KR20050111918A - Pixel test method for array of light emitting panel and deriver thereof - Google Patents

Abstract

The present invention provides a pixel inspection method capable of inspecting elements of a pixel circuit arranged in a light emitting display panel array.

The present invention is a pixel inspection method of a display panel array in which pixel circuits in which light emitting elements are formed on pixel electrodes are arranged in a matrix form. First, the pixel circuit according to the present invention includes a driving transistor for outputting a current corresponding to the voltage difference between the gate electrode and the first main electrode to the second main electrode, and a diode transistor for diode-connecting the driving transistor. In the display panel array having such a pixel circuit, the driving transistor turns on a diode transistor for diode-connecting the driving transistor while the electrode and the pixel electrode are electrically connected to each other. Next, the electron beam is irradiated to the pixel electrode while the diode transistor is turned on. Then, the amount of electrons emitted from the pixel electrode is detected. It may be determined whether the driving transistor and the diode transistor are normal based on the detected amount of electrons.

Description

Pixel test method for array of light emitting panel and deriver

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix display panel, and more particularly, to a pixel inspection method and a scan driving apparatus capable of performing pixel inspection of an organic EL display panel array having an active matrix structure.

In general, an organic EL display device is a display device for electrically exciting a fluorescent organic compound to emit light, and is capable of displaying an image by voltage driving or current driving N × M organic light emitting cells arranged in a matrix form.

Such an organic light emitting cell has a diode characteristic and is also called an organic light emitting diode (OLED), and has a structure of an anode (ITO), an organic thin film, and a cathode electrode layer (metal), as shown in FIG. 1. The organic thin film has a multilayer structure including an emitting layer (EML), an electron transport layer (ETL), and a hole transport layer (HTL) to improve the emission efficiency by improving the balance between electrons and holes. It also includes a separate electron injecting layer (EIL) and a hole injecting layer (HIL). These organic light emitting cells are arranged in an N × M matrix to form an organic EL display panel.

The organic EL display panel may be driven by a simple matrix method and an active matrix type using a thin film transistor (hereinafter, referred to as TFT). In the simple matrix method, the anode and the cathode are orthogonal and the line is selected and driven, whereas the active matrix type connects the thin film transistor to each indium tin oxide (ITO) pixel electrode and maintains the voltage maintained by the capacitor capacitance connected to the thin film transistor. According to the driving method. Accordingly, the active matrix display panel includes at least one thin film transistor and a capacitor in the pixel.

Such a display panel is assembled to a module, and a full inspection is performed. However, if the inspection is carried out after assembly to the module, a problem arises in that a waste cost increases when a defective product occurs. Particularly, in the active matrix organic EL display panel, a plurality of elements are formed in the pixel, and the characteristic variation of the internal elements caused by the poly-silicon process is large, so that defective products are likely to occur. If it occurs, the wasted cost is even greater.

Accordingly, there is a need for a pixel inspection method capable of inspecting a display panel array and a driving apparatus capable of performing pixel inspection of the array so that defects of elements of the pixel circuit can be found before assembly to the module.

An object of the present invention is to provide a pixel inspection method capable of inspecting elements of a pixel circuit arranged in a display panel array.

Another object of the present invention is to provide a driving apparatus capable of performing inspection driving of a pixel circuit arranged in a display panel array.

A pixel inspection method of a display panel array according to an aspect of the present invention is a pixel inspection method of a display panel array in which pixel circuits in which light emitting elements are formed on pixel electrodes are arranged in a matrix form.

The pixel circuit

A capacitor charging a voltage corresponding to an applied data signal; And a first transistor including a gate electrode connected to one electrode of the capacitor, a first electrode to which power is applied, and a second electrode to output a current corresponding to a voltage difference between the gate electrode and the first electrode. A second transistor turned on in response to a first control signal to diode-connect the first transistor;

a) turning on the second transistor while the second electrode of the first transistor and the pixel electrode are electrically connected to each other;

b) irradiating an electron beam to a pixel electrode while the second transistor is turned on; And

c) detecting the amount of electrons emitted from the pixel electrode.

The pixel circuit may further include a third transistor that is turned on in response to a second control signal to electrically connect the second electrode of the first transistor to the pixel electrode.

In step a), the third transistor may be turned on.

According to another aspect of the present invention, a driving apparatus for inspecting an array of a light emitting display panel includes a plurality of scan lines extending in a first direction and transmitting a selection signal, insulated from and intersecting the scan lines, and extending in a second direction. A driving apparatus for inspecting an array of a light emitting display panel including a plurality of data lines to be transmitted and a plurality of pixel circuits respectively connected to the scan lines and the data lines.

The pixel circuit may include a first transistor including a gate electrode to which a data signal is applied, a first electrode to which power is applied, and a second electrode to output a current corresponding to a voltage difference between the gate electrode and the first electrode; A second transistor turned on in response to the selection signal to diode-connect the first transistor; A third transistor turned on in response to a control signal to electrically connect the second electrode of the first transistor to the pixel electrode; And a pixel electrode of the light emitting device electrically connected to the second electrode of the second transistor through the third transistor,

The drive for inspecting the array,

A shift register for generating selection signals to be sequentially applied to the plurality of scan lines; And receiving the selection signal and an inspection signal indicating an inspection operation or a driving operation, and generating the selection signal and the control signal to turn on the second transistor and the third transistor when the inspection signal indicating the inspection operation is input. And a signal applying unit configured to generate and output the selection signal for turning on the second transistor and the control signal for turning off the third transistor when the test signal indicating the driving operation is inputted.

When the inspection signal instructing the inspection operation is input, the signal applying unit may output the control signal at the same level as the selection signal.

The signal applying unit includes a logic gate configured to input the inspection signal and the selection signal and output the control signal, wherein the logic gate correlates with the selection signal when the inspection signal instructing the inspection operation is input. The control signal for turning on the same third transistor may be output without the same.

According to another aspect of the present invention, a SOP light emitting display device includes: a plurality of scan lines extending in a first direction and sequentially transmitting a selection signal; a plurality of scan lines insulated from and intersecting the scan lines, extending in a second direction, and transmitting a data signal An SOP light emitting display device including a data line, a scan line driver configured to drive the scan line, and at least a portion of the data driver including the data line, on a light emitting display panel including a scan line and a plurality of pixel circuits respectively connected to the data line. as,

The pixel circuit,

A first transistor including a gate electrode to which a data signal is applied, a first electrode to which power is applied, and a second electrode to output a current corresponding to a voltage difference between the gate electrode and the first electrode; A second transistor turned on in response to the selection signal to diode-connect the first transistor; A third transistor turned on in response to a control signal to electrically connect the second electrode of the first transistor to the pixel electrode; And a pixel electrode of the light emitting device electrically connected to the second electrode of the second transistor through the third transistor,

The scan driver receives the selection signal and an inspection signal indicating an inspection operation or a driving operation, and when the inspection signal indicating an inspection operation is input, the selection signal for turning on the second transistor and the third transistor and the selection signal; A signal applying unit generating and outputting a control signal and generating and outputting the selection signal for turning on the second transistor and the control signal for turning off the third transistor when the test signal instructing a driving operation is input; do.

The signal applying unit includes a logic gate that inputs the test signal and the selection signal and outputs the control signal, wherein the logic gate is independent of the selection signal when the test signal instructing the test operation is input. A control signal for turning on the same third transistor may be output.

The pixel circuit may include a first capacitor configured to store a voltage corresponding to the applied data signal; A fourth capacitor turned on in response to the selection signal and connected in parallel with the first capacitor; A second capacitor charging a voltage corresponding to the threshold voltage of the first transistor; And a fifth transistor that is turned on in response to another selection signal applied after the selection signal to transfer the data signal.

DETAILED DESCRIPTION Hereinafter, exemplary 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. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification.

First, a pixel circuit and an operation thereof for explaining an array inspection method according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 is an arbitrary pixel circuit formed in an organic EL display panel array, and FIG. 2 is a view showing waveforms of signal lines applied to the pixel circuit of FIG.

As shown in Fig. 1, the pixel circuit includes transistors M1-M5, capacitors Cst and Cvth, and an organic EL element OLED.

The transistor M1 is a driving transistor for driving the organic EL element OLED. The transistor M1 is connected between a power supply for supplying the voltage VDD and the organic EL element OLED, and is applied to the gate by a voltage applied to the gate. The current flowing through the organic EL device OLED is controlled through the controller. Transistor M3 diode-connects transistor M1 in response to a selection signal from immediately preceding scan line Sk-1. One electrode A of the capacitor Cvth is connected to the gate of the transistor M1, and the capacitor Cst and the transistor M4 are connected between the other electrode B of the capacitor Cvth and a power supply for supplying the voltage VDD. Are connected in parallel. The transistor M4 supplies the power supply VDD to the other electrode B of the capacitor Cvth in response to the selection signal from the immediately preceding scan line Sk-1. The transistor M5 transmits the data signal transmitted from the data line Dm to the other electrode B of the capacitor Cvth in response to the selection signal from the current scan line Sk. The transistor M2 is connected between the drain of the transistor M1 and the anode of the organic EL element OLED, and responds to the selection signal from the immediately preceding scan line Sk-1 and the drain of the transistor M1 and the organic EL element OLED. ). The organic EL element OLED emits light corresponding to the current input from the transistor M1 through the transistor M2.

Next, the operation of the pixel circuit described above will be described in detail.

2 is a diagram illustrating waveforms of a scan selection signal and a light emission control signal applied to a pixel circuit.

As shown in FIG. 2, when the low level select signal is applied to the immediately preceding scan line Sk-1 during the period T1, the transistor M3 is turned on so that the transistor M1 is in a diode-connected state. Accordingly, the voltage between the gate and the source of the transistor M1 changes until the threshold voltage Vth of the transistor M1 becomes. At this time, since the source of the transistor M1 is connected to the power supply VDD, the voltage applied to the gate of the transistor M1, that is, the node A of the capacitor Cvth, is the power supply voltage VDD and the threshold voltage Vth. Is the sum of.

In addition, when the low level select signal is applied to the immediately preceding scan line Sk-1 during the period T1, the transistor M4 is also turned on, and the power supply VDD is applied to the node B of the capacitor Cvth. The voltage V _CVth charged in the capacitor Cvth is _expressed by Equation 2 below.

Here, VCvth means a voltage charged in the capacitor Cvth, VCvthA means a voltage applied to the node A of the capacitor Cvth, VCvthB means a voltage applied to the node B of the capacitor Cvth. .

In addition, during the period T1, a high level signal is applied to the emission control line EMIk so that the transistor M2 is turned off so that the current flowing through the transistor M1 flows to the organic EL element OLED. . During the period T1, a high level signal is applied to the current scan line Sk, so that the transistor M5 is turned off.

Next, during a period T2, when a low level scan voltage is applied to the current scan line Sk, the transistor M5 is turned on and the data voltage Vdata transferred from the data line Dk is applied to the node B. do. In addition, since the voltage corresponding to the threshold voltage Vth of the transistor M1 is already charged in the capacitor Cvth, the data voltage Vdata and the threshold voltage Vth of the transistor M1 are stored in the gate of the transistor M1. The voltage corresponding to the sum of is applied. That is, the gate-source voltage Vgs of the transistor M1 is expressed by Equation 3 below.

In addition, during the period T2, the light emission control line EMIk is applied with a low level signal, so that the transistor M2 is turned on. The transistor M2 is turned on so that a current I _OLED corresponding to the gate-source voltage V _GS of the transistor M1 is supplied to the anode electrode D of the organic EL element OLED. The magnitude of the current I _{OLED is} shown in Equation 4.

Here, the current I _OLED is a current flowing to the anode electrode D of the organic EL element OLED, Vgs is a voltage between the source and the gate of the transistor M1, Vth is a threshold voltage of the transistor M1, and Vdata is The data voltage, β represents a constant value. As can be seen from Equation 4, since the current I _OLED is determined according to the data voltage Vdata and the power supply VDD, the influence of the threshold voltage of the driving transistor can be eliminated.

Hereinafter, a display panel array inspection method will be described, taking as an example a case where the pixel circuit includes transistors M1 to M5 and capacitors Cst and Cvth. In the display panel array, pixel circuit elements, that is, transistors M1 to M5 and capacitors Cst and Cvth, are formed on a substrate, and an anode electrode D of an organic EL element OLED is formed thereon. This means that the organic EL layer and the cathode are formed on the anode electrode D before being formed.

3 is a view for explaining an array inspection method according to an exemplary embodiment of the present invention and shows waveforms applied to signal lines during a test period.

As shown in FIG. 3, during the test period, a low level signal is applied to the immediately preceding scan line Sk-1 and a low level signal is also applied to the signal line EMIk. While applying low-level signals to the immediately preceding scan line Sk-1 and the signal line EMIk, an electron beam (e-beam) is irradiated to the anode electrode D of the organic EL element OLED, and the anode electrode D The amount of electrons bounced from

The case where the transistors M1, M2 and M3 operate normally will be described. Since the low level is applied to the gate electrodes of the transistors M2 and M3 through the scan line Sk-1 and the signal line EMIk, the transistors M2 and M3 are turned on. Therefore, electrons are injected into the node C and diffused to the node A by the electron beam irradiated to the anode electrode D. When the electrons diffuse to the node A, the gate electrode of the transistor M1 is lowered by the electrons and lower than the power supply VDD. Therefore, when the voltage difference between the gate and the source of the transistor M1 occurs, and the voltage difference Vgs between the gate and the source is greater than the threshold voltage of the transistor M1, the transistor M1 is turned on to form a channel. When the transistor M1 is turned on, electrons injected into the node C may diffuse through the node M1 to the node F. As a result, since the electron beam irradiated to the anode electrode D is diffused from the anode electrode D to the node F, the amount of electrons bounced from the anode electrode D becomes significantly smaller.

On the other hand, the case where at least one of the transistor M1, the transistor M2, and the transistor M3 does not operate normally will be described. When the transistor M2 or the transistor M3 does not operate normally, even if a low level is applied to the gate electrodes of the transistors M2 and M3 through the scan line Sk-1 and the signal line EMIk, the transistor M2 or the transistor M3 does not turn on normally. You may not. Then, even if the electron beam is irradiated on the anode electrode D, electrons cannot diffuse from the anode electrode D to the node C, and most of the electrons are bounced off the anode electrode D. In addition, even when the transistor M1 does not operate normally, electrons injected from the anode electrode D may pass through the node M through the transistor M2 and diffuse through the transistor M3 to the node A. have. However, since the transistor M1 does not operate normally, even when electrons are accumulated in the node A, the voltage difference between the gate and the source of the transistor M1 becomes greater than or equal to the threshold voltage of the transistor M1, so that the transistor M1 is not turned on. Therefore, since the electrons accumulated in the node C cannot be diffused to the node F, they are bounced from the anode electrode D by an amount that cannot be diffused.

In this way, in the state where the transistors M2 and M3 are turned on, electrons are injected into the anode electrode D by injecting electrons, and then the amount of electrons bounced from the anode electrode D is detected to detect the driving elements in the pixel. You can check that they are operating normally. That is, if the amount of electrons bounced out of the anode electrode D is almost the same as the amount of electrons injected by the electron beam, it can be determined that the transistor M2 or the transistor M3 is defective. In addition, when only a part of the electrons injected by the electron beam is detected, it may be determined that the transistor M1 is defective.

4 is a view schematically showing the configuration of a scan driving apparatus 200 capable of inspecting an array according to an embodiment of the present invention.

The scan driver 200 is applied to the selection signal and the emission control lines EMI1… EMIk,… EMIn applied to the scan lines S0,… Sk,… Sn of the pixel circuits 110 of the display panel array 100. A scan driving device for generating a light emission control signal, wherein the scan driving device generates a normal drive signal for displaying an image or a test drive signal for inspecting an array based on a test enable signal. Here 'k' is any natural number from 1 to n, and scan line Sk refers to any one of a plurality of scan lines formed in the array.

The scan driver 200 includes a shift register 210, a level shifter 220, a buffer 230, and a signal applying unit 240. The shift register 210 is the 0th to nth selection signals SR0, ... SRk, ... SRn to be applied to each of the scan lines S0, ... Sk, ... Sn based on the start signal STV and the clock signal CLK. Generate and output to the level shifter 220. In detail, the shift register 210 sequentially shifts the start signal STV according to the input clock signal CLK, and sequentially outputs n + 1 signals as the selection signals SR0 to SRn. The level shifter 220 receives the power sources Vdd and Vss from a power supply unit (not shown) to shift the 0th to nth selection signals SR0 to SRn received from the shift register 210 to a predetermined voltage level. . The buffer 230 buffers the zeroth to nth selection signals SR0 to SRn shifted to a predetermined voltage level and outputs the buffered signal to the signal applying unit 240. The signal applying unit 240 receives the selection signals SR0 to SRn from the buffer 230, applies n + 1 selection signals to be applied to the scan lines S0 to Sn, and applies the selection signals SR0 to SRn. Based on the SRn) and the test enable signal TEST_EN, n light emission control signals are generated and applied to the corresponding light emission control lines EMI1 to EMIn.

5 is a view showing in detail the configuration of the signal applying unit 240 of FIG.

The signal applying unit 240 includes n NOR gates 241 each of which the selection signals SR0 to SRn and the test enable signal TEST_EN are input signals. Accordingly, the signal applying unit 340 applies the input selection signals SR0 to SRn to the corresponding scan lines S0 to Sn and simultaneously selects the signals SRk and the test enable signal through the NOR gate 241. It receives (TEST_EN) as an input, performs NOR operation, generates a light emission control signal, and applies it to each corresponding light emission control line EMI1 to EMIn.

Table 1 is a chart showing the relationship between the input signal and the output signal of the signal applying unit 240 during the normal drive and the test drive.

input Print TEST_EN SRk-1 Sk-1 EMIk Normal drive low low low high low high high low Inspection driven high low low low high high high low

As can be seen from Table 1, in the case of normal driving for image display instead of inspection driving for array inspection, emission control applied to the selection signal and the emission control line applied to the scan line Sk-1 as shown in FIG. The signals should be inverted from each other. To this end, a low level signal is applied as the test enable signal TEST_EN. Then, the signal applying unit 240 applies the signal of the selection signal SRk-1 to the scan line Sk-1 as it is, and inverts the selection signal SRk-1, that is, the high level, by the NOR gate 241. Is applied to the emission control line EMIk.

On the other hand, in the case of the inspection driving for the array inspection according to an embodiment of the present invention, the same signal is applied to the selection signal applied to the scan line Sk-1 and the emission control signal applied to the emission control line as shown in FIG. Should be. Therefore, when the high level signal is applied as the test enable signal TEST_EN and the selection signal Sk-1 is low level, the signal applying unit 240 applies the low level selection signal SRk-1 as it is. Is applied to (Sk-1). In addition, since the test enable signal TEST_EN is high level, the NOR gate 241 always outputs a low level signal regardless of the selection signal SRk-1, and the low level signal output from the NOR gate 241 is output. It is applied to the emission control line EMIk. Therefore, since the low level is applied to both the scan line Sk-1 and the emission control line EMIk, the pixel inspection according to the exemplary embodiment of the present invention can be performed.

By using the scan driver 200 including the signal applying unit as described above, the normal driving and the pixel inspection driving of the array of the display panel can be easily performed. In particular, by using the scan driver 200, the pixel inspection can be easily performed even in a system on panel (SOP) display device in which driving devices are formed on the display panel.

In the above-described embodiment of the present invention, a case in which five transistors and two capacitors are included in one pixel circuit is described as an example. However, the present invention is a pixel circuit including two transistors and one capacitor as shown in FIG. Applicable to In addition, the embodiment of the present invention has been described in the case where all the pixel circuits are PMOS transistors, but the present invention can be applied to the case in which the pixel circuits include NMOS transistors. A signal in which the signal is inverted may be used.

That is, the scope of the present invention is not limited to the same structure as the embodiment, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the claims also belong to the scope of the present invention.

According to the present invention, in the state where the transistors M2 and M3 are turned on, electrons are injected to the anode electrode D by injecting electrons, and then the amount of electrons bounced from the anode electrode D is detected to detect the amount of electrons in the pixel. It is possible to check whether the driving elements are defective. Therefore, since the array pixel inspection can be performed before assembling the module, it is possible to prevent the cost of defective products.

By using the scan driver according to the present invention, pixel inspection can be performed more easily, and in particular, pixel inspection can be easily performed even in a system on panel (SOP) display device in which driving devices are formed on the display panel.

FIG. 1 is an arbitrary pixel circuit formed in an organic EL display panel array, and FIG. 2 is a view showing waveforms of signal lines applied to the pixel circuit of FIG.

2 is a diagram illustrating waveforms of a scan selection signal and a light emission control signal applied to a pixel circuit.

3 is a view for explaining an array inspection method according to an exemplary embodiment of the present invention and shows waveforms applied to signal lines during a test period.

4 is a view schematically showing the configuration of a scan driving apparatus 200 capable of inspecting an array according to an embodiment of the present invention.

5 is a view showing in detail the configuration of the signal applying unit 240 of FIG.

Claims (10)

A pixel inspection method of a display panel array in which pixel circuits in which light emitting elements are formed on pixel electrodes are arranged in a matrix form, The pixel circuit A capacitor charging a voltage corresponding to an applied data signal; And A first transistor including a gate electrode connected to one electrode of the capacitor, a first electrode to which power is applied, and a second electrode to output a current corresponding to a voltage difference between the gate electrode and the first electrode; A second transistor turned on in response to a first control signal to diode-connect the first transistor; a) turning on the second transistor while the second electrode of the first transistor and the pixel electrode are electrically connected to each other; b) irradiating an electron beam to a pixel electrode while the second transistor is turned on; And c) detecting the amount of electrons emitted from the pixel electrode Pixel inspection method of the display panel array comprising a. The method of claim 1, The pixel circuit, And a third transistor turned on in response to a second control signal to electrically connect the second electrode of the first transistor to the pixel electrode. The method of claim 2, The method of claim 1, wherein the third transistor is turned on. A plurality of scan lines extending in a first direction and transmitting a selection signal, a plurality of data lines insulated from and intersecting the scan lines and extending in a second direction and transferring data signals, a plurality of data lines respectively connected to the scan line and the data line A driving device for inspecting an array of a light emitting display panel including a pixel circuit, The pixel circuit, A first transistor including a gate electrode to which a data signal is applied, a first electrode to which power is applied, and a second electrode to output a current corresponding to a voltage difference between the gate electrode and the first electrode; A second transistor turned on in response to the selection signal to diode-connect the first transistor; A third transistor turned on in response to a control signal to electrically connect the second electrode of the first transistor to the pixel electrode; And A pixel electrode of the light emitting device electrically connected to the second electrode of the second transistor through the third transistor, The drive for inspecting the array, A shift register for generating selection signals to be sequentially applied to the plurality of scan lines; And Receiving the selection signal and an inspection signal indicating an inspection operation or a driving operation; when the inspection signal indicating an inspection operation is input, the selection signal and the control signal for turning on the second transistor and the third transistor are generated; And a signal applying unit configured to output and generate and output the selection signal for turning on the second transistor and the control signal for turning off the third transistor when the test signal instructing a driving operation is input. The method of claim 4, wherein And the signal applying unit outputs the control signal at the same level as the selection signal when the inspection signal instructing the inspection operation is input. The method of claim 4, wherein The signal applying unit A logic gate for inputting the inspection signal and the selection signal and outputting the control signal; And the logic gate outputs a control signal for turning on the same third transistor irrespective of the selection signal when the inspection signal instructing an inspection operation is input. A plurality of scan lines extending in a first direction and sequentially transmitting selection signals, a plurality of data lines insulated from and intersecting the scan lines and extending in a second direction and transferring data signals, respectively, connected to the scan lines and the data lines An SOP light emitting display device comprising: a light emitting display panel including a plurality of pixel circuits, wherein at least part of a scan line driver for driving the scan line and a data driver including the data line are formed; The pixel circuit, A first transistor including a gate electrode to which a data signal is applied, a first electrode to which power is applied, and a second electrode to output a current corresponding to a voltage difference between the gate electrode and the first electrode; A second transistor turned on in response to the selection signal to diode-connect the first transistor; A third transistor turned on in response to a control signal to electrically connect the second electrode of the first transistor to the pixel electrode; And A pixel electrode of the light emitting device electrically connected to the second electrode of the second transistor through the third transistor, The scan driving unit, Receiving the selection signal and an inspection signal indicating an inspection operation or a driving operation; when the inspection signal indicating an inspection operation is input, the selection signal and the control signal for turning on the second transistor and the third transistor are generated; And a signal applying unit configured to output and generate and output the selection signal for turning on the second transistor and the control signal for turning off the third transistor when the test signal instructing a driving operation is input. . The method of claim 7, wherein And the signal applying unit includes a logic gate configured to input the test signal and the selection signal and to output the control signal. The method of claim 8, And the logic gate outputs a control signal for turning on the same third transistor regardless of the selection signal when the inspection signal instructing a inspection operation is input. The method of claim 7, wherein The pixel circuit, A first capacitor storing a voltage corresponding to the applied data signal; A fourth capacitor turned on in response to the selection signal and connected in parallel with the first capacitor; A second capacitor charging a voltage corresponding to the threshold voltage of the first transistor; And A fifth transistor that is turned on in response to another selection signal applied after the selection signal to transfer the data signal A light emitting display further comprising.