JPH0643490A - Method for manufacturing and inspecting active matrix substrate and manufacture of liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide the method for manufacturing and inspecting the active matrix substrate, by which a picture element defect can be detected in a comparatively short time, and also, exactly even before an injection process of a liquid crystal, and the method for manufacturing the liquid display device. CONSTITUTION:In an active matrix substrate 4 in which a driving cell 10 of each picture element consisting of a switch element 6 for selecting a picture element, and a capacity element 8 connected in series to this switch element 6 is arrayed like a matrix, or an LCD 2 having this substrate 4, a prescribed charge is accumulated in the capacity element 8 connected to a prescribed switch element, from one terminal line of a video signal input terminal line 32 and a common electrode terminal line 33, and thereafter, the charge is detected from one of the video signal terminal line 32 or the common electrode terminal line 33, by which a defect of a picture element is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an active matrix substrate, a method for inspecting an active matrix substrate, and a method for manufacturing a liquid crystal display device, and more particularly, to efficiently detect pixel defects in the liquid crystal display device before and after liquid crystal injection. Regarding the method that can be detected.

[0002]

2. Description of the Related Art Liquid crystal display devices (LCDs) can be classified into several types according to their driving methods. An active matrix method is known as one of LCD driving methods. In this type of LCD, a switch element and, if necessary, a capacitor element are integrated and connected for each pixel at a matrix intersection of a gate line and a data line to improve display performance such as contrast and response. ing.

An LCD of active matrix type has an active matrix substrate, and the surface of this substrate is
Driving cells for each pixel, each of which is composed of a switch element for selecting a pixel and a capacitive element connected in series to the switch element, are arranged in a matrix. In the driving cell for each pixel, display electrodes corresponding to the pixel are arranged in a matrix.

On such an active matrix substrate, counter substrates are arranged substantially in parallel with each other at a predetermined interval. The counter substrate is made of, for example, a glass substrate, and a transparent counter electrode is laminated on the surface of the counter substrate facing the active matrix substrate side. And
Liquid crystal is injected between the counter substrate and the driving substrate to form a liquid crystal layer. L like this
To manufacture a CD, an active matrix substrate,
A counter substrate on which a counter electrode is formed is separately manufactured,
These may be combined in parallel at a predetermined interval and liquid crystal may be injected into these spaces to form a sealed liquid crystal layer.

By the way, not all LCDs manufactured in this way are good LCDs without pixel defects, so it is necessary to inspect the LCDs for pixel defects. LC of active matrix system after liquid crystal injection
As a method of inspecting the pixel defect of D, a method of actually driving the LCD and analyzing the image by an image processing device to detect a defect, or a method of visually detecting the defect is adopted. Further, as a method for inspecting a pixel defect of an active matrix type LCD after injecting liquid crystal, for example, a method disclosed in Japanese Patent Laid-Open No. 63-123093 is known.

However, in such a method, since the inspection is performed by actually displaying a picture on the LCD, the measuring time is long and high productivity cannot be expected. Further, in this way, the pixel defect is inspected on the LCD after the liquid crystal is injected, and if a pixel defect is found to occur, the LCD in which the defect is found is discarded. It has the problem that it must be done. This is because it is not realistic from the viewpoint of manufacturing cost to extract the liquid crystal of the LCD once injected with the liquid crystal, and compensate the defective portion or replace the defective drive substrate and then replace the liquid crystal again.

[0007]

Therefore, there has been proposed a method of inspecting the pixel defect of the LCD before the liquid crystal injection step. The following method is known as a main method for inspecting a pixel defect of an LCD before liquid crystal injection.

First, there is known a method in which a needle is directly placed on the surface of the active matrix substrate in the X and Y rows to perform a DC (direct current) test on the driving cell circuit corresponding to each pixel. In this technology, in order to detect defects in each pixel,
The DC test is repeated in the X and Y directions. in this way,
Needs as many needles as there are X and Y pixels, and has the drawback that the test time is long (about 1 to 5 minutes). In particular, the H / V scanner (horizontal / vertical scanning circuit) with no X and Y terminals It cannot be used on LCD.

Secondly, a method (measurement time 1 to 2 minutes) of detecting a pixel defect as the intensity of light using a special crystal is known. In this method, instead of the liquid crystal, a special plate-shaped crystal whose refractive index changes according to the applied voltage is placed on the surface of the active matrix substrate, and a laser beam is applied to the crystal to emit the light. By detecting transmitted light or reflected light, a pixel defect can be caught. In this method, the information detected as light needs to be processed again by the camera, which complicates the processing. In addition, the test cannot be performed in the actual driving state. Further, if the pixel size is several tens of μm or less, there is a problem that the resolution is insufficient and detection cannot be performed.

As a third method, an LCD before liquid crystal injection
From above with a camera or linear sensor (measurement time 3
~ 5 minutes). However, this method can detect physical defects of pixels, but cannot detect electrical defects.

The present invention has been made in view of the above situation, and a method of manufacturing an active matrix substrate and a liquid crystal capable of accurately detecting a pixel defect in a relatively short time even before a liquid crystal injection step. An object of the present invention is to provide a display device manufacturing method, an inspection method, and an inspection apparatus.

[0012]

In order to achieve the above object, in the method for manufacturing an active matrix substrate of the present invention, a certain amount of electric charge is accumulated in a capacitive element provided for each pixel, and then this accumulated electric charge is accumulated. By detecting the charge,
It includes an inspection step of detecting a pixel defect. Further, the method for inspecting an active matrix substrate of the present invention includes the steps of accumulating a certain amount of electric charge in a capacitive element connected to a predetermined switch element and the step of detecting the electric charge from a video signal terminal line. The charge accumulated in the capacitor can be input from either the video signal input terminal line or the common electrode terminal line. Further, the accumulated charges can be read through either the video signal input terminal line or the common electrode terminal line. The method for manufacturing a liquid crystal display device of the present invention includes the above-described active matrix substrate inspection step. The active matrix substrate inspection apparatus of the present invention, in accordance with the drive signal from the drive signal generating means for supplying a drive signal for sequentially driving the drive cells, the drive signal from the drive signal generating means,
The inspection signal writing means for accumulating a fixed charge in the capacitive element, and the charge accumulated in each capacitive element in accordance with the drive signal from the drive signal generating means are read out, and the charge is detected to detect a pixel defect. And a detection means for detecting. The active matrix substrate to be inspected by the inspection method of the present invention can be used as a drive substrate for other flat panel display devices besides the liquid crystal display device.

[0013]

According to the method of the present invention, the driving cells formed of the switch elements and the capacitive elements provided on the active matrix substrate corresponding to each pixel are sequentially scanned in the same manner as in the case of actual liquid crystal driving. , A certain amount of electric charge is accumulated in the capacitive element, and then the accumulated electric charge is sequentially read. As a result, if there is a defect in the switch element or the capacitor element of the predetermined driving cell corresponding to the pixel, or the data line or gate line connected thereto, the defect information can be read.

Therefore, according to the method of the present invention, the active matrix substrate before the liquid crystal injection step can be inspected under the condition similar to the actual driving state, and can be correlated with the actual display level as compared with other methods. The pixel defect detection can be performed before the liquid crystal injection process. Moreover, the portion that becomes the pixel defect can be inspected at high speed (for example, about 5 seconds or less).
Further, the inspection resolution depends on the pixel holding capacitance of the capacitive element and does not depend on the size of the pixel, so that accurate inspection for each pixel is possible. Further, it is possible to inspect an active matrix substrate in which a horizontal scanning circuit and a vertical scanning circuit are integrated. By performing the inspection by applying the method of the present invention in synchronization with the horizontal scanning circuit and the vertical scanning circuit, it is possible to accurately inspect the address position of the pixel line which becomes the pixel defect. Furthermore, the method of the present invention can be applied even after injecting liquid crystal. In an active matrix drive substrate for LCD using a thin film transistor, in order to hold the applied voltage written through the data line until the next writing, the capacitive element is connected on the substrate in parallel so that it is connected to the liquid crystal. It is desirable to build in. The capacitive element connected in parallel to the liquid crystal is classified according to its formation method. An additional capacitive type in which a pixel element is formed by overlapping a pixel electrode with a part of an adjacent gate line through an insulating layer. There are a capacitance element and a storage capacitance type capacitance element in which an electrode terminal on the side opposite to the portion connected to the switch element is connected to a common electrode terminal line different from the gate line. In the case where the capacitor element is of the additional capacitor type, charge accumulation and reading with respect to the capacitor element may be performed through the video signal input terminal line. Further, in the case where the capacitor is of the storage type, charges can be stored and read from the capacitor not only from the video signal input terminal line but also from the common electrode terminal line. In particular, if the electric charge accumulated in the capacitance element is not detected from the video signal input terminal line but from the common electrode terminal line directly connected to one electrode terminal of each capacitance element, the parasitic capacitance based on the data line is detected. It is possible to prevent the influence of 1) as much as possible, and to increase the detection level of the charge accumulated in each capacitance element, and it is possible to improve the detection accuracy. In addition, if the amplifier in the detection circuit that determines the pixel defect by reading the charge accumulated in the capacitive element is put into a virtual short-circuit state and a constant voltage is supplied to the ground side terminal of the amplifier, during the inspection, A voltage having a polarity that suppresses driving is applied to each switch element that is not scanned at a certain time, as in the case of actual driving. As a result, there is no possibility of erroneously determining a normal switch element as a defective switch element during actual driving. That is, it is possible to perform the inspection in the same state as that during normal driving.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on the embodiments shown in the drawings. 1 is a schematic cross-sectional view of a main part of a liquid crystal display (LCD) having an active matrix substrate, FIG.
FIG. 3 is a schematic diagram showing a circuit configuration when a pixel defect detecting device is connected to the active matrix circuit of the active matrix substrate according to the first embodiment of the present invention. FIG. 3 shows an active matrix circuit for inspecting the active matrix substrate. FIG. 4 is a time chart of applied inspection drive signals, FIG. 4 is a graph showing a determination method by a pixel defect determination circuit, FIG. 5 is a plan view showing types of capacitive elements, and FIG. 6 is an equivalent circuit diagram showing types of capacitive elements. FIG. 7 is a schematic diagram showing a circuit configuration when a pixel defect detecting device is connected to an active matrix circuit of an active matrix substrate according to a second embodiment of the present invention, and FIG. 8 is related to a second embodiment of the present invention. An equivalent circuit diagram at the time of reading out the charges accumulated in the capacitive element during the inspection process of the active matrix substrate, FIG. FIG. 10 is an equivalent circuit diagram at the time of reading the charges accumulated in the capacitive element during the inspection process of the active matrix substrate according to the first embodiment, and FIG. 10 is during the inspection process of the active matrix substrate according to the third embodiment of the present invention. FIG. 11 is an equivalent circuit diagram at the time of reading out the charges accumulated in the capacitive element, FIG. 11 is a circuit diagram showing an example of an I / V amplifier used in another embodiment of the present invention, and FIG. 12 is a diagram at the time of inspection and at the time of actual driving. FIG. 13 is a schematic diagram showing an applied state of a voltage applied to a transistor which is not scanned at a certain time point, and FIG. 13 is a graph showing characteristics of a transistor as a switch element used in an embodiment of the present invention.

First, an outline of a method of manufacturing a liquid crystal display device (LCD) according to the first embodiment of the present invention will be described. L
In order to manufacture a CD, it is necessary to manufacture an active matrix substrate. Although the active matrix substrate is not particularly limited in the present invention, for example, the TFT active matrix substrate 4 having the configuration shown in FIG. 1 is used. In the following description, an example in which the active matrix substrate is used as a liquid crystal driving substrate will be described.
In the example shown in FIG. 1, each pixel is driven, for example, on a glass substrate 5 by a switch element (not shown) for selecting a pixel and a capacitive element (not shown) connected in series to this switch element. Cells are arranged in a matrix.
The driving cell for each pixel includes a display electrode 1 corresponding to the pixel.
2 are arranged in a matrix. In the TFT type active matrix substrate, thin film transistors (TFTs) as switch elements formed by depositing an amorphous silicon film or a polysilicon film on the glass substrate 5 and integrated capacitors are formed in a matrix. I am doing it. It should be noted that the driving cell including the switch element and the capacitive element is formed on the glass substrate.
The active matrix substrate is not limited to the FT type active matrix substrate, and the switch elements and the capacitive elements may be formed in a matrix on a semiconductor substrate to form an active matrix substrate. The connection relationship of the driving cells arranged in a matrix is shown in FIG. The driving cells 10 are arranged in a matrix at the intersections of the gate lines 26 and the data lines 28 to form an active matrix circuit 20. The gate line 26 is connected to the vertical scanning circuit 22. The data line 28 is connected to the video signal input terminal line 32 via the scanning switch circuit 30. Each scanning switch circuit 30 is composed of, for example, a switching CMOS, and the driving of the switches is controlled by the horizontal scanning circuit 24. On the other hand, the capacitive element 8 of the driving cell 10 provided for each pixel is connected in series to the switch element 6, and one terminal thereof is the common electrode terminal line 3
It is connected to 3.

In this embodiment, the vertical scanning circuit 22, the horizontal scanning circuit 24, the switch circuit 30, the video signal input terminal line 32, the common electrode terminal line 33, the gate line 26 and the data line 28 are provided together with the driving cells 10. , Are formed on the surface of the same active matrix substrate 4. The horizontal scanning circuit 24 and the vertical scanning circuit 22 may be formed on a substrate different from the active matrix substrate on which the driving cells 10 are formed in a matrix. Further, in the example shown in FIG. 2, only one video signal input terminal line 32 is formed, but when the liquid crystal display is in color, three video signal input terminal lines corresponding to RGB are required. Become.

In the embodiment shown in FIGS. 1 and 2, the driving cell 1
The switch element 6 forming 0 is shown in FIG.
As shown in (A), it is composed of a thin film transistor formed on a transparent substrate. Further, the capacitive element 8 is shown in FIG.
As shown in FIG. 6A and FIG. 6A, the pixel electrode 12a
Is formed by a storage capacitor type capacitive element 8a which uses a transparent electrode or the like which is formed by being overlapped with and integrated with a part of an insulating layer as a common electrode terminal 33a. In the present invention, the specific structure of the active matrix substrate is not limited to the embodiment shown in FIG. 1 and can be modified in various ways. For example, as the switch element, a MOS transistor, MIM element, diode element, varistor element, etc. formed on a semiconductor substrate or a transparent substrate can be used. Further, as the capacitor element, as shown in FIGS. 5B and 6B, the pixel electrode 12b is overlapped with a part of the adjacent gate line 26b through an insulating layer to form the capacitor element. It is also possible to use the additional capacitance type capacitive element 8b to be formed. In FIGS. 5 and 6, 26a and 26b are gate lines, and 28a and
28b is a data line, 6a and 6b are thin film transistors, 8a and 8b are capacitive elements, and 18a and 1b.
8b is a liquid crystal element for each pixel.

Such an active matrix substrate 4
In order to manufacture the LCD 2 by using, for example, as shown in FIG. 1, the counter substrate 14 having the counter electrode 16 is arranged substantially parallel to the active matrix substrate 4 at a predetermined interval, and between them, The liquid crystal may be injected to form the liquid crystal layer 18. The counter substrate 14 is made of, for example, a glass substrate, and a transparent counter electrode 16 made of, for example, an ITO film is laminated on the surface of the counter substrate 14 facing the driving substrate 4 side. In FIG. 1, reference numeral 15 indicates a color filter. LC according to one embodiment of the present invention
In the manufacturing method of D, after the active matrix substrate 4 as described above is manufactured (before or after being combined with the counter substrate 14), the pixel defect is detected by the following method.

First, as shown in FIG. 2, the inspection switch circuit 34 is connected to the video signal input terminal line 32. One switch terminal 34 of the inspection switch circuit 34
a is connected to the inspection signal writing power supply 36. The voltage applied from the writing power supply 36 is the LCD
Is almost the same as the voltage when actually driving. The other switch terminal 34b of the inspection switch circuit 34 is connected to the determination means 40 via a current-voltage conversion (I / V) amplifier 38. The determination unit 40 is composed of, for example, an image processing device, and includes the inspection switch circuit 34 and the I / V amplifier 38.
Pixel information input through is analyzed.

The inspection switch circuit 34 is configured to switch between connection to the terminal 34a and connection to the terminal 34b at a constant cycle. The switching cycle of this switch is not particularly limited, but it can be performed, for example, in synchronization with a field signal which is one of the video control signals. Since the field signal is repeated at a predetermined cycle as shown in FIG.
As shown in (B) and (C) of the figure, the inspection signal is written by applying the write voltage V1 in the first one field time (a pattern in the figure), and in the next field time. The inspection signal is read (b pattern in the figure), and the inspection is performed by repeating the a pattern and the b pattern. Note that, in FIG. 3, (A) shows a time chart of the field signal, (B) shows a time chart showing the potential state of the video signal input terminal line 32,
FIG. 7C is a time chart showing the switch switching state of the inspection switch circuit 34. Switching of the inspection switch circuit 34 is performed based on, for example, the drive signal generating means 35 shown in FIG. Drive signal generating means 3
The horizontal scanning circuit 2 is used as a part of the inspection device.
4 and the vertical scanning circuit 22 are supplied with drive signals. This drive signal includes the field signal shown in FIG.

FIG. 3 supplied from the drive signal generating means 35.
When the inspection switch circuit 34 is connected to the one terminal 34a side in synchronization with the field signal shown in (A), the horizontal scanning circuit 24 and the vertical scanning circuit 22 are also driven in synchronization with the field signal. Then, the driving cells 10 for one field arranged in a matrix are sequentially scanned. At that time, the voltage V1 from the write power supply 36 and the common power supply terminal line 33 are applied to the capacitive element 8 of each driving cell 10.
The difference in voltage from is applied and charge is accumulated. For example, the voltage V1 is 12 volts, and the common power supply terminal line 33
Is about 6 volts, and the difference voltage is applied to the capacitive element 8.

When the next field signal arrives, the connection of the inspection switch circuit 34 is switched to the terminal 34b side. At the same time, the horizontal scanning circuit 24 and the vertical scanning circuit 22 sequentially start scanning the driving cells 10 for one field in synchronization with the field signal. Then, a detection signal corresponding to the electric charge accumulated in the capacitive element 8 of each driving cell 10 flows through the video signal input terminal line 32 in accordance with the scanning order.

When the switch element 6 and the capacitive element 8 of each driving cell 10 are normal, the charge accumulated in the capacitive element in the previous field time is kept almost unchanged, and the next field time is maintained. Is discharged when reading. Therefore, it is confirmed that the operation of each driving cell 10 is normal by sequentially detecting the current due to the discharge of electric charge in each driving cell 10 by the determination means 40. Further, when there is an abnormality in the switch element 6 or the capacitive element 8 of the predetermined driving cell 10, the discharge current from the cell circuit 10 having the abnormality becomes abnormally lower than in the normal case. You can observe the defects.

For example, as shown by the solid line in FIG. 4, when the cell circuit 10 corresponding to each pixel is normal, in one field time from writing X to reading Y,
The potentials at both ends of each capacitance element 8 are slightly reduced by natural discharge or the like, but hardly change. Therefore, the determination means 40
Then, the value at the point Y of the charge accumulated in each capacitive element 8 can be read to determine that it is normal. However,
For example, when there is an abnormality in the switch element of the cell circuit and the leak current is too large, the locus indicated by the dotted line Z in the figure is followed during one field time, and at the time of reading, the Y1 point that is extremely lower than the Y point The electric potential of will be read. Further, when the terminal connection of the capacitive element 8 is incomplete (capacitor is open) or the like, the trajectory as shown by the dotted line V in the figure is followed, and charge cannot be stored in the capacitive element.

In the LCD, the brightness of the liquid crystal display surface is affected by the change in the potential of the capacitive element 8 for one field. Therefore, if the active matrix substrate is inspected before the liquid crystal is injected by using the method of this embodiment, it is possible to relatively accurately inspect the abnormality that becomes the pixel defect after the liquid crystal is injected. In other words, if the inspection is performed using the method of the present invention, it is possible to obtain a result having a correlation with the display defect level during actual driving.

Specific defects that can be judged by using the judging means 40 of this embodiment include the following defects. (1) Defect when the terminal connection of the capacitive element 8 is incomplete (capacitor is open). In this case, the discharge current is not detected in the portion corresponding to the defective pixel. This is because charge cannot be stored in the capacitive element as indicated by the dotted line V in FIG. (2) A defect in which the capacitive element 8 is short-circuited. In this case, a large discharge current is detected in the portion corresponding to the defective pixel as compared with the peripheral pixels. This is because the current directly flows from the common electrode terminal line 33. (3) The defect that the switch element 6 is always on. In this case, in the data line 28 including the defective pixel,
The discharge current decreases. Cell circuit 10 corresponding to defective pixel
This is because the switch element 6 of 1 affects the reading of the other cell circuit 10 connected to the same data line 28. (4) The defect that the switch element 6 is always off. In this case, the discharge current is not detected in the portion corresponding to the defective pixel. This is because even if the switch element 6 is selected, it does not turn on. (5) A defect in which leakage occurs in the capacitive element 8. In this case, the discharge current detected from the part corresponding to the defective pixel is detected lower than the part corresponding to the peripheral pixels. This is because as shown by the dotted line Z in FIG. 4, the leakage current makes the accumulation and retention of charges incomplete. (6) A defect in which the gate line 26 is broken. In this case, the discharge current from the same gate line 26 is not detected. (7) A defect in which the data line 28 is broken. In this case, the discharge current from the same data line 28 is not detected.

With respect to other defect modes as well, it is possible to detect the defect and determine the type of the defect by analyzing the pixel voltage detected by the determining means 40. The present invention is not limited to the above-mentioned embodiments, but can be variously modified within the scope of the present invention.

For example, in the above-mentioned embodiment, the active matrix substrate 4 before the liquid crystal is injected is used to detect pixel defects which may occur in the future.
Even after the liquid crystal is injected, it can be applied by improving this method. The equivalent circuit including the drive circuit after injecting the liquid crystal is such that a capacitance of several% of the capacitance of the capacitance element is added in parallel to the capacitance element 8 in parallel with the capacitance element 8. Therefore, the equivalent circuit is the same as that shown in FIG. Although almost the same, if a constant DC voltage is applied to the drive circuit 20 after the liquid crystal is injected, electrolysis may occur. In order to avoid this, writing and reading to and from each driving cell may be repeated for each field in the patterns of a, b, c, and b shown in FIG. If writing and reading are repeated with a, b, c, and b patterns, the writing voltage V1 in the first field and the writing voltage V2 in the next field
Since it is not the same as the above, by applying a DC voltage of (V1 + V2) / 2 to the common electrode terminal line 33, an AC voltage is applied to the liquid crystal, which causes electrolysis of the liquid crystal. That's not it. In addition, this pattern c enables simultaneous measurement under two conditions, in the case where a potential is applied to the liquid crystal corresponding to the pixel and the driving cell in the + direction and when the potential is applied in one direction.

As an advantage of performing such a method of the present invention for the inspection of the LCD after injecting the liquid crystal, it is possible to specify the defective address and it is possible to perform some evaluation without looking at the actual display. Is mentioned.

The method of the present invention also includes a horizontal scanning circuit 24.
Also, the present invention can be applied to an active matrix substrate in which the vertical scanning circuit 22 is not incorporated. In that case, the method of the present invention can be used by externally attaching a circuit for sequentially driving each driving cell circuit 10 to the substrate. In the case of this embodiment, compared with the conventional method, in which the needles are directly placed in the X and Y columns and the driving cells corresponding to each pixel are tested by DC (direct current), the real time is obtained. It is excellent in that it can be measured.

Further, in the above-mentioned embodiment, the writing and reading are repeated at the cycle of one field, but the cycle can be changed in the present invention. By changing this period, it becomes possible to read out the charge information stored in the capacitor after an arbitrary time has passed, and it is possible to use it for further advanced failure analysis of the LCD. Specifically, the period can be changed from one pixel period (0.0 nS unit) to 1H period or several field periods by temporarily stopping the vertical scanning circuit 22 or the like. Furthermore, in the above-described embodiment, the video signal input terminal line 32 is configured to apply a potential for accumulating charges to each capacitor element 8. However, the present invention is not limited to this, and the common electrode terminal line 33 side is applied. It can also be configured to apply a potential for charge storage.

FIG. 7 is a schematic circuit diagram showing a state in which the inspection device is connected to the drive circuit of the active matrix substrate according to the second embodiment of the present invention. The same members as those in the first embodiment described above are designated by the same reference numerals, and the description thereof is partially omitted. The inspection method according to this embodiment is performed as follows.

First, as shown in FIG. 7, the inspection switch circuit 34A is connected to the video signal input terminal line 32. One switch terminal 3 of the inspection switch circuit 34A
4a is connected to the inspection signal writing power supply 36. The voltage applied from the writing power supply 36 is LC
It is almost the same as the voltage when D is actually driven. The other switch terminal 34b of the inspection switch circuit 34A is connected to the reference potential. The switch circuit 34A is an inspection switch circuit 34 connected to the common electrode terminal line 33.
It operates in synchronization with B. The common electrode terminal line 33 is connected to the determination means 40 via an I / V amplifier 38. The determination unit 40 is composed of, for example, an image processing device, and is configured to analyze the pixel information input through the I / V amplifier 38.

The inspection switch circuit 34A is configured to switch between connection to the terminal 34a and connection to the terminal 34b at a constant cycle. Moreover, in synchronization with the operation of the inspection switch circuit 34A, the inspection switch circuit 34B is also switched between the case of connecting to the reference potential and the case of opening the connection to the reference potential. That is, the capacitive element 8 is supplied from the inspection signal writing power supply 36 through the video input terminal line 32 and the data line 28.
When the inspection signal is written by sequentially accumulating electric charges to the switch circuit 34B, the switch circuit 34B is connected to the reference potential,
The determination means 40 does not read the potential. Also,
When the switch circuit 34A is switched to connect to the switch terminal 34b, the switch circuit 34B is opened, the charges accumulated in each capacitance element 8 are sequentially read, and the discharge current thereof is converted into a voltage to determine the means. 40
To monitor.

The switching cycle of this switch is not particularly limited, but it can be performed, for example, in synchronization with a field signal which is one of the video control signals. Since the field signal is repeated at a predetermined cycle as shown in FIG. 3 (A), the switching of the inspection switch circuits 34A, 34B is performed by the first 1 switch as shown in FIG. 3 (B), (C). During the field time, the inspection signal is written by applying the write voltage V1 (a pattern in the figure), the inspection signal is read in the next field time (b pattern in the figure), and the a pattern and the b pattern are repeated. To inspect. 4A shows a time chart of the field signal, FIG. 4B shows a time chart showing the potential state of the video signal input terminal line 32, and FIG. 4C shows an inspection switch. 6 is a time chart showing a switch switching state of the circuit 34. Switching between the inspection switch circuits 34A and 34B is performed based on, for example, the drive signal generating means 35 shown in FIG. The drive signal generating means 35 is used as a part of the inspection device and supplies a drive signal to the horizontal scanning circuit 24 and the vertical scanning circuit 22. This drive signal includes the field signal shown in FIG.

When the inspection switch circuit 34A is connected to one of the terminals 34a in synchronization with the field signal shown in FIG. 3A, the horizontal scanning circuit 24 and the vertical scanning circuit 22 also receive the field signal. The driving cells 10 for one field, which are driven in synchronism with each other and are arranged in a matrix, are sequentially scanned. At that time, each driving cell circuit 10
Of the voltage V1 from the writing power source 36
And a voltage difference from the common power supply terminal line 33 is applied, and charges are accumulated. For example, the voltage V1 is 12 volts,
The voltage from the common power terminal line 33 is about 6 volts,
The difference voltage is applied to the capacitive element 8.

Then, when the next field signal arrives, the connection of the inspection switch circuit 34A is switched to the terminal 34b side, and the inspection switch circuit 34B is opened. At the same time, the horizontal scanning circuit 24 and the vertical scanning circuit 22 sequentially start scanning the driving cells 10 for one field in synchronization with the field signal. Then,
A detection signal corresponding to the charge accumulated in the capacitive element 8 of each driving cell 10 flows through the common power supply terminal line 32 according to the scanning order.

When the switch element 6 and the capacitive element 8 of each driving cell 10 are normal, the charge accumulated in the capacitive element in the previous field time is kept almost unchanged, and the charge is stored in the next field time. Is discharged when reading. Therefore, the current due to the discharge of charges in each driving cell circuit 10 is converted into a voltage by the amplifier 38,
By sequentially detecting it by the determination means 40, it is confirmed that the operation of each driving cell 10 is normal. Further, when there is an abnormality in the switch element 6 or the capacitive element 8 of the predetermined driving cell 10, the discharge current from the cell circuit 10 having the abnormality becomes abnormally lower than in the normal case. You can observe the defects.

For example, as shown by the solid line in FIG. 4, when the cell circuit 10 corresponding to each pixel is normal, in one field time from writing X to reading Y,
The potentials at both ends of each capacitance element 8 are slightly reduced by natural discharge or the like, but hardly change. Therefore, the determination means 40
Then, the value at the point Y of the charge accumulated in each capacitive element 8 can be read to determine that it is normal. However,
For example, if there is an abnormality in the switch element of the cell circuit and the leak current is too large, the locus indicated by the dotted line Z in the figure is followed during one field time, and at the time of reading, the Y1 point that is extremely lower than the Y point is read. The electric potential of will be read. Further, when the terminal connection of the capacitive element 8 is incomplete (capacitor is open) or the like, the trajectory as shown by the dotted line V in the figure is followed, and charge cannot be stored in the capacitive element.

In the LCD, the brightness of the liquid crystal display surface is affected by the change in the potential of the capacitive element 8 for one field. Therefore, if the active matrix substrate is inspected before the liquid crystal is injected by using the method of this embodiment, it is possible to relatively accurately inspect the abnormality that becomes the pixel defect after the liquid crystal is injected. In other words, if the inspection is performed using the method of the present invention, it is possible to obtain a result having a correlation with the display defect level during actual driving.

The following defects can be exemplified as specific defects that can be judged by the judgment means 40 of this embodiment. (1) Defect when the terminal connection of the capacitive element 8 is incomplete (capacitor is open). In this case, the discharge current is not detected in the portion corresponding to the defective pixel. This is because charge cannot be stored in the capacitive element as indicated by the dotted line V in FIG. (2) A defect in which the capacitive element 8 is short-circuited. In this case, a large discharge current is detected in the portion corresponding to the defective pixel as compared with the peripheral pixels. This is because the current directly flows from the common electrode terminal line 33. (3) The defect that the switch element 6 is always on. In this case, in the data line 28 including the defective pixel,
The discharge current decreases. Cell circuit 10 corresponding to defective pixel
This is because the switch element 6 of 1 affects the reading of the other cell circuit 10 connected to the same data line 28. (4) The defect that the switch element 6 is always off. In this case, the discharge current is not detected in the portion corresponding to the defective pixel. This is because even if the switch element 6 is selected, it does not turn on. (5) A defect in which leakage occurs in the capacitive element 8. In this case, the discharge current detected from the part corresponding to the defective pixel is detected lower than the part corresponding to the peripheral pixels. This is because as shown by the dotted line Z in FIG. 4, the leakage current makes the accumulation and retention of charges incomplete. (6) A defect in which the gate line 26 is broken. In this case, the discharge current from the same gate line 26 is not detected. (7) A defect in which the data line 28 is broken. In this case, the discharge current from the same data line 28 is not detected.

In this embodiment, also in the other defect modes, it is possible to detect the defect and determine the kind of the defect by analyzing the pixel voltage detected by the judging means 40. Particularly, in the embodiment of the present invention as shown in FIG. 7, compared with the embodiment shown in FIG.
The charge of each capacitive element 8 is read from 3,
Since the configuration is not such that the charge of the capacitive element 8 is read from the video signal input terminal line 32, it has the following advantages.

That is, in the embodiment shown in FIG. 7, the inspection switch circuit 34 is connected to the video signal input terminal line 32, and one switch terminal 34a of the inspection switch circuit 34 is connected to the inspection signal writing power source 36. By connecting the other switch terminal 34b to the amplifier 38 and the determination means 40, the charge is read from the capacitor 8 from the common electrode terminal line 33.

Therefore, in the circuit configuration of this embodiment shown in FIG. 7, an equivalent circuit diagram showing the relationship between the voltage V of the capacitive element and the read voltage Vx at the time of writing when the charge of the capacitive element 8 is read is as follows: As shown in FIG. On the other hand, FIG.
FIG. 9 is an equivalent circuit diagram showing the relationship between the voltage V of the capacitive element and the read voltage Vx at the time of writing when the charge of the capacitive element 8 is read in the circuit configuration of the embodiment shown in FIG. 8 and 9, Cs is the capacitance of the capacitive element 8, C _sig1 is the parasitic capacitance parasitic on the video signal input terminal line 32, and C _sig2 is the parasitic capacitance parasitic on the data line 28. .

Based on the equivalent circuit shown in FIG.
On the other hand, assuming that the electric charge of Q = Cs × V is accumulated, the relation between the voltage V of the capacitive element and the read voltage Vx is calculated as follows.
The following formula 1 is obtained. On the other hand, based on FIG. 8, the relationship between the voltage V of the capacitive element at the time of writing and the read voltage Vx in this example is calculated, and the following mathematical formula 2 is obtained.

[Equation 1]

[Equation 2] Comparing Expressions 1 and 2 above, it is found that the read voltage Vx in Expression 2 is larger than the read voltage Vx in Expression 1. That is, compared with the embodiment shown in FIG. 2, according to the method of the present embodiment shown in FIG.
The read voltage Vx (that is, the detection level) can be set large. For example, C _sig1 is 4 _pF and C _sig2
Is 20 pF and Cs is 150 fF, the first
The detection level Vx obtained by Equation 1 showing the embodiment is about 0.
It is 006 × V, whereas the detection level Vx obtained by the mathematical formula 2 showing the second embodiment is about 0.03 × V, and it can be confirmed that the detection level is significantly improved. If the detection level is improved, the accuracy of the detection of the pixel defect or the determination of the type of defect by the determination means 40 is improved.

FIG. 10 is a circuit diagram showing a method for detecting a pixel defect according to the third embodiment of the present invention. In the embodiment shown in FIG. 10, the video signal input terminal line 32 is always grounded to the reference potential, the common electrode terminal line 33 is provided with a test switch circuit 34C, and one switch terminal 34a is used for test signal writing. It is connected to the power supply 36, and the other switch terminal 34 b is connected to the determination means 40 via the I / V amplifier 38.

An equivalent circuit diagram showing the relationship between the voltage V of the capacitive element and the read voltage Vx at the time of writing in such an embodiment has the circuit configuration shown in FIG. 8 similarly to the embodiment shown in FIG. The time detection level will be improved. Further, in each of the above-described embodiments, the active matrix substrate 4 before the liquid crystal is injected is used to detect pixel defects that may occur in the future, but the present method is improved even after the liquid crystal is injected. It is applicable by doing. The equivalent circuit including the drive circuit after injecting liquid crystal is
The equivalent circuit is almost the same as the circuit shown in FIG. 7 because a capacity of several% of the capacity of the capacitive element is added in parallel to the capacitive element 8 as a capacitive component.
When a constant DC voltage is applied to the drive circuit 20, electrolysis may occur. To avoid this,
With the patterns of a, b, c, and b shown in FIG. 3, writing and reading with respect to each driving cell may be repeated for each field. If writing and reading are repeated in the patterns of a, b, c, and b, the writing voltage V1 in the first field is not the same as the writing voltage V2 in the next field. Therefore, the common electrode terminal line 33 On the other hand, by applying a DC voltage of (V1 + V2) / 2, an AC voltage is applied to the liquid crystal, and there is no risk of electrolysis of the liquid crystal. In addition, this pattern c enables simultaneous measurement under two conditions, in the case where a potential is applied to the liquid crystal corresponding to the pixel and the driving cell in the + direction and when the potential is applied in one direction. Such a method of the present invention,
The advantage of performing the inspection of the LCD after injecting the liquid crystal is that the defective address can be specified and the evaluation can be performed to some extent without looking at the actual display.

The method of the present invention also includes a horizontal scanning circuit 24.
Also, the present invention can be applied to an active matrix substrate in which the vertical scanning circuit 22 is not incorporated. In that case, the method of the present invention can be used by externally attaching a circuit for sequentially driving each driving cell circuit 10 to the substrate. In the case of this embodiment, compared with the conventional method, in which the needles are directly placed in the X and Y columns and the driving cells corresponding to each pixel are tested by DC (direct current), the real time is obtained. It is excellent in that it can be measured.

Further, in the above-described embodiment, writing and reading are repeated in one field cycle, but this cycle can be changed in the present invention. By changing this period, it becomes possible to read out the charge information stored in the capacitor after an arbitrary time has passed, and it is possible to use it for further advanced failure analysis of the LCD.

Specifically, the period can be changed from one pixel period (0.0 nS unit) to 1H period or several field periods by temporarily stopping the vertical scanning circuit 22 or the like.

The following examples can be given as preferred examples of the present invention. In this embodiment, instead of using the normal virtual short-circuit and virtual ground I / V amplifier 38 used in the above-described respective embodiments, as shown in FIG. 11, although it is a virtual short, the ground side terminal 50 of the amplifier is used.
Is not grounded to the ground, but the I / V amplifier 38a connected to the constant voltage source 52 is used. As the voltage applied from the constant voltage source 52 (tentatively referred to as virtual potential),
Although not particularly limited, +0.5 to 11 V, and preferably about 6 V which is a voltage applied to the common electrode terminal line 33 during actual driving. In FIG. 11, reference numeral 54,
Reference numeral 56 is a resistor for obtaining an amplification gain.

In each of the above-described embodiments, a normal virtual short-circuit and virtual ground amplifier is used as the I / V amplifier 38 used as a part of the inspection apparatus, and a current corresponding to the electric charge accumulated in each capacitance element 8 is used. The defect is detected for each pixel by flowing it to the ground side and converting the current into a voltage. However, it has been found by the present inventors that the use of the virtual ground amplifier 38 has the following problems. That is, as shown in FIG. 12A, during the inspection, the virtual ground voltage (0 V) is applied to the source side terminal S of each switch element 6 which is not scanned at a certain time point. The voltage of the gate line 26 is also 0 volt, and if the switch element is perfectly normal, the switch element 6 does not turn on. However, as shown in FIG. 13, in the switch element 6 composed of a TFT, for example, the voltage difference Vgs between the voltage of the gate side terminal G and the voltage of the source side terminal S is 0.
Even if it is a bolt, the drain side terminal D of the switch element 6
The current Id flowing to may not always be 0. That is, the transistor as the switch element 6 may not be completely turned off. This is because the characteristic curve of Id with respect to Vgs deviates to the plus side or minus side of Vgs due to manufacturing error of the transistor.

During actual driving of the liquid crystal device, a voltage of, for example, 1.5 to 10.5 volts is constantly applied to the video signal input terminal line 32, and the source side terminal S of the transistor constituting the switch element 6 is applied. Is applied with a voltage of 1.5 V or higher. As a result, Vgs of the unscanned transistor at the time of actual driving becomes −1.5 V or less, and as shown in FIG. 13, the transistor having the manufacturing error within the predetermined error range has the same value as the unscanned transistor. , Current Id hardly flows (OFF state), and no malfunction occurs.

However, at the time of inspection, Vgs of the transistor which is the non-scanned switch element 6 becomes completely 0 volt, and there is a fear that a leak current may flow (transistor on state) even in a transistor which operates normally during actual driving. There is. For this reason, even a transistor as the switch element 6 that operates normally during actual driving may be erroneously detected as a non-normal transistor. Such a problem also applies when the switch element 6 is an element other than a transistor.

In the present embodiment, as shown in FIG. 11, the amplifier 38a is put into a virtual short-circuit state and a constant voltage is supplied to the ground side terminal 50 of the amplifier 38a, so that scanning is performed during the inspection. A voltage having a polarity that suppresses driving is applied to each switch element 6 that is not present, as in the case of actual driving. As a result, there is no possibility of erroneously determining a normal switch element as a defective switch element during actual driving. That is, it is possible to perform the inspection in the same state as that during normal driving.

As a modification of this embodiment, the virtual potential supplied from the constant voltage source 50 shown in FIG. 11 can be made variable. In that embodiment, it is possible to inspect active matrix substrates with different drive voltage ranges. Further, the virtual potential is a potential difference that acts on the capacitive element 8 by providing a potential difference on the plus side or the minus side with respect to the potential applied to the common electrode terminal line 33, for example, in the range of 2 to 3 volts. It is also possible to increase the sensitivity and improve the measurement sensitivity.

[0058]

As described above, according to the present invention, the active matrix substrate before the liquid crystal injection step is
It can be inspected under conditions similar to the actual driving state,
As compared with other methods, it is possible to detect defects that are correlated with the actual display level before the liquid crystal injection process. Moreover, it is possible to inspect a pixel defect portion at a high speed (for example, about 5 seconds or less), and the device configuration for the inspection can be simplified as compared with the related art. Further, the inspection resolution depends on the pixel holding capacitance of the capacitive element and does not depend on the size of the pixel, so that accurate inspection for each pixel is possible. Further, it is possible to inspect an active matrix substrate in which a horizontal scanning circuit and a vertical scanning circuit are integrated. By performing the inspection by applying the method of the present invention in synchronization with the horizontal scanning circuit and the vertical scanning circuit, it is possible to accurately inspect the address position of the pixel line which becomes the pixel defect. Furthermore, the method of the present invention can be applied even after injecting liquid crystal.

Particularly, if the charge accumulated in the capacitance element is not detected from the video signal input terminal line but from the common electrode terminal line directly connected to one side electrode terminal of each capacitance element, the data line is detected. It is possible to prevent the influence of the parasitic capacitance based on this as much as possible, and to increase the detection level of the electric charge accumulated in each capacitance element, and it is possible to improve the detection accuracy.

If the amplifier in the detection circuit for reading out the charge accumulated in the capacitive element to judge the pixel defect is put into a virtual short-circuit state and a constant voltage is supplied to the ground side terminal of the amplifier, the inspection can be performed. A voltage having a polarity that suppresses driving is applied to each of the switch elements that are not scanned therein, as in the case of actual driving. As a result, there is no possibility of erroneously determining a normal switch element as a defective switch element during actual driving. That is, it is possible to perform the inspection in the same state as that during normal driving.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a main part of a liquid crystal display device (LCD) having an active matrix substrate.

FIG. 2 is a schematic diagram showing a circuit configuration when a pixel defect detection device is connected to the active matrix circuit of the active matrix substrate according to the first embodiment of the present invention.

FIG. 3 is a time chart diagram of an inspection drive signal applied to an active matrix circuit to inspect an active matrix substrate.

FIG. 4 is a graph showing a determination method by a pixel defect determination circuit.

FIG. 5 is a plan view showing types of capacitive elements.

FIG. 6 is an equivalent circuit diagram showing types of capacitive elements.

FIG. 7 is a schematic diagram showing a circuit configuration when a pixel defect detecting device is connected to an active matrix circuit of an active matrix substrate according to a second embodiment of the present invention.

FIG. 8 is an equivalent circuit diagram at the time of reading charges accumulated in a capacitive element during an inspection process of an active matrix substrate according to a second embodiment of the present invention.

FIG. 9 is an equivalent circuit diagram at the time of reading the charge accumulated in the capacitive element during the inspection process of the active matrix substrate according to the first example of the present invention.

FIG. 10 is an equivalent circuit diagram at the time of reading out charges accumulated in a capacitive element during an inspection process of an active matrix substrate according to a third example of the present invention.

FIG. 11 is a circuit diagram showing an example of an I / V amplifier used in another embodiment of the present invention.

FIG. 12 is a schematic diagram showing an applied state of a voltage applied to a transistor that is not scanned at a certain time point during inspection and during actual driving.

FIG. 13 is a graph showing characteristics of a transistor as a switch element used in an example of the present invention.

[Explanation of symbols]

 2 ... LCD 4 ... Active matrix substrate 6 ... Switch element 8 ... Capacitance element 10 ... Driving cell 14 ... Counter substrate 16 ... Counter electrode 18 ... Liquid crystal layer 20 ... Active matrix circuit 22 ... Vertical scanning circuit 24 ... Horizontal scanning circuit 26 ... Gate line 28 ... Data line 30 ... Switch circuit 32 ... Video input terminal line 33 ... Common electrode terminal line 34, 34A, 34B, 34C ... Inspection switch circuit 35 ... Drive signal generating means 36 ... Writing power supply 38, 38a ... I / V amplifier 40 ... Judgment means 50 ... Ground side terminal 52 ... Constant voltage source

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Serial number within the agency FI Technical indication location H01L 29/784 (72) Inventor Yuji Hayashi 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Incorporated (72) Inventor Toshikazu Maekawa 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (19)

[Claims] 1. A method of manufacturing an active matrix substrate in which driving cells for each pixel, each of which is composed of a switch element for selecting a pixel and a capacitive element connected in series to the switch element, are arranged in a matrix. 2. The method for manufacturing an active matrix substrate according to claim 1, including a step of detecting a defect of a pixel by detecting a fixed charge after the fixed charge is stored in the capacitive element. 2. The active matrix substrate according to claim 1, wherein the electric charge from the capacitive element is detected from a video signal input terminal line connected to the driving cell via a scanning switch circuit. Production method. 3. The method of manufacturing an active matrix substrate according to claim 1, wherein the electric charge from the capacitive element is detected from a common electrode terminal line connected to one electrode terminal of the capacitive element. 4. The accumulation of electric charges in the capacitance element is performed from a video signal input terminal line connected to the driving cell through a scanning switch circuit. 5. The method for manufacturing an active matrix substrate according to any one of 1. 5. The active matrix according to claim 1, wherein charge is accumulated in the capacitance element from a common electrode terminal line connected to one side electrode terminal of the capacitance element. Substrate manufacturing method. 6. The method for manufacturing an active matrix substrate according to claim 1, wherein the switch element is a thin film transistor. 7. The common electrode terminal line connected to the electrode terminal on one side of the capacitive element is formed on the substrate.
7. A method for manufacturing an active matrix substrate according to any one of items 6 to 6. 8. The one-side electrode terminal of the capacitive element is formed by a part of a gate line for driving a switch element of an adjacent driving cell adjacent to the capacitive element.
7. The method for manufacturing an active matrix substrate according to any of 6. 9. At each intersection of the data line and the gate line,
A plurality of driving cells arranged in a matrix corresponding to pixels, a vertical scanning circuit connected to the gate line and scanning the gate line in the vertical direction, and connected to the data line via a scanning switch circuit A video signal is supplied to the data line connected to the driving cell via a horizontal scanning circuit for scanning the data line in the horizontal direction and a scanning switch circuit connected to the output section of the horizontal scanning circuit. The video signal input terminal line and the video signal input terminal line are formed on the same substrate.
5. The method for manufacturing an active matrix substrate according to any one of 1. 10. A plurality of driving cells arranged in a matrix corresponding to pixels at each intersection of a data line and a gate line, and connected to the gate line, and the gate line is vertically scanned. A vertical scanning circuit, a horizontal scanning circuit that is connected to the data line through a scanning switch circuit, and horizontally scans the data line, and a scanning switch circuit that is connected to the output section of the horizontal scanning circuit. A video signal input terminal line for supplying a video signal to a data line connected to the driving cell, wherein the driving cell comprises a switch element for selecting a pixel and a capacitive element connected in series to the switch element. An active matrix substrate composed of a counter substrate, a counter substrate having a counter electrode and arranged to face the active matrix substrate, the active matrix substrate and the counter substrate A method of manufacturing a liquid crystal display device comprising a liquid crystal layer held between, wherein after a certain charge is accumulated in a capacitor element connected to the predetermined switch element, A method of manufacturing a liquid crystal display device, comprising the step of detecting a defect in a pixel by detecting an electric charge. 11. A plurality of driving cells arranged in a matrix corresponding to pixels at each intersection of a data line and a gate line, and connected to the gate line, and the gate line is vertically scanned. A vertical scanning circuit, a horizontal scanning circuit that is connected to the data line through a scanning switch circuit, and horizontally scans the data line, and a scanning switch circuit that is connected to the output section of the horizontal scanning circuit. A video signal input terminal line for supplying a video signal to a data line connected to the drive cell, wherein the drive cell is connected in series to the switch element for selecting a pixel and one side of the switch element. An active matrix substrate composed of a capacitive element whose electrode terminals are connected to a common electrode terminal line, and a counter substrate having a counter electrode and arranged to face the active matrix substrate. And a liquid crystal layer held between the active matrix substrate and a counter substrate, wherein the video signal input terminal line and the common electrode terminal line are either terminals. A step of detecting a pixel defect by accumulating a certain amount of electric charge from a line to a capacitive element connected to a predetermined switch element through the switch circuit, and then detecting the electric charge from the common terminal line. A method for manufacturing a liquid crystal display device, comprising: 12. A method for inspecting an active matrix substrate in which driving cells for each pixel, each of which is composed of a switch element for selecting a pixel and a capacitive element connected in series to the switch element, are arranged in a matrix. 2. A method for inspecting an active matrix substrate, comprising: detecting a defect of a pixel by detecting a charge accumulated in each capacitance element after accumulating a constant charge in the capacitance element. 13. A step of accumulating charges in the capacitance element,
13. The method for inspecting an active matrix substrate according to claim 12, wherein the step of detecting electric charges from the capacitive element is switched in one field cycle. 14. An amplifier connected to either one of a video signal input terminal line and a common electrode terminal line is put into a virtual short-circuit state in order to detect electric charge from the capacitance element, and moreover, it is connected to a ground side terminal of the amplifier. The method for inspecting an active matrix substrate according to claim 12, wherein a constant voltage is supplied. 15. The constant voltage applied to the ground side terminal of the amplifier is in the range of 0.5 to 11 volts.
15. The method for inspecting an active matrix substrate according to any one of 14 to 14. 16. An inspection for inspecting an active matrix substrate in which a driving cell for each pixel, which is composed of a switch element for selecting a pixel and a capacitive element connected in series to the switch element, is arranged in a matrix. In the device, drive signal generating means for supplying a drive signal for sequentially driving each drive cell, and inspection signal writing means for accumulating a constant electric charge in the capacitive element in accordance with the drive signal from the drive signal generating means. And an inspection means for the active matrix substrate, which has a detection means for detecting a pixel defect by reading out the electric charge accumulated in each capacitive element in accordance with the drive signal from the drive signal generating means and detecting the electric charge. apparatus. 17. The active element according to claim 16, further comprising a changeover switch that switches between accumulation of electric charges from the voltage applying unit to the capacitive elements and detection of electric charges accumulated in each of the capacitive elements in one field cycle. Matrix substrate inspection device. 18. The active matrix substrate according to claim 16, wherein an amplifier forming a part of the detecting means is in a virtual short circuit state, and has a constant voltage source for supplying a constant voltage to a ground side terminal of the amplifier. Inspection device. 19. The constant voltage applied to the ground side terminal of the amplifier is in the range of 0.5 to 11 volts.
19. The inspection device for an active matrix substrate according to any one of items 18 to 18.