JPH10104563A - Tft substrate testing method, tester and tester control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make possible testing a TFT substrate in the state before a liquid crystal is injected into them after a transparent electrode is stuck to the TFT substrate by arranging a counter electrode oppositely to a pixel electrode and detecting the charge variable amount of the counter electrode according to the potential change of the pixel electrode by drive of a thin film transistor(TFT) substrate. SOLUTION: The counter electrodes 20 of a test module 2 are oppositely arranged between with the pixel electrodes 10 arranged on the upper surface of the TFT substrate 1 to be tested at a minute gap. The charge variable amounts on the counter electrodes 20 caused by the potential change of the pixel electrodes 10 answering to respective counter electrodes 20 are transferred from plural pixel electrodes 20 arranged on the lower surface of the test module 2 through a charge coupled device 30 to be outputted as a continuous signal by a charge detection part 37. An output signal from the test module 2 is converted to a digital signal by an A/D converter 5 through a CDS 4, and the output amounts of the charges from respective counter electrodes 20 are detected, and the TFT substrate is tested by the variable amount of the charges.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method for inspecting a TFT liquid crystal panel, an inspection apparatus and a control method of the inspection apparatus, and more particularly, to an inspection method for inspecting a TFT substrate before liquid crystal is injected. The present invention relates to an inspection device and a control method of the inspection device.

[0002]

2. Description of the Related Art In recent years, liquid crystal display panels have been used for personal computers, word processors, liquid crystal televisions, and the like, and the demand for them has been rapidly increasing. Accordingly, there has been an increasing demand for an inspection apparatus capable of inspecting a liquid crystal display panel at low cost in a short time.

A TFT using a thin film transistor (Thin F)
ilm Transistor) After manufacturing a TFT substrate, a liquid crystal display panel arranges a transparent substrate on which a transparent electrode is formed via a spacer, and injects liquid crystal into a space formed between the TFT substrate and the transparent substrate. Manufactured.

Conventionally, as a method for inspecting a TFT liquid crystal display panel, a transparent substrate is bonded to a TFT substrate, and liquid crystal is injected to complete the TFT liquid crystal display panel. In general, a method of displaying a pattern and judging on / off of light of each pixel visually or by image processing has been used.

However, in this inspection method, a transparent substrate must be bonded to the TFT substrate to inject the liquid crystal even for a defective panel, and the cost is greatly increased.
Various inspection methods have been developed in the state of a substrate.

As one of the methods, there is a method of determining the quality of each pixel electrode by measuring the potential of the auxiliary capacitance line Cs when each pixel electrode is driven.

The invention disclosed in Japanese Patent Application Laid-Open No. 5-240800 employs a method using an electro-optical element, in which a TFT liquid crystal display panel substrate is driven and the potential of a pixel electrode is measured through the electro-optical element. Thus, each pixel electrode is inspected.

Further, in the invention disclosed in Japanese Patent Application Laid-Open No. 6-27494, a probe is arranged in non-contact with a pixel electrode, and a change in potential is detected via a capacitance between the pixel electrode and the probe. By doing so, the quality of each pixel electrode is determined.

[0009]

In the above-described method of driving each pixel electrode and measuring the potential of Cs, a short ring that electrically shorts a gate wiring and a source wiring is divided and each gate wiring is separated. It is necessary to input a signal for each source wiring. The short ring is provided to prevent the electrostatic breakdown of the TFT substrate. If the short ring is divided, the TFT substrate may become defective due to the electrostatic breakdown in a process after the inspection. Therefore, it is desirable that the inspection can be performed with the short ring left.

In the case of Japanese Patent Laid-Open No. 5-240800, the lighting brightness of a reflective liquid crystal, which is opposed to the upper surface of a liquid crystal display substrate to be inspected at a small interval, is measured by a CCD.
The potential of each pixel electrode is measured by taking an image with a camera. However, the use of reflective liquid crystal has disadvantages such as an increase in error factors and the surface of the reflective liquid crystal being easily damaged. In addition, since it is difficult to perform inspection unless the voltage applied to the pixel electrode is increased, there is a problem that inspection cannot be performed under conditions close to actual use.

In the case of JP-A-6-27494, a probe is arranged in non-contact with each pixel electrode, and a change in potential between each pixel electrode and the probe is measured. With the accompanying increase in the number of pixels,
There is a problem that the inspection time becomes enormous.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a TFT before a liquid crystal is injected by bonding a transparent substrate to a TFT substrate. An object of the present invention is to provide an inspection method capable of performing inspection in a state of a substrate, having high inspection accuracy, and shortening the inspection time.

The object of the invention described in claims 4 to 10 is that T
T before the liquid crystal is injected by bonding the transparent substrate to the FT substrate
Inspection is possible in the state of the FT board, the inspection accuracy is high,
An object of the present invention is to provide an inspection apparatus capable of shortening an inspection time.

It is an object of the present invention to provide a control method of a TFT substrate inspection apparatus capable of increasing inspection accuracy.

[0015]

A TFT according to claim 1
The method of inspecting the substrate includes the steps of: arranging the counter electrode to face the pixel electrode of the TFT substrate at a minute interval;
Detecting the amount of change in the charge of the counter electrode in accordance with the change in the potential of the pixel electrode due to the driving of the FT substrate.

In order to detect the amount of change in the charge of the counter electrode according to the change in the potential of the pixel electrode due to the driving of the TFT substrate,
It is possible to perform an inspection in a state of the TFT substrate before a liquid crystal is injected by bonding a transparent substrate to the TFT substrate.

According to a second aspect of the present invention, there is provided a method for inspecting a TFT substrate, comprising: arranging a plurality of opposing electrodes at a minute interval with respect to a pixel electrode of the TFT substrate; Detecting the amount of change in the charge of the plurality of opposing electrodes in accordance with the change in the number of pixels, and continuously determining the quality of each pixel electrode by continuously reading out the amount of change in the plurality of detected charges.

Since the amount of change in the electric charge of the plurality of opposing electrodes according to the change in the potential of each pixel electrode due to the driving of the TFT substrate is continuously read out, the liquid crystal is injected before the liquid crystal is injected by bonding the transparent substrate to the TFT substrate. The inspection can be performed in the state of the TFT substrate, the inspection accuracy is high, and the inspection time can be reduced.

According to a third aspect of the present invention, there is provided a method of inspecting a TFT substrate according to the second aspect, wherein the step of detecting the amount of change in the electric charge of the plurality of opposing electrodes is performed on the plurality of opposing electrodes. Applying a first predetermined potential;
The method includes the steps of: changing the potential of each pixel electrode to a second predetermined potential; and detecting the amount of change in the charges of the plurality of counter electrodes.

According to a fourth aspect of the present invention, there is provided an inspection apparatus for a TFT substrate, wherein the counter electrode is disposed to face the pixel electrode of the TFT substrate at a minute interval, and the potential of the pixel electrode is changed by driving the TFT substrate. Detecting means for detecting the amount of change in the electric charge of the counter electrode.

The inspection means detects the amount of change in the electric charge of the counter electrode in accordance with the change in the potential of the pixel electrode due to the driving of the TFT substrate. Inspection in the state of is possible.

According to a fifth aspect of the present invention, there is provided an inspection apparatus for a TFT substrate, comprising: a plurality of opposed electrodes arranged to be opposed to a pixel electrode of the TFT substrate at a minute interval; Detecting means for detecting an amount of change in the electric charge of the plurality of opposing electrodes in accordance with the change; and detecting the amount of change in the plurality of electric charges detected by the detecting means continuously to judge pass / fail of each pixel electrode. Data processing means.

The data processing means continuously reads out the detected change amounts of the plurality of charges to determine the quality of each pixel electrode. Therefore, the transparent substrate is bonded to the TFT substrate and the TFT substrate before the liquid crystal is injected. In this state, the inspection can be performed, the inspection accuracy is high, and the inspection time can be reduced.

A TFT substrate inspection apparatus according to a sixth aspect is the TFT substrate inspection apparatus according to the fifth aspect, wherein the plurality of counter electrodes are arranged one-dimensionally.

The inspection time is reduced by inspecting the one-dimensionally arranged counter electrodes while moving them in one direction.

According to a seventh aspect of the present invention, there is provided an inspection apparatus for a TFT substrate, wherein the plurality of counter electrodes are two-dimensionally arranged.

By making the total size of the plurality of two-dimensionally arranged counter electrodes larger than the total size of the pixel electrodes on the TFT substrate, inspection can be performed at once without moving.

According to an eighth aspect of the present invention, there is provided the TFT substrate inspection apparatus according to any one of the fifth to seventh aspects, wherein each of the plurality of counter electrodes corresponds to one of the pixel electrodes. I do.

According to a ninth aspect of the present invention, there is provided the TFT substrate inspecting apparatus according to any one of the fifth to seventh aspects, wherein a plurality of the counter electrodes are one of the pixel electrodes.
Corresponding to one.

Since a plurality of the plurality of counter electrodes correspond to one of the pixel electrodes, the inspection accuracy is further improved by comprehensively determining the change amounts of the plurality of charges of the counter electrode. .

According to a tenth aspect of the present invention, there is provided the TFT substrate inspecting apparatus according to any one of the fifth to ninth aspects, wherein the detecting means comprises: Switching means for performing switching between the first and second electrodes, a charge change amount detecting means for detecting a charge change amount, and switching between each of the plurality of counter electrodes and the charge change amount detecting means. And second switching means.

According to an eleventh aspect of the present invention, there are provided a plurality of opposing electrodes which are arranged to be opposed to a pixel electrode of a TFT substrate at a small interval, and for switching between each of the plurality of opposing electrodes and a predetermined voltage. A first switching means, a charge change amount detecting means for detecting a charge change amount, and a second switching means for performing switching between each of the plurality of counter electrodes and the charge change amount detecting means. A method for controlling an inspection apparatus for a TFT substrate, comprising: a step of turning off a second switching means; a step of turning on and off the first switching means; and a step of driving the TFT substrate. A step for changing the potential of the pixel electrode; a step for turning on the second switching means; And a step for detecting the amount.

By turning off the second switching means, turning on the first switching means and then turning it off, the potential of the counter electrode is set to a predetermined potential, and the charge of the counter electrode changes according to the change of the potential of the pixel electrode. By detecting the amount, the inspection accuracy is increased.

According to a twelfth aspect of the present invention, there is provided a method of controlling a TFT substrate inspection apparatus according to the eleventh aspect, wherein the potential of the counter electrode with respect to the charge variation detecting means is an absolute value. Is a negative value equal to or greater than a predetermined value.

By setting the potential of the counter electrode with respect to the charge change amount detecting means to a negative value, electrons are always sent from the counter electrode. Therefore, it is possible to transfer charges from the counter electrode correctly.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] As Embodiment 1 of the present invention, a case where a counter electrode of an inspection module is a two-dimensional area sensor arranged two-dimensionally will be described below with reference to the drawings.

(System Configuration of Overall Inspection Apparatus) FIG.
FIG. 1 is a schematic configuration diagram of a main part of an inspection device and a TFT substrate to be inspected according to a first embodiment of the present invention. The inspection apparatus includes an inspection module 2 including a plurality of counter electrodes 20, a charge-coupled device 30, a shift gate 35, and a charge detection unit 37, a CDS (correlated double sampling) 4 for suppressing reset noise, and A / D conversion. Device 5 and data processing unit 6
And

The counter electrode 20 of the inspection module 2 is a pixel electrode 1 arranged on the upper surface of the TFT substrate 1 to be inspected.
0 and a small distance from each other. The plurality of opposing electrodes 20 arranged on the lower surface of the inspection module 2 change the amount of charge on the opposing electrode 20 caused by the change in the potential of the pixel electrode 10 corresponding to each opposing electrode 20 via the charge-coupled device 30. And transferred as a continuous signal by the charge detection unit 37. A detailed description of the operation and operation principle of the inspection module 2 will be described later.

The output signal from the inspection module 2 is a CD
The reset noise is suppressed by S4. And CD
The signal output from S4 is converted into a digital signal by the A / D converter 5, and the amount of charge output from each counter electrode 20 is detected. The data processing unit 6 includes an A / D converter 5
By reading the output signal from the
The operation of each pixel electrode 10 is inspected by converting the amount of change in the potential of the pixel electrode 10 corresponding to the above to two-dimensional data processing.

FIG. 2 is an enlarged view of the TFT substrate 1 to be inspected by the inspection device according to the first embodiment of the present invention. As shown in FIG. 2, a TFT substrate 1 used for a liquid crystal display panel has a plurality of gate lines 11 functioning as scanning lines formed in parallel, and a source functioning as a signal line so as to be orthogonal to the gate lines 11. A plurality of wirings 12 are formed in parallel. Both wirings 11,
A thin film transistor 13 is formed in the vicinity of the position where the pixel electrode 12 intersects.
Is connected.

The inspection apparatus according to the first embodiment of the present invention includes a counter electrode 20 corresponding to a change in the potential of the pixel electrode 10.
Is measured, and the inspection is performed based on the measured value. Various structures are known for the wiring, the pixel electrode, and the thin film transistor of the TFT substrate 1. Any structure can be inspected by the inspection apparatus according to the first embodiment of the present invention. It is.

In the inspection step, the TFT
As long as the thin film transistor 13 and the pixel electrode 10 are formed on the substrate 1 and the thin film transistor 13 is in an operating state, the inspection can be performed in any process before bonding to the glass substrate.

The short rings 14, 15 in FIG.
Are electrically connected to the gate wiring 11 and the source wiring 12, respectively, and are provided to prevent static electricity which adversely affects the TFT substrate 1. Although these short rings 14 and 15 are formed at the stage of manufacturing the TFT substrate 1, the TFs are formed after the TFT substrate 1 is manufactured.
The transparent substrate on the opposite side to the T substrate 1 is bonded, and liquid crystal is injected to cut and remove it at a later stage of manufacturing a liquid crystal display panel.

The inspection apparatus according to the first embodiment of the present invention performs inspection under substantially the same conditions as the lighting inspection after the liquid crystal display panel is assembled. The inspection can also be performed by driving the panel under the same lighting conditions as the liquid crystal display panel using a mounting driver. Even when the short rings 14 and 15 remain, the inspection can be performed by driving the panel by the driving method disclosed in Japanese Patent Application Laid-Open No. 6-82836.

(Basic Configuration of Inspection Module) Next, the electrical characteristics of the inspection module 2 will be described.

FIG. 3 shows the counter electrode 20 of the inspection module 2.
FIG. 2 is a diagram showing a circuit for transferring electric charges from a charge-coupled device 30 to a charge-coupled device 30. The circuit shown in FIG. 3 is referred to as a counter electrode unit.

Each counter electrode section includes a counter electrode 20, a voltage setting wire (counter voltage setting wire) 40 for the counter electrode, and a voltage setting circuit (counter voltage setting MOSFET (Me
talOxide Semiconductor Field Effect Transistor
)) 41, shift gate 35, and charge-coupled device 3
Contains 0. A capacitance component is formed between the opposing electrode 20 and the pixel electrode 10 of the TFT substrate 1 that is disposed to oppose. An inspection is performed via a capacitor formed between the counter electrode 20 and the pixel electrode 10. Note that a gas such as air, a liquid such as water, alcohol or liquid crystal, or a solid such as an insulating sheet can be used as the capacitance component. When performing inspection while moving the inspection element 2,
It is conceivable to use an air layer as the capacity component. In this case, if the capacitance between the pixel electrode 10 and the counter electrode 20 is made to be the same as that after the liquid crystal panel is assembled, the relative permittivity of the liquid crystal is several times larger than that of air. It is necessary to set the distance from the liquid crystal panel 20 to a fraction of the distance after the liquid crystal panel is assembled, which makes it extremely difficult to control the position of the inspection module 2. For this reason, it is desirable to increase the interval to such an extent that the position of the inspection module 2 can be controlled, and to perform the inspection in a state where the capacitance is reduced accordingly. Also,
Instead of the air layer, a liquid layer having a relative dielectric constant larger than that of the liquid crystal may be used, and the distance between the pixel electrode 10 and the counter electrode 20 may be increased accordingly.

The counter electrode 20 is provided with a counter voltage setting wire 40.
And a switching element. In the present embodiment, a counter voltage setting MO is used as a switching element.
Although the SFET 41 is used, another switching element may be used. When the common voltage setting MOSFET 41 is turned on, the common electrode 20 has the same potential as the common voltage setting wiring 40. That is, when a signal of the potential to be set as the potential of the counter voltage 20 is input to the counter voltage setting wiring 40, the potential of the counter electrode 20 is set freely by turning on the counter voltage setting MOSFET 41. be able to.

The counter electrode 20 and the charge-coupled device 30 are connected via a shift gate 35. When the shift gate 35 is turned on, the counter electrode 20 and the charge-coupled device 30
Is transmitted to the charge-coupled device 30. The transmitted charges are sequentially transferred by the charge-coupled device 30 and output from the charge detection unit 37 as a continuous signal. When both the opposing voltage setting MOSFET 41 and the shift gate 35 are off, the charge on the opposing electrode 20 is kept constant. Therefore, when the potential of the pixel electrode 10 changes, the potential of the counter electrode 20 also changes by the amount of the change.

As shown in FIG. 4, the charge-coupled device 30 and the shift gate 35 have the functions of the common voltage setting wiring 40 and the common voltage setting MOSFET 41, and It is also possible to omit the counter voltage setting MOSFET 41.

(Schematic Configuration of Inspection Element Lower Surface) FIG. 5 shows a schematic configuration of the sensor unit 3 on the lower surface of the inspection module 2 when the inspection module 2 is a two-dimensional area sensor. The inspection module sensor unit 3 includes a counter electrode 20, a charge-coupled device 30, a vertical transfer unit 31, a horizontal transfer unit 32, a shift gate 35, a charge detection unit 37, a counter voltage setting wiring 40, and a counter voltage setting MOSFET 41. .

A plurality of opposing voltage setting wirings 40 and a plurality of vertical transfer sections 31 of the charge-coupled device are formed in parallel. Further, the counter voltage setting wirings 40 and the vertical transfer units 31 are alternately arranged as shown in FIG. 5, and a plurality of opposing electrodes 20 are arranged between them. Each counter electrode 20
The shift gate 35 is connected to the counter voltage setting wiring 40 via the counter voltage setting MOSFET 41.
Is connected to the vertical transfer unit 31 via the.

The opposite voltage setting wirings 40 are all electrically connected and kept at the same potential. The vertical transfer unit 31 is connected to the horizontal transfer unit 32 of the charge-coupled device, and charges are transferred from the counter electrode 20 via the vertical transfer unit 31 and the horizontal transfer unit 32, and the amount of the charge is determined by the charge detection unit 37. Is detected by

(Correspondence between Pixel and Counter Electrode) FIG. 6 is a diagram showing the correspondence between the pixel electrode 10 and the counter electrode 20. (A) shows that one of the pixel electrodes 10 is a counter electrode 20.
It corresponds to plural. The values obtained from the plurality of counter electrodes 20 corresponding to one pixel electrode 10 are integrated, and the amount of change in the potential of the corresponding pixel electrode 10 is obtained by calculation.
In (b), the pixel electrode 10 and the counter electrode 20 have a one-to-one correspondence, and the amount of change in the potential of the corresponding pixel electrode 10 is obtained from the value obtained from each counter electrode 20. According to the present embodiment, the inspection can be performed in either case (a) or (b).

(Inspection Principle) With reference to FIG. 7, a method of measuring the amount of change in electric charge when the potential of the pixel electrode 10 changes will be described. Here, the capacitance of a capacitor formed between the pixel electrode 10 and the counter electrode 20 is represented by C. During the measurement, it is assumed that the counter voltage setting wiring 40 is kept constant at the potential Vc0, and the charge-coupled device 30 is kept constant at the potential Vc2.

First, as shown in (a), the MOSFET 41 for setting the opposite voltage is turned on, and the shift gate 35 is turned off. At this time, the potential of the counter electrode 20 becomes equal to the potential Vc0 of the counter voltage setting wiring 40.

Next, as shown in (b), the MOSFET 41 for setting the counter voltage is turned off. At this time, the potential of the pixel electrode 10 is set to Vd0.

(C) shows a state where the potential of the pixel electrode 10 has changed from Vd0 to Vd1. Since both the counter electrode setting MOSFET 41 and the shift gate 35 are off, the amount of charge on the counter electrode 20 is kept constant. Therefore, the potential difference between the pixel electrode 10 and the counter electrode 20 is kept constant. When the potential of the pixel electrode 10 changes from Vd0 to Vd1, the potential of the counter electrode 20 changes as in the following equation.

Vc1 = Vc0 + (Vd1-Vd0) (1) Next, as shown in (d), the shift gate 35 is turned on. The potential of the counter electrode 20 is the potential V of the charge-coupled device 30
Since it is equal to c2, the charge shown in the expression (2) is sent to the charge-coupled device 30.

Q = C (Vc1−Vc2) = C (Vc0−Vc2 + Vd1−Vd0) (2) At this time, the thin film transistor 1 of the pixel on the TFT substrate 1
When 3 is off, the amount of charge on the pixel electrode 10 is kept constant, so the potential of the pixel electrode 10 changes to the value shown in equation (3).

Vd2 = Vd1 + (Vc2−Vc1) According to the above process, the pixel electrode 10 is turned on from the time when the common voltage setting MOSFET 41 is turned off in (b) until the shift gate is turned on in (d). An electric charge corresponding to the amount (Vd1−Vd0) of the change in the potential of the pixel is sent from the counter electrode 20 to the charge coupled device 30. .. (3) Next, as shown in FIG.
Both T41 and shift gate 35 are turned off. At this time, the charge of each counter electrode 20 is sequentially transferred in the charge-coupled device 30. The transferred charge is output as a continuous signal from the charge detection unit 37, the reset noise is suppressed by the CDS 4, and is converted into a digital signal by the A / D converter 5. Then, the outflow amount Q of the charge for each counter electrode 20 is obtained by the following equation.

Q = C (Vc1−Vc2) = C (Vc0−Vc2 + Vd1−Vd0) (4) Therefore, the amount of change in the potential of the pixel electrode is as follows.

Vd1−Vd0 = Q / C + (Vc2−Vc0) (5) Since the values of Q, C, Vc2 and Vc0 are known, the amount of change in potential can be obtained by calculation. In the data processing unit 6, the pixel electrode 1 corresponding to the counter electrode 20
A pass / fail judgment is made by calculating the amount of change in the potential of 0 by calculation and comparing it with a normal value. Since the charge-coupled device 30 can transfer only electrons as charges, Vc0 and Vc2 are set so that Q takes a negative value.
Must be set. That is, since Q = C (Vc1−Vc2) = C (Vc0−Vc2 + Vd1−Vd0) <0 (6), Vd0 and Vd1 are always set to satisfy Vc0−Vc2 <Vd0−Vd1 (7). The potentials of the counter electrode setting wiring 40 and the charge-coupled device 30 are set in consideration of the range of change.

(Driving Method and Inspection Result) Next, the details of an inspection method when actually driving the TFT substrate and the inspection module to inspect each pixel will be described.

Referring to FIG. 8 and FIG. 9, changes in the driving signals of the TFT substrate 1 and the inspection module 2 and the pixel electrode 10 will be described.
And the change in the potential of the counter electrode 20 will be described. The drive signal for the TFT substrate 1 shown in FIG. 8 is generated by the source signal Vg immediately before the gate signal Vg (t) of the TFT substrate 1 becomes high level.
The voltage of s (t) changes, and in this driving method, only the ON failure is detected as a defect. In addition, T shown in FIG.
The drive signal of the FT substrate 1 is a gate signal V of the TFT substrate 1.
Immediately after g (t) goes high, the source signal Vs
The voltage of (t) changes, and in this driving method, both the ON failure and the OFF failure are detected as defects.

By using a plurality of signals for driving the TFT substrate 1, the type of defect can be determined. In the inspection apparatus according to the present embodiment, the TFT
Since the inspection is performed on the substrate 1 in a state substantially equivalent to that of the TFT liquid crystal display panel, a signal for inspection of the TFT liquid crystal display panel can be used as it is as a drive signal for detecting a defect. As a driving signal for testing a TFT liquid crystal display panel and a method of testing, a method disclosed in Japanese Patent Application Laid-Open No. 6-82836 can be applied.

First, a description will be given with reference to FIG. (A)
The change of the drive signals Vg (t) and Vs (t) of the gate wiring 11 and the source wiring 12 of the TFT substrate 1 is shown. Gate signal Vg (t) repeats a high level and a low level at a constant cycle. When the gate signal Vg (t) is at a high level, the thin film transistor 13 is turned on, and the potential Vs (t) of the source wiring 12 is written to the pixel electrode 10. Immediately before the rise of the gate signal Vg (t), the potential of the source signal Vs (t) changes.

(B) shows the MOSFET 4 for setting the opposite voltage.
5 shows a drive signal Vs1 (t) input to one gate electrode 44 (see FIG. 3). When the drive signal Vs1 (t) is at a high level, the opposing voltage setting MOSFET 41 is turned on, and the potential of the opposing electrode 20 becomes Vc0.

(C) shows the drive signal Vs2 (t) input to the shift gate electrode 36 (see FIG. 3). When the drive signal Vs2 (t) goes high, the shift gate 3
5 is turned on, and an amount of charge corresponding to the potential difference between the counter electrode 20 and the charge-coupled device 30 is sent from the counter electrode 20 to the charge-coupled device 30.

(D) and (e) show changes in the potential Vd (t) of the pixel electrode 10 and the potential Vc (t) of the counter electrode 20 when the pixel electrode 10 operates normally. (F) and (g) show changes in the potential Vd (t) of the pixel electrode 10 and the potential Vc (t) of the counter electrode 20 when the electrode 10 has an ON failure. Further, (h) and (i) show the pixel electrode 10 when the pixel electrode 10 has an off-failure.
Potential Vd (t) and the potential Vc (t) of the counter electrode 20
Shows the change in Although the inspection device according to the first embodiment can detect other types of point defects and line defects,
As an example, two types of defects, that is, an ON defect and an OFF defect of the pixel electrode 10 will be described.

First, Vs1 (t) is set to a high level immediately before the first rise of the gate signal Vg (t). When the gate signal Vg (t) goes high, the potential Vs (t) = + Vs of the source signal is written to the pixel electrode 10, and Vd (t) = + Vs. At this time, the counter electrode 2
The potential of 0 is maintained at Vc0.

Just before the second rising of the gate signal Vg (t), Vs1 (t) is set to the low level, and is input to the shift gate electrode 36 immediately after the second falling of the gate signal Vg (t). The drive signal Vs2 (t) is set to a high level. After setting Vs1 (t) to low level,
The charge corresponding to the amount of change in the potential of the pixel electrode 10 that has changed until 2 (t) is changed to the high level is charged.
Sent to

When the gate signal Vg (t) goes high, the potential Vs of the source signal is applied to the pixel electrode 10.
(T) = − Vs is written, and the potential of the pixel electrode 10 becomes Vd.
(T) = − Vs When the pixel electrode 10 is normal, the amount of change in the potential of the pixel electrode 10 is -2 Vs as shown in (d), and the amount of electrons expressed by the following equation is sent to the charge-coupled device 30.

−Q = −CΔV1 = C (Vc0 + Vc2-2Vs) (8) When the pixel electrode 10 has an ON failure, as shown in (f), the charge amount of the potential of the pixel electrode 10 is −2Vs. As a result, the number of electrons -Q sent to the charge-coupled device 30 decreases, and ΔV1 ′ becomes smaller than ΔV1 as shown in (g). When the pixel electrode 10 has an off-failure, as shown in (h), the amount of change in the potential of the pixel electrode 10 is substantially -2 Vs, so that the pixel electrode 10 is not detected as a defect.

The first measurement is performed as described above. Next, the second measurement is performed as follows at a position where the phase of the source signal is shifted by 180 °.

Immediately before the fourth rising of the gate signal Vg (t), Vs1 (t) is set to the high level.

When the gate signal Vg (t) goes high, the potential Vs (t) of the source signal is applied to the pixel electrode 10.
= −Vs is written, and Vd (t) = − Vs. At this time, the potential of the counter electrode 20 is maintained at Vc0.

Immediately before the fifth rising of the gate signal Vg, Vs1 (t) is set to the low level, and the gate signal Vg is set to the low level.
Immediately after the fifth falling of (t), the drive signal Vs2 (t) input to the shift gate electrode 36 is set to the high level. After setting Vs1 (t) to low level,
Charges corresponding to the amount of change in the potential of the pixel electrode 10 that has changed until (t) is changed to the high level are sent to the charge-coupled device 30.

When the gate signal Vg (t) goes high, the potential Vs of the source signal is applied to the pixel electrode 10.
(T) = + Vs is written, and the potential of the pixel electrode 10 becomes Vd.
(T) = + Vs. When the pixel electrode 10 is normal, the amount of change in the potential of the pixel electrode 10 is +2 Vs as shown in (d), and the amount of electrons expressed by the following equation is sent to the charge-coupled device 30.

−Q = −CΔV2 = C (Vc0 + Vc2 + 2Vs) (9) When the pixel electrode 10 has an ON failure, as shown in (f), the amount of change in the potential of the pixel electrode 10 is less than + 2Vs. The number of electrons -Q sent to the charge-coupled device 30 increases, and ΔV2 ′ becomes larger than ΔV2 as shown in (g). When the pixel electrode 10 has an off-error, as shown in (h), the amount of change in the potential of the pixel electrode 10 is almost +2 Vs, and is not detected as a defect.

Next, description will be made with reference to FIG. (A) is T
The change of the drive signals Vg (t) and Vs (t) of the gate wiring 11 and the source wiring 12 of the FT substrate 1 is shown.
Gate signal Vg (t) repeats a high level and a low level at a constant cycle. When the gate signal Vg (t) is at a high level, the thin film transistor 13 is turned on, and the potential Vs (t) of the source wiring 12 is written to the pixel electrode 10.
Immediately after the fall of the gate signal Vg (t), the source signal V
The potential of s (t) changes. The potential of the source signal Vs (t) repeats the potential of + Vs and −Vs each time the gate signal Vg (t) goes to a high level.

(B) shows the MOSFET 4 for setting the opposite voltage.
Drive signal Vs1 (t) input to the first gate electrode 44
Is shown. When the drive signal Vs1 (t) is at a high level,
The opposing voltage setting MOSFET 41 is turned on, and the potential of the opposing electrode 20 becomes Vc0.

(C) shows the drive signal Vs2 (t) input to the shift gate electrode 36. Drive signal Vs2
When (t) becomes high level, the shift gate 35 is turned on, and an amount of charge corresponding to the potential difference between the counter electrode 20 and the charge-coupled device 30 is sent from the counter electrode 20 to the charge-coupled device 30.

(D) and (e) show the potential Vd (t) of the pixel electrode 10 when the pixel electrode 10 is operating normally.
5 shows changes in the potential Vc (t) of the counter electrode 20. (F) and (g) show the potential Vd (t) of the pixel electrode 10 and the counter electrode 20 when the pixel electrode 10 has an ON failure.
Shows the change in the potential Vc (t). Further, (h) and (i) show the pixel electrode 10 when the pixel electrode 10 has an off-failure.
Potential Vd (t) and the potential Vc (t) of the counter electrode 20
Shows the change in First, Vs1 (t) is set to a high level immediately before the first rising of the gate signal Vg (t).

When the gate signal Vg (t) goes high, the potential Vs (t) of the source signal is applied to the pixel electrode 10.
= + Vs is written, and Vd (t) = + Vs. At this time, the potential of the counter electrode 20 is maintained at Vc0.

Immediately before the second rising of the gate signal Vg (t), Vs1 (t) is set to the low level, and immediately after the second falling of the gate signal Vg (t), the signal is input to the shift gate electrode 36. The drive signal Vs2 (t) is set to a high level. After setting Vs1 (t) to low level, Vs2
Charges corresponding to the amount of change in the potential of the pixel electrode 10 that has changed until (t) is changed to the high level are sent to the charge-coupled device 30.

When the gate signal Vg (t) goes high, the potential Vs of the source signal is applied to the pixel electrode 10.
(T) = − Vs is written, and the potential of the pixel electrode 10 becomes Vd.
(T) = − Vs When the pixel electrode 10 is normal, the amount of change in the potential of the pixel electrode 10 is -2 Vs as shown in (d), and the amount of electrons shown in Expression (8) is sent to the charge-coupled device 30. . When the pixel electrode 10 has an ON failure, the change in the potential of the pixel electrode 10 is smaller than -2 Vs as shown in FIG. g) as shown in g)
1 ′ becomes smaller than ΔV1. When the pixel electrode 10 has an off-failure, as shown in (h), the amount of change in the potential of the pixel electrode 10 is less than -2 Vs, so that the number of electrons -Q sent to the charge-coupled device 30 decreases, and ( As shown in i), ΔV1 ″ becomes smaller than ΔV1.

The first measurement is performed as described above. Next, at the position where the phase of the source signal is shifted by 180 °, the second measurement is performed.
The second measurement is performed as follows.

Immediately before the fourth rising of the gate signal Vg (t), Vs1 (t) is set to the high level.

When the gate signal Vg (t) goes high, the potential Vs (t) of the source signal is applied to the pixel electrode 10.
−Vs is written, and Vd (t) = − Vs. At this time, the potential of the counter electrode 20 is maintained at Vc0.

Immediately before the fifth rising of the gate signal Vg (t), Vs1 (t) is set to the low level, and immediately after the fifth falling of the gate signal Vg (t), the signal is input to the shift gate electrode 36. The drive signal Vs2 (t) is set to a high level. After setting Vs1 (t) to low level,
The charge corresponding to the amount of change in the potential of the pixel electrode 10 that has changed until 2 (t) is changed to the high level is charged.
Sent to

When the gate signal Vg (t) goes high, the potential Vs of the source signal is applied to the pixel electrode 10.
(T) = + Vs is written, and the potential of the pixel electrode 10 becomes Vd.
(T) = + Vs. When the pixel electrode 10 is normal, the amount of change in the potential of the pixel electrode 10 is +2 Vs as shown in (d), and the amount of electrons shown in Expression (9) is sent to the charge-coupled device 30. When the pixel electrode 10 has an ON failure, the change in the potential of the pixel electrode 10 is less than +2 Vs as shown in (f), so that the number of electrons -Q sent to the charge-coupled device 30 increases, and (g) ΔV2 ′ as shown in FIG.
Becomes larger than ΔV2. When the pixel electrode 10 has an off-state defect, as shown in (h), the amount of change in the potential of the pixel electrode 10 is less than +2 Vs, so that the number of electrons -Q sent to the charge-coupled device 30 increases, and (i) )
2 ″ becomes larger than ΔV2.

The second measurement is performed as described above. As described above, the inspection can be performed more accurately by performing the inspection twice at the position where the phase of the source signal is shifted by 180 °.

(Semiconductor Structure of Test Element) FIG. 10 shows an example of a cross-sectional structure of the counter electrode portion of the test module according to the present embodiment. The counter electrode portion of the inspection module 2 includes a counter electrode charge storage layer 21, a signal charge transfer layer 33, a transfer gate electrode 34, a shift gate 35, a shift gate electrode 36, a counter voltage setting wiring 40, a counter voltage setting source 42, It includes a counter voltage setting gate 43, a counter voltage setting gate electrode 44, a channel stopper 52, an insulating film 53, and a passivation film 54. These are formed on a silicon substrate in which a p-type well 51 is formed on an n-type substrate 50. The counter electrode charge storage layer 21 functioning as a counter electrode is formed of an n-type semiconductor layer, and is surrounded by p-type semiconductor layers 35, 43 and 51 and an insulating film 53. Since the inspection is performed via the capacitance component in a state where the capacitor is opposed to the pixel electrode 10, a capacitor is formed between the counter electrode charge storage layer 21 and the pixel electrode 10 during the inspection.

The common voltage setting wiring 40 and the common voltage setting MOSFET 41 are formed next to the common electrode charge storage layer 21. Counter voltage setting MOSFET 41
Is composed of a common voltage setting source 42, a common voltage setting gate 43, a common electrode charge storage layer 21 as a drain, and a gate electrode 44.

The shift gate 35 includes the counter electrode charge storage layer 21 functioning as a source and the shift gate 3
8. It is composed of a signal charge transfer layer 33 functioning as a drain and a shift gate electrode 36, and is formed next to the counter electrode charge storage layer 21. The charge-coupled device 30 includes a signal charge transfer layer 33 and a transfer gate electrode 34. The transfer gate electrode 34 is driven by an appropriate timing signal in order to sequentially transfer the electrons sent to the charge-coupled device 30. The surface of the test module substrate is covered with a passivation film 54.

Further, the structure shown in FIG. 11 or FIG. 12 may be used as the structure of the counter electrode portion of the inspection module 2. 11A and FIG. 12A show the cross-sectional structure of the counter electrode portion, and FIG. 11B shows the structure of the electrode on the front surface. The structure of the counter electrode portion shown in FIG. 11 is the same as that of FIG. 10 except that the counter electrode 20 is formed on the surface of the inspection module 2.
Since the structure is the same as that of the counter electrode shown in, the detailed description will not be repeated. The structure of the counter electrode portion shown in FIG.
The structure of the counter electrode shown in FIG. 10 is the same as that of FIG. 10 except that counter electrode 20 and counter voltage setting wiring 40 are formed on the surface of test module 2, and thus detailed description will not be repeated. The counter electrode 20 has a structure electrically connected to the counter electrode charge storage layer 21, but the surface area of the counter electrode 20 is different between FIG. 11 and FIG.

In the structure shown in FIG. 11, the surface area of the counter electrode 20 is larger than in the structure shown in FIG.
Therefore, the capacitance of the capacitor formed between the pixel electrode 10 and the counter electrode 20 as viewed from the counter electrode 20 side can be increased. In the structure shown in FIG. 12, the counter voltage setting wiring 40 extends on the surface of the inspection module 2 and the surface area of the counter electrode 20 is reduced. Therefore, the capacitance of the capacitor formed between the pixel electrode 10 and the counter electrode 20 when viewed from the counter electrode side is reduced.

In both cases, the capacitance formed between the pixel electrode 10 and the counter electrode 20 has the same capacitance as viewed from the pixel electrode 10 side, but the capacitance as viewed from the counter electrode 20 side is the same. Because of the difference, the amount of charge delivered to the charge coupled device 30 is different. Thus, by changing the surface area of the counter electrode 20, it is possible to adjust the amount of charges transferred by the charge-coupled device 30 to be appropriate.

As described above, the present embodiment has the following advantages. (1) Before bonding the TFT substrate and injecting liquid crystal, TF
Inspection can be performed in a T substrate state.

(2) Since the amount of charge of the counter electrode is directly measured using the charge-coupled device, it is possible to measure with higher accuracy than an inspection device using an electro-optical device.

(3) Inspection of a TFT substrate while leaving a short ring for electrically short-circuiting a gate wiring and a source wiring, as compared with a method in which each pixel electrode is driven one by one by a probe and inspected. Therefore, it is possible to prevent the TFT substrate from being electrostatically damaged in a later step. Further, by synchronizing the driving of the TFT substrate and the driving of the inspection module, the speed of the inspection can be increased. Further, the inspection module has a plurality of opposing electrodes, and the amount of change in electric charge of the plurality of opposing electrodes can be measured simultaneously by transferring the amount of change in electric charge by the charge-coupled device, so that the inspection can be speeded up.

(4) Before measuring the amount of change in the potential of the pixel electrode, measure the potential of the counter electrode of the inspection module after setting the potential of the counter electrode such that the potential of the counter electrode with respect to the charge-coupled device becomes a sufficiently negative value. Is performed, electrons are always sent from the counter electrode to the charge-coupled device. Since the charge-coupled device can transfer only electrons, it is possible to transfer charges correctly in this manner.

(5) Since the inspection module is a semiconductor element, the accuracy of the position and the size of the counter electrode is very high, and the position accuracy of detecting a defective pixel is high.

[Second Embodiment] FIG. 13 shows a schematic configuration of a sensor unit 3 'of an inspection module according to a second embodiment of the present invention. Although the inspection module 2 according to the first embodiment shown in FIG. 5 is a two-dimensional area sensor, the inspection module 3 ′ according to the second embodiment has the counter electrodes 20 arranged one-dimensionally. Other configurations and functions are the same as those of the embodiment, and therefore detailed description will not be repeated.

The inspection module 3 'inspects one vertical or horizontal line on the TFT substrate, and moves to the next line to perform the inspection. By repeating this operation, it is possible to inspect the entire TFT substrate. Embodiment 1
Although the inspection time is longer than that of the inspection module, the cost of the inspection module itself can be reduced. Since other effects are the same as those of the first embodiment, detailed description will not be repeated.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of an inspection device according to a first embodiment.

FIG. 2 is a plan view of a TFT substrate to be inspected by the inspection device according to the first embodiment.

FIG. 3 is a diagram showing an electrical configuration of a counter electrode unit of the inspection module.

FIG. 4 is a diagram showing an electrical configuration of a counter electrode portion of the inspection module when a function of a counter voltage setting MOSFET is substituted by a charge-coupled device and a shift gate.

FIG. 5 is a schematic configuration diagram of a sensor section on a lower surface of the inspection module when the inspection module is a two-dimensional area sensor.

FIG. 6 is a diagram showing a correspondence relationship between a pixel electrode of a TFT substrate and a counter electrode of an inspection module.

FIG. 7 is a diagram showing a method of controlling a pixel electrode of a TFT substrate and a counter electrode of an inspection module.

FIG. 8 is a diagram showing a driving method and a change in potential of a pixel electrode and a counter electrode when a point defect of ON failure of a pixel electrode is detected.

FIG. 9 is a diagram illustrating a driving method and a change in potential of a pixel electrode and a counter electrode when detecting a point defect such as an ON defect and an OFF defect of a pixel electrode.

FIG. 10 is a diagram illustrating an example of a cross-sectional view of a structure of a counter electrode unit of the inspection module.

FIG. 11 is a diagram showing an example of a cross-sectional view and a plan view of the structure of a counter electrode portion of the inspection module when the surface area of the counter electrode is increased.

FIG. 12 is a diagram illustrating an example of a cross-sectional view and a plan view of a structure of a counter electrode unit of the inspection module when the surface area of the counter electrode is reduced.

FIG. 13 is a schematic configuration diagram of a sensor unit on the lower surface of the inspection module when the inspection module is a one-dimensional line sensor.

[Explanation of symbols]

 Reference Signs List 1 TFT substrate 2 Inspection module 4 Correlated double sampling 5 A / D converter 6 Data processing unit 10 Pixel electrode 20 Counter electrode 30 Charge-coupled device 35 Shift gate 37 Charge detection unit

Claims (12)

[Claims] A step of arranging a counter electrode opposite to a pixel electrode of a TFT substrate at a minute interval; and changing a charge of the counter electrode according to a change in a potential of the pixel electrode by driving the TFT substrate. Detecting a quantity of the TFT substrate. 2. The method according to claim 1, further comprising: arranging a plurality of opposing electrodes at a minute interval with respect to a pixel electrode of the TFT substrate; and arranging the plurality of opposing electrodes according to a change in potential of each pixel electrode due to driving of the TFT substrate. Detecting the amount of change in charge of the pixel electrode; and continuously reading the detected amounts of change in the plurality of charges to determine the quality of each of the pixel electrodes.
T board inspection method. 3. The method according to claim 1, wherein the step of detecting the amount of change in the electric charge of the plurality of counter electrodes includes the steps of: applying a first predetermined potential to the plurality of counter electrodes; The method for inspecting a TFT substrate according to claim 2, further comprising: changing the potential to a potential; and detecting a change amount of a charge of the plurality of counter electrodes. 4. An opposing electrode disposed to face a pixel electrode of a TFT substrate at a minute interval, and a change amount of electric charge of the opposing electrode according to a change in potential of the pixel electrode due to driving of the TFT substrate. An inspection apparatus for a TFT substrate, comprising: a detection unit for detecting a voltage. 5. A plurality of opposing electrodes which are arranged at a minute interval to a pixel electrode of a TFT substrate, and a plurality of opposing electrodes corresponding to a change in potential of each pixel electrode due to driving of the TFT substrate. A TFT comprising: a detecting unit for detecting a change amount of electric charge; and a data processing unit for continuously reading out the change amounts of a plurality of electric charges detected by the detecting unit to judge the quality of each pixel electrode. Board inspection equipment. 6. The inspection apparatus for a TFT substrate according to claim 5, wherein the plurality of counter electrodes are one-dimensionally arranged. 7. The TFT substrate inspection apparatus according to claim 5, wherein the plurality of counter electrodes are two-dimensionally arranged. 8. The TFT substrate inspection apparatus according to claim 5, wherein each of the plurality of counter electrodes corresponds to one of the pixel electrodes. 9. The TFT substrate inspection apparatus according to claim 5, wherein a plurality of said plurality of counter electrodes correspond to one of said pixel electrodes. 10. The detecting means comprises: first switching means for switching between each of the plurality of opposed electrodes and a predetermined voltage; and charge change detecting means for detecting a change in charge. The TF according to any one of claims 5 to 9, further comprising: a second switching unit configured to perform switching between each of the plurality of counter electrodes and the charge change amount detection unit.
T board inspection equipment. 11. A plurality of opposing electrodes disposed to be opposed to a pixel electrode of a TFT substrate at a minute interval, and a first switching for switching between each of the plurality of opposing electrodes and a predetermined voltage. Means, charge change detecting means for detecting a charge change amount, and second switching means for performing switching between each of the plurality of counter electrodes and the charge change amount detecting means. A method for controlling a TFT substrate inspection apparatus, comprising: turning off the second switching means; turning on and off the first switching means; and driving the TFT substrate to drive a potential of a pixel electrode. And turning on the second switching means, and the charge change amount detecting means detects a change amount of the charge of the counter electrode. The method of the inspection apparatus of the TFT substrate and a step of leaving. 12. The potential of said counter electrode with respect to a potential change detecting means is a negative value whose absolute value is not less than a predetermined value.
A method for controlling a TFT substrate inspection apparatus according to claim 11.