JP2003114658A - Display device and its inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device and its inspection method capable of judging easily whether pixel TFTs (thin film transistors) operate normally or not before liquid crystal elements are formed even in a large-sized panel. SOLUTION: In this display device inspection method, whether pixel TFTs operate normally or not is judged by monitoring potential changes of source signal lines S1 to Sx due to electric discharges of storage capacitors 1001. At that time, respective source lines S1 to Sx are connected respectively to a wiring 1111 for read-out via analog buffers AB1 to ABx in order to reduce the influence of the wiring capacitance CL of the wiring 1111 for read-out at the time of reading out the potential of the source signal lines to the outside of a substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device in which a liquid crystal element is formed on a substrate and a semiconductor element (element using a semiconductor thin film) is arranged for each pixel. The present invention relates to a method for inspecting the display device. Further, the present invention relates to an electronic device including a display device using the inspection method.

[0002]

2. Description of the Related Art In recent years, a technique for forming a thin film transistor (hereinafter referred to as a TFT) on a substrate having an insulating surface has made great progress, and applied to an active matrix type display device in which a TFT is arranged for each pixel. Is being promoted. In particular, TF using a polysilicon (polycrystalline silicon) film
Since T has higher field effect mobility (also referred to as mobility) than a conventional TFT using an amorphous silicon (amorphous silicon) film, it can operate at high speed. Therefore, the pixel is controlled by the drive circuit formed on the pixel substrate, which is conventionally performed by the drive circuit formed on the single crystal IC substrate attached to the substrate on which the pixel is formed (pixel substrate). It is possible.

Here, an example of an active matrix type display device which performs display by controlling the orientation of the liquid crystal element for each pixel is shown below.

Here, the liquid crystal element refers to an element having a structure in which a liquid crystal layer made of a liquid crystal material is sandwiched between two electrodes. By applying a voltage between the two electrodes, the orientation of the liquid crystal layer sandwiched between them is controlled, and the transmittance of the liquid crystal layer is controlled. An image is displayed by controlling the transmittance of the liquid crystal layer for each pixel.

Here, in this specification, by applying a voltage between two electrodes of a liquid crystal element, it is possible to control the orientation of the liquid crystal layer sandwiched between the electrodes and to control the transmittance of the liquid crystal layer. , We will drive the liquid crystal element.

FIG. 9 is a block diagram showing the structure of a conventional liquid crystal display device. In FIG. 9, a liquid crystal display device includes a pixel region in which a plurality of pixels are formed, a gate signal line driver circuit and a source signal line which select a pixel by a source signal line and a gate signal line in the pixel region and input a signal. It has a drive circuit. The gate signal line drive circuit, the source signal line drive circuit, and the pixel region are formed on the pixel substrate. With this configuration, it is possible to reduce the influence of wiring resistance and wiring capacitance between the driving circuit and the pixel region, which is a problem when the driving circuit is externally attached.

The detailed structure of the pixel portion is shown in FIG. Figure 1
0, in the pixel region, y (y is a natural number) gate signal lines G1 to Gy are arranged in the row direction, and x (x is a natural number) source signal lines S1 to Sx are arranged in the column direction. ing. At each intersection of these source signal lines S1 to Sx and gate signal lines G1 to Gy, the gate electrode of the pixel TFT 1002 forming each pixel is connected to the gate signal line, and one of the source terminal or the drain terminal of the pixel TFT 1002 is connected. Is connected to the source signal line. Pixel T
The source terminal and the drain terminal of the FT 1002, which are not connected to the source signal line, are connected to one electrode of the liquid crystal element 1003 and one electrode of the storage capacitor 1001. The pixel TFT 1002 of the storage capacitor 1001
The electrode on the side not connected with and the electrode on the side of the liquid crystal element 1003 not connected to the pixel TFT 1002 are
It is connected to the common potential line 1004. Common potential line 10
The potential of 04 is the common potential V _com .

In this specification, of the two electrodes of the liquid crystal element, the electrode on the side connected to the pixel TFT is called the pixel electrode, and the other electrode is called the counter electrode.

The operation of the display device shown in FIGS. 9 and 10 for displaying will be described with reference to the timing chart shown in FIG. In FIG. 11, G1 to Gy are
The signal potential input to the gate signal line is shown. Also, S1
To Sx represent signal potentials input to the source signal lines S1 to Sx.

Here, in FIG. 11, the pixel TFT 1002
The description will be made by taking an example in which the n-channel TFT is
The FT 1002 may be a p-channel TFT.

A period in which the display device displays one image is one frame period (F). The length of one frame period is set such that human eyes do not feel flickering when a moving image is displayed. Normally, the length of one frame period is 1 /
It is set to about 60 seconds.

First, in response to a signal input to the gate signal line G1 from the gate signal line drive circuit, the gate signal line G
The pixel TFT (pixel TFT of the first row) whose gate electrode is connected to 1 is turned on. At this time, the pixel TFT in which the gate electrode is connected to the other gate signal lines G2 to Gy
Is in the off state.

In this specification, turning on the TFT means that the source and drain are brought into conduction due to the potential difference between the source terminal and the gate electrode. On the contrary, the state in which the TFT is off indicates that the source and the drain are in a non-conductive state due to the potential difference between the source terminal and the gate electrode. In addition, inputting a signal to a signal line so that a TFT whose gate electrode is connected to the signal line is turned on is referred to as selecting a signal line.

From the source signal line drive circuit, the source signal line S
The analog signals are sequentially input to 1 to Sx. The analog potential of the analog signal is input to the pixel electrode of the liquid crystal element and one electrode of the storage capacitor through the source and drain of the pixel TFT in the first row which is turned on. According to the potential difference between the input analog potential and the potential of the counter electrode of the liquid crystal element given by the common potential line,
Drives the liquid crystal element. Note that the storage capacitor provided in parallel with the liquid crystal element is provided for holding a voltage applied between two electrodes (a pixel electrode and a counter electrode) of the liquid crystal element for one frame period.

Here, the period during which the gate signal line G1 is selected is referred to as a line period L1. Generally, a period in which the gate signal line Gi (i is a natural number equal to or smaller than y) is selected is referred to as a line period Li.

Next, the gate signal line G2 is selected and has analog signals sequentially input to the source signal lines S1 to Sx through the source and drain of the pixel TFT in the second row which is turned on. The analog potential is input to the pixel electrode of the liquid crystal element and the electrode of the storage capacitor. The liquid crystal element is driven according to the potential difference between the input analog potential and the potential of the counter electrode of the liquid crystal element given by the common potential line.

The above operation is carried out for all the gate signal lines G1 to G.
Repeating for y, when one of the line periods L1 to Ly ends, one frame period F1 ends.

Here, if the direction of the electric field between the two electrodes (pixel electrode and counter electrode) of the liquid crystal element is biased in the same direction for a long time, the liquid crystal material has a property of deteriorating. Therefore, usually
The liquid crystal display device is driven (reversed drive) by periodically reversing the direction of the electric field between the two electrodes of the liquid crystal element. A case where a driving method (frame inversion driving) in which the direction of the electric field applied between the two electrodes of the liquid crystal element is inverted in each successive frame period is used as the inversion driving method will be described below. The inversion driving method is not limited to this.

It should be noted that if the liquid crystal material is not easily deteriorated even if the electric field in the same direction is continuously applied for a long time, it is not necessary to frequently perform the inversion drive.

FIG. 11 shows a timing chart when the frame inversion drive is used. In the first frame period F1 and the second frame period F2, the polarities of the signals input to the source signal lines S1 to Sx are inverted. In the first frame period F1, a potential higher than that of the common power supply line connected to the counter electrode of the liquid crystal element is input to the source signal lines S1 to Sx. On the other hand, in the second frame period F2, the source signal lines S1 to Sx
A potential lower than the potential of the common power supply line connected to the counter electrode of the liquid crystal element is input to. Again, in the third frame period F3, a potential higher than the potential of the common power supply line connected to the counter electrode of the liquid crystal element is input to the source signal lines S1 to Sx. In this way, a signal in which the polarities of the signals input to the source signal lines S1 to Sx are inverted is input every frame period, and an image is displayed.

It is desired to determine whether or not the operation of the pixel TFT included in each pixel of the above-mentioned active matrix type display device is normally performed at an early stage of the process of manufacturing the display device. As a result, it is possible to reduce waste and reduce costs, except for a panel having a pixel TFT that does not operate normally.

Therefore, a display device having the structure shown in FIG. 3 has been proposed. Here, the pixel TFT 1002 and the storage capacitor 1001 are formed, and the pixel electrode 11 of the liquid crystal element is formed.
It is assumed that the inspection is performed when 10 is formed. In FIG. 3, a source signal line driver circuit, a gate signal line driver circuit, and a pixel region are formed over a pixel substrate. The structure of the pixel is the same as the structure shown in FIG. 10, and thus the same portions are denoted by the same reference numerals and the description thereof will be omitted.
Since the liquid crystal element in FIG. 10 has not been formed yet, only the pixel electrode 1110 is shown instead. _Let C _S be the electrostatic capacitance of the storage capacitor 1001.

The source signal lines S1 to Sx are read wirings 111 via switches SWA1 to SWAx, respectively.
Connected to 1. The read wiring 1111 is electrically connected to the PAD on the pixel substrate. In the PAD, a detection circuit provided outside the pixel substrate is connected. In this way, the read wiring 1111 is electrically connected to the outside of the pixel substrate. In addition, the signals output from the source signal line drive circuit are the switches SWB1 to SWB.
It is input to the source signal lines S1 to Sx via WBx.
Here, the wiring capacitance of each of the source signal lines S1 to Sx is C _SL , and the wiring capacitance of the read wiring 1111 is C _L.

The pixel TFT 1002 of the display device having the above structure
A method for checking whether or not the normal operation is performed will be described below.

By inputting a signal from the source signal line drive circuit, accumulating electric charge in the storage capacitor 1001 of each pixel, and sequentially reading the electric charge by a detection circuit provided outside, it is determined whether the pixel TFT 1002 operates normally. inspect.

As the first procedure, charges are stored in the storage capacitor of each pixel. The operation of storing charges in the storage capacitor 1001 of each pixel is the same as the operation at the time of image display described above, and thus the description thereof is omitted here. It should be noted that when the charge is stored in the storage capacitor 1001 of each pixel, all the switches S
WB1 to SWBx are turned on, and the output signal of the source signal line driver circuit is input to the source signal lines S1 to Sx. The signal potential applied to the source signal line from the source signal line driver circuit is V _in (V) (V _in is different from V _com ). Here, the potential V _com of the common potential line is set to 0
(V). If the pixels are normal, the potentials of the holding capacitors 1001 of all the pixels connected to the pixel TFTs 1002 become V _in (V), and charges are stored in the holding capacitors 1001.

As a second procedure, all pixel TFTs 10 are
02 is turned off. After that, the switches SWB1 to
With SWBx turned on, the output signal of the source signal line drive circuit is set to 0 (V), and all the source signal lines S1 to Sx are set.
A signal is written in to, and the potentials of all the source signal lines S1 to Sx are set to 0 (V).

As the third procedure, the switches SWA1 to SWA
WAx is selected one by one in order so that two or more source signal lines are not connected to the read wiring 1111.

Here, a case where the switch SWA1 is selected will be described as an example. When the switch SWA1 is selected and the source signal line S1 is connected to the call wiring 1111, the switch SWB1 corresponding to the source signal line S1 is turned off so that the potential of the source signal line S1 is not fixed. . In this state, when the gate signal line G1 is selected, the pixel TFT 100 included in the pixels in the first row
The charges accumulated in the second storage capacitor 1001 are read out to the read wiring 1111 via the source signal line S1. A change in the potential of the source signal line S1 due to the charges accumulated in the storage capacitor 1001 is input to an external detection circuit and detected. The same operation is performed for all switches SWA1 to SWA
WAx is sequentially selected and repeated for the source signal lines S1 to Sx.

The above second to third procedures are repeated for all pixel rows.

The voltage (detection voltage) V _ex input to the external detection circuit is given by equation 1.

[0032]

[Formula 1] V _ex = {C _S / (C _SL + C _L +
C _S )} V _in

Here, in each pixel, the storage capacitor 1
The operation of reading the charge accumulated in 001 is performed, and the signal writing operation is normally performed in the pixel in which the detection voltage V _ex is detected, that is, the pixel TFT 1002.
Is confirmed to work normally and the storage capacitor 1001 can be charged and discharged. On the other hand, in the pixel in which the detection voltage V _ex is not detected, it can be seen that there is a problem in the pixel TFT 1002 and the like.

The detection voltage V _ex is amplified by the amplifier included in the detection circuit.

Thus, it is possible to inspect whether the pixel TFT of the display device operates normally before forming the liquid crystal element.

[0036]

When the panel is small, the wiring capacitance C _SL of the source signal line and the wiring capacitance C _L of the read wiring are small, and the detection voltage V _ex given by the equation 1 is used.
Does not become so small, but in a large-sized panel, the routing of the source signal line and the read wiring becomes long, and the wiring capacitance increases. In particular, since the wiring capacitance C _L of the read wiring increases, the detection voltage V _ex is small. for that reason,
There is a problem that it is difficult to judge whether or not there is a problem in the pixel TFT.

It is therefore an object of the present invention to solve the above problems and provide a display device and a method for inspecting the display device, which can easily determine whether or not a pixel TFT normally operates even in a large panel.

[0038]

In order to reduce the influence of the wiring capacitance C _L of the read wiring, each source signal line is connected to the read wiring via an analog buffer.

As a result, it is possible to provide a display device and a method for inspecting the same, which makes it easy to determine whether or not the pixel TFT normally operates even in a large panel.

The structure of the present invention will be described below.

According to the present invention, a pixel, a first signal line, a driver circuit for outputting a signal to the first signal line, a second signal line, and a first signal line are formed over a substrate having an insulating surface. A switch and a second switch, wherein the pixel is a TFT
And a storage capacitor, and one of a source terminal and a drain terminal of the TFT is connected to the first signal line,
The other is connected to one electrode of the storage capacitor, the first signal line is connected to the second signal line via the first switch, and the output terminal of the drive circuit is A display device that is connected to the first signal line via a second switch, and the second signal line is electrically connected to the outside of the substrate having the insulating surface. A display device is provided, in which the first signal line is connected to the first switch through the analog buffer.

According to the present invention, a plurality of pixels, a plurality of first signal lines, a drive circuit for outputting a signal to the plurality of first signal lines, and a second signal are formed on a substrate having an insulating surface. A line, a plurality of first switches, and a plurality of second switches, each of the plurality of pixels has a TFT and a storage capacitor, and the source terminal and the drain terminal of the TFT are One is connected to one of the plurality of first signal lines, the other is connected to one electrode of the storage capacitor, and the plurality of first signal lines are respectively connected to the plurality of first signal lines. Via one of the different switches,
Any one of the plurality of first signal lines connected to the second signal line, and each of the plurality of output terminals of the drive circuit is connected to one of the plurality of second switches via a different one of the plurality of second switches. A display device electrically connected to the outside of the substrate having the insulating surface, wherein the second signal line is connected to a different one of the plurality of analog buffers; 1 signal line, via one of the different one of the plurality of analog buffers,
A display device is provided, which is connected to a different one of the plurality of first switches.

According to the present invention, a pixel, a first signal line, a driver circuit for outputting a signal to the first signal line, a second signal line, and a first signal line are formed over a substrate having an insulating surface. A switch and a second switch, wherein the pixel is a TFT
And a liquid crystal element, and a storage capacitor, wherein the liquid crystal element is
It has a first electrode, a second electrode, and a liquid crystal layer sandwiched between the first electrode and the second electrode, and one of a source terminal and a drain terminal of the TFT is The first signal line is connected, and the other is connected to the first electrode of the liquid crystal element and one electrode of the storage capacitor.
Signal line is connected to the second signal line via the first switch, and the output terminal of the drive circuit is connected to the second signal line.
Is a display device electrically connected to the outside of the substrate having the insulating surface, the analog signal buffer being connected to the first signal line via the switch The display device is provided in which the first signal line is connected to the first switch via the analog buffer.

According to the present invention, a plurality of pixels, a plurality of first signal lines, a driving circuit for outputting a signal to the plurality of first signal lines, and a second signal are formed on a substrate having an insulating surface. A line, a plurality of first switches, and a plurality of second switches, each of the plurality of pixels has a TFT, a liquid crystal element, and a storage capacitor, and the liquid crystal element is the first Electrode, a second electrode, and a liquid crystal layer sandwiched between the first electrode and the second electrode. One of the source terminal and the drain terminal of the TFT is one of the plurality of electrodes. Of the first signal lines of the liquid crystal element and the other of the first signal lines are connected to the first electrode of the liquid crystal element and one electrode of the storage capacitor. , Connected to the second signal line via any one of the plurality of first switches which is different A plurality of output terminals of the drive circuit are respectively connected to different ones of the plurality of first signal lines through one different one of the plurality of second switches, The second signal line is
A display device electrically connected to the outside of a substrate having an insulating surface, the display device having a plurality of analog buffers, wherein each of the plurality of first signal lines is one of the plurality of analog buffers. A display device is provided, which is connected to a different one of the plurality of first switches via a different one.

An electronic device using the display device may be used.

According to the present invention, a pixel, a first signal line, a driver circuit for inputting a signal to the first signal line, a second signal line, and a first signal line are formed over a substrate having an insulating surface. A switch, and the pixel includes a TFT, a first electrode and a second electrode.
Of the source terminal or drain terminal of the TFT, one of which is connected to the first signal line and the other of which is connected to the first electrode of the holding capacitor. A method for inspecting a display device, comprising an analog buffer, turning on the TFT, inputting a first potential from the drive circuit to the first signal line, and holding a charge in the storage capacitor. And disconnecting the connection between the first signal line and the drive circuit, and outputting the potential of the first signal line to the second signal line via the analog buffer and the first switch. There is provided a method for inspecting a display device.

According to the present invention, a pixel, a first signal line, a driving circuit, a second signal line, and a first switch are provided over a substrate having an insulating surface, and the pixel is a TFT.
And a storage capacitor having a first electrode and a second electrode, one of a source terminal and a drain terminal of the TFT is connected to the first signal line, and the other is the storage capacitor. A method for inspecting a display device connected to the first electrode of the above, comprising: an analog buffer; and a detection circuit provided outside the substrate having the insulating surface, turning on the TFT, and driving the TFT. The first potential from the circuit
The signal is stored in the storage capacitor and the TFT is turned off, and the first signal line is
A procedure of setting a second potential different from the first potential, and a procedure of outputting the second potential to the second signal line via the analog buffer and the first switch, A procedure for amplifying the difference between the potential input to the second signal line and the third potential in the detection circuit to obtain the first voltage, and disconnecting the connection between the first signal line and the drive circuit. , A step of turning on the TFT and outputting the potential of the first signal line to the second signal line via the analog buffer and the first switch; and the second signal. The difference between the electric potential input to the line and the third electric potential,
A method of inspecting a display device, comprising: a step of amplifying in the detection circuit to obtain a second voltage; and a step of comparing the first voltage and the second voltage.

According to the present invention, a pixel, a first signal line, a driving circuit, a second signal line, and a first switch are provided over a substrate having an insulating surface, and the pixel is a TFT.
And a storage capacitor having a first electrode and a second electrode, one of a source terminal and a drain terminal of the TFT is connected to the first signal line, and the other is the storage capacitor. A method for inspecting a display device connected to the first electrode of the above, comprising: an analog buffer, a detection circuit provided outside the substrate having the insulating surface, and a memory, and turning on the TFT. , A step of inputting a first potential from the drive circuit to the first signal line to hold electric charge in the storage capacitor, turning off the TFT, and connecting the first signal line to the first signal line. A second potential different from the potential, a step of outputting the second potential to the second signal line via the analog buffer and the first switch, and a second potential The potential input to the signal line and the third
A step of amplifying the difference in potential of the first voltage in the detection circuit, storing the first voltage in a memory, disconnecting the first signal line from the drive circuit,
A step of turning on the TFT and outputting the potential of the first signal line to the second signal line via the analog buffer and the first switch; and the second signal line. The difference between the electric potential input to the input terminal and the third electric potential is amplified in the detection circuit to become the second voltage, and the first voltage and the second voltage stored in the memory are compared. There is provided a method for inspecting a display device.

According to the present invention, a pixel, a first signal line, a first driving circuit, and a second pixel are formed on a substrate having an insulating surface.
Signal line, a first switch, and a second drive circuit, and the pixel has a TFT and a storage capacitor having a first electrode and a second electrode. One of the source terminal and the drain terminal is connected to the first signal line, and the other is a method of inspecting a display device connected to the first electrode of the storage capacitor, which comprises an analog buffer and
A detection circuit provided outside the substrate having the insulating surface, turning on the TFT, inputting a first potential from the first drive circuit to the first signal line, and holding the holding circuit. The procedure of holding electric charge in a capacitor, the procedure of turning off the TFT and setting the first signal line to a second potential different from the first potential, and the procedure of setting the second potential to the analog ON by the buffer and the second drive circuit
Via the first switch, which can be switched off,
A step of outputting to the second signal line, a step of amplifying a difference between a potential input to the second signal line and a third potential in the detection circuit to obtain a first voltage, One signal line is disconnected from the first drive circuit to turn on the TFT, and the potential of the first signal line is turned on / off by the analog buffer and the second drive circuit. The procedure of outputting to the second signal line via the first switch that is switched and the difference between the potential input to the second signal line and the third potential are amplified in the detection circuit. However, there is provided a method for inspecting a display device, which comprises a procedure of setting a second voltage and a procedure of comparing the first voltage and the second voltage.

According to the present invention, a pixel, a first signal line, a first driving circuit, and a second pixel are formed on a substrate having an insulating surface.
Signal line, a first switch, and a second drive circuit, and the pixel has a TFT and a storage capacitor having a first electrode and a second electrode. One of the source terminal and the drain terminal is connected to the first signal line, and the other is a method of inspecting a display device connected to the first electrode of the storage capacitor, which comprises an analog buffer and
A detection circuit provided outside the substrate having the insulating surface and a memory are provided, the TFT is turned on, and a first potential is input from the first drive circuit to the first signal line. , A procedure for retaining charges in the storage capacitor, and the TF
A procedure in which T is turned off and the first signal line is set to a second potential different from the first potential, and the second potential is set by the analog buffer and the second drive circuit. The procedure of outputting to the second signal line via the first switch that is switched on / off and the difference between the potential input to the second signal line and the third potential are detected. Procedure for amplifying the voltage in the circuit to obtain the first voltage, storing the first voltage in the memory, disconnecting the first signal line from the first drive circuit, and turning on the TFT. And outputs the potential of the first signal line to the second signal line through the analog buffer and the first switch that is turned on / off by the second drive circuit. The procedure and the potential input to the second signal line Note that the method further includes a step of amplifying the third potential difference in the detection circuit to obtain a second voltage, and a step of comparing the first voltage stored in the memory with the second voltage. A method for inspecting a display device is provided.

According to the present invention, a pixel, a first signal line, a driving circuit, a second signal line, and a first switch are provided on a substrate having an insulating surface, and the pixel is a TFT.
And a storage capacitor having a first electrode and a second electrode, one of a source terminal and a drain terminal of the TFT is connected to the first signal line, and the other is the storage capacitor. A method for inspecting a display device connected to the first electrode of the above, comprising: an analog buffer; and a detection circuit provided outside the substrate having the insulating surface, turning on the TFT, and driving the TFT. The first potential from the circuit
The signal is stored in the storage capacitor and the TFT is turned off, and the first signal line is
A procedure for setting a second potential different from the first potential and the second potential for the analog buffer and the first switch that is turned on / off by a shift register included in the drive circuit are included. Via the second signal line, and a step of amplifying the difference between the potential input to the second signal line and the third potential in the detection circuit to obtain the first voltage. , Disconnecting the connection between the first signal line and the drive circuit and turning on the TFT,
The potential of the first signal line is set to the analog buffer,
A procedure for outputting to the second signal line via the first switch, which is turned on / off by a shift register included in the drive circuit, and a potential input to the second signal line and the first signal line. Of the potential difference of No. 3 is amplified in the detection circuit to obtain the second voltage, and the procedure of comparing the first voltage with the second voltage. An inspection method is provided.

According to the present invention, a pixel, a first signal line, a driving circuit, a second signal line, and a first switch are provided on a substrate having an insulating surface, and the pixel is a TFT.
And a storage capacitor having a first electrode and a second electrode, one of a source terminal and a drain terminal of the TFT is connected to the first signal line, and the other is the storage capacitor. A method for inspecting a display device connected to the first electrode of the above, comprising: an analog buffer, a detection circuit provided outside the substrate having the insulating surface, and a memory, and turning on the TFT. , A step of inputting a first potential from the drive circuit to the first signal line to hold electric charge in the storage capacitor, turning off the TFT, and connecting the first signal line to the first signal line. A procedure of setting a second potential different from the potential, and setting the second potential to the analog buffer,
A procedure of outputting to the second signal line through the first switch, which is turned on / off by a shift register included in the drive circuit, and a potential input to the second signal line and a third A step of amplifying the difference in potential of the first voltage in the detection circuit, storing the first voltage in a memory, disconnecting the first signal line from the drive circuit, The TFT is turned on, and the potential of the first signal line is passed through the analog buffer and the first switch that is turned on / off by a shift register included in the driving circuit to the second switch. Of outputting to the signal line of No. 2, the procedure of amplifying the difference between the potential input to the second signal line and the third potential in the detection circuit to obtain the second voltage, and storing in the memory. Was the first Inspection method of a display device; and a procedure for comparing the the pressure second voltage is provided.

In the procedure for comparing the first voltage and the second voltage, a method for inspecting a display device is characterized in that a difference between the first voltage and the second voltage is calculated. Good.

The inspection method of the display device may be characterized in that the third potential and the potential of the second electrode are equal.

An electronic device using the inspection method may be used.

[0056]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 is a circuit diagram showing the configuration of the display device of the present invention. Note that the same parts as those shown in FIG. 3 shown in the conventional example are denoted by the same reference numerals and the description thereof will be omitted.

Unlike the conventional liquid crystal display device, in the liquid crystal display device of the present invention, the analog buffers AB1 to ABx are
Source signal lines S1 to Sx and switches SWA1 to SA
It is arranged between each WAx.

Here, it is assumed that the pixel TFT 1002 is inspected for normal operation at the stage where only the pixel electrode of the liquid crystal element is formed, that is, before the liquid crystal material is filled. Note that the present invention is not limited to this, and if the connection with the TFTs or the storage capacitors, which configures each drive circuit (source signal line drive circuit, gate signal line drive circuit) and pixel region of the display device is completed, which stage? You may inspect at.

In FIG. 1, the liquid crystal element is not yet formed, and only the pixel electrode 1110 is shown.

A method of inspecting the display device shown in FIG. 1 will be described below.

As a first procedure, a signal is input to the storage capacitor 1001 of each pixel to hold the voltage. In addition,
The operation of inputting a signal to the storage capacitor 1001 included in each pixel is similar to that of the conventional example, and thus the description thereof is omitted here. Here, when a signal is input to the storage capacitor 1001, the source signal line driver circuit and each source signal line S1 to
Switches SWB1 to SWBx provided between Sx
Is turned on, the output of the source signal line driver circuit
The source signal lines S1 to Sx are input. Further, the switches SWA1 to SWAx are in the off state.

When a signal is input to the storage capacitor 1001 of each pixel, the signal potential applied to the source signal line from the source signal line driver circuit is V _in (V _in is different from V _com ) (V) And Here, the electric potential (common electric potential) V _com of the common electric potential line 1004 is set to 0 (V). If the pixel is normal, the voltage is held between both electrodes of the storage capacitors 1001 of all the pixels.

As a second procedure, all pixel TFTs 10 are
02 is turned off. Then, the switches SWB1 to
With SWBx turned on, the output signal of the source signal line drive circuit is set to 0 (V), and all the source signal lines S1 to Sx are set.
Signal to the source signal lines S1 to Sx to 0
(V). At this time, since the pixel TFT 1002 is in the off state, the voltage held between both electrodes of the storage capacitor 1001 in the first procedure remains unchanged. afterwards,
The switches SWB1 to SWBx are turned off. At this time, the potentials of the source signal lines S1 to Sx are kept at 0 (V) by the wiring capacitance.

The subsequent operation will be described.

[0066]

As a third procedure, the pixel TFT 1002
Are all in the off state, the switches SWA1 to SWA
Select WAx sequentially. Thus, the source signal lines S1 to S1
The potential of Sx is output to the read wiring 1111 via the analog buffers AB1 to ABx. The potential output to the read wiring 1111 and the reference potential V ₀
Of the source signal lines S1 to S as the reference voltage _Vref.
The reference voltage V _ref corresponding to each x V _ref 1 to V _ref
Notated as x. Each the reference voltage V _ref 1 to V _ref x, after being amplified by the amplifier in the detection circuit provided outside, is stored in the connected to the detection circuit memory.

The reference potential V ₀ can be any potential. Note that here, the common potential is V _com .

The subsequent operation will be described with reference to the timing chart of FIG.

In FIG. 2, G1 to Gy are respectively
Indicates the potential input to the gate signal lines G1 to Gy. T
_SWA1~ T_SWAxAre switches SWA1 to SWAx, respectively.
Indicates the potential of the signal that drives the
Switches SWA1 to SWAx are
It is assumed to be on. V_out(Q, p) is q (q
Is a natural number less than or equal to y) row p (p is a natural number less than or equal to x) column
Voltage V from the pixel _outIndicates.

As a fourth procedure, as shown in the timing chart of FIG. 2, a signal is input to the gate signal line G1,
The pixel TFTs of the pixels in the first row are turned on. Thereafter, the signal T _SWA1 ~T _SWAx, switch SWA1~
Select SWAx one by one. First, signal T _SWA1
The switch SWA1 is selected by and the potential of the source signal line S1 changed by discharging the electric charge of the storage capacitor 1001 in the first row and the first column is output to the reading wiring 1111. All the switches SWA1 to SWAx are selected in order, and the potentials of the source signal lines S1 to Sx changed due to the discharge of the charges of the storage capacitors of the pixels in the first row are sequentially output to the read wiring.

In this way, the detection voltage V _out corresponding to the potential difference between the potential of the read wiring 1111 corresponding to each pixel of the first row and the reference potential V ₀ is provided to the external detection circuit.
(1,1) to V _out (1, x) are input. Here, the detection voltage V _out is given by Expression 2.

[0073]

[Formula 2] V _out = {C _S / (C _SL + C _BU + C
_S )} V _in

C _BU is the capacity of the analog buffer.
The capacity C _{BU of the} analog buffer is much smaller than the capacity C _L of the read wiring. Therefore, in the conventional example, Equation 1
Unlike the detection voltage V _ex shown by, the detection voltage V _out has a detectable level. The detection voltages V _out (1,1) to V _out (1, x) input to the external detection circuit are amplified by the amplifier.

Here, in the external detection circuit, the signal obtained by amplifying the reference voltage V _ref 1 is read out from the memory, and the detected voltage V _out (1,1) to V _out (1, x) is amplified respectively. And compare respectively. Reference voltage V _ref
1 amplified by an amplifier and the detection voltage V
The difference between the signals obtained by amplifying _out (1,1) by the amplifier is V
_{Let it be sub} (1, 1). Here, the amplification rates of the reference voltage V _ref 1 and the detection voltage V _out (1,1) by the amplifier are the same. For example, if the difference V _sub (1, 1) does not occur, it means that the pixel TFT in the 1st row and 1st column has an abnormality, and the storage capacitor cannot be charged and discharged.

The second procedure to the fourth procedure for all pixel rows
Repeat the procedure. Thus, by examining the differences V _sub (1,1) to V _sub (y, x) corresponding to all the pixels, it is possible to inspect whether the pixel TFTs 1002 of all the pixels have any problem.

In FIG. 2, the pixel TF of the pixel in the 1st row and the 2nd column
There is a problem with T or the storage capacitance, and the voltage V _sub (2,1) is not output (indicated by 9301 in FIG. 2).

In the inspection method of the present invention, the source signal line S1
~ For each Sx, the reference voltage V _ref is obtained, and since the evaluation is performed using the voltage V _sub corresponding to the difference between the detection voltage V _out and the reference voltage V _ref , the characteristic variations of the TFTs forming the analog buffers AB1 to ABx are calculated. The effect of offset voltage due to can be eliminated.

Generally, a voltage of about 5 (V) is applied between the two electrodes of the liquid crystal element with the common potential V _com as the center to display black. Therefore, the common potential V _{com is set} to 0
(V), and a signal of 5 (V) is input to the pixel TFT 1002 from the source signal line driver circuit, that is, in the formula 2, V _in (V) is set to 5 (V), and the inspection is performed by the above-described inspection method. An example of the case of performing is shown.

The electrostatic capacitance Cs of the storage capacitor 1001 is set to 0.2
(PF) and to the respective C _L a wiring capacitance of the source signal line S1~Sx to 10 (pF). Further, it is assumed that the capacity C _BU of each of the analog buffers AB1 to ABx is small enough to be ignored. Assuming that there is no problem in the pixel TFT 1002 or the like that constitutes a certain pixel, the detection voltage V _out is 0.02 (V) from the equation 2. here,
The reference voltage V _ref is 0 (V). Therefore, if the amplification factor of the amplifier included in the detection circuit is 50 times, the difference V _sub
As a result, 1 (V) should be output. When such a difference V _sub is not detected, it can be determined that the pixel TFT is defective.

Thus, even in a large panel, the pixel T
It can be checked whether the FT works properly.

In the present embodiment, the analog buffers AB1 to ABx, the source signal line drive circuit, the gate signal line drive circuit, the switches SWA1 to SWAx and their ON / OFF states.
Drive circuit for controlling off, switches SWB1 to SWBx
A well-known circuit can be freely used for the driver circuit, the memory, and the detection circuit which control ON / OFF thereof.

[0083]

EXAMPLES Examples of the present invention will be described below.

Example 1 In this example, in the display device having the structure shown in the embodiment mode, the switch SWA is used.
1 shows an example in which a test drive circuit for controlling ON / OFF of 1 to SWAx is provided.

FIG. 4 shows the structure of the display device of this embodiment. The same parts as those in FIGS. 1 and 3 are denoted by the same reference numerals, and the description thereof will be omitted. The inspection drive circuit inputs signals to the switches SWA1 to SWAx to change ON / OFF.

FIG. 5 shows a configuration example of the inspection drive circuit.

The inspection drive circuit is a D-FF (Deley Flip
Flop) 9401 composed of shift register 940
2, NAND circuits 9403, 9404, 9405, and buffer circuits 9406, 940 including inverters.
It consists of 7,9408.

Although FIG. 5 shows only the portion corresponding to the three source signal lines of the inspection drive circuit, actually, the inspection drive circuit includes all the source signal lines S1 to S.
It is composed of a circuit corresponding to x.

Buffer circuits 9406, 9407, 940
8 output 9409, 9410, and 9411 are sequentially output as shifted pulses, and the switch SWA shown in FIG.
1, SWA2, SWA3 are input to switch ON / OFF. Thus analog buffers AB1, AB2, AB
The source signal lines S1, S2, and S3 and the read wiring 111 are sequentially connected via S3.

Note that the detection drive circuit is not limited to the above structure, and a shift register or the like having a known structure can be freely used.

Further, FIG. 8 shows an example of an analog buffer circuit.

The analog buffer is a differential circuit 5501,
The current mirror circuit 5502, the constant current source 5503, the high potential side power supply line 5521, and the low potential side power supply line 5522 are included. The high-potential-side power supply line 5521 is kept at the potential of Vdd, and the low-potential-side power supply line 5522 is kept at the potential of Vss. Here, Vdd is higher than Vss.
The differential circuit 5501 is composed of TFTs 5505 and 5506, and the current mirror circuit 5502 is a TFT 5
507 and 5508. Constant current source 550
3 is composed of a TFT 5504, and a TFT 550
A constant voltage V _bias is applied to the gate electrode of _No. 4. The TFT 5504 operates in the saturation region and has a voltage V _bias.
A constant drain current corresponding to is supplied. TFT5504
The gate electrode 5510 of is the input terminal of the analog buffer, and the gate electrode 5511 of the TFT 5506 is the output terminal of the analog buffer.

The analog buffer having the structure shown in FIG.
This is an example of a structure using an operational amplifier (differential amplifier circuit), but the analog buffer is not limited to the above structure. The source follower type may be used, or a circuit having another known configuration may be freely used.

Here, the inspection method is the same as that of the embodiment, and therefore its explanation is omitted here.

Further, in this embodiment, the source signal line drive circuit, the gate signal line drive circuit, and the switches SWA1 to SWA.
As the WAx, the switches SWB1 to SWBx, and the drive circuit, the memory, and the detection circuit that control the ON / OFF of the switches, circuits having known configurations can be freely used.

(Embodiment 2) In this embodiment, an example in which the inspection drive circuit shown in FIG. 4 in Embodiment 1 is also used as the source signal line drive circuit will be described.

In FIG. 7, switches SWA1 to SWA
x, switches SWBa1 to SWBax, switch SW
Bb1 to SWBbx are arranged. Source signal line drive
The dynamic circuit uses an analog signal A corresponding to the luminance information of the pixel.
Wiring S that outputs D_AD1-S _ADx and switch opening and closing
Wiring S for outputting pulses SMP1 to SMPx for_{SM P}
1-S_SMPhave x. The pulses SMP1 to SMPx are
The pulses are sequentially shifted, and each pulse is
Is not output to. As these pulses SMP1 to SMPx
Is a shift register or the like included in the source signal line driver circuit.
You can use the output.

Switch SWBa1 and switch SWBb
When both 1's are in the ON state, the same effect as the switch SWB1 being in the ON state in the embodiment and the example 1 is obtained. Further, when at least one of the switch SWBa1 and the switch SWBb1 is turned off, the switch SW
It has the same effect as when B1 is turned off. Other switches SWBa2 to SWBax, switch SWBb2
The same applies to SWBbx.

The signal T _B is input to the switches SWBa1 to SWBax. By this signal T _B , the switch S
Switch on / off of WBa1 to SWBax all at once. With the switches SWBa1 to SWBax turned on,
When the pulses SMP1 to SMPx are input from the source signal line driving circuit, the switches SWBb2 to SWBbx are sequentially turned on, and the wirings S _AD 1 to S _AD x and the source signal lines S 1 to S 1
Sx are sequentially connected, and the analog signal AD is sequentially input to the source signal lines S1 to Sx.

In addition, when the switches SWBa1 to SWBax are off, the pulse SMP is applied from the source signal line drive circuit.
1 to SMPx are input, switches SWA1 to SWA
Ax is sequentially turned on, and the read wiring 1111 and the source signal lines S1 to Sx are sequentially connected. Thus, the potentials of the source signal lines S1 to Sx are input to the read wiring 1111.

In the above structure, for example, when the analog signal AD is written to the source signal line S1, when the pulse SMP1 is output, the switch SWBa1 and the switch SWA1 are simultaneously turned on. At this time, the other switch SW
Since A2 to SWAx are off, the writing of the analog signal AD to the source signal line S1 is normally performed. Note that when writing the analog signal AD to the source signal line, the source signal line in which writing is performed and the reading wiring 1111 may be disconnected.

Although not shown and described, switches SWAa1 to SWAax and switches SWAb1 to SWA connected in series instead of switches SWA1 to SWAx.
Provide Abx. Switch SWAa1 and switch SW
When both Ab1 are turned on, the switch SWA
It has the same effect as turning 1 on. Also,
When at least one of the switch SWAa1 and the switch SWAb1 is in the off state, there is the same effect as when the switch SWA1 is in the off state. Other switches SWAa2-SWAax, switches SWAb2-SW
The same applies to Abx.

Pulses SMP1 to SMPx are input to the switches SWAa1 to SWAax from the source signal line drive circuit. In addition, the switches SWAb1 to SWAbx
_A signal T _A is input to. With this signal T _A , the switches SWAa1 to SWAax can be switched on / off all at once. Here, when inputting the analog signal AD to the source signal line, the switches SWAb1 to SWAb
Turn off Abx. As described above, when the analog signal is written to the source signal line, the source signal line in which writing is performed and the reading wiring may be disconnected.

Here, the inspection method is the same as that of the embodiment, and therefore its explanation is omitted here.

Switches SWAa1 to SWAax, switches SWAb1 to SWAbx, switches SWBa1 to SW
As the configuration of Bax, the switches SWBb1 to SWBbx, and the source signal line driver circuit, a circuit having a known configuration can be freely used.

With the above structure, it is possible to reduce the area in which the circuit for inspection is closed in the panel, and it is possible to downsize the display device.

(Embodiment 3) In this embodiment, an example of the configuration of the external detection circuit of the display device of the present invention will be shown.

In FIG. 6, external detection circuit 3501
Is an amplifier 3502 that performs signal amplification and a comparison circuit 350.
3, resistors 3505 to 3507, a switch 3508 for switching the connection, and the like.

The output from the PAD of the substrate of the display device to be inspected is connected to the input terminal 3510, and the inspection is performed by the procedure shown in the embodiment mode. The switch 3508 selects whether the output of the amplifier 3502 is input to the memory 3555 or directly to the comparison circuit 3503. The comparison circuit calls the signal stored in the memory 3555 and outputs the difference from the signal input from the amplifier 3502 to the output terminal 3511.

As the comparison circuit 3503, a circuit having a known structure can be freely used.

The amplifier 3502 has a voltage gain of about 10 to 1000 times and amplifies and detects the detection voltage.
The gain of the amplifier is preferably about 100 times.

This embodiment can be implemented by freely combining with Embodiments 1 and 2.

(Embodiment 4) In this embodiment, electronic equipment using the liquid crystal display device of the present invention will be described with reference to FIG.

FIG. 12A shows a schematic diagram of a personal computer using the display device of the present invention. The personal computer includes a main body 2702a, a housing 2702b, a display unit 2702c, operation switches 2702d, a power switch 2702e, and an external input port 2702f. The display device of the present invention can be used for the display portion 2702c.

FIG. 12B shows a schematic diagram of an image reproducing device using the display device of the present invention. The image reproducing device is the main body 2
703a, housing 2703b, recording medium 2703c, display unit 2703d, audio output unit 2703e, operation switch 2
703f. The display device of the present invention can be used for the display portion 2703d.

FIG. 12C shows a schematic view of a television receiver using the display device of the present invention. The TV receiver is the main unit 2
704a, a housing 2704b, a display portion 2704c, and an operation switch 2704d. The display device of the present invention can be used for the display portion 2704c.

The present invention is not limited to the above-mentioned applied electronic equipment and can be applied to various electronic equipment.

This embodiment can be implemented by freely combining with Embodiments 1 to 3.

[0119]

With the above structure, it is possible to provide a display device capable of inspecting the pixel portion TFT even in a large panel. As a result, defective products can be removed before the liquid crystal is sealed, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 illustrates a structure of a display device of the present invention.

FIG. 2 is a diagram showing a timing chart showing a method for inspecting a display device of the present invention.

FIG. 3 is a diagram showing a configuration of a conventional display device.

FIG. 4 is a diagram showing a configuration of a display device of the invention.

FIG. 5 is a diagram showing a drive circuit for inspection of a display device of the present invention.

FIG. 6 is a diagram showing an external detection circuit of a display device of the present invention.

FIG. 7 illustrates a structure of a display device of the present invention.

FIG. 8 is a circuit diagram of an analog buffer of the present invention.

FIG. 9 is a diagram showing a configuration of a conventional display device.

FIG. 10 is a circuit diagram of a pixel portion of a conventional display device.

FIG. 11 is a diagram showing a timing chart showing a driving method of a display device.

FIG. 12 is a diagram showing an applied device using the display device of the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09F 9/30 338 G09F 9/30 338 5G435 9/35 9/35 G09G 3/20 621 G09G 3/20 621M 670 670Q F-term (reference) 2H092 GA59 JA24 JB77 MA56 NA30 PA06 2H093 NA16 NC09 NC11 NC34 ND54 ND56 5C006 BB16 BC20 BF24 BF25 BF37 EB01 EB05 5C080 AA10 BB05 DD15 DD22 DD25 FF11 JJ02 JJ03 JJ04 JJ06 KK02 KK43 5C094 AA41 AA43 BA03 BA43 CA19 EA03 EA04 EA07 GB10 5G435 AA17 AA19 BB12 CC09 KK05 KK09 KK10

Claims (15)

[Claims] 1. A pixel and a first pixel are formed on a substrate having an insulating surface.
Signal line, a drive circuit that outputs a signal to the first signal line, a second signal line, a first switch, and a second switch, and the pixel includes a TFT and a holding circuit. A source terminal and a drain terminal of the TFT, one of
The first signal line is connected to the first signal line, the other is connected to one electrode of the storage capacitor, and the first signal line is connected to the second signal line via the first switch. An output terminal of the drive circuit is connected to the first signal line via the second switch, and the second signal line is electrically connected to the outside of the substrate having the insulating surface. A display device having an analog buffer, wherein the first signal line is connected to the first switch via the analog buffer. 2. A plurality of pixels, a plurality of first signal lines, a drive circuit for outputting a signal to the plurality of first signal lines, and a second signal line on a substrate having an insulating surface. , A plurality of first switches and a plurality of second switches, each of the plurality of pixels has a TFT and a storage capacitor, and one of a source terminal and a drain terminal of the TFT is ,
One of the plurality of first signal lines is connected, the other is connected to one electrode of the storage capacitor, and the plurality of first signal lines are respectively connected to the plurality of first switches. The second through any one of the
The plurality of output terminals of the drive circuit are respectively connected to different signal lines of the plurality of first switches through one different one of the plurality of second switches. A display device connected to a book, wherein the second signal line is electrically connected to the outside of the substrate having the insulating surface, and has a plurality of analog buffers. The display device is characterized in that each line is connected to a different one of the plurality of first switches via a different one of the plurality of analog buffers. 3. A pixel and a first pixel on a substrate having an insulating surface.
Signal line, a drive circuit that outputs a signal to the first signal line, a second signal line, a first switch, and a second switch, and the pixel includes a TFT and a liquid crystal. An element and a storage capacitor, and the liquid crystal element has a first electrode, a second electrode, and a liquid crystal layer sandwiched between the first electrode and the second electrode. , One of the source terminal and the drain terminal of the TFT is
The other end is connected to the first signal line, the other end is connected to the first electrode of the liquid crystal element and one electrode of the storage capacitor, and the first signal line is connected to the first switch via the first switch. Connected to the second signal line, the output terminal of the drive circuit is connected to the first signal line via the second switch, and the second signal line has the insulating surface. A display device electrically connected to the outside of a substrate, comprising: an analog buffer, wherein the first signal line is connected to the first switch via the analog buffer. And display device. 4. A plurality of pixels, a plurality of first signal lines, a drive circuit for outputting a signal to the plurality of first signal lines, and a second signal line on a substrate having an insulating surface. A plurality of first switches and a plurality of second switches, each of the plurality of pixels has a TFT, a liquid crystal element, and a storage capacitor, and the liquid crystal element has a first electrode. And a second electrode and a liquid crystal layer sandwiched between the first electrode and the second electrode, and one of the source terminal and the drain terminal of the TFT is
One of the plurality of first signal lines is connected, the other is connected to the first electrode of the liquid crystal element and one electrode of the storage capacitor, and the plurality of first signal lines is connected. Respectively through the different one of the plurality of first switches, the second switch
The plurality of output terminals of the drive circuit are respectively connected to different signal lines of the plurality of first switches through one different one of the plurality of second switches. A display device connected to a book, wherein the second signal line is electrically connected to the outside of the substrate having the insulating surface, the display device having a plurality of analog buffers, and the plurality of first signals. The display device is characterized in that each line is connected to a different one of the plurality of first switches via a different one of the plurality of analog buffers. 5. The electronic device according to claim 1, wherein the display device is used. 6. A pixel and a first pixel are provided on a substrate having an insulating surface.
Signal line, a drive circuit for inputting a signal to the first signal line, a second signal line, and a first switch, and the pixel includes a TFT, a first electrode, and a second electrode. And a storage capacitor having an electrode, one of a source terminal and a drain terminal of the TFT is connected to the first signal line, and the other is connected to a first electrode of the storage capacitor. A method for inspecting a display device, comprising an analog buffer, turning on the TFT, inputting a first potential from the drive circuit to the first signal line, and holding a charge in the storage capacitor. And disconnecting the connection between the first signal line and the drive circuit, and outputting the potential of the first signal line to the second signal line via the analog buffer and the first switch. A method of inspecting a display device, comprising: 7. A pixel and a first pixel are provided on a substrate having an insulating surface.
Signal line, a drive circuit, a second signal line, and a first switch, and the pixel has a TFT and a storage capacitor having a first electrode and a second electrode. A source terminal or drain terminal of the TFT, one of which is connected to the first signal line and the other of which is connected to the first electrode of the storage capacitor. And a detection circuit provided outside the substrate having the insulating surface, turning on the TFT, inputting a first potential from the drive circuit to the first signal line, and holding the storage capacitor. To hold electric charge, to turn off the TFT and to set the first signal line to a second potential different from the first potential, and to set the second potential to the analog buffer. And the second switch via the first switch. A step of outputting to a line, a step of amplifying a difference between a potential input to the second signal line and a third potential in the detection circuit to obtain a first voltage, and a step of The drive circuit is disconnected and the T
The FT is turned on, and the potential of the first signal line is changed via the analog buffer and the first switch.
A step of outputting to the second signal line; a step of amplifying a difference between the potential input to the second signal line and the third potential in the detection circuit to obtain a second voltage; A method of inspecting a display device, comprising: a step of comparing a first voltage with the second voltage. 8. A pixel and a first pixel on a substrate having an insulating surface.
Signal line, a drive circuit, a second signal line, and a first switch, and the pixel has a TFT and a storage capacitor having a first electrode and a second electrode. A source terminal or a drain terminal of the TFT, one of which is connected to the first signal line and the other of which is connected to the first electrode of the storage capacitor. A detection circuit provided outside the substrate having the insulating surface, and a memory, turning on the TFT, and inputting a first potential from the drive circuit to the first signal line, A step of holding charges in the storage capacitor; a step of turning off the TFT to set the first signal line to a second potential different from the first potential; and a step of setting the second potential to Through the analog buffer and the first switch, A step of outputting to a second signal line; a step of amplifying a difference between a potential input to the second signal line and a third potential in the detection circuit to obtain a first voltage; Of storing the voltage in the memory, and disconnecting the connection between the first signal line and the drive circuit,
The FT is turned on, and the potential of the first signal line is changed via the analog buffer and the first switch.
A step of outputting to the second signal line; a step of amplifying a difference between the potential input to the second signal line and the third potential in the detection circuit to obtain a second voltage; A method of inspecting a display device, comprising a step of comparing a first voltage stored in a memory with the second voltage. 9. A pixel and a first pixel are provided on a substrate having an insulating surface.
Signal line, a first drive circuit, a second signal line, and
And a second drive circuit, the pixel has a TFT and a storage capacitor having a first electrode and a second electrode, and the source terminal or the drain terminal of the TFT is A method for inspecting a display device, one of which is connected to the first signal line and the other of which is connected to the first electrode of the storage capacitor, wherein an analog buffer and an external surface of the substrate having the insulating surface are provided. A detection circuit provided, turning on the TFT, inputting a first potential from the first driving circuit to the first signal line, and holding electric charge in the storage capacitor; Turning off the TFT and setting the first signal line to a second potential different from the first potential; and setting the second potential to the analog buffer and the second potential.
And a difference between a potential input to the second signal line and a third potential, the procedure of outputting to the second signal line via the first switch that is switched on / off by the drive circuit of Is amplified in the detection circuit to obtain a first voltage, and the connection between the first signal line and the first drive circuit is cut off,
The TFT is turned on, and the potential of the first signal line is set to the second via the analog buffer and the first switch that is turned on / off by the second drive circuit. A step of outputting to a signal line; a step of amplifying the difference between the potential input to the second signal line and the third potential in the detection circuit to obtain a second voltage; and the first voltage And a procedure of comparing the second voltage with the second voltage. 10. A pixel, a first signal line, a first drive circuit, a second signal line, a first switch, and a second drive circuit are formed on a substrate having an insulating surface. The pixel has a TFT and a storage capacitor having a first electrode and a second electrode, and one of a source terminal and a drain terminal of the TFT is connected to the first signal line. The other is a method for inspecting a display device connected to the first electrode of the storage capacitor, which includes an analog buffer, a detection circuit provided outside the substrate having the insulating surface, and a memory. Then, turning on the TFT, inputting a first potential from the first driving circuit to the first signal line, and holding electric charge in the storage capacitor; and turning off the TFT, The first signal line has a second potential different from the first potential. And procedures, the second potential, and the analog buffer, the second
And a difference between a potential input to the second signal line and a third potential, the procedure of outputting to the second signal line via the first switch that is switched on / off by the drive circuit of Is amplified in the detection circuit to obtain a first voltage, a procedure of storing the first voltage in a memory, disconnection of the first signal line and the first drive circuit,
The TFT is turned on, and the potential of the first signal line is set to the second via the analog buffer and the first switch that is turned on / off by the second drive circuit. A step of outputting to a signal line; a step of amplifying a difference between the potential input to the second signal line and the third potential in the detection circuit to obtain a second voltage; And a procedure for comparing the first voltage with the second voltage. 11. A pixel, a first signal line, a driving circuit, a second signal line, and a first switch are provided over a substrate having an insulating surface, and the pixel includes a TFT. A storage capacitor having a first electrode and a second electrode, and one of a source terminal and a drain terminal of the TFT is connected to the first signal line, and the other is connected to the storage capacitor of the storage capacitor. 1. A method for inspecting a display device connected to one electrode, comprising: an analog buffer; and a detection circuit provided outside the substrate having the insulating surface, turning on the TFT, A procedure of inputting a first potential to the first signal line to hold an electric charge in the storage capacitor, turning off the TFT and setting the first signal line to a first potential different from the first potential. And a step of setting the second potential to the analog And a potential input to the second signal line via a buffer and a first switch that is turned on / off by a shift register included in the drive circuit, and a potential input to the second signal line. And a third potential difference are amplified in the detection circuit to obtain a first voltage, and the connection between the first signal line and the drive circuit is cut off, and the T
The FT is turned on, and the potential of the first signal line is set to the second via the analog buffer and the first switch that is turned on / off by the shift register included in the drive circuit. A step of outputting to a signal line; a step of amplifying the difference between the potential input to the second signal line and the third potential in the detection circuit to obtain a second voltage; and the first voltage And a procedure of comparing the second voltage with the second voltage. 12. A pixel, a first signal line, a driving circuit, a second signal line, and a first switch are provided over a substrate having an insulating surface, and the pixel has a TFT. A storage capacitor having a first electrode and a second electrode, and one of a source terminal and a drain terminal of the TFT is connected to the first signal line, and the other is connected to the storage capacitor of the storage capacitor. 1. A method for inspecting a display device connected to one electrode, comprising: an analog buffer, a detection circuit provided outside the substrate having the insulating surface, and a memory, and turning on the TFT. A procedure of inputting a first potential to the first signal line from a driver circuit and holding charge in the storage capacitor; turning off the TFT; and setting the first signal line to the first potential. Is a different second potential, and the second potential is The procedure of outputting to the second signal line through the analog buffer and the first switch which is turned on / off by the shift register included in the driving circuit; and the procedure of inputting to the second signal line. A step of amplifying a difference between the potential and the third potential in the detection circuit to obtain a first voltage; a step of storing the first voltage in a memory; a step of storing the first signal line and the drive circuit. Disconnect the connection
The FT is turned on, and the potential of the first signal line is set to the second via the analog buffer and the first switch that is turned on / off by the shift register included in the drive circuit. A step of outputting to a signal line; a step of amplifying a difference between the potential input to the second signal line and the third potential in the detection circuit to obtain a second voltage; And a procedure for comparing the first voltage with the second voltage. 13. The method according to claim 7, wherein in the procedure of comparing the first voltage and the second voltage, the difference between the first voltage and the second voltage is set. A method for inspecting a display device, which comprises: 14. The method of inspecting a display device according to claim 7, wherein the third potential and the second electrode have the same potential. 15. The electronic device according to claim 6, wherein the inspection method is used.