007] When measuring the impedance of an organic light emitting diode used to compensate for the threshold voltage of a driving transistor of an organic light emitting diode display device, current leakage may occur in areas other than the sensing path, resulting in measurement errors, or an undesirable current path may be formed in the organic light emitting diode in the display panel when power is applied, resulting in image quality issues such as screen flicker. Summary of the Invention

[0008] Accordingly, the present invention is directed to a gate driver, an organic light emitting diode display device using the same, and a driving method thereof that substantially obviate one or more problems due to limitations and disadvantages of the related art.

[0009] An object of the present invention is to provide an organic light emitting diode display device capable of preventing a driving transistor from affecting a light emitting diode when power is applied and when impedance is measured.

[0010] Another object of the present invention is to provide an organic light emitting diode display device capable of blocking a path of current flowing into an organic light emitting diode when power is applied and when impedance is measured.

[0011] Still another object of the present invention is to provide an organic light emitting diode display device capable of preventing screen flickering that is undesirable to a user due to abnormal voltage formed in an organic light emitting diode when power is applied.

[0012] Still another object of the present invention is to provide an organic light emitting diode display device capable of preventing degradation of product performance by preventing abnormal operation when power is applied.

[0013] The following description will partially list additional advantages, objects, and features of the present invention, some of which will become apparent to those skilled in the art from the following explanation or may be learned through practice of the present invention. These and other advantages of the present invention may be realized and obtained through the structures specifically pointed out in the specification, claims, and drawings.

[0014] To achieve these objects and other advantages, and in accordance with the intent of the present invention, as embodied and broadly described herein, an organic light emitting diode display device includes: a driving transistor connected to one end of an organic light emitting diode to provide an operating current to the organic light emitting diode; a light emitting switching transistor that switches according to a light emitting control signal to control the flow of current provided from the driving transistor to the organic light emitting diode; and a timing controller for controlling to maintain the light emitting switching transistor in an off state before internal terminals of a pixel of a display panel are stabilized when power is applied, so that the driving transistor does not affect the organic light emitting diode.

[0015] The organic light emitting diode display device according to the present invention may further include a level shifter configured to receive a control signal from the timing controller and provide an operating voltage to the light emitting control driver.

[0016] In the organic light emitting diode display device according to the present invention, the timing controller may output a control signal for changing a reference voltage of the light emitting control driver when power is applied.

[0017] In another aspect of the present invention, an organic light-emitting diode display device includes: a driving transistor connected to one end of an organic light-emitting diode to provide an operating current to the organic light-emitting diode; a light-emitting switching transistor that switches according to a light-emitting control signal to control the flow of current provided from the driving transistor to the organic light-emitting diode; and a timing controller for controlling to maintain the light-emitting switching transistor in an off state when measuring the impedance of the organic light-emitting diode so that the driving transistor does not affect the organic light-emitting diode.

[0018] In another aspect of the present invention, a gate driver includes: a first scan driver for providing a first scan signal for transmitting a data voltage to a gate electrode of a driving transistor, wherein the driving transistor is used to provide an operating current to an organic light emitting diode; a second scan driver for providing a second scan signal for transmitting a voltage stored in a storage capacitor to a drain electrode of the driving transistor, wherein the storage capacitor is connected to the gate electrode of the driving transistor; and a light emitting control driver for outputting a light emitting control signal for controlling the flow of current provided from the driving transistor to the organic light emitting diode, so that the driving transistor does not affect the organic light emitting diode when measuring the impedance of the organic light emitting diode.

[0019] In another aspect of the present invention, a gate driver includes: a first scan driver for providing a first scan signal for transmitting a data voltage to a gate electrode of a driving transistor, wherein the driving transistor is used to provide an operating current to an organic light emitting diode; a second scan driver for providing a second scan signal for transmitting a voltage stored in a storage capacitor to a drain electrode of the driving transistor, wherein the storage capacitor is connected to the gate electrode of the driving transistor; and a light emitting control driver for outputting a light emitting control signal for controlling the flow of current provided from the driving transistor to the organic light emitting diode so that the driving transistor does not affect the organic light emitting diode when power is applied.

[0020] In another aspect of the present invention, a method for driving an organic light-emitting diode display device includes: determining a predetermined driving condition through a timing controller; generating a control signal through the timing controller, the control signal being used to block a current provided from a driving transistor to an organic light-emitting diode so that the driving transistor does not affect the organic light-emitting diode before an internal terminal of a pixel of a display panel is stabilized; providing the control signal to a light-emitting control driver through the timing controller; and controlling through the light-emitting control driver such that a light-emitting switching transistor disposed between the driving transistor and the organic light-emitting diode is turned off.

[0021] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this application, illustrate embodiments of the present invention and together with the description serve to explain the principle of the present invention. In the drawings:

[0023] Figure 1 is a diagram showing a pixel structure of an organic light emitting diode display device according to the present invention;

[0024] Figure 2 is a diagram showing a circuit structure of a sub-pixel of an organic light emitting diode display device according to the present invention;

[0025] Figure 3 is a waveform diagram showing a signal applied to a pixel to compensate for the threshold voltage of a driving transistor;

[0026] Figure 4 is a diagram showing a current path formed instantaneously between VDD and VSS;

[0027] Figure 5 is a schematic block diagram showing a configuration of supplying power to an organic light emitting diode display device according to an embodiment for solving the problem;

[0028] Figure 6 is a timing waveform diagram of the voltage level applied to the driving transistor D-TFT in the pixel, the output signal of the timing controller, the light emitting control signal, the first scanning signal, and the second scanning signal;

[0029] Figure 7 Is the display pixel circuit in Figure 6 Schematic diagram of the operating state in the first period (step 1). DETAILED DESCRIPTION

[0030] While specific structures or functions are described for the purpose of explaining the embodiments of the present invention, the embodiments of the present invention may be implemented in various forms and should not be limited to the embodiments disclosed herein.

[0031] Since the present invention can be modified in various ways and has many exemplary embodiments, specific exemplary embodiments will be shown in the drawings and described in detail. However, it should be understood that the present invention is not limited to these specific exemplary embodiments, but includes all modifications, equivalents and replacements included in the spirit and scope of the present invention.

[0032] Terms such as "first," "second," and the like may be used to describe various components, but these components should not be construed as being limited by these terms. These terms are used only to distinguish one component from another. For example, a "first" component may be referred to as a "second" component, and similarly, a "second" component may be referred to as a "first" component without departing from the scope of the present invention.

[0033] It should be understood that when an element is referred to as being “connected to” or “coupled to” another element, it can be directly connected or directly coupled to the other element, or it can be connected or coupled to the other element with other elements interposed therebetween. On the other hand, it should be understood that when an element is referred to as being “directly connected to” or “directly coupled to” another element, it is connected or coupled to the other element without other elements interposed therebetween. Other expressions describing the relationship between components, i.e., “between,” “directly between,” “adjacent,” “directly adjacent,” etc., should be similarly interpreted.

[0034] The terms used in this application are intended only to describe specific exemplary embodiments and are not intended to limit the present invention. It will be further understood that the terms "including" or "having" used in this application are intended to indicate the presence of a referenced feature, step, operation, component, part, or combination thereof, but do not preclude the presence or addition of one or more other features, steps, operations, components, parts, or combinations thereof.

[0035] Unless otherwise indicated, all terms (including technical and scientific terms) used in this application should be understood to have the same meaning as understood by those skilled in the art. It must be understood that the terms defined by dictionaries are consistent with their meanings in the context of the relevant technology and should not be defined in an idealized or overly formal manner unless the context clearly indicates otherwise.

[0036] On the other hand, when implementing the embodiment in other ways, the functions or operations specified in the specific blocks can be performed in an order different from the order specified in the flow chart. For example, two consecutive blocks can be executed roughly at the same time in practice, and these blocks can be executed in reverse according to the related functions or operations.

[0037] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0038] Figure 1 is a diagram showing a pixel structure of an organic light emitting diode display device 100 according to an embodiment of the present invention.

[0039] Reference Figure 1 According to an embodiment of the present invention, an organic light emitting diode display device 100 may include: an organic light emitting display panel 110, on which a plurality of data lines DL and a plurality of gate lines GL are provided and a plurality of sub-pixels SP defined by the plurality of data lines DL and the plurality of gate lines GL are arranged; a data driver 120 for driving the plurality of data lines DL and a gate driver 130 for driving the plurality of gate lines GL.

[0040] In addition, the organic light emitting diode display device 100 according to the embodiment of the present invention may further include a timing controller 140 for controlling the data driver 120 and the gate driver 130 .

[0041] The timing controller 140 may provide various types of control signals to the data driver 120 and the gate driver 130 to control the data driver 120 and the gate driver 130 .

[0042] The timing controller 140 starts scanning according to the timing implemented in each frame, converts input image data received from the outside into data signals suitable for use in the data driver 120, outputs the converted image data, and controls data driving at appropriate times according to scanning.

[0043] The timing controller 140 may be a timing controller used in general display technology or a control device including a timing controller that performs other control functions.

[0044] The timing controller 140 may be implemented independently from the data driver 120 or may be implemented integrated with the data driver 120 .

[0045] The data driver 120 supplies data voltages to the plurality of data lines DL, thereby driving the plurality of data lines DL. Here, the data driver 120 is also referred to as a source driver.

[0046] The data driver 120 may include at least one source driver integrated circuit (SDIC).

[0047] Each source driver integrated circuit (SDIC) may include a shift register, a latch circuit, a digital-to-analog converter (DAC), and an output buffer.

[0048] In some cases, each source driver integrated circuit (SDIC) may further include an analog-to-digital converter (ADC).

[0049] The gate driver 130 sequentially supplies scan signals to the plurality of gate lines GL, thereby sequentially driving the plurality of gate lines GL. Here, the gate driver 130 is also referred to as a scan driver.

[0050] The gate driver 130 may include at least one gate driver integrated circuit (GDIC).

[0051] Each gate driver integrated circuit (GDIC) may include, for example, a shift register and a level shifter.

[0052] The gate driver 130 sequentially supplies a scan signal of an on voltage or an off voltage to the plurality of gate lines GL under the control of the timing controller 140 .

[0053] The data driver 120 converts the image data Data received from the timing controller 140 into analog data voltages, and when a specific gate line is turned on by the gate driver 130 , the data driver 120 supplies the analog data voltages to the plurality of data lines DL.

[0054] like Figure 1 As shown in FIG, the data driver 120 may be located only on one side (e.g., the upper side, the lower side, the left side, or the right side) of the organic light-emitting display panel 110. In some cases, depending on a driving method, a panel design method, etc., the data driver 120 may be located on both sides (e.g., the upper side and the lower side or the left side and the right side) of the organic light-emitting display panel 110.

[0055] like Figure 1 As shown in FIG, the gate driver 130 may be located only on one side (e.g., the left side, right side, upper side, or lower side) of the organic light-emitting display panel 110. In some cases, depending on a driving method, a panel design method, etc., the gate driver 130 may be located on both sides (e.g., the left and right sides or the upper and lower sides) of the organic light-emitting display panel 110.

[0056] The timing controller 140 receives various types of timing signals including a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), an input data enable (DE) signal, and a clock signal (CLK) from the outside (eg, a host system).

[0057] The timing controller 140 receives timing signals such as a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), an input DE signal, and a clock signal, and generates and outputs various types of control signals to the data driver 120 and the gate driver 130 so as to control the data driver 120 and the gate driver 130.

[0058] For example, the timing controller 140 outputs various types of gate control signals GCS, including a gate start pulse (GSP), a gate shift clock (GSC), and a gate output enable signal (GOE), in order to control the gate driver 130 .

[0059] Here, the gate start pulse (GSP) controls the operation start timing of one or more gate driver integrated circuits constituting the gate driver 130. The gate shift clock (GSC) is a clock signal commonly input to one or more gate driver integrated circuits and controls the shift timing of the scan signal (gate pulse). The gate output enable signal GOE specifies the timing information of one or more gate driver integrated circuits.

[0060] In addition, the timing controller 140 outputs various types of data control signals DCS, including a source start pulse (SSP), a source sampling clock (SSC), and a source output enable signal (SOE), in order to control the data driver 120 .

[0061] Here, the source start pulse (SSP) controls the data sampling start timing of one or more source driver integrated circuits constituting the data driver 120. The source sampling clock (SSC) is a clock signal used to control the data sampling timing of each source driver integrated circuit. The source output enable signal (SOE) controls the output timing of the data driver 120.

[0062] Each sub-pixel SP arranged on the organic light emitting display panel 110 includes circuit elements such as an organic light emitting diode (OLED) as a self-luminous element and a driving transistor for driving the organic light emitting diode (OLED).

[0063] The type and number of circuit elements constituting each sub-pixel SP may be variously determined according to provided functions and design methods.

[0064] Figure 2 1 is a diagram showing a circuit structure of a sub-pixel of an organic light emitting diode display device according to the present invention. Figure 3 As shown in , pixel operations are performed in three periods (step 1, step 2, and step 3).

[0065] Each subpixel SP includes a driving transistor D-TFT, first to fifth TFTs T1 to T5, a storage capacitor Cst, and an organic light emitting diode OLED. The first to fifth TFTs T1 to T5 and the driving transistor D-TFT are implemented as p-type metal oxide semiconductor thin film transistors (MOSTFTs). Although p-type MOSTFTs are described in this embodiment, n-type MOSTFTs may be used, and descriptions of structural variations will be omitted.

[0066] The driving transistor D-TFT supplies a driving current from an input terminal of a high potential driving voltage VDD to the organic light emitting diode OLED and controls the driving current by a gate-source voltage. The gate electrode (control electrode) of the driving transistor D-TFT is connected to a first node N1. The source electrode (first electrode) of the driving transistor D-TFT is connected to an input terminal of a high potential driving voltage VDD, and the drain electrode (second electrode) thereof is connected to a second node N2.

[0067] The first TFT T1 switches a current path between the data line and the third node N3 in response to the first scan pulse Scan1. The first TFT T1 is turned on during the second period (step 2) to provide the data voltage Vdata to the third node N3. The gate electrode of the first TFT T1 is connected to the first gate line. The source electrode of the first TFT T1 is connected to the data line, and the drain electrode thereof is connected to the third node N3.

[0068] The second TFT T2 switches the current path between the first node N1 and the second node N2 in response to the second scan pulse Scan2. The second TFT T2 is a sampling TFT and is turned on during the second period (step 2) to diode-connect the drive transistor D-TFT so that the threshold voltage of the drive transistor D-TFT is applied to the first node N1. The gate electrode of the second TFT T2 is connected to the second gate line. The source electrode of the second TFT T2 is connected to the first node N1 and the drain electrode thereof is connected to the second node N2.

[0069] The third TFT T3 switches the current path between the third node N3 and the input terminal of the reference voltage Vref in response to the light emission control pulse EM. The third TFT T3 is turned on during the first period and the third period (steps 1 and 3) to apply the reference voltage Vref to the third node N3. The gate electrode of the third TFT T3 is connected to the light emission control signal line, and the third TFT T3 supplies the reference voltage Vref to the third node in response to the light emission control pulse EM. The source electrode of the third TFT T3 is connected to the input terminal of the reference voltage Vref, and the drain electrode thereof is connected to the third node N3.

[0070] The fourth TFT T4 switches the current path between the second node N2 and the fourth node N4 in response to the light emission control pulse EM. The fourth TFT T4 is turned on during the first and third periods (steps 1 and 3) to form a current path between the drive transistor D-TFT and the organic light emitting diode OLED. The fourth TFT T4 is turned off during the second period (step 2) to block the current path between the drive transistor D-TFT and the organic light emitting diode OLED. The gate electrode of the fourth TFT T4 is connected to the light emission control signal line, the source electrode is connected to the second node N2, and the drain electrode is connected to the fourth node N4.

[0071] The fifth TFT T5 switches a current path between the input terminal of the reference voltage Vref and the fourth node N4 in response to the second scan pulse Scan2. The fifth TFT T5 is turned on during the first and second periods (step 1 and step 2) to apply the reference voltage Vref to the fourth node N4.

[0072] A gate electrode of the fifth TFT T5 is connected to the second gate line, a source electrode of the fifth TFT T5 is connected to the fourth node N4, and a drain electrode thereof is connected to an input terminal of a reference voltage Vref.

[0073] The storage capacitor Cst is connected between the first node N1 and the third node N3 to maintain the gate voltage of the driving transistor D-TFT.

[0074] This organic light emitting diode display device compensates for changes in the threshold voltage of the driving transistor D-TFT by a voltage compensation driving method. In the organic light emitting diode display device for voltage compensation, after a storage capacitor is connected to the gate of the driving transistor D-TFT and a sampling TFT T2 is connected between the gate and drain of the driving transistor D-TFT, the sampling TFT T2 is turned on to make the driving transistor D-TFT diode-connected, thereby reducing the threshold voltage (V th ) is stored in the storage capacitor Cst.

[0075] In order to compensate the threshold voltage of the driving transistor D-TFT, as Figure 3As shown in , the pixel operation is performed in three steps. In step 1, because the first scan signal Scan1 is output as a high signal, the first transistor T1 is in the off state; because the second scan signal Scan2 is output as a low signal, the sampling transistor T2 and the fifth transistor T5 are in the on state, and because the light emitting control signal EM is output as a low signal, the fourth transistor provided between the drain terminal of the driving transistor D-TFT and the anode of the organic light emitting diode is in the on state. Therefore, since the second transistor T2 as the sampling transistor is in the on state during step 1, the gate and source of the driving transistor D-TFT are connected, thereby resulting in a diode connection. Through this operation, as shown in FIG. Figure 4 As shown in , a current path connecting two diodes from VDD to VSS is instantaneously formed, causing the organic light-emitting diode to emit light momentarily. At this point, the user does not want the organic light-emitting diode to emit light, which can lead to image quality issues such as screen flicker. Even when power is applied (powered on), the light-emission control signal is output as a low signal, so screen flicker occurs due to the undesired current path, resulting in image quality issues.

[0076] Figure 5 is a schematic block diagram showing a configuration of supplying power to an organic light emitting diode display device according to an embodiment for solving such a problem.

[0077] As shown in the figure, the power control circuit 200, the gate driver 130 and the timing controller 140 are included. The gate driver 130 includes a Figure 2 The first transistor T1 provides a first scan signal Scan1 to the first scan driver 131, Figure 2 The second scan driver 132 provides a second scan signal Scan2 to the second transistor T2 and the fifth transistor T5. Figure 2 The third transistor T3 and the fourth transistor T4 provide a light emitting control driver 133 that provides a light emitting control signal EM, and the level shifter 134, the level shifter 134 is used to receive the high voltage signal VGH and the low voltage signal VGL from the power control circuit 200, amplify their voltage levels and provide operating powers EVGH and EVGL to the light emitting control driver 133.

[0078] At this time, the level shifter 134 receives a voltage level control signal from the timing controller 140. The level shifter 134 receives the control signal from the timing controller 140 and provides an operating voltage to the light emission control driver 133. The voltage level control signal is used to change the reference voltage of the light emission control driver 133, causing the light emission control driver 133 to output a logic high signal. Therefore, the fourth TFT T4, which serves as the light emission switching transistor in the pixel circuit, switches the current path between the second node N2 and the fourth node N4 in response to the light emission control pulse EM.

[0079] At this time, the voltage level VDD provided to the driving transistor D-TFT in the pixel, the output signal T-CON OUT of the timing controller 140, the light emitting control signal (or pulse) EM OUT, the first scan signal Scan1 and the second scan signal Scan2 are as follows: Figure 6 appears as shown in the timing waveform diagram.

[0080] At this time, the first period (step 1) refers to the time until the internal terminals of the pixels of the display panel stabilize when power is applied and the time for impedance measurement, and step 2 refers to the display period. As shown in the figure, in step 1, the output signal T-CON OUT of the timing controller 140, the output signal EM OUT of the light emission control driver, and the first scan signal Scan1 show a logic high, and the second scan signal Scan2 shows a logic low. Therefore, in the pixel circuit, as shown in FIG. Figure 7 As shown in FIG, by the second scan signal Scan2 indicating a logic low, the second transistor T2 and the fifth transistor T5 are turned on, and the third transistor T3 and the fourth transistor T4 are turned off. Therefore, during a first period T1 representing the time when power is applied and impedance is measured, the current path from the drive transistor D-TFT to the organic light emitting diode OLED is blocked. In other words, the emission control switch transistor T4 switches according to the emission control signal EM OUT, thereby controlling the flow of current from the drive transistor D-TFT to the organic light emitting diode OLED.

[0081] The impedance of the organic light emitting diode is transmitted to the data driver through the sensing path, which is connected to the reference voltage supply line through the fifth transistor T5 turned on by the second scan signal Scan2.

[0082] As described above, the organic light emitting diode display device according to the present invention can prevent the occurrence of a screen flicker phenomenon that is undesirable to the user due to a current path from a driving transistor to an organic light emitting diode when power is applied and when impedance is measured.

[0083] The organic light emitting diode display device according to the present invention may have the following effects.

[0084] First, it prevents screen flickering from occurring when power is applied.

[0085] Second, it prevents screen flickering when measuring impedance.

[0086] Third, it can prevent screen flickering that users don't want.

[0087] While the invention has been described with reference to exemplary embodiments, those skilled in the art will appreciate that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as described in the appended claims.

Claims

1. An organic light emitting diode display device, comprising: an organic light emitting diode comprising an organic compound layer formed between an anode electrode and a cathode electrode; a gate driver comprising a first scan driver for providing a first scan signal, a second scan driver for providing a second scan signal, and a light emitting control driver for providing a light emitting control signal; a driving transistor connected to one end of the organic light emitting diode to provide an operating current to the organic light emitting diode; as well as a level shifter configured to receive a voltage level control signal and provide an operating voltage to the light emitting control driver, The voltage level control signal is used to enable the light emitting control driver to provide a light emitting control signal when power is applied or when impedance is measured, so as to block a current path from the driving transistor to the organic light emitting diode.

2. The organic light emitting diode display device according to claim 1, further comprising: A light emitting switching transistor is switched according to a light emitting control signal to control the flow of current supplied from the driving transistor to the organic light emitting diode.

3. The organic light emitting diode display device according to claim 2, wherein the driving transistor includes a gate electrode connected to a first node (N1), a source electrode connected to an input terminal of a high potential driving voltage, and a drain electrode connected to a second node (N2); as well as The organic light emitting diode display device further includes: a first TFT that switches a current path between the data line and a third node (N3) in response to a first scan signal; a second TFT that switches a current path between the first node (N1) and the second node (N2) in response to a second scan signal; a third TFT that switches a current path between a third node (N3) and an input terminal of a reference voltage (Vref) in response to a light emitting control signal; a fourth TFT, the fourth TFT switching a current path between the second node (N2) and a fourth node (N4) in response to a light emitting control signal; a fifth TFT that switches a current path between an input terminal of a reference voltage (Vref) and a fourth node (N4) in response to a second scan signal; A storage capacitor (Cst) is connected between the first node (N1) and the third node (N3) to maintain a gate voltage of the driving transistor.

4. The organic light emitting diode display device according to claim 3, The driving transistor and the first to fifth TFTs are implemented by p-type metal oxide semiconductor thin film transistors or n-type metal oxide semiconductor thin film transistors.

5. The organic light emitting diode display device according to claim 1 , further comprising: A power control circuit provides a high voltage signal and a low voltage signal to the first scan driver, the second scan driver, the light emission control driver, and the level shifter.

6. The organic light emitting diode display device according to claim 1, The organic compound layer includes a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer and an electron injection layer.

7. The organic light emitting diode display device according to claim 1, A first period indicating a time until internal terminals of pixels of the display panel are stabilized when power is applied and a time for impedance measurement and a second period indicating a display period are driven.

8. The organic light emitting diode display device according to claim 2, wherein the first scan driver is used to provide a first scan signal for transmitting a data voltage to a gate electrode of a driving transistor, and the driving transistor is used to provide an operating current to the organic light emitting diode; wherein the second scan driver is used to provide a second scan signal for transmitting a voltage stored in a storage capacitor to a drain electrode of the driving transistor, wherein the storage capacitor is connected to a gate electrode of the driving transistor; as well as wherein the light emission control driver is configured to output a light emission control signal for controlling the flow of current supplied from the drive transistor to the organic light emitting diode, so that the drive transistor does not affect the organic light emitting diode when measuring the impedance of the organic light emitting diode, The light emission control driver changes the voltage supplied from the power control circuit according to the supplied reference signal to output a light emission control signal.

9. The organic light emitting diode display device according to claim 8, The level shifter is configured to receive a high voltage signal and a low voltage signal from the power control circuit, amplify voltage levels of the high voltage signal and the low voltage signal, and provide operating power to the light emission control driver.

10. The organic light emitting diode display device according to claim 2, further comprising: a timing controller configured to control the light-emitting switch transistor to be kept in an off state so that, when measuring the impedance of the organic light-emitting diode, the driving transistor does not affect the organic light-emitting diode before an internal terminal of a pixel of a display panel is stabilized; When measuring the impedance of the organic light emitting diode, the timing controller outputs a control signal for changing the reference voltage of the light emitting control driver.

11. The organic light emitting diode display device according to claim 2, wherein the first scan driver is used to provide a first scan signal for transmitting a data voltage to a gate electrode of a driving transistor, and the driving transistor is used to provide an operating current to the organic light emitting diode; wherein the second scan driver is used to provide a second scan signal for transmitting a voltage stored in a storage capacitor to a drain electrode of the driving transistor, wherein the storage capacitor is connected to a gate electrode of the driving transistor; as well as wherein the light emission control driver is configured to output a light emission control signal for controlling the flow of current supplied from the drive transistor to the organic light emitting diode so that the drive transistor does not affect the organic light emitting diode when power is applied, The light emission control driver changes the voltage supplied from the power control circuit according to the supplied reference signal to output a light emission control signal.

12. The organic light emitting diode display device according to claim 11, The level shifter is configured to receive a high voltage signal and a low voltage signal from the power control circuit, amplify voltage levels of the high voltage signal and the low voltage signal, and provide operating power to the light emission control driver.

13. The organic light emitting diode display device according to claim 2, further comprising: a timing controller configured to control the light emitting switching transistor to be kept in an off state before internal terminals of pixels of the display panel are stabilized when power is applied so that the driving transistor does not affect the organic light emitting diode, The timing controller outputs a control signal for changing a reference voltage of the light emitting control driver when power is applied.

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