JP3203864B2 - Active matrix substrate manufacturing method, inspection method and apparatus, and liquid crystal display device manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an active matrix substrate, a method of inspecting the same, and a method of manufacturing a liquid crystal display device. Regarding methods that can be detected.

[0002]

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

An active matrix type LCD has an active matrix substrate, and the surface of the substrate is
Driving cells for each pixel, which include a switch element for selecting a pixel and a capacitor 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 pixels are arranged in a matrix.

[0004] On such an active matrix substrate, opposing substrates are arranged substantially in parallel at a predetermined interval. The opposing substrate is formed of, for example, a glass substrate, and a transparent opposing electrode is laminated on a surface of the opposing substrate facing the active matrix substrate. And
Liquid crystal is injected between the counter substrate and the driving substrate to form a liquid crystal layer. Such L
To manufacture a CD, an active matrix substrate and
The counter electrode on which the counter electrode is formed is manufactured separately,
These may be combined substantially in parallel at predetermined intervals, and a liquid crystal may be injected into these gaps to form a sealed liquid crystal layer.

[0005] Incidentally, not all LCDs manufactured in this way are good LCDs without pixel defects, and it is necessary to inspect the LCDs for pixel defects. Active matrix LC after liquid crystal injection
As a method of performing the pixel defect inspection of D, a method of actually driving an LCD and analyzing an image of the LCD by an image processing device to detect a defect or a method of visually detecting a defect is adopted. Further, as a method of performing a pixel defect inspection of an active matrix type LCD after injecting liquid crystal, for example, a method disclosed in Japanese Patent Application 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, a long measurement time is required, and high productivity cannot be expected. In addition, since the inspection for pixel defects is performed on the LCD after liquid crystal injection, if it is discovered that a pixel defect has occurred, the LCD on which the defect is found is discarded. There is a problem that must be done. This is because it is not practical in terms of manufacturing cost and the like to remove the liquid crystal of the LCD once filled with the liquid crystal, compensate the defective portion or replace the defective driving substrate, and then re-add the liquid crystal.

[0007]

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

First, there is known a method in which a needle is directly placed on the surface of an active matrix substrate in X and Y columns to perform a DC (direct current) test on a driving cell circuit corresponding to each pixel. In this technique, in order to detect the defect of each pixel,
The DC test is repeated in the X and Y directions. in this way,
Needles for the number of X and Y pixels are required, and there is a drawback that the test time is long (about 1 to 5 minutes). In particular, a built-in H / V scanner (horizontal / vertical scanning circuit) without X and Y terminals is provided. It cannot be used with LCD.

Secondly, there is known a method of detecting a pixel defect as light intensity using a special crystal (measurement time is 1 to 2 minutes). In this method, instead of liquid crystal, a special plate-like crystal whose refractive index changes according to the applied voltage is placed on the surface of an active matrix substrate, and a laser beam is applied to the crystal, and the light is applied to the crystal. By detecting the transmitted light or the reflected light, a pixel defect is captured. In this method, since the information detected as light needs to be processed again by the camera, the processing is complicated. In addition, the test cannot be performed in the actual driving state. Further, when the size of the pixel is several tens 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 is used.
Is inspected from above with a camera or linear sensor (measurement time 3
~ 5 minutes). However, in this method, a physical defect of a pixel can be detected, but an electrical defect cannot be detected.

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

[0012]

In order to achieve the above object, according to a method of manufacturing an active matrix substrate of the present invention, a constant charge is accumulated in a capacitor provided for each pixel, and then the accumulated charge is accumulated. By detecting the charge,
An inspection step for detecting a pixel defect is included. Further, the method for inspecting an active matrix substrate according to the present invention includes a step of accumulating a fixed charge in a capacitor connected to a predetermined switch element, and a step of detecting the charge from a video signal input terminal line. The charge stored in the capacitor can be input from one of the video signal input terminal line and the common electrode terminal line. The reading of the stored charge can be performed through one of the video signal input terminal line and the common electrode terminal line. This
Here, in order to detect the charge from the capacitive element,
Either video signal input terminal line or common electrode terminal line
Put the amplifier connected to one side in a virtual short-circuit state, and
Supply a positive constant voltage to the ground terminal of the amplifier . The method for manufacturing a liquid crystal display device according to the present invention includes the above-described active matrix substrate inspection step. The active matrix substrate inspection apparatus of the present invention includes a driving signal generating unit that supplies a driving signal for sequentially driving the driving cells,
In accordance with a drive signal from the drive signal generation means, an inspection signal writing means for accumulating a constant charge in a capacitor, and in accordance with a drive signal from the drive signal generation means,
Reading out charges accumulated in the capacitive element, by detecting the charge, have a detection means for detecting a defective pixel, the amplifier constituting a part of the detection means virtual short
And a positive constant voltage is supplied to the ground terminal of the amplifier.
A constant voltage source . Note that the active matrix substrate inspected by the inspection method of the present invention can be used as a driving substrate for other flat display devices other than the liquid crystal display device.

[0013]

According to the method of the present invention, a driving cell comprising a switch element and a capacitor element provided on an active matrix substrate corresponding to each pixel is sequentially scanned, for example, in substantially the same manner as in actual liquid crystal driving. Then, a certain amount of charge is accumulated in the capacitor, and then the accumulated charge is sequentially read. As a result, when there is a defect in a switch element or a capacitor element of a predetermined driving cell corresponding to a pixel or a data line or a 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 conditions similar to the actual driving state, and can be correlated with the actual display level as compared with other methods. The detected pixel defect can be performed before the liquid crystal injection step. In addition, a portion that becomes a pixel defect can be inspected at high speed (for example, about 5 seconds or less).
In addition, since the resolution of the inspection depends on the pixel holding capacitance of the capacitor and does not depend on the size of the pixel, an accurate inspection can be performed for each pixel. Further, it is possible to inspect an active matrix substrate in which a horizontal scanning circuit and a vertical scanning circuit are integrated. If the inspection is performed by applying the method of the present invention in synchronization with the horizontal scanning circuit and the vertical scanning circuit, the address position of a pixel line that becomes a pixel defect can be accurately inspected. Furthermore, the method of the present invention can be applied even after liquid crystal is injected. In an active matrix driving substrate for an LCD using thin film transistors, in order to hold an applied voltage written through a data line until the next writing, a capacitive element is mounted on the substrate so as to be connected in parallel to the liquid crystal. It is desirable to build in. Capacitors connected in parallel to the liquid crystal are classified according to the method of formation. An additional capacitance type in which a capacitor is formed by overlapping a pixel electrode with a part of an adjacent gate line via an insulating layer. There are a capacitance element and a storage capacitance type capacitance element in which an electrode terminal opposite to a portion connected to a switch element is connected to a common electrode terminal line different from a gate line. In the case where the capacitance element is an additional capacitance type, accumulation and readout of electric charge to and from the capacitance element may be performed through a video signal input terminal line. Further, when the capacitor is of the storage type, the charge 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 detection of the electric charge stored in the capacitance element is performed not 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 can be obtained. Can be prevented as much as possible, and the detection level of the electric charge accumulated in each capacitance element can be increased, so that the detection accuracy can be improved. Further, by reading the charge accumulated in the capacitor as a virtual short-circuit state amplifier in the detection circuit to determine a defective pixel, and configured to provide a constant voltage to the ground 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 actual driving. As a result, there is no possibility that a normal switch element during actual driving is erroneously determined as a defective switch element. That is, it is possible to inspect the same state as that in the normal driving.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. FIG. 1 is a schematic sectional view of a main part of a liquid crystal display (LCD) having an active matrix substrate, and FIG.
FIG. 3 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. 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 detection 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 a diagram showing a second embodiment of the present invention. FIG. 9 is an equivalent circuit diagram at the time of reading out the electric charge accumulated in the capacitance element during the inspection process of the active matrix substrate, and FIG. FIG. 10 is 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 according to one embodiment. FIG. 10 is a diagram illustrating the active matrix substrate according to the third embodiment of the invention during the inspection process. FIG. 11 is an equivalent circuit diagram at the time of reading charges accumulated in the capacitor, FIG. 11 is a circuit diagram showing an example of an I / V amplifier used in another embodiment of the present invention, and FIG. FIG. 13 is a schematic diagram showing a state of application of a voltage applied to a transistor which is not scanned at a certain time, and FIG. 13 is a graph showing characteristics of a transistor as a switch element used in the embodiment of the present invention.

First, an outline of a method of manufacturing a liquid crystal display (LCD) according to a first embodiment of the present invention will be described. L
To manufacture a CD, it is necessary to manufacture an active matrix substrate. Although the present invention is not particularly limited as the active matrix substrate, for example, a TFT type active matrix substrate 4 having the configuration shown in FIG. 1 is used. In the following description, an example in which an 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 by, for example, a switch element (not shown) for selecting a pixel on a glass substrate 5 and a capacitor element (not shown) connected in series to the 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, a thin film transistor (TFT) as a switching element formed by forming an amorphous silicon film or a polysilicon film on a glass substrate 5 and an integrated capacitor are formed in a matrix. I have. Note that a driving cell including a switching element and a capacitor is formed on a glass substrate.
The present invention is not limited to the FT type active matrix substrate, and a switch element and a capacitor element may be formed in a matrix on a semiconductor substrate to form an active matrix substrate. FIG. 2 shows the connection relationship of the driving cells arranged in a matrix. The driving cells 10 are arranged in a matrix at 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 a video signal input terminal line 32 via a scanning switch circuit 30. Each scanning switch circuit 30 is formed 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 connected to the common electrode terminal line 3.
3 is connected.

In this embodiment, the vertical scanning circuit 22, the horizontal scanning circuit 24, the switching 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 formed on the surface of the same active matrix substrate 4. Note that the horizontal scanning circuit 24 and the vertical scanning circuit 22 may be formed on a substrate different from the active matrix substrate in which the driving cells 10 are formed in a matrix. In the example shown in FIG. 2, only one video signal input terminal line 32 is formed. However, when the liquid crystal display is color, three video signal input terminal lines corresponding to RGB are required. Become.

In the embodiment shown in FIGS.
0 of FIG. 5A and FIG.
As shown in (A), it is composed of a thin film transistor formed on a transparent substrate. In addition, the capacitive element 8
As shown in FIG. 6A and FIG.
Is formed by a storage capacitor 8a using a transparent electrode or the like which is integrated by being overlapped with an intervening 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 variously modified. For example, as the switch element, a MOS transistor, a MIM element, a diode element, a varistor element, or the like formed on a semiconductor substrate or a transparent substrate can be used. Further, as shown in FIGS. 5B and 6B, the capacitor element is formed by overlapping the pixel electrode 12b with a part of the adjacent gate line 26b via an insulating layer, as shown in FIGS. It is also possible to use the additional capacitance type capacitive element 8b to be formed. 5 and 6, reference numerals 26a and 26b denote gate lines, and 28a and 26b
28a is a data line, 6a and 6b are thin film transistors, 8a and 8b are capacitive elements, 18a and 1
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, an opposing substrate 14 having an opposing electrode 16 is disposed at a predetermined distance from the active matrix substrate 4 and substantially parallel to each other. Liquid crystal may be injected to form the liquid crystal layer 18. The opposing substrate 14 is made of, for example, a glass substrate, and a transparent opposing electrode 16 made of, for example, an ITO film is laminated on a surface of the opposing substrate 14 facing the driving substrate 4. In FIG. 1, reference numeral 15 denotes a color filter. LC according to one embodiment of the present invention
In the manufacturing method D, after manufacturing the active matrix substrate 4 as described above (before or after combining with the counter substrate 14), pixel defects are detected using the following method.

First, as shown in FIG. 2, an 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
Is substantially the same as the voltage at the time of actually driving. The other switch terminal 34 b of the inspection switch circuit 34 is connected to the determination means 40 via a current-voltage conversion (I / V) amplifier 38. The judging means 40 is composed of, for example, an image processing device, and includes the inspection switch circuit 34 and the I / V amplifier 38.
The 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 regular intervals. The switching cycle of this switch is not particularly limited, but can be performed, for example, in synchronization with a field signal which is one of video control signals. The field signal is repeated at a predetermined cycle as shown in FIG.
(B) and (C), the test signal is written by applying the write voltage V1 in the first one field time (pattern a in the figure), and in the next field time. The inspection signal is read (pattern b in the drawing), and the inspection is performed by repeating the pattern a and the pattern b. 3A shows a time chart of a field signal, FIG. 3B shows a time chart showing a potential state of the video signal input terminal line 32, and FIG.
FIG. 7C is a time chart showing a switch switching state of the inspection switch circuit 34. The 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
Reference numeral 5 denotes a horizontal scanning circuit which is used as a part of the inspection apparatus.
4 and the vertical scanning circuit 22. 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 one terminal 34a in synchronization with the field signal shown in FIG. 3A, 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 this time, the voltage V1 from the writing power supply 36 and the common power supply terminal line 33 are connected to the capacitive element 8 of each driving cell 10.
And a charge is accumulated. For example, if 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 comes, the connection of the inspection switch circuit 34 is switched to the terminal 34b. 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 capacitor 8 of each driving cell 10 flows through the video signal input terminal line 32 in accordance with the scanning order.

When the switching element 6 and the capacitance element 8 of each driving cell 10 are normal, the electric charge accumulated in the capacitance element in the previous field time keeps almost the same state, and the next field time Is discharged at the time of reading. Therefore, the normal operation of each driving cell 10 is confirmed by sequentially detecting the current due to the discharge of the electric charge in each driving cell 10 by the determination unit 40. Further, when there is an abnormality in the switch element 6 or the capacitance element 8 of the predetermined driving cell 10, the discharge current from the abnormal cell circuit 10 becomes abnormally low as compared with the normal case. Defects can be observed.

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

In an LCD, the brightness of the liquid crystal display surface is affected by a change in the potential of the capacitor 8 for one field. Therefore, if the active matrix substrate is inspected before injecting the liquid crystal using the method as in the present embodiment, it is possible to inspect with relatively high accuracy an abnormality that causes a pixel defect after injecting the liquid crystal. 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 at the time of actual driving.

The following defects can be exemplified as specific defects that can be determined by using the determination means 40 of the present embodiment. (1) Defects when the terminal connection of the capacitive element 8 is incomplete (the capacitor is open). In this case, no discharge current is detected in a portion corresponding to the defective pixel. This is because, as shown by the dotted line V in FIG. 4, charge cannot be accumulated in the capacitor. (2) A defect in which the capacitor 8 is short-circuited. In this case, a larger discharge current is detected in the portion corresponding to the defective pixel than in the surrounding pixels. This is because a current flows directly from the common electrode terminal line 33. (3) A defect in which 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 has an effect on reading of another cell circuit 10 connected to the same data line 28. (4) A defect that the switch element 6 is always turned off. In this case, no discharge current is detected in a 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 a leak has occurred in the capacitor 8. In this case, the discharge current detected from the portion corresponding to the defective pixel is detected lower than the portion corresponding to the peripheral pixels. This is because, as shown by the dotted line Z in FIG. (6) A defect in which the gate line 26 is disconnected. In this case, no discharge current from the same gate line 26 is detected. (7) A defect in which the data line 28 is disconnected. In this case, no discharge current from the same data line 28 is detected.

For other defect modes, it is possible to detect a defect and to determine the type of the defect by analyzing the pixel voltage detected by the judging means 40. It should be noted that the present invention is not limited to the above-described embodiments, and can be variously modified within the scope of the present invention.

For example, in the above-described embodiment, the active matrix substrate 4 before injecting the liquid crystal is used to detect a pixel defect which may occur in the future.
Even after injecting the liquid crystal, it can be applied by improving this method. Since the equivalent circuit including the driving circuit after the liquid crystal is injected has a capacity of several% of the capacitance of the capacitor as a capacitance component in parallel with the capacitor 8, the equivalent circuit is the same as the circuit 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 a, b, c, and b shown in FIG. By repeating writing and reading in the patterns a, b, c and b, a writing voltage V1 for the first field and a writing voltage V2 for the next field are obtained.
Therefore, when a DC voltage of (V1 + V2) / 2 is applied to the common electrode terminal line 33, an AC voltage is applied to the liquid crystal, and the liquid crystal is subjected to electrolysis. It is not. Further, the pattern c enables simultaneous measurement under two conditions, that is, when a potential is applied in the + direction and when a potential is applied in one direction to the liquid crystal and the driving cell corresponding to the pixel.

The advantages of performing such a method of the present invention for inspection of an LCD after injecting liquid crystal are that a defect address can be specified and that a certain evaluation can be made without looking at an actual display. Is mentioned.

Further, the method of the present invention employs 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 of the driving cell circuits 10 to the substrate. In the case of this embodiment, a needle is directly set on the X and Y columns, which is a method of the related art, and a driving cell corresponding to each pixel is tested in DC (direct current) in real time. It is excellent in that it can be measured.

Further, in the above-described embodiment, writing and reading are repeated in one field cycle. However, it is possible in the present invention to change this cycle. By changing this cycle, it is possible to read out the charge information stored in the capacitor after an elapse of an arbitrary time, and it is possible to use the information for further advanced failure analysis and the like. Specifically, the cycle can be changed from one pixel cycle (unit of 0.0 ns) to 1H cycle to several field cycles by temporarily stopping the vertical scanning circuit 22 or the like. Further, in the above-described embodiment, the configuration is such that the potential for accumulating the electric charge in each capacitance element 8 is applied from the video signal input terminal line 32. However, the present invention is not limited thereto. It is also possible to adopt a configuration in which a potential for charge storage is applied.

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

First, as shown in FIG. 7, an 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
This is about 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 includes a test 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 a determination unit 40 via an I / V amplifier 38. The determination unit 40 is configured by, for example, an image processing device, and analyzes 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. In addition, in synchronization with the operation of the inspection switch circuit 34A, the inspection switch circuit 34B switches between a case where the connection to the reference potential is established and a case where the connection to the reference potential is opened. That is, from the inspection signal writing power supply 36, through the video input terminal line 32 and the data line 28,
When the test 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 be connected to the switch terminal 34b, the switch circuit 34B is opened, sequentially reads out the charges accumulated in each of the capacitance elements 8, converts the discharge current into a voltage, and converts the discharge current into a voltage. 40
Monitor.

The switching cycle of this switch is not particularly limited. For example, it can be performed in synchronization with a field signal which is one of video control signals. Since the field signal is repeated at a predetermined period as shown in FIG. 3A, the switching of the inspection switch circuits 34A and 34B is performed by changing the first one as shown in FIGS. 3B and 3C. At the field time, the inspection signal is written by applying the write voltage V1 (pattern a in the figure), and the inspection signal is read at the next field time (pattern b), and the pattern a and the pattern b are repeated. Inspection is carried out. 4A shows a time chart of a field signal, FIG. 4B shows a time chart showing a potential state of the video signal input terminal line 32, and FIG. 4C shows a test switch. 5 is a time chart illustrating a switch switching state of a circuit 34. The switching of 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 terminal 34a in synchronization with the field signal shown in FIG. 3A, the horizontal scanning circuit 24 and the vertical scanning circuit 22 also transmit the field signal. , And sequentially scans the driving cells 10 for one field arranged in a matrix. At this time, each driving cell circuit 10
The voltage V1 from the writing power source 36 is
And a voltage difference from the common power supply terminal line 33 is applied, and the electric charge is accumulated. For example, if the voltage V1 is 12 volts,
The voltage from the common power supply terminal line 33 is about 6 volts,
The difference voltage is applied to the capacitor 8.

When the next field signal comes, the connection of the inspection switch circuit 34A is switched to the terminal 34b, 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 stored in the capacitor 8 of each driving cell 10 flows through the common power supply terminal line 32 in accordance with the scanning order.

When the switching element 6 and the capacitance element 8 of each driving cell 10 are normal, the electric charge accumulated in the capacitance element in the previous field time keeps almost the same state, and the next field time Is discharged at the time of reading. Therefore, the current due to the discharge of the electric charge in each driving cell circuit 10 is converted into a voltage by the amplifier 38,
By sequentially detecting this 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 capacitance element 8 of the predetermined driving cell 10, the discharge current from the abnormal cell circuit 10 becomes abnormally low as compared with the normal case. Defects can be observed.

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

In an LCD, the brightness of the liquid crystal display surface is affected by the change in potential of the capacitor 8 for one field. Therefore, if the active matrix substrate is inspected before injecting the liquid crystal using the method as in the present embodiment, it is possible to inspect with relatively high accuracy an abnormality that causes a pixel defect after injecting the liquid crystal. 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 at the time of actual driving.

The following defects can be exemplified as specific defects that can be determined by using the determination means 40 of the present embodiment. (1) Defects when the terminal connection of the capacitive element 8 is incomplete (the capacitor is open). In this case, no discharge current is detected in a portion corresponding to the defective pixel. This is because, as shown by the dotted line V in FIG. 4, charge cannot be accumulated in the capacitor. (2) A defect in which the capacitor 8 is short-circuited. In this case, a larger discharge current is detected in the portion corresponding to the defective pixel than in the surrounding pixels. This is because a current flows directly from the common electrode terminal line 33. (3) A defect in which 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 has an effect on reading of another cell circuit 10 connected to the same data line 28. (4) A defect that the switch element 6 is always turned off. In this case, no discharge current is detected in a 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 a leak has occurred in the capacitor 8. In this case, the discharge current detected from the portion corresponding to the defective pixel is detected lower than the portion corresponding to the peripheral pixels. This is because, as shown by the dotted line Z in FIG. 4, the accumulation and retention of electric charges become incomplete due to the leak current. (6) A defect in which the gate line 26 is disconnected. In this case, no discharge current from the same gate line 26 is detected. (7) A defect in which the data line 28 is disconnected. In this case, no discharge current from the same data line 28 is detected.

In this embodiment, for other defect modes as well, it is possible to detect a defect and analyze the type 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 to the embodiment shown in FIG.
The charge of each capacitance element 8 is read from 3.
The configuration does not read the charge of the capacitor 8 from the video signal input terminal line 32, and thus 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 of the switch terminals 34a of the inspection switch circuit 34 is connected to the inspection signal writing power source 36. , And the other switch terminal 34 b is connected to the amplifier 38 and the judging means 40, thereby reading out charges from the capacitor 8 from the common electrode terminal line 33.

Therefore, in the circuit configuration of the present embodiment shown in FIG. 7, an equivalent circuit diagram showing the relationship between the voltage V of the capacitive element at the time of writing and the read voltage Vx when reading out the charge of the capacitive element 8 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 at the time of writing and the read voltage Vx in the case where 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 capacitor 8, C _sig1 is a parasitic capacitance parasitic on the video signal input terminal line 32, and C _sig2 is a parasitic capacitance parasitic on the data line 28. .

Based on the equivalent circuit shown in FIG.
On the other hand, assuming that the charge of Q = Cs × V is accumulated, the relationship between the voltage V of the capacitive element and the read voltage Vx is obtained.
Equation 1 below is obtained. On the other hand, the relationship between the voltage V of the capacitive element at the time of writing and the read voltage Vx at the time of writing in the present embodiment is calculated based on FIG.

(Equation 1)

(Equation 2) Comparing Expressions 1 and 2, it is found that the read voltage Vx in Expression 2 is higher than the read voltage Vx in Expression 1. That is, compared to the embodiment shown in FIG. 2, according to the method of this embodiment shown in FIG.
The read voltage Vx (that is, the detection level) can be increased. 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 Expression 1 showing the embodiment is about 0.5.
006 × V, whereas the detection level Vx obtained by Expression 2 showing the second embodiment is about 0.03 × V, which confirms that the detection level is greatly improved. If the detection level is improved, the accuracy of detection of a pixel defect or determination of the type of a defect by the determination unit 40 is improved.

FIG. 10 is a circuit diagram showing a pixel defect detecting method 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, an inspection switch circuit 34C is provided for the common electrode terminal line 33, and one of the switch terminals 34a is used for writing the inspection signal. The other switch terminal 34b 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 at the time of writing and the read voltage Vx in such an embodiment has the circuit configuration shown in FIG. 8 as in the embodiment shown in FIG. The detection level at the time is improved. In each of the embodiments described above, the active matrix substrate 4 before the injection of the liquid crystal is used to detect a pixel defect that may occur in the future. 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 since a capacitance of several% of the capacitance of the capacitance element is added as a capacitance component in parallel with the capacitance element 8.
When a constant DC voltage is applied to the drive circuit 20, electrolysis may occur. To avoid this,
Writing and reading to and from each driving cell may be repeated for each field in the patterns a, b, c, and b shown in FIG. If writing and reading are repeated in the patterns 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. By applying a DC voltage of (V1 + V2) / 2 to the liquid crystal, an AC voltage is applied to the liquid crystal, and there is no fear of electrolysis of the liquid crystal. Further, the pattern c enables simultaneous measurement under two conditions, that is, when a potential is applied in the + direction and when a potential is applied in one direction to the liquid crystal and the driving cell corresponding to the pixel. Such a method of the present invention,
Advantages of the inspection of the LCD after liquid crystal injection include the fact that a defect address can be specified and that some evaluation can be performed without looking at an actual display.

Further, the method of the present invention employs 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 of the driving cell circuits 10 to the substrate. In the case of this embodiment, a needle is directly set on the X and Y columns, which is a method of the related art, and a driving cell corresponding to each pixel is tested in DC (direct current) in real time. It is excellent in that it can be measured.

Further, in the above-described embodiment, writing and reading are repeated in one field cycle. However, the present invention can change this cycle. By changing this cycle, it is possible to read out the charge information stored in the capacitor after an elapse of an arbitrary time, and it is possible to use the information for further advanced failure analysis and the like.

More specifically, the period can be changed from one pixel period (in units of 0.0 ns) to 1H period to several field periods by temporarily stopping the vertical scanning circuit 22 or the like.

Further, as an embodiment of the present invention, an I / V
As shown in FIG. 11, an I / V amplifier 38a connected to a constant voltage source 52 without causing the ground terminal 50 of the amplifier to be grounded, as shown in FIG. The voltage applied from the constant voltage source 52 (tentatively,
The term “virtual potential” is not particularly limited.
0.5 to 11 volts, and preferably about 6 volts, which is the voltage applied to the common electrode terminal line 33 during actual driving. In FIG. 11, reference numerals 54 and 56 are resistors for obtaining an amplification gain.

In each of the above-described embodiments , as the I / V amplifier 38 used as a part of the inspection device, a current corresponding to the electric charge accumulated in each capacitance element 8 flows to the ground side, and the current is converted into a voltage. , to detect defects in each pixel, the normal virtual short
It has been found by the present inventors that the following problems are encountered when the amplifier 38 having a short circuit and virtual grounding is used. That is, as shown in FIG. 12A, the virtual ground voltage (0) is applied to the source side terminal S of each switch element 6 that is not scanned at a certain time during the inspection.
V) is applied. At this time, the voltage of the gate line 26 is also 0 volt, and if the switch element is completely normal, the switch element 6 does not turn on. However, as shown in FIG. 13, for example, the switching element 6 composed of a TFT has a voltage difference Vgs between the voltage of the gate terminal G and the voltage of the source terminal S of 0 volts. The current Id flowing to the drain terminal D may not always be zero. 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 shifts to the plus side or the minus side of Vgs due to a transistor manufacturing error or the like.

When the liquid crystal device is actually driven, a voltage of, for example, 1.5 to 10.5 volts is constantly applied to the video signal input terminal line 32, and is applied to the source terminal S of the transistor constituting the switch element 6. Is applied with a voltage of 1.5 volts or more. As a result, Vgs of the unscanned transistor at the time of actual driving is −1.5 volts or less, and as shown in FIG. 13, among the transistors having a manufacturing error within a predetermined error range, the unscanned transistor has , The current Id hardly flows (off state), and no malfunction occurs.

However, at the time of inspection, Vgs of the transistor which is not scanned and which is the switch element 6 becomes completely 0 V, and a leak current may flow (the transistor is in an ON state) even in a normally operating transistor during actual driving. There is. For this reason, even if the transistor as the switch element 6 operates normally during actual driving, there is a risk that the transistor may be erroneously detected as not a normal transistor. Such a problem is the same 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 in a virtual short-circuit state, and a constant voltage is supplied to the ground terminal 50 of the amplifier 38a. As in the case of actual driving, a voltage having a polarity that suppresses driving is applied to each of the switching elements 6 that are not present. As a result, there is no possibility that a normal switch element during actual driving is erroneously determined as a defective switch element. That is, it is possible to inspect the same state as that in the 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 the case of this embodiment, it is possible to inspect active matrix substrates in different driving voltage ranges. In addition, the virtual potential is provided with a potential difference on the plus side or the minus side in a range of, for example, 2 to 3 volts with respect to the potential applied to the common electrode terminal line 33, so that the potential difference acting on the capacitor 8 is reduced. It is also possible to increase the measurement sensitivity and improve the measurement sensitivity.

[0058]

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

In particular, if the detection of the electric charge stored in the capacitance element is performed not 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 data line can be detected. As a result, it is possible to increase the detection level of the electric charge accumulated in each capacitance element by minimizing the influence of the parasitic capacitance based on the parasitic capacitance, thereby improving the detection accuracy.

If the amplifier in the detection circuit for reading out the charge stored in the capacitance element and judging a pixel defect is placed in a virtual short circuit state and a constant voltage is supplied to the ground terminal of the amplifier, the inspection can be performed. A voltage having a polarity that suppresses driving is applied to each switch element that is not scanned in the same manner as in actual driving. As a result, there is no possibility that a normal switch element during actual driving is erroneously determined as a defective switch element. That is, it is possible to inspect the same state as that in the normal driving.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a main part of a liquid crystal display (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 an active matrix circuit of the active matrix substrate according to the first embodiment of the present invention.

FIG. 3 is a time chart of an inspection drive signal applied to an active matrix circuit for inspecting 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 detection 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 out charges accumulated in a capacitance 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 out charges accumulated in the capacitance element during the inspection step of the active matrix substrate according to the first embodiment of the present invention.

FIG. 10 is an equivalent circuit diagram at the time of reading out charges accumulated in a capacitance element during an inspection process of an active matrix substrate according to a third embodiment 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 point in time during inspection and 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 Switching 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 Test switch circuit 35 Drive signal generating means 36 Write power supply 38, 38a I / V amplifier 40 determination means 50 ground terminal 52 constant voltage source

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuji Hayashi 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Shunichi Maekawa 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo JP-A-2-72392 (JP, A) JP-A-4-3091 (JP, A) JP-A-57-38498 (JP, A) JP-A-3-142499 (JP, A) JP-A-3-200121 (JP, A) JP-A-5-90373 (JP, A) JP-A-1-241598 (JP, A) JP-A-4-9926 (JP, A) JP-A-4-369685 (JP, A) JP-A-5-10999 (JP, A) JP-A-5-158056 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1 / 1368 G02F 1/13 101

Claims (17)

(57) [Claims] 1. A method for manufacturing an active matrix substrate in which driving cells for each pixel, each of which includes a switch element for selecting a pixel and a capacitor element connected in series to the switch element, are arranged in a matrix. in, after accumulating a predetermined charge to the capacitor element, by detecting the accumulated charge, it viewed including the step of detecting the defective pixels, in order to perform the detection of the charge from the capacitive element, video
Either the signal input terminal wire or the common electrode terminal wire
Put the connected amplifier in a virtual short circuit state, and
A method of manufacturing an active matrix substrate, wherein a positive constant voltage is supplied to a ground terminal . 2. The active matrix substrate according to claim 1, wherein the detection of the electric charge from the capacitive element is performed from a video signal input terminal line connected to the driving cell via a scanning switch circuit. Production method. 3. The method for manufacturing an active matrix substrate according to claim 1, wherein the detection of the electric charge from the capacitance element is performed from a common electrode terminal line connected to one electrode terminal of the capacitance element. 4. A video signal input terminal line connected to the driving cell via a scanning switch circuit to accumulate the electric charge in the capacitance element. The method for manufacturing an active matrix substrate according to any one of the above. 5. The method of manufacturing an active matrix substrate according to claim 1, wherein the accumulation of the electric charge in the capacitance element is performed from a common electrode terminal line connected to one electrode terminal of the capacitance element. Method. 6. The method for manufacturing an active matrix substrate according to claim 1, wherein said switch element is a thin film transistor. 7. A common electrode terminal line connected to one side electrode terminal of the capacitor is formed on the substrate.
7. The method for manufacturing an active matrix substrate according to any one of items 6 to 6. One electrode terminal of claim 8, wherein said capacitive element is active according to claim 1 or 2, constituted by a portion of the gate line for driving the switching elements of the adjacent drive cells adjacent to the capacitor Manufacturing method of matrix substrate. 9. At each intersection of a data line and a gate line,
A plurality of driving cells arranged in a matrix corresponding to the 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 And supplying a video signal to a 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 an output section of the horizontal scanning circuit. 9. The video signal input terminal line is formed on the same substrate.
The method for manufacturing an active matrix substrate according to any one of the above. 10. A plurality of driving cells arranged in a matrix so as to correspond to pixels at each intersection position between a data line and a gate line, and connected to the gate line to scan the gate line in a vertical direction. A vertical scanning circuit, a horizontal scanning circuit connected to the data line via a scanning switch circuit, and scanning the data line in the horizontal direction, and a scanning switch circuit connected to an 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 includes a switch element for selecting a pixel and a capacitor element connected in series to the switch element. An active matrix substrate, comprising: a counter substrate having a counter electrode and disposed opposite to the active matrix substrate; and an active matrix substrate and a counter substrate. A method of manufacturing a liquid crystal display device that includes a retained liquid crystal layer between, after accumulating a predetermined charge to a capacitor which is connected to the predetermined switching device, from the video signal input terminal line by detecting the charge, see contains a step of detecting a defective pixel, when detecting the charge from said video signal input terminal line
Then, temporarily connect an amplifier connected to the video signal input terminal line.
Short-circuit, and a positive constant current
A method for manufacturing a liquid crystal display device, comprising supplying pressure . 11. A plurality of driving cells arranged in a matrix so as to correspond to pixels at each intersection of a data line and a gate line, and connected to the gate line to scan the gate line in a vertical direction. A vertical scanning circuit, a horizontal scanning circuit connected to the data line via a scanning switch circuit, and scanning the data line in the horizontal direction, and a scanning switch circuit connected to an 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, the driving cell being connected in series with the switch element for selecting a pixel and the switch element, and having one end connected to the switch element. An active matrix substrate having an electrode terminal connected to a common electrode terminal line and a capacitive element; and a counter substrate having a counter electrode and disposed opposite to the active matrix substrate. And a liquid crystal display device comprising: a liquid crystal layer held between the active matrix substrate and a counter substrate; and a terminal of one of the video signal input terminal line and the common electrode terminal line. Detecting a defect of a pixel by detecting a charge from the common electrode terminal line after accumulating a constant charge from a line to a capacitance element connected to a predetermined switch element through the switch circuit.
Seen, when detecting the charge from the common electrode terminal line, before
The amplifier connected to the common electrode terminal line is
And a method of supplying a positive constant voltage to a ground terminal of the amplifier . 12. A method for inspecting an active matrix substrate in which a driving cell for each pixel, comprising a switch element for selecting a pixel and a capacitor element connected in series to the switch element, is arranged in a matrix. In the method, after a certain amount of charge is accumulated in the capacitive element, by detecting the charge accumulated in each capacitive element, a defect of a pixel is detected , and a charge is detected from the capacitive element.
Either the signal input terminal wire or the common electrode terminal wire
Put the connected amplifier in a virtual short circuit state, and
A method for inspecting an active matrix substrate, wherein a positive constant voltage is supplied to a ground terminal . 13. A step of accumulating electric charge in the capacitance element,
13. The method for inspecting an active matrix substrate according to claim 12, wherein the step of detecting the charge from the capacitance element is switched at a cycle of one field. 14. The constant voltage applied to the ground terminal of the amplifier, according to claim is in the range of 0.5 to 11 volts 12
Or an inspection method of an active matrix substrate according to item 13 . 15. An inspection for inspecting an active matrix substrate in which driving cells for each pixel, each of which includes a switch element for selecting a pixel and a capacitor element connected in series to the switch element, are arranged in a matrix. In the apparatus, a driving signal generating means for supplying a driving signal for sequentially driving each driving cell, and a test signal writing means for accumulating a constant charge in a capacitance element in accordance with the driving signal from the driving signal generating means And detecting means for reading out the electric charge accumulated in each capacitor element in accordance with the driving signal from the driving signal generating means and detecting the electric charge, thereby detecting a pixel defect.
The amplifier constituting a part of the detection means is in a virtual short-circuit state.
Yes, a constant power supply that supplies a positive constant voltage to the ground terminal of the amplifier.
An inspection device for an active matrix substrate having a pressure source . 16. The switch according to claim 15 , further comprising a changeover switch for switching between the accumulation of the electric charge from the inspection signal writing means to the capacitance element and the detection of the electric charge accumulated in each capacitance element in one field cycle. Inspection equipment for active matrix substrates. 17. The constant voltage applied to the ground terminal of the amplifier, according to claim 15 which is in the range of 0.5 to 11 volts
17. An inspection device for an active matrix substrate according to item 16 .