JPH0659283A - Method and device for inspecting tft-lcd - Google Patents

Abstract

PURPOSE:To provide a method and a device capable of simply and rapidly inspecting the connection relation of each TFT, connection conditions of gate lines and data lines themselves and the presence and the absence of short circuits between gate lines and data lines in a TFT-LCD. CONSTITUTION:In an active color LCD using TFTs, cell capacitors of LCD are charged through data lines by turning ON TFTs, then the charged condition is hold by turning OFF TFTs, discharge is executed through the source and the drain of the TFTs and the resistances connected to an earth side, it is judged whether the functions of the TFT-LCD and the wiring conditions are normal or not by the current or voltage waveforms during the discharge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus using the same for inspecting a TFT-LCD used as an active matrix color LCD.

[0002]

2. Description of the Related Art In recent years, active matrix type LCDs have become dominant as color displays using liquid crystals.
This is because the necessary signals are written to the liquid crystal only for a certain short period, and the signals are held as the gate of the input circuit to the liquid crystal is opened during the other periods, and the liquid crystal functions as a dynamic memory. There are features.

In order to perform the operation of opening the gate for the rest of the time, the gate is closed for a necessary period for writing the signal as described above.
An mTransistor, that is, a field effect transistor (FET) is normally used.

In recent years, in color display devices using liquid crystals, among active matrix systems, systems using TFT-LCD are increasing.

An outline of the TFT-LCD is as shown in FIG. 1. However, since a single liquid crystal display device has a large number of pixels, the TFT arranged corresponding to each pixel.
4 and its gate lines 3 and data lines 5 are also extremely large.

The functions of these TFTs, the connection relation between the TFT 4 and the data line 5 or the gate line 3, and further the relation between the gate lines and between the data lines are not always normal.

Therefore, it is essential for the liquid crystal display device to inspect whether these conditions are normal or not.

Despite this, a conventional efficient inspection method for the above-mentioned points in the TFT-LCD has not been established, and therefore, the above-mentioned points are not tested in advance and T
Assemble the FT-LCD device, or at most 1
Up to now, it has been a great deal to check the relationship between each TFT and the connection line around it.

On the other hand, a liquid crystal cell capacitor (and an auxiliary capacitor connected in parallel with the liquid crystal cell capacitor) is charged and discharged by voltage input from a data line while controlling ON / OFF by a TFT. Then, a method of judging whether or not the connection relation of each of the above points is normal by using the amount of electric charge due to discharge is also proposed.

However, in order to measure the charge amount, it is necessary to separately provide a measuring integrator (actually an integrating capacitor) and a measuring instrument related thereto.

However, it is extremely complicated to separately provide an integrator for measurement and a measuring instrument related to the integrator, and it is against the economic efficiency in performing the inspection.

[0012]

SUMMARY OF THE INVENTION The present invention is a TFT-L.
It is an object of the present invention to provide a method and a device therefor capable of simply and efficiently inspecting whether or not each of the above points is normal in a CD without providing an integrating capacitor and a measuring instrument related thereto. .

[0013]

In order to solve the above problems, the structure of the present invention is, in an active color LCD using a TFT, turning on the TFT and charging the cell capacitor of the LCD through a data line,
Next, after keeping the charged state by turning off the TFT, the TFT is turned on again to discharge through the resistor connected to the ground side through the source and drain of the TFT, and the current waveform or voltage in the discharge. It consists of a TFT-LCD inspection method that determines whether the function of the TFT and the connection state of the wiring are normal depending on the waveform.

As a device therefor, an inspection device is provided which is provided with a waveform detector for detecting a waveform of a current conducted through a resistor connected to the source side of the TFT or a voltage across the resistor.

[0015]

The basic principle of the present invention will be described with reference to FIG.

FIG. 2 shows a cell capacitor C _s (actually, the TFT, which is the capacitance of one liquid crystal cell in the present invention and the auxiliary capacitance added when the TFT is an array).
In the array stage, the added auxiliary capacitance itself constitutes the cell capacitor C _s, and after the liquid crystal is enclosed in each cell, the auxiliary capacitance and the capacitance of the liquid crystal cell itself are
It will constitute the cell capacitor C _s . ), A TFT connected to the TFT via the drain side, a data line connected to the source side of the TFT, a gate line connected to the gate side of the TFT, and also connected to the source side of the TFT. second switch interposed between the resistance R _g and the data line and the first switch S _d, the resistance R _g inspecting apparatus for inspecting a waveform of the current to conduct 11 and resistor R _g and the inspection device interposed between the S _r is indicated.

When the gate voltage V _G and the data voltage V _D as shown in FIG. 3 are applied to the circuit of FIG. 2 and the switch S _d is initially turned on, the cell capacitor C _s is The data voltage V _D charges the gate voltage V _G during the period when the pulse voltage is present.

The second switch S _r is off during the period when the first switch S _d is on. This is because it is not necessary to measure the data voltage V _D by the inspection device 11.

Next, when the TFT is turned off after the conduction period of the pulse of the gate voltage V _G has passed, the resistance between the source and drain of the TFT is as follows:
_Since the size of _G is 10 ⁵ to 10 ⁶ times as large as in the case of ON, the charge charged in the cell capacitor C _s is at most gradually reduced by leakage, and the charged state is maintained.

Next, when the source and drain of the TFT are turned on again by the conduction of the pulse of the gate voltage V _G , the first switch S _d is turned off and the drain and the waveform inspector are connected. When the switch S _r interposed in is turned on, the electric charge stored in the cell capacitor C _s is
It will be discharged through the resistor R _g connected to the drain and the source.

The reason why the first switch S _d is turned off is that the discharge current does not cause an unnecessary accident on the data power supply side, but the first switch S _d is turned off.
_d is not an essential component of the manufacture of the present invention.

However, the resistance R _g is a resistance between the drain of each TFT and the ground including the guard ring when a guard ring is connected to each terminal at the stage of manufacturing the TFT-LCD. If the guard ring is removed, for convenience of measurement on the detector 11 side, the resistance is artificially connected, and the source and drain are normally connected when the TFT is ON. The resistance (R _on ) is a resistance designed to be 1/100 or less.

By turning on the second switch S _r , the current or voltage based on the discharge is caught by the waveform inspection device, but the second switch S _r is not an essential component of the present invention either.

The inspection of the waveform of voltage or current due to discharge is
An oscilloscope may be used as an analog method, but for more accurate judgment, it is also possible to input the output voltage or current value into the computer and thereby display the voltage or current waveform in a graph in time series. Therefore, speedy measurement can be realized by such a method.

Part of the waveform of voltage or current due to discharge is
A sawtooth wave as shown in FIG. 3D is exhibited, but its time constant is approximately T = C _s (R _on + R _g ).

Since the size of the cell capacitor C _s is also known in advance, if the current wave time constant for conducting R _g matches the prediction in advance, the cell capacitor of the TFT, the gate line and the data line are The connection relationship of is found to be normal.

On the other hand, when the time constant T of the voltage or current due to discharge changes and the waveform does not match the prediction in advance, the value of R _on or C _s usually changes from the standard. Which means that the connection relation of the TFT or its periphery is abnormal.

On the other hand, if no current is conducted to the resistor Rg, it means that the cell capacitor C _s has not been charged, and the connection relation between the TFT and the gate line or the data line is abnormal. It has existed.

Here, a specific example of discharge output and abnormality in each element or connection will be described. As will be described later in Example 1, in the actual inspection of the TFT-LCD, a plurality of gate lines for each row of TFTs arranged corresponding to each pixel and a plurality of data lines for each column of TFTs are provided. A plurality of gate lines and a plurality of data lines are sequentially switched, and a relay is used to determine whether the function of the TFT-LCD corresponding to all pixels and the connection state of wiring are normal.

In such a case, as shown in FIG. 4A, when the data line is disconnected between the TFT ₂ and the TFT ₃ , C _s1 and C _s2 are charged. Therefore, as shown in each discharge waveform in FIG. 4 (b),
No discharge waveform appears in C _s1 and C _s2 . On the other hand, C _s3 is charged and a discharge output appears. That is, the disconnection of the data line can be detected by the difference in the discharge output waveform due to the change in each gate as shown in FIG.

As shown in FIG. 5A, the gate line is T
If there is a disconnection between FT ₁ and TFT ₂ , C
_Since charging is not performed in _s1 and C _s2 , no discharge output appears. On the other hand, C _s1 is charged and discharge output appears. That is, it is possible to know the location of the disconnection of the gate line by the difference in the discharge waveform for each gate line as shown in FIG.

As shown in FIG. 6A, when the gate line connected to the TFT ₂ is short-circuited with the data line, T
In FT ₂ , even if the discharge output is measured, since the data line is connected to the gate line, if the output waveform is obtained with the gate line connected to TFT ₂ connected to the power supply, the gate applied voltage Itself appears in the data terminal and is shown in FIG.
The output waveform is similar to that of the TFT _{2 in} (b). However, when the normal output waveform is obtained, since the waveform input circuit amplifies with a high amplification factor, the measured value of the output is often saturated and measurement becomes impossible. In the TFT ₁ and TFT ₃ corresponding to the gate line which is not short-circuited with other data lines,
Even if you connect each gate line to the power supply for the measured value,
Since the shorted portion of the data line is connected to the ground, the horizontal output due to the ground voltage as shown in TFT ₁ and TFT ₃ in FIG. 6B is read. That is, due to the abnormal output waveform as shown in FIG.
It is possible to detect a short circuit between the data line and the gate line.

Even if the gate and the source of the TFT ₂ are short-circuited, the power supply input from the gate line is measured through the TFT ₃ , so that it is exactly the same as the short circuit between the data line and the gate line. Will result in an output waveform of In this case, the portion of the TFT ₂ is actually inspected, and the saturation output as shown in the TFT ₂ of FIG. 6B is derived from the short circuit between the data line and the gate line, or the saturation output of the TFT. Is it a short between the gate and the source,
It is necessary to check if there is a short circuit between the data line and the gate line.

As shown in FIG. 7A, when the gate and drain of the TFT are short-circuited, the data line and gate line are connected via the gate and drain of the TFT. Therefore, when the discharge output is measured with the gate line turned _on , the output divided by the resistance R _on when the TFT is _on and the detection resistance R _g , that is, R _g / (R _on + R _g ) will occur. In reality, the presence of a slight capacitance or the like between the gate and the drain causes a slight time delay, and after a substantially linear rising state as shown in FIG. It will indicate the output value.
That is, a short circuit between the gate and drain of the TFT can be detected by the output as shown in FIG.

As shown in FIG. 8 (a), if the between the source and the drain of the TFT are short-circuited via a voltage or current from the gate line, it can not be charged to the C _s. Therefore, no discharge appears. However, since there is a coupling capacitance between the gate line and the data line via the TFT, a rapid attenuation curve as shown in FIG. "Curve") appears. That is, a short circuit between the source and the drain of the TFT can be detected from the attenuation curve as shown in FIG.

However, when C _s does not function as a capacitance and both electrodes are short-circuited, and when the TFT is
In the case where the drain and C _s are short-circuited also, it is impossible to charge and discharge, will exhibit such output waveform as well FIG. 8 (b). In this case,
Whether the output curve as shown in (b) originates from a short circuit between the source and drain of the TFT, a short circuit between the two electrodes of C _s , and further a short circuit between the drain of the TFT and C _s. It is necessary to inspect.

If the gate of the TFT is disconnected from the gate line, C _s is not charged through the TFT, and the discharge output waveform due to this does not appear. The output waveform in this case is shown in FIG. 9 due to the stray capacitance between the gate line and the data line and the connection resistance R _g of the data line.
The discharge output is as shown in (b). However, the discharge power has a smaller discharge power than the discharge output for the source, short or C _s between the drain short. In the case where between the source side and the data lines of the TFT are short-circuited also, since the charging and discharging of C _s is performed, it is similar output waveform and FIG. 9 (b) is obtained. In this case, it is necessary to specifically check whether the gate line or the source line of the TFT is short-circuited. Thus, depending on the discharge output waveform, the TFT
-It is possible to roughly know whether the function of the LCD or the connection state of the wiring is necessary.

EXAMPLE An example of the present invention will be described on the premise of the above operating principle.

[0038]

Embodiment 1 FIG. 10 shows an embodiment actually used in the present invention.

That is, the gate lines G ₁ , G ₂ , ... Of each row of TFTs arranged corresponding to each pixel as described in claim ₂ .
... with respect to _{G m,} switch _{S g1, S g2, ......... S} gm
Similarly, the data lines D ₁ and D for the columns of each TFT are similarly provided.
₂ , D ₃ , ... D _n , switches S _d1 , S _d2 ,
... S _dn is provided, and the switches S _r1 , S _r2 , ... S are provided corresponding to each data line even in the waveform inspection device.
_rn is provided.

In FIG. 10, the relays are used to sequentially switch the switches S _g1 , S _g2 , ... S _gn , and the switches S _d1 , S _d2 , ... S _dm , S _r1 , S _r2 ,
... When S _rn is sequentially switched, it becomes possible to sequentially and efficiently inspect whether the connection relationship of the TFTs corresponding to all pixels is normal or abnormal by the switching. Incidentally, FIG.
In, in each data line, the resistance R _g provided between the part connected to the relay and the part connected to the ground is a resistance for convenience of discharge output measurement,
In order to reduce the measurement error, the resistance value R _on when the TFT is ON is designed to be about 1/100 or less.

On the other hand, the input impederlessness of the amplifier for making the measurement is designed to be very large.

In such a case, as shown in FIG. 6A, even if the data line and the gate line are short-circuited, most of the current passes through the resistors R _g1 , R _g2 ,.
It is possible to prevent the gate power supply from being directly input to the input unit side of the amplifier and protect the amplifier and the measuring meter.

[0043]

[Embodiment 2] In an apparatus capable of inspecting all TFTs as shown in FIG. 10, particularly when all cell capacitors are charged as shown in FIG.
When a normal waveform is obtained in each cell capacitor as shown in FIG. 11B, the whole can operate normally.

On the other hand, when the time constant T shows an abnormal value at some distant places as shown in FIG. 11C, it is found that the TFT or LCD itself has an abnormality. If the discharge waveform cannot be obtained, it means that the connection between the TFT and the gate line or the data line at that location is broken.

As shown in FIG. 11D, all or a part of the specific column (a part is shown in FIG. 11D).
When the discharge waveform is not obtained, it means that there is an abnormality in the connection of the data line itself connecting the column.

Similarly, as shown in FIG. 11 (e), when the discharge waveform cannot be obtained for the gate line of a specific row, it means that the connection of the gate line of the row is abnormal.

[0047]

[Embodiment 3] In the device capable of inspecting all TFTs shown in FIG. 10, in particular, when the cell capacitors are charged every other row with respect to the gate line as shown in FIG. When the discharge waveform is obtained according to the every other line as in (b), it confirms that the connection is normal.

On the other hand, as shown in FIG. 12C, when a discharge waveform is obtained for a gate line that is not originally ON, a short circuit exists between the part and the part adjacent to the gate line. It supports what you do.

[0049]

[Embodiment 4] In the device capable of inspecting all the TFTs shown in FIG. 10, particularly, as shown in FIG. When discharging is performed, as shown in FIG. 13B, at least when the discharging waveform from each cell capacitor is obtained every other column, the connection of at least the charged TFT is normal. It turns out.

On the other hand, as shown in FIG.
When the discharge waveform is obtained on the data line of the column which is not charged, it confirms that a short circuit exists between the data line and the portion adjacent to the data line.

In order to inspect the entire condition of the TFT-LCD as described above, a display plate corresponding to the arrangement of the individual TFTs is used. Very convenient for searching.

Fifth Embodiment In general, the cell capacitor C _s in a normal case is known in advance, and the ranges of R _g and R _on are also known.

Therefore, when the respective elements and the connection relation are normal, the upper and lower limits of the discharge voltage or the discharge current detected by the waveform inspector of FIG. 2 are naturally determined as shown in FIG. .

Therefore, the TFT-LCD is judged by judging whether the output by the actual detected discharge voltage or discharge current is in the range of the upper limit and the lower limit shown in FIG.
It is possible to judge whether the function of each element and the connection state of the wiring are normal.

[0054] Then, in the fifth embodiment, as shown in FIG. 10, gate lines _G 1 of each row of the TFT are arranged to correspond to each _pixel, G 2, with respect ...... _{G m,} the switch _{S g1,}
S _g2, the ......... _{S gm} provided, likewise the data lines _D 1 for the columns of the _TFT, D _2, D 3, to ...... _{D n,} the switch _{S d1, S} d2, the ...... _{S dn} provided, Also for the waveform inspection device, the switch S is provided corresponding to each data line.
_r1 , S _r2 , ... S _rn are provided and a relay is used.
When the switches S _g1 , S _g2 , ... S _gn are sequentially switched, and the data switches S _d1 , S _d2 , ... S _dm and the relay switches S _r1 , S _r2 , ... S _rn are sequentially switched. , T corresponding to all pixels by the switching
Whether the connection relationship of FT is normal or abnormal is sequentially inspected efficiently. At the time of the inspection, an oscilloscope is connected as the detector 11 to the relay side, and the output discharge waveform is changed every switching of each data line and gate line. It is determined whether or not it is within the range of the maximum output and the minimum output as shown in FIG. 14, and it is determined whether or not the function of each element and the connection state of the wiring are normal.

When the oscilloscope is used, a visual judgment is inevitably made, and a specific examination is made on the portion of the combination of the data line and the gate line where the abnormality has occurred. However, it is not always suitable for the measurement when a large number of liquid crystals are included.

[0056]

[Sixth Embodiment] A sixth embodiment is similar to the fifth embodiment.
A configuration for detecting whether or not the discharge output waveform is between the maximum output and the minimum output is shown. As shown in FIG. 15, a plurality of predetermined times are set after the discharge and the discharge output at the predetermined time is set. The maximum or minimum value is set in advance, and the microcomputer determines whether the discharge voltage or discharge current at each predetermined time is within the range of normal values, and the function of the element and the connection state of the wiring are normal. It is determined whether or not

In the sixth embodiment, as in the fifth embodiment,
It is not necessary to visually check all discharge outputs.

The actual discharge curve is as shown in FIG.
Because of the stray capacitance, it initially shows a rising curve, but thereafter, it decreases according to an exponential function which is a normal discharge curve, so that the time immediately after the initial rising is finished and a predetermined time of a few times thereafter (t ₁ in FIG. 15). , T ₂ and t ₃ ), and
The judgment can be realized.

[0059]

[Embodiment 7] Embodiment 7 shows a structure in which stray capacitance existing between the gate line and the ground of the data line is taken into consideration.

Since both the gate line and the data line have stray capacitance with the ground, the gate turns on with a delay as the distance from the driving point increases, and turns off after a lapse of a predetermined time. even since, to C _s, does not mean that a rectangular pulse as shown in FIG. 16 (a) is applied, and FIG. 16 (b) rising output shown in the slow applied current or applied voltage Is input, and charging and discharging are performed based on this.

Therefore, in the TFT and the LCD whose distance from the driving point on the gate side is long, the discharge output is not necessarily a typical exponential function as shown in FIG. As shown in b), the rising is slightly slow, and the curve at the time of discharge tends to be slow.

Therefore, the upper and lower limits of the normal output discharge curve in Example 5 or 6 also differ depending on the position of the TFT-LCD, and originally, the upper and lower discharge outputs are set for each gate line and data line. It is desirable to display.

However, it is extremely complicated to specify and inspect such upper limit output and lower limit output in each TFT-LCD.

In the seventh embodiment, as shown in FIG. 18, the TFT-LC is arranged according to the order of the gate line and the data line.
D is divided into groups, and the upper and lower limits of normal discharge output are set for each group.

As a result, accurate output of the upper and lower limits of the discharge can be obtained for each group based on the arrangement order of the gate lines and the data lines, which in turn enables accurate inspection.

The number of divisions of the actual inspection depends on the number of each gate line and each data line, but 3 to 5 divisions are made for each data line and each gate line, and 9 (3 × 3) Through 2
Often divided into 5 (5 x 5) groups.

In this case, both the method using the oscilloscope shown in the fifth embodiment and the method using the microcomputer shown in the sixth embodiment can be adopted.

[0068]

[Embodiment 8] Embodiment 8 shows a method for judging whether or not R _off, which is the leak resistance when the TFT is OFF, is normal.

[0069] leakage resistance _{R off,} after charging the _{C s,} govern the degree of slow discharge of _{C s} during the time _{T h} where the TFT turned OFF.

C _s when R _on and R _off are normal
19 (a) shows the charge / discharge state and the detected discharge output of
The discharge state of C _s and the output based on this when R _on is smaller than the normal value and R _off is normal are shown in FIG.
As shown in FIG. 9 (b), since the time constant during discharge is small, a quick discharge curve is shown.

In this case, when the judgment as to whether or not the detected discharge output is between the maximum output and the minimum output is mechanically applied as shown in Examples 5 and 6, FIG.
The output of (b) is below the minimum output because the discharge value is rapidly attenuated, and an abnormal output is shown.

Certainly, when focusing _on only R _on , this is an abnormal output (however, even if R _on is usually smaller than the normal value, as long as it is not extremely small, It is often a good product.)

On the other hand, when attention is paid to whether the leak resistance R _off is normal, this point cannot be discriminated only by focusing on the discharge output measurement curve on the lower side of FIG. 19B. .

With reference to the time when the TFT is turned _off , the discharge output voltage for conducting the leak resistance R _{off of the} TFT is e = E · exp (-t / C _s R _off ) (however, E: C when the TFT is turned off
The voltage value between both poles of _s is shown. In this case, the discharge output voltage e when the leak time is set to two types of _Th1 and _{Th2
1, e 2} is _{e 1 = E · exp (-T} h1 / C s R off) e 2 = E · exp (-T h2 / C s R off) ( where the resistance _{R g} in FIG. 2 , R _off , so it is ignored.)

Then, after the passage of T _h1 and T _h2 ,
By the ON the TFT, respectively, resulting _{C s}
The discharge output of e ₁ ′ = e ₁ · exp (−t / C _s R _on ) · R _g / (R _on + R _g ) ≈e ₁ · exp (−t / C _s R _on ) · R _g / R _on e ₂ ′ = e ₂ · exp (−t / C _s R _on ) · R _g / (R _on + R _g ) ≈e ₂ · exp (−t / C _s R _on ) · R _g / R _on Yes (however, t represents the passage of time with respect to the point where each TFT is turned on. Note that R _g in FIG.
Is much smaller than R _on and ignores it. ).

In such a case, the output voltages e ₁ ′ and e ₂ ′ after setting different leak times T _h1 and T _h2.
If the waveforms of 1 are not so different, this is because the value of R _off is normal and the values of e ₁ and e ₂ are not so different.

That is, as shown in FIGS. 19 (c) and 19 (d), when different leak times T _h1 and T _h2 are set in the cases corresponding to FIGS. 19 (a) and 19 (b), It is determined that the output measurement waveform e ₂ ′ of 19 (d) does not differ from the output waveform e ₁ ′ of FIG. 19 (b), and it is determined that the leak resistance R _{off in} this case is normal. Is.

As described above, whether or not the leak resistance R _off is normal can be determined by setting two kinds of leak time T _h and comparing measured output waveforms corresponding to each leak time. Become.

[0079]

As described above, according to the method of the present invention, the TFT-L can be quickly manufactured with an extremely simple structure.
The CD is normal, the connection between the TFT and the circuits around it is normal, and the connection between the gate lines in each row and the data lines in each column, and the gate lines. Whether or not there is a short circuit between the data lines and whether or not there is a short circuit between the data lines can be determined. Particularly, the method of setting the maximum discharge output and the minimum discharge output according to claim 9 can measure the above points quickly and easily, and the leak resistance R _off when the TFT is OFF is normal. It is possible to easily determine whether or not there is any.

As described above, the present invention is a TFT-LCD.
Since it is possible to actually check the function in the manufacturing process of, the value of the present invention is enormous.

[0081]

[Brief description of drawings]

FIG. 1 is a basic circuit diagram showing a basic configuration of a TFT-LCD circuit which is a prerequisite of the present invention.

FIG. 2 is a voltage waveform graph showing the principle of operation of each element that is a premise of the present invention.

FIG. 3: Output waveform graph showing the basic principle of the present invention.

4 (a) and (b): Circuit diagram and output graph on detection side Situation when data line is broken and each TF based on it
The output status of the T-LCD is shown.

5 (a), (b): Circuit diagram and output graph of detection side Situation when gate line is broken and each TF based on this
The output status of the T-LCD is shown.

6A and 6B are a circuit diagram and an output graph on the detection side, showing a situation where a data line and a gate line are short-circuited and an output situation of a TFT-LCD based on the situation.

7A and 7B are a circuit diagram and an output graph on the detection side. FIG. 7A shows a circuit diagram when a gate and a drain of a TFT are short-circuited and an output waveform in this case.

8A and 8B are a circuit diagram and an output graph on the detection side. FIG. 8A shows a circuit diagram in the case where the TFT sort and the drain are short-circuited and an output waveform in this case.

9A and 9B are a circuit diagram and an output graph of a detection side, a circuit diagram when a gate of a TFT and a gate line are short-circuited, and an output waveform in this case.

FIG. 10: Overall circuit diagram showing a circuit configuration of a first embodiment for specifically realizing the present invention.

FIG. 11 is a plan view of a display plate simulating an arrangement of TFT-LCDs, showing a circuit configuration of a second embodiment specifically realizing the present invention.

FIG. 12: Plan view of a display plate simulating the arrangement of TFT-LCDs. FIG. 12 shows a circuit configuration of a third embodiment for specifically realizing the present invention.

FIG. 13: Plan view of a display plate simulating the arrangement of TFT-LCDs. FIG. 13 shows a circuit configuration of embodiment 4 for specifically realizing the present invention.

14 is an output discharge graph showing the operating principle of Example 5. FIG.

FIG. 15: Output discharge graph The operating principle of Example 6 is shown.

16A and 16B are graphs showing that different application inputs are performed depending on the part of the TFT-LCD. FIG. 16 shows the operating principle of the seventh embodiment.

17 (a), (b): Graph showing that different discharge outputs are obtained depending on the position of the TFT-LCD. FIG. 17 shows the operating principle of Example 7.

FIG. 18: Schematic diagram showing that the TFT-LCD is divided into groups along the gate lines and the data lines. FIG. 18 shows the configuration of Example 7.

19 (a), (b), (c), (d): Graph showing charging and discharging characteristics of C _s and discharge output on the detection side. FIG. 19 shows the operating principle of Example 8.

[Explanation of sign]

 1: Liquid crystal (LCD) 2: Pixel electrode 3: Gate line 4: TFT 5: Data line 6: Common electrode 7: Color filter 8: Polarizing plate 9: Glass substrate 11: Inspection device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 29/784

Claims (12)

[Claims] 1. An active color-LC using a TFT.
In D, the TFT is turned on, the cell capacitor of the LCD is charged through the data line, and then the TFT
After keeping the state of charge in the OFF state, the TFT is turned on again, discharging is performed through the resistor connected to the ground side through the source and drain of the TFT, and the current waveform or voltage waveform in the discharge causes
TFT-LCD inspection method for determining whether the functions of the TFT-LCD and the wiring connection state are normal 2. A functional abnormality of all TFTs in a TFT-LCD or a TFT is detected by sequentially inspecting each data line and each gate line according to an arrangement of gate lines and data lines connected to a plurality of TFTs. The inspection method according to claim 1, wherein an abnormality in connection with surrounding wiring and an abnormality in connection with a specific gate line or data line are detected. 3. The inspection method according to claim 2, wherein the cell capacitors are charged every other row with respect to the gate lines, and the presence or absence of a short circuit between the gate lines is inspected. 4. The inspection method according to claim 2, wherein the cell capacitors of the data lines are charged every other column, and the presence or absence of a short circuit between the data lines is inspected. 5. An apparatus for performing an inspection method according to claim 1, further comprising a waveform detector of a current conducted through a resistor connected to the source side of the TFT or a voltage across the resistor. 6. A relay, which sequentially switches the connection between the gate line and the data line for a sequential arrangement of the gate line and the data line connected to a plurality of TFTs, and connects the relay and the waveform detector. An apparatus for performing the inspection method according to claim 5. 7. A display plate having a display unit corresponding to each cell of the LCD is provided, and normal and abnormal parts of the inspection result are displayed by the display plate at the position corresponding to each liquid crystal number. A device for performing the inspection method according to Item 6. 8. A discharge state when the function of the TFT-LCD and the connection state of the wiring are normal or a discharge state when the discharge voltage is maximum and a discharge state when the discharge voltage is minimum are preset, and the actual discharge current or 2. The method for inspecting a TFT-LCD according to claim 1, wherein it is judged whether or not the discharge voltage is within the range of the maximum discharge state and the minimum discharge state. 9. A relay for sequentially switching the connection between the gate line and the data line for a sequential arrangement of the gate line and the data line connected to a plurality of TFTs, the relay and the oscilloscope being connected to each other, It is characterized by determining whether or not the image of the oscilloscope of the discharge current or the discharge voltage output for each gate line and each data line is within the range of the discharge curve by the maximum value and the discharge curve by the minimum value. The inspection method according to claim 9. 10. A relay for sequentially switching the connection between the gate line and the data line with respect to a sequential arrangement of the gate line and the data line connected to a plurality of TFTs, and connecting the relay and the microcomputer, Whether the discharge current or discharge voltage output to the microcomputer for each gate line and each data line is within the range of the maximum value and the minimum value of the discharge current or discharge voltage set at each predetermined time 10. The inspection method according to claim 9, wherein 11. A TFT having a relay for sequentially switching the connection between the gate line and the data line with respect to the sequential arrangement of the gate line and the data line connected to the plurality of TFTs, and the TFT according to the arrangement order of the gate line and the data line. The LCD is divided into a plurality of groups, and the maximum discharge current or the minimum discharge current is preset for each groove. 12. By setting two kinds of time for turning off the TFT and comparing the discharge current or discharge voltage corresponding to each set time, the leak resistance in the state where the TFT is turned off is normal. The inspection method according to claim 1, further comprising inspecting whether or not