KR20050113701A - Pixel test method for array of light emitting panel - Google Patents

Abstract

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

In an exemplary embodiment, a pixel inspection method of a light emitting display panel array includes a plurality of scan lines extending in a first direction and sequentially transmitting a selection signal, a plurality of data lines extending in a second direction and transferring a data signal, A pixel inspection method of a light emitting display panel array, in which a recovery circuit connected to a data line is formed, wherein a selection signal is sequentially applied to a plurality of scan lines in a first step, and a selection signal is applied to a pixel to be inspected in a next step. During this time, a test data signal is applied, and for other times, a voltage that can be initialized is applied as a data signal. Then, an electron beam is irradiated to the pixel electrode of the inspection target pixel, and the amount of electrons bounced from the pixel electrode is detected.

Description

Pixel test method for array of light emitting panel

The present invention relates to an active matrix display panel, and more particularly, to a pixel inspection method 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) in order 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 rows are selected and driven, whereas the active matrix type has a voltage held by a capacitor capacitance connected to each indium tin oxide (ITO) pixel electrode and 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 pixel circuit of a display panel array so that defects of elements of the pixel circuit can be found before assembly to the module.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a pixel inspection method capable of inspecting elements of a pixel circuit arranged in a light emitting display panel array.

According to an aspect of the present invention, a pixel inspection method of a light emitting display panel array includes a plurality of scan lines extending in a first direction and sequentially transmitting selection signals, and a plurality of data lines extending in a second direction and transferring data signals And a pixel inspection method of a light emitting display panel array having a recovery circuit connected to the scan line and the data line, respectively.

a) sequentially applying selection signals to the plurality of scan lines;

b) applying a test data signal to a test target pixel for a time when a selection signal is applied, and applying a voltage that can be initialized as a data signal for another time;

c) irradiating an electron beam to the pixel electrode of the inspection target pixel; And

d) detecting an amount of electrons bounced from the pixel electrode.

The test data signal may be a white data signal, and the voltage that may be initialized may be a black data signal.

Step c) may include adjusting the electron beam so that the amount of electrons corresponding to the inspection data signal is irradiated.

The pixel circuit may include: a first transistor turned on in response to a selection signal to transfer a data signal; A first capacitor charging a voltage corresponding to the data signal transmitted through the first transistor; And a second transistor configured to output a current corresponding to the voltage charged in the first capacitor.

A third transistor turned on in response to another selection signal applied before the selection signal and connected in parallel with the first capacitor; A second capacitor connected in series with the first capacitor to charge a voltage corresponding to the threshold voltage of the second transistor; The electronic device may further include a fourth transistor that is turned on in response to the other selection signal to diode-connect the second transistor.

The display device may further include a fifth transistor disposed between the second transistor and the pixel electrode and turned on in response to a control signal to apply a current output from the second transistor to the pixel electrode.

According to another aspect of the present invention, a pixel inspection method of a light emitting display panel array includes a plurality of data lines extending in a column direction and transmitting data voltages, a plurality of scanning lines extending in a row direction and transmitting a selection signal and the scan lines and the A pixel inspection method of a light emitting display panel array in which a plurality of pixels connected to data lines are arranged in a matrix form,

The pixel may include a transistor in which a current corresponding to a voltage between a control electrode and a second main electrode flows in a first main electrode, and the second main electrode is electrically connected to a first power source; A first capacitor having a first end electrically connected to the control electrode; And a second capacitor electrically connected between a second power supply and a second end of the first capacitor,

The inspection method,

a) diode-connecting said transistor and electrically connecting a second end of said first capacitor to a second power source in accordance with a prior selection signal sequentially transmitted;

b) applying a data voltage to a second terminal of the first capacitor in accordance with a sequentially transmitted current selection signal and connecting a first main electrode of the transistor to a pixel electrode; And

c) irradiating an electron beam to pixel electrodes of pixels in at least one row of said plurality of pixels,

The data voltage when the current selection signal is applied to the pixels of the row to which the electron beam is to be irradiated is an inspection voltage, and the current selection signal is to be applied to the pixels of at least one row of a plurality of rows other than the row to which the electron beam is to be irradiated. The data voltage when is applied is an initialization voltage.

The steps a) to c) may be repeatedly performed while changing the row to which the electron beam is to be irradiated, and the row to which the initialization voltage is applied may be any row other than the row to which the electron beam is to be irradiated.

The test voltage may be a white data voltage and the initialization voltage may be a black data voltage.

The pixel may include a first switching device configured to transfer the data voltage to a second terminal of the first capacitor in response to the current selection signal; A second switching element diode-connecting the transistor in response to the last selection signal; A third switching element connected between a second end of the first capacitor and the second power supply and turned on in response to the immediately previous selection signal; And a fourth switching device connected between the first main electrode of the transistor and the pixel electrode to be turned off in response to the immediately previous selection 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. In FIG. 1, Sk is any one of S0 to Sn, and Dk represents any one of D1 to Dm.

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 the drain of the transistor M1 and the organic EL element OLED in response to a selection signal from the immediately preceding scan line Sk-1. ). 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 1 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 2 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 3.

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.

Next, a pixel inspection method of the display panel array including the pixel circuit of FIG. 1 will be described in detail with reference to FIGS. 3 to 4.

In general, an element for driving pixels and an anode electrode of an organic EL element are formed on a rear substrate, and an organic EL layer including a light emitting layer formed on the anode electrode is formed. On the front substrate, a power electrode line for applying a power supply voltage VSS to the cathode electrode and the cathode electrode of the organic EL element is formed. The back substrate and the front substrate are combined so that the anode electrode and the cathode electrode correspond to each other to complete the display panel. As described above, the front substrate on which the elements of the pixel circuit and the anode electrode are formed before the display panel is completed is called a display panel array.

3 is a diagram schematically illustrating a display panel array.

As shown in FIG. 3, the display panel array 100 includes n + 1 scan lines S0,..., Sk,... Sn extending in the row direction, and m data lines D1, ..., Dk, which extend in the column direction. Dm) and a pixel circuit 110 connected to two scanning lines and one data line, respectively. The pixel circuit 110 includes only the transistors M1 to M5, the capacitors Cst and Cvth, and the anode electrode D of the organic EL element OLED.

4 is a view illustrating waveforms of a scan selection signal and a data signal applied to a display panel array during one frame in the pixel inspection method according to the first exemplary embodiment of the present invention.

First, selection signals are sequentially applied to the n scan lines S0 to Sn, and, for example, full white data signals are applied to all data lines while the selection signals are applied to the scan lines.

Specifically, when the selection signal is first applied to the scan line S0, the transistor M3 of the pixels P11 to P1m of the first row of the display panel array is turned on so that the voltage between the gate and the source of the transistor M1 becomes the transistor ( The voltage is changed until the threshold voltage Vth of M1 is reached, and the voltage applied to the node A of the capacitor Cvth becomes the sum of the power supply voltage VDD and the threshold voltage Vth. In addition, the transistor M4 is also turned on so that the power source VDD is applied to the node B of the capacitor Cvth, and the voltage V _CVth charged to the capacitor Cvth is represented by Equation 2 of the transistor M1. The threshold voltage Vth is obtained.

Then, when the ON signal is applied to the emission control line EMI1 and the selection signal is applied to the scan line S1, the transistor M5 of the pixels P11 to P1m is turned on to each of the data lines D1 to Dm. Is applied to the node B so that the transistor M1 is in a state for outputting a predetermined current based on the equations (2) and (3). However, the transistor M2 is also turned on by the ON signal of the emission control line EMI1, but since the anode electrode D is in a floating state, no current flows. On the other hand, when the selection signal is applied to the scan line S1, similarly to the pixels P11 to P1m while the selection signal is applied to the scan line S0, the transistor C is in the capacitor Cvth of the pixels P21 to P2m. The threshold voltage Vth of M1 is charged.

Then, when the ON signal is applied to the emission control line EMI2 and the selection signal is applied to the scan line S2, the transistor M5 of the pixels P21 to P2m is turned on to each data line D1 to Dm. Is applied to the node B so that the transistor M1 is in a state for outputting a predetermined current based on the equations (2) and (3). However, the transistor M2 is also turned on by the ON signal of the emission control line EMI2, but no current flows because the anode electrode D is in a floating state.

Subsequently, while the selection signals are sequentially applied to the scan lines S3 to Sn, the pixels P31 to P3m to Pn1 to Pnm also have the pixels P11 to P1m and the pixels P21 to P2m. It works the same.

In this manner, after the display panel array is driven one frame, the inspection of the pixels P11 to P1m and the pixels P21 to P2m is performed. After the pixel is driven, the number of pixel rows that can be inspected at one time is determined according to the time to maintain the driven state. In the case of a pixel circuit including five transistors and two capacitors according to an embodiment of the present invention, one frame is After driving, each pixel maintains the driving state for a time capable of inspecting two rows of pixels, that is, the pixels P11 to P1m and the pixels P21 to P2m. Therefore, pixel checking is performed every two rows.

In the pixel inspection, an electron beam (e-beam) is applied to the anode electrodes D of the signal pixels P11 to P1m and the pixels P21 to P2m while the on signals are applied to the emission control lines EMI1 and EMI2. Irradiation and at this time detect the amount of electrons bounced from the anode electrode D and emitted. Then, if the transistor M1 is not defective, the pixels P11 to P1m and the pixels P21 to P2m are driven, i.e., a current corresponding to the data signal and the power supply voltage flows in the transistor M1. Since the formed channel is maintained, electrons irradiated to the anode electrode D by the electron beam (e-beam) are diffused through the transistor M2 and the transistor M1 to the power supply line VDD, and the anode electrode ( The amount of electrons bounced off immediately in D) becomes small. However, when a large amount of electrons emitted from the anode electrode D is detected, the transistor M1 may be determined to be defective.

In addition, although the first embodiment of the present invention applies a full white data signal, other data signals may be applied in some cases. In addition, the performance of the transistor M1 may be inspected according to the relationship between the applied data signal and the amount of electrons detected by the anode electrode. For example, when the white data signal is applied, the transistor M1 has a channel formed so that a large amount of current can flow, so that the electrons irradiated to the anode can be diffused more quickly through the transistor M1. When the black data signal is applied, the transistor M1 has a channel formed so that a small amount of current can flow, so that electrons irradiated to the anode can hardly diffuse past the transistor M1 and can be emitted and detected from the anode. .

In this first embodiment of the present invention, the data preference is applied for the entire time of driving one frame. For example, as described above, when one frame driving is performed to inspect the pixels P11 to P1m and P21 to P2m in the first and second rows, the time when the selection signal is applied to the scan lines S1 and S2. The data signal is applied not only during t1 but also during the time t2 when the selection signal is applied to the other scan lines S3 to Sn. Therefore, the transistors M1 of all the pixels of the display panel array are driven.

The potentials of the gate nodes of the transistors M1 of all the pixels are increased because the data voltage is applied. The potential of the gate node of the transistor M1 thus raised is not lowered because the anode electrode is floating, and is maintained even after the end of frame driving. In this state, when the frame driving for the next pixel inspection is performed, the gate node of the transistor M1 is further increased by adding a data voltage to a potential that is currently high. Therefore, the voltage difference between the gate node of the transistor M1 and the source VDD of the transistor M1 gradually decreases, or even the potential of the gate electrode becomes higher than that of the source electrode, so that the transistor M1 is not driven. Pixel inspection cannot be performed.

A second embodiment of the present invention for solving this problem will be described with reference to FIG.

5 is a view illustrating waveforms of a scan selection signal and a data signal applied to a display panel array during one frame in the pixel inspection method according to the second exemplary embodiment of the present invention.

First, the selection signals are sequentially applied to the n scan lines S0 to Sn, and the selection signals are connected to the scan lines Sk and Sk + 1 to which the pixels Pk1 to Pkm and Pk + 1l to Pk + 1m to be inspected are connected. Only during the time t1 is applied, a white data voltage is applied to the data line, and a data voltage higher than the white data voltage, for example, a black data voltage, is applied to the data line.

Specifically, when the selection signal is first applied to the scan line Sk-1, the transistor M3 of the pixels Pk1 to Pkm in the first row of the display panel array is turned on to increase the voltage between the gate and the source of the transistor M1. The voltage is changed until the threshold voltage Vth of the transistor M1 is reached, and the voltage applied to the node A of the capacitor Cvth becomes the sum of the power supply voltage VDD and the threshold voltage Vth. In addition, the transistor M4 is also turned on so that the power source VDD is applied to the node B of the capacitor Cvth, and the voltage V _CVth charged to the capacitor Cvth is represented by Equation 2 of the transistor M1. The threshold voltage Vth is obtained.

Then, when the ON signal is applied to the emission control line EMIk and the selection signal is applied to the scan line Sk, the transistor M5 of the pixels Pk1 to Pkm is turned on to each of the data lines D1 to Dm. Is applied to the node B so that the transistor M1 is in a state for outputting a predetermined current based on the equations (2) and (3). However, the transistor M2 is also turned on by the ON signal of the emission control line EMIk, but no current flows because the anode electrode D is in a floating state. On the other hand, when the selection signal is applied to the scan line Sk, similarly to the pixels Pk1 to Pkm while the selection signal is applied to the scan line Sk-1, capacitors of the pixels Pk + 11 to Pk + 1m are applied. The threshold voltage Vth of the transistor M1 is charged at Cvth.

Next, when the ON signal is applied to the emission control line EMIk + 1 and the selection signal is applied to the scan line Sk + 1, the transistor M5 of the pixels Pk + 11 to Pk + 1m is turned on. The data voltage transmitted by each of the data lines D1 to Dm is applied to the node B so that the transistor M1 is in a state for outputting a predetermined current based on the equations (2) and (3). However, the transistor M2 is also turned on by the ON signal of the emission control line EMIk + 1, but no current flows because the anode electrode D is in a floating state.

As such, after the display panel array is driven one frame, the inspection of the pixels Pk1 to Pkm and the pixels Pk + 11 to Pk + 1m is performed.

The pixel inspection is performed by applying an electron beam to the anode electrodes D of the pixels Pk1 to Pkm and the pixels Pk + 11 to Pk + 1m in a state where an ON signal is applied to the emission control lines EMIk and EMIk + 1. This is performed by irradiating an e-beam and detecting the amount of electrons bounced and emitted from the anode electrode D at this time. If the transistor M1 is not defective, the pixels Pk1 to Pkm and the pixels Pk + 11 to Pk + 1m are driven, that is, a current corresponding to the difference between the data signal and the power supply voltage is applied to the transistor M1. Since the flowable channel is formed, electrons irradiated by the electron beam (e-beam) on the anode electrode D are diffused through the transistor M2 and the transistor M1 to the power supply line VDD, and the anode The amount of electrons bounced off the electrode D immediately becomes small. However, when a large amount of electrons emitted from the anode electrode D is detected, the transistor M1 may be determined to be defective.

After the inspection of the pixels Pk1 to Pkm and the pixels Pk + 11 to Pk + 1m is finished, the pixels Pk + 21 to Pk + 2m and the pixels Pk + 31 to Pk + 3m are removed. In order to inspect, after performing one frame driving in the same manner as described above, the electron beam is irradiated and inspected.

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 where the pixel circuits include NMOS transistors. Can be applied. 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, by applying a high voltage data signal to a pixel in a row that is not an inspection object, it is possible to prevent the potential of the gate node of the driving transistor from continuously rising and reset to an initial state, thereby making pixel inspection easier and more accurate. Can be done. Further, by using the pixel inspection method according to the present invention, pixels of any structure can be inspected.

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 diagram schematically illustrating a display panel array.

4 is a diagram illustrating waveforms of a scan selection signal and a data signal applied during one frame in the pixel inspection method according to the first exemplary embodiment of the present invention.

5 is a diagram illustrating waveforms of a scan selection signal and a data signal applied during one frame in the pixel inspection method according to the second exemplary embodiment of the present invention.

Claims (13)

A light emitting display panel including a plurality of scan lines extending in a first direction and sequentially transmitting a selection signal, a plurality of data lines extending in a second direction and transferring a data signal, and a recovery circuit connected to the scan line and the data line, respectively. In the pixel inspection method of the array, a) sequentially applying selection signals to the plurality of scan lines; b) applying a test data signal to a test target pixel for a time when a selection signal is applied, and applying a voltage that can be initialized as a data signal for another time; c) irradiating an electron beam to the pixel electrode of the inspection target pixel; And d) detecting the amount of electrons bounced from the pixel electrode Pixel inspection method of the display panel array comprising a. The method of claim 1, And the inspection data signal is a white data signal. The method of claim 2, And the resettable voltage is a black data signal. The method of claim 1, C), And adjusting the electron beam so that the amount of electrons corresponding to the inspection data signal is irradiated. The method of claim 1, The pixel circuit, A first transistor that is turned on in response to the selection signal to transfer the data signal; A first capacitor charging a voltage corresponding to the data signal transmitted through the first transistor; And And a second transistor (M1) for outputting a current corresponding to the voltage charged in the first capacitor. The method of claim 5, A third transistor turned on in response to another selection signal applied before the selection signal and connected in parallel with the first capacitor; A second capacitor connected in series with the first capacitor to charge a voltage corresponding to the threshold voltage of the second transistor; And a fourth transistor that is turned on in response to the other selection signal to diode-connect the second transistor. The method according to claim 5 or 6, And a fifth transistor (M5) disposed between the second transistor and the pixel electrode and turned on in response to a control signal to apply a current output from the second transistor to the pixel electrode. A plurality of data lines extending in a column direction and transmitting data voltages, a plurality of scanning lines extending in a row direction and transmitting a selection signal and a plurality of pixels connected to the scanning lines and the data lines, respectively, in a matrix form In the pixel inspection method of the display panel array, The pixel, A current corresponding to a voltage between the control electrode and the second main electrode flows through the first main electrode, and the second main electrode is electrically connected to a first power source; A first capacitor having a first end electrically connected to the control electrode; And A second capacitor electrically connected between a second power supply and a second end of the first capacitor, The inspection method, a) diode-connecting said transistor and electrically connecting a second end of said first capacitor to a second power source in accordance with a prior selection signal sequentially transmitted; b) applying a data voltage to a second terminal of the first capacitor in accordance with a sequentially transmitted current selection signal and connecting a first main electrode of the transistor to a pixel electrode; And c) irradiating an electron beam to pixel electrodes of pixels in at least one row of said plurality of pixels, The data voltage when the current selection signal is applied to the pixels of the row to which the electron beam is to be irradiated is an inspection voltage, and the current selection signal is to be applied to the pixels of at least one row of a plurality of rows other than the row to which the electron beam is to be irradiated. And the data voltage when the is applied is an initialization voltage. The method of claim 8, And the steps a) to c) are repeatedly performed while changing a row to which the electron beam is to be irradiated. The method of claim 8, And the rows to which the initialization voltage is applied are all rows other than the row to which the electron beam is to be irradiated. The method of claim 8, And the inspection voltage is a white data voltage. The method of claim 8, And the initialization voltage is a black data voltage. The method of claim 8, The pixel, A first switching element transferring the data voltage to a second end of the first capacitor in response to the current selection signal; A second switching element diode-connecting the transistor in response to the last selection signal; A third switching element connected between a second end of the first capacitor and the second power supply and turned on in response to the immediately previous selection signal; And And a fourth switching element connected between the first main electrode and the pixel electrode of the transistor and turned off in response to the immediately preceding selection signal.