JPH05256794A - Apparatus for inspecting active matrix liquid crystal board and electrooptical element for the apparatus - Google Patents

Abstract

PURPOSE: To accurately detect a defect by conducting the pixel electrode of an active matrix liquid crystal display board with a thin film transparent electrode on the upper surface of an electrooptical element, and receiving the intensity change of the light passed through the element by a photoreceiver. CONSTITUTION: The detected light emitted from a light source 1 is illuminated to an electrooptical element 2 via a beam splitter 30. Then, after it is reflected by the optical reflector 9 of the element 2, it is incident to a photoreceiver 3 via the splitter 30, a lens 32 and a zoom lens 35. An A-D converter 41 electrically connected to the photoreceiver 3, an image processor 42, a drive circuit 43 and a CPU 44 are assembled in a controller 40, a display 4 is connected to the processor 42, and an operation board 23 is connected to the CPU 44. The controller 40 converts the intensity of the light received by the photoreceiver 3 to corresponding voltage, displays the intensity, and displays the number, position and type of defects of the board 5 in response to the amplitude of the corresponding voltage on the monitor 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection device for inspecting defects that may occur in an active matrix liquid crystal display substrate used for liquid crystal display panels and the like, and an electro-optical element suitable for use in the inspection device.

[0002]

2. Description of the Related Art In order to increase the area and density of a liquid crystal display panel so as to be suitable for a liquid crystal television, etc., a pixel electrode provided for each pixel arranged in a matrix and a pixel electrode commonly provided for each pixel electrode. An active matrix liquid crystal display using an active matrix liquid crystal display substrate including the gate wiring, the source wiring, and the thin film transistor provided is advantageous, and at present, the relatively small ones are being put into practical use. Usually, in this type of liquid crystal display panel, after manufacturing an active matrix liquid crystal display substrate, a transparent substrate or the like is arranged on the active matrix liquid crystal display substrate via a spacer,
A liquid crystal display panel is manufactured by enclosing liquid crystal in a space formed between an active matrix liquid crystal display substrate and a transparent substrate. In the LCD TV currently produced under such a background, the number of pixels is 25-
Many of them have a number of 500,000, and some have a number of pixels of 1 million or more.

[0003]

By the way, in order to form such a large number of pixels and a large number of wirings corresponding thereto on a substrate, various film forming processes are performed in a clean room in which dust is adjusted to be extremely small. Although it is formed, when the pixel and wiring width become extremely small,
The presence of a slight amount of microdust contained in the manufacturing atmosphere directly leads to disconnection defects and short circuit defects of the pixel electrodes, gate wirings, source wirings, and the like. At present, some of these defects are allowed in the active matrix liquid crystal display substrate, but if the number of defects is more than that, it is considered as a product defect.

However, with the current manufacturing technology, it is extremely difficult to reduce the number of these defects below the allowable limit. Therefore, in a liquid crystal display panel having a large number of pixels, the defective rate is extremely high, This causes the high price of large LCD panels. Conventionally, as a method of inspecting the active matrix liquid crystal display substrate when the active matrix liquid crystal display substrate is completed, a method using a prober is known,
The number of elements on the active matrix liquid crystal display substrate is too large and the inspection time is too long, which is not practical.

Therefore, conventionally, when a liquid crystal display panel is manufactured using an active matrix liquid crystal display substrate, the inspection is not carried out in the production line of the active matrix liquid crystal display substrate, and the process shifts to the next manufacturing process and the manufacturing is completed. We are energizing the liquid crystal display panel after that and visually inspecting whether each pixel actually works. Even if a defect is found at this point, it is difficult to deal with and it is discarded, so this is an active matrix liquid crystal display. Yield is a major cause of very poor results.

The present invention has been made to solve the above-mentioned problems, and defects in the active matrix liquid crystal display substrate can be detected reliably and quickly before assembling the liquid crystal panel, and the number of defects and defect types can be grasped. An object of the present invention is to provide an inspection device that can be easily performed, and to provide an electro-optical element that is suitable for use in the inspection device and has high resolution.

[0007]

In order to solve the above problems, the present invention comprises a plurality of gate wirings, a plurality of source wirings and a plurality of pixel electrodes formed on a substrate. In an apparatus for inspecting an active matrix liquid crystal display substrate having a thin film transistor, the electro-optical element is disposed above the active matrix liquid crystal display substrate so as to face each other with a minute gap, and the optical property changes when an electric field is applied, Between a light source for irradiating an optical element with light, a light receiver for irradiating the electro-optical element and capturing light emitted from the electro-optical element, and a pixel electrode on the active matrix liquid crystal display substrate and the electro-optical element And a measuring means for measuring the change of the light captured by the light receiver. Than it is.

In order to solve the above-mentioned problems, the invention described in claim 2 uses a polymer-dispersed liquid crystal as the electro-optical element described in claim 1, and the measuring means measures the intensity of light captured by a photodetector. It is intended.

In order to solve the above-mentioned problems, the invention described in claim 3 uses the Pockels crystal as the electro-optical element according to claim 1, and the polarization amount of the reflected light after irradiating the Pockels crystal with light as the measuring means. The change is measured.

In order to solve the above-mentioned problems, the invention described in claim 4 is for the inspection device of the active matrix liquid crystal display substrate according to claim 1, and a transparent case in which liquid crystal is sealed, and this transparent case. The light reflector is attached to the bottom surface of the case.

[0011]

The electro-optical element changes its optical properties when an electric field is applied. Therefore, when this electro-optical element is arranged on the active matrix liquid crystal display substrate and electricity is applied between the pixel electrode on the active matrix liquid crystal display substrate and the thin film transparent electrode on the upper part of the electro-optical element,
The optical properties of the electro-optical element change depending on the electric field generated by each pixel electrode. If there is a break in the pixel electrode, gate wiring, source wiring or other parts on the active matrix liquid crystal display substrate, part of the pixel electrode will not operate even if electricity is applied, and the electro-optical element on the pixel electrode will not operate. Does not cause an optical change.

Further, when there is a short circuit defect, an abnormal phenomenon that does not occur in a normal pixel occurs such that the electro-optical element operates only by energizing either the source wiring or the gate wiring. Therefore, by detecting the optical change of the electro-optical element with the light receiver in this way, defects of the active matrix liquid crystal display substrate can be found collectively and quickly.

As the electro-optical element used here, polymer dispersed liquid crystal or Pockels crystal can be used. In particular, the polymer-dispersed liquid crystal has a region in which the amount of transmitted light changes linearly when the voltage is changed, and by utilizing this linearity, a change in voltage can be easily captured as a change in the amount of transmitted light. Further, it is preferable to apply a bias voltage between the pixel electrode and the thin film transparent electrode above the electro-optical element up to a voltage corresponding to this linear region.

The above-mentioned properties of the polymer-dispersed liquid crystal are as follows.
It is suitable for inspecting active matrix liquid crystal display substrates having fine wiring and pixel electrodes. It should be noted that Mylar or the like is preferably attached as an insulating material to the surface of the polymer-dispersed liquid crystal facing the substrate so as not to destroy the pixels on the active matrix liquid crystal display substrate.

Further, by irradiating the electro-optical element with light, capturing the reflected light with a light receiver, and converting the amount of change of the reflected light into a corresponding voltage, a defect of the pixel electrode of the active matrix liquid crystal display substrate is corresponded. It can be grasped as a change in voltage.

[0016]

1 shows a schematic structure of a main part of an embodiment of an inspection apparatus according to the present invention. A light source 1, an electro-optical element 2 on which detection light is incident by the light source 1, and an electric element The electro-optical element 2 includes a light receiver 3 that receives reflected light from the optical element 2 and a monitor 4 that is connected to the light receiver 3.
The active matrix liquid crystal display substrate 5 can be arranged on the opposite surface of the substrate.

Reference numeral 7 in the drawing is a voltage applying device for applying a constant voltage between the thin film transparent electrode 2a on the upper surface of the electro-optical element 2 and the active matrix liquid crystal display substrate 5, and this device is a source wiring. A pulse voltage can be separately applied to the voltage application wiring connected to the gate wiring and the gate wiring, and the pulse voltage, pulse width, and period can be changed. Details of this device will be described later.

Although the light source 1 is composed of a halogen lamp in this embodiment, various laser beams may be used as the light source 1 in addition to the halogen lamp. The electro-optical element 2 is composed of a liquid crystal sheet or a Pockels crystal plate whose optical performance changes when an electric field is applied. The electro-optical element 2 shown in FIG. 1 is formed by forming or adhering a light reflector 9 such as a gold vapor deposition film on the bottom surface of a liquid crystal sheet 8 in which a liquid crystal is sealed inside a transparent case.

The liquid crystal sheet 8 is, more specifically, NC.
Like AP (nematic curvilinear aligned phase), the light transmittance changes according to the magnitude of the electric field created in the liquid crystal sheet 8. As a liquid crystal to be sealed in the liquid crystal sheet 8, a droplet-like liquid crystal is polymerized, for example, a spherical shape (droplet) of the polymer containing liquid crystal dispersed in the polymer is adjusted to turn on / off the electric field. A liquid crystal in which the refractive index of the polymer and that of the liquid crystal are off or off and transparent or opaque appears when the liquid crystal is off is suitable.

As another example of the electro-optical element 2, it is also possible to use a Pockels crystal in which the polarization amount of reflected light changes depending on the magnitude of the electric field that acts. The electro-optical element 2 used in the present invention is not limited to the above as long as optical properties such as light transmittance and polarization amount of reflected light change at a constant rate when an electric field is applied. Instead, either one may be used. The light receiver 3 may be a CCD camera or the like.

The active matrix liquid crystal display substrate 5 to be inspected by the method of the present invention is a known one used for liquid crystal display panels. For example, as shown in FIG. 2 to FIG. A source wiring 10 and a large number of gate wirings 11 for flowing a scanning signal are formed on a substrate 12 in an aligned state, a pixel electrode 13 is formed between them, and each pixel electrode 13 forms a switching element 14 (thin film transistor). It is configured to be connected to the source wiring 10 and the gate wiring 11 via the. Although various structures are known for the wiring structure of the active matrix liquid crystal display substrate 5, the pixel electrode structure, and the structure of the switching element, any kind of structure can be applied to the method of the present invention. Therefore, the structure of the active matrix liquid crystal display substrate is not particularly limited.

Reference numeral 15 shown in FIGS. 2 to 8 is a shorting bar connected to the source wirings 10 ...
Indicates a shorting bar connected to the gate wirings 11 ... In addition, these shorting bar 15,
Although 16 is formed at the manufacturing stage of the active matrix liquid crystal display substrate 5, a transparent substrate is arranged on the active matrix liquid crystal display substrate after the manufacturing of the active matrix liquid crystal display substrate 5, and liquid crystal is sealed between them. It is cut and removed in a later step such as manufacturing a liquid crystal display panel.

The shorting bars 15 and 16 prevent static electricity which adversely affects the thin film transistors. In the present inspection method, any of the shapes shown in FIGS. 3 to 7 can be inspected. Of course, the inspection method of the present invention can be applied to a mounting driver instead of the shorting bar. However, the detection of the line defect on the source and gate wirings in FIG. 3 and the line defect on the source wiring in FIG. 4 is considered to be difficult in the inspection without the above-mentioned optical method, but it is particularly detected at the substrate stage. The point defect, which is said to be difficult, can be inspected at this time as well.

The voltage applying device 7 comprises a switch 7a and a power source 7b. The thin film transparent electrode 2a on the upper surface of the electro-optical element 2 and the shorting bars 15 and 16 of the active matrix liquid crystal display substrate 5 are provided on the voltage applying device 7. It is electrically connected, and a voltage can be applied to all the pixel electrodes 13 on the active matrix liquid crystal display substrate 5 from the gate wiring and the source wiring. The voltage application device 7 can separately apply a pulse voltage to each of the source line 10 and the gate line 11, and the pulse voltage, pulse width, and period can be freely changed.

If one example of the connection structure of the voltage applying device 7 and the active matrix liquid crystal display substrate 5 is described in detail, the structure is shown in FIG. For example, in the case of a shorting bar shape as shown in FIG. 8, current detecting means is provided on each of the gate side and the source side from two terminals capable of outputting a pulse voltage within ± 15 V from the voltage applying device 7. It is designed to be in contact with each shorting bar 15 and 16 via a probe (probe) by wiring between them. Furthermore, electric power is supplied from one terminal that can apply a constant voltage to its two terminals. Wiring is provided on the thin film transparent electrode 2a on the upper surface of the optical element. 9 to 12 are for explaining the detailed structure of the inspection apparatus according to the embodiment of the present invention. In FIG. 9, 20 is a bed, 21 is a substrate storage unit (cassette rack) arranged on the left side of the bed 20, 22 is an inspection head, and 23 is an operation panel.

A guide rail 25 is laid in the left-right direction at the center of the upper surface of the bed 20, and a table 26 can be moved in the left-right direction along the guide rail 25. Further, a mechanism for moving the table 26 in a direction perpendicular to the guide rail 25 is incorporated in the bottom of the table 26, and the table 26 moves in the horizontal direction on the bed 20 in the left-right front-back direction (that is, X, Y directions). Direction).

A cassette 27 (see FIG. 13) accommodating a plurality of active matrix liquid crystal display substrates 5 is accommodated in the substrate accommodation portion 21, and the active matrix is opened from the opening of the cassette 27 above the substrate accommodation portion 21. The liquid crystal display substrate 5 can be sequentially taken out and placed on the table 26.

An outline of the internal structure of the inspection head 22 is shown in FIG.
, And an example of the detailed internal structure is shown in FIG. However, the layout of the optical devices in FIG. 11 can be freely changed depending on the installation position or direction of the liquid crystal panel. 10 and 11, for ease of explanation, an example in which panels are installed vertically is shown.

The light source 1 and the light receiver 3 are housed inside the inspection head 22, and the light source 1 and the light receiver 3 are directed toward the beam splitter 30, respectively. Beam splitter 30
And a light source 1 between the lens 31 and the filter 31 for adjustment.
Further, a lens 32 for adjustment is provided between the beam splitter 30 and the light receiver 3. Further, on the left side of the beam splitter 30 of FIG. 10, a holder 33 on which the electro-optical element 2 is mounted is provided, and the holder 33 is translated along the support shafts 34, 34 in the horizontal direction of FIG. 10 or FIG. You can do it. A zoom lens 35 is attached to the front part of the light receiver 3 so that the reflected light from the electro-optical element 2 can be efficiently incident on the light receiver 3.

According to the above configuration, the detection light emitted from the light source 1 is applied to the electro-optical element 2 by the beam splitter 30 and then reflected by the light reflector 9 of the electro-optical element 2, and then the beam splitter 30 is used. The lens 32 and the zoom lens 35 can be passed through to enter the light receiver 3. In FIG. 10, reference numeral 40 indicates a control unit, and inside the control unit 40, an A / D converter 41, an image processor 42, a drive circuit 43, and a CPU 44 that are electrically connected to the light receiver 3 are provided. The display 4 is connected to the image processor 42, and the operation panel 23 is connected to the CPU 44.

The control unit 40 converts the intensity of light received by the light receiver 3 into an equivalent voltage and displays the intensity, and the number of defects of the active matrix liquid crystal display substrate 5 according to the magnitude of the equivalent voltage. And the position and type are displayed on the monitor 4. When displaying the number of defects, by inputting the size of one pixel, the corresponding voltage distribution can be masked, and the determination can be performed thereafter. Further, FIG. 12 shows a state in which the active matrix liquid crystal display substrate 5 is placed on the table 26.

An air passage 27 is formed in the table 26 so as to vertically pass through the table 26, and a flexible pipe (not shown) is connected to the bottom opening of the passage 27 so as not to hinder the movement of the table 26. The pipe is connected to a vacuum pump. That is, with the above configuration, the active matrix liquid crystal display substrate 5 is placed on the upper surface of the table 26, and the active matrix liquid crystal display substrate 5 can be attracted to the upper surface of the table 26 by vacuuming through the passage 27. There is.

Next, a case of inspecting the active matrix liquid crystal display substrate 5 shown in FIGS. 2 to 8 by using the inspection apparatus configured as described above will be described according to the flow shown in FIG. First, in the production line of the active matrix liquid crystal display substrate 5, a mask forming step, a thin film forming step, a resist step, an exposing step,
A source line 10, a gate line 11, a pixel electrode 13, a switching element 14, and shorting bars 15 and 16 are formed on a substrate 12 through various processes such as an etching process, a cleaning process, and an ion implantation process, and an active matrix liquid crystal display. The substrate 5 is manufactured. This production line is referred to as step S _{1 as} shown in FIG. The active matrix liquid crystal display substrate 5 of this example
In this case, the source line 10, the gate line 11, the pixel electrode 13, the switching element 14, and the shorting bar 1
One square area formed by forming 5, 15, 16 and 16
A plurality of substrates (four in this embodiment) are formed on one substrate 12 as shown in FIG. 13 or FIG.

The active matrix liquid crystal display substrate 5 manufactured in step S ₁ remains in the cassette in step S ₂ and remains in the cassette.
1 is conveyed and set. Active matrix liquid crystal display substrate 5 housed in the substrate housing 21
Are taken out from the substrate storage section 21 and placed on the table 26 in step S ₃ . After the active matrix liquid crystal display substrate 5 is installed on the upper surface of the table 26, the active matrix liquid crystal display substrate 5 is vacuum chucked and fixed on the upper surface of the table 26 in step S ₄ .

Next, in step S ₅ , the table 26 is moved along the guide rail 25 (movement in the X-axis direction) to the facing surface of the scanning head 22, and in step S ₆ , the table 26 is further moved forward, backward, leftward and rightward by a small distance. The table 26 is moved and accurately positioned under the scanning head 2 at a prescribed position.

Next, in step S ₇ , the scanning head 22
The holder 33 provided at the position is moved to bring the electro-optical element 2 close to the active matrix liquid crystal display substrate 5. At this time, the positioning pivot 33a formed on the outer peripheral portion of the holder 33 is pressed against a predetermined position of the active matrix liquid crystal display substrate 5 to align the positioning pivot 33a and the active matrix liquid crystal display substrate 5, and a minute gap is formed. Secure. The alignment here is, as shown in FIG.
An active matrix liquid crystal in which a plurality of regions are formed on one rectangular substrate 12, and a gate wiring, a source wiring, a pixel electrode, a switching element, a shorting bar, etc. are independently formed in each of the plurality of regions. In the display substrate 5, the positioning pivots 33a of the holder 33 are brought into contact with the predetermined positions at the four corners of the substrate 12 to make the active matrix liquid crystal display substrate 5 and the electro-optical element 2 parallel to each other.

In step S ₈ , the shorting bar 1 of the active matrix liquid crystal display substrate 5
The electrodes of the voltage applying device 7 are connected to 5 and 16. And
In step S ₈₁ , the voltage value is gradually increased so that the source side becomes a positive voltage with respect to the gate side, and the leak current between the source wiring 10 and the gate wiring 11 is monitored using the current detecting means. If the leak current is detected, it is determined that a short circuit (referred to as a cross short) between the source wiring 10 and the gate wiring 11 has occurred. If there is no leak current, the process proceeds to step S ₉ . The active matrix liquid crystal display substrate 5 in which the cross short circuit has occurred is repaired by the repair device or is discarded in step S ₈₁ .

Next, a bias voltage is applied between the electrodes on the upper surface of the electro-optical element which are pre-wired in step S ₉ and the electrodes which are wired on the gate side and the source side in step S ₈ . This bias voltage is applied to the reference voltage (for example, ground level) with a maximum voltage of ± 15 V in an appropriate mode to perform defect inspection. By this operation, an electric field is generated between the thin film transparent electrode 2a on the upper surface of the electro-optical element and the pixel electrode on the active matrix liquid crystal display substrate 5.

Next, the behavior of the electro-optical element 2 in this case will be described in detail. When the above-described liquid crystal sheet is used as the electro-optical element 2, the spherical liquid crystal molecules are in a disordered direction and scatter light and do not pass light when no electric field is applied, as shown in FIG. However, as shown in FIG. 17, when an electric field is applied, liquid crystal molecules in a spherical shape face the same direction and pass light. Further, the transparent electrode has a region that linearly changes when the voltage applied to the polymer-dispersed liquid crystal is changed, and by utilizing this linearity, the voltage change can be captured as a change in the amount of transmitted light. Furthermore, the pixel electrode 13 and the electro-optical element 2
A bias voltage is applied between the upper thin film transparent electrode 2a and a voltage corresponding to this linear region.

When the liquid crystal sheet 8 is used as described above, the electro-optical element that receives an electric field generated by applying a voltage between the pixel electrodes 13 ... And the thin film transparent electrode 2a on the upper surface of the electro-optical element 2. In No. 2, if the electric field changes due to each pixel electrode 13, the amount of light transmission changes accordingly. In step S ₉ , the electro-optical element 2 is irradiated with light from the light source 1, and the intensity of the light that has passed through the electro-optical element 2, is reflected by the light reflector 9 and has passed through the electro-optical element 2 again is received. Measure with the instrument 3.

Next, in step S ₁₀ , the light received by the light receiver 3 is calculated by the control unit 40 to calculate an equivalent voltage.
If the value of this equivalent voltage can be identified, checked substantial voltage developed on each of the pixels based on the threshold value, determining the acceptability of the pixels in the brightness or corresponding voltage values of the image in step S _11. In order to decide whether to adopt the active matrix liquid crystal display substrate 5, a designated standard is set, and for example, 1
By deciding the value of how many defects are allowed in the liquid crystal display element of, 000,000 pixels, the user can judge whether to adopt the active matrix liquid crystal display substrate 5 from the data of the processed image.

If it is found that the number of defects of the active matrix liquid crystal display substrate 5 is within the allowable range, the active matrix liquid crystal display substrate 5 that has been inspected is transported to the next production line in step S ₁₂ . Here, if the number of defects of the active matrix liquid crystal display substrate 5 is out of the allowable range, those which can be repaired are sent to the repair device in step S ₁₃ or to the cutting device and the deposit device in step S _14. perform repair can be returned to the production line of the step S ₁₂ after repair. Moreover, those difficult repair by the step S ₁₁ is disposed of in a step S _15.

Next, the defects in the active matrix liquid crystal display substrate 5 to be detected in step S _9, since various types of defects is considered will be described with a few examples of them. The voltage applied to the gate and source wirings is the reference voltage in the initial state. (a) First, when there is a short circuit defect in the source and the gate as shown by the symbol L in FIG. 18, only by applying a positive voltage to the source wiring, the pixel electrode 13 becomes bright only in the pixels shown in black in FIG. , The pixel electrodes 13 of other normal pixels are not affected as indicated by the diagonal lines. (b) Next, in the case of a defect in which the gate wiring and the drain wiring are short-circuited as indicated by the symbol M as shown in FIG. 19, one pixel electrode is obtained by simply applying a positive voltage to the gate line from the initial state. Only the pixels indicated by black in FIG. 19 are brightened, and the pixel electrodes 13 of other normal pixels do not change as shown by the diagonal lines. (c) Next, as shown in FIG. 20, when the gates of the transistors that form the switching element 14 are broken as indicated by the symbol N, a positive voltage is applied to the source line and the gate line to form one pixel electrode 13 20 does not change as shown by the black-painted portion in FIG. 20, and the other normal pixel electrodes 13 obtain a corresponding voltage such that all the normal pixel electrodes 13 become brighter. (d) Next, when the source of the transistor that constitutes the switching element 14 is disconnected as shown by symbol P as shown in FIG. 21, one pixel electrode 13 is formed by applying a positive voltage to the source wiring and the gate line. The pixel electrode 13 of another normal pixel does not change as shown by the black portion in FIG.
A voltage equivalent to that which makes all bright is obtained as indicated by the diagonal lines. (e) Next, as shown in FIG. 22, when the gate wiring 11 is broken as indicated by the symbol Q, by applying a positive voltage to the source wiring and the gate wiring, one row of the pixel electrodes 13 on the right side of the broken portion ... 22 does not change as shown by the black-painted portion in FIG. 22, and a corresponding voltage is obtained so that all the pixel electrodes 13 of other normal pixels become bright as shown by the diagonal lines. (f) Next, as shown in FIG. 23, when the source wiring 10 is broken as indicated by reference symbol R, a positive voltage is applied to the source wiring and the gate wiring to apply a positive voltage to the pixel electrodes in a row below the broken portion. .. does not change as shown by the black-painted portion in FIG. 23, and a corresponding voltage is obtained such that the pixel electrodes 13 of other normal pixels are all brighter as shown by the diagonal lines.

In the above description and the drawings, for the sake of clarity, it is described that the brightness and darkness of the pixel electrode 13 of the active matrix liquid crystal display substrate 5 are directly recognized, but in reality, the electro-optic corresponding to the pixel electrode 13 is recognized. The part of the element 2 is observed as a light-dark distribution, and the controller 40
By comparing it with the dimensional pitch of one pixel, the method of distinguishing light and dark in pixel units is adopted. Further, although the above-mentioned method applies a positive voltage, the defect can be identified by applying a negative voltage. That is, it will be described below.

The voltage applied to the gate and source wirings is the reference voltage in the initial state. (h) First, when there is a short-circuit defect in the source and the gate as shown by the symbol L in FIG. 18, only by applying a negative voltage to the source wiring, the pixel electrode 13 darkens only the pixel shown by the black portion in FIG. , The pixel electrodes 13 of other normal pixels are not affected as indicated by the diagonal lines. (i) Next, in the case of a defect in which the gate wiring and the drain wiring are short-circuited as indicated by the symbol M as shown in FIG. 19, one pixel electrode is obtained by only applying a negative voltage to the gate wiring from the initial state. Only the pixels indicated by black in FIG. 19 are darkened, and the pixel electrodes 13 of other normal pixels do not change as shown by the hatched lines. (j) Next, as shown in FIG. 20, when the gate of the transistor which constitutes the switching element 14 is disconnected as indicated by the symbol N, a positive voltage is applied to the gate line and a negative voltage is applied to the source line to form one pixel. The electrode 13 does not change as shown by the black-painted portion of FIG. 20, and the other normal pixel electrodes 13 obtain a corresponding voltage such that they are all dark as shown by the diagonal lines. (k) Next, as shown in FIG. 21, when the source of the transistor forming the switching element 14 is disconnected as indicated by the symbol P, a positive voltage is applied to the gate line and a negative voltage is applied to the source line to form one pixel. The electrode 13 does not change as shown by the black portion in FIG. 21, and the pixel electrode 1 of another normal pixel
As for 3, the corresponding voltage can be obtained such that all are dark as shown by the diagonal lines. (l) Next, as shown in FIG. 22, when the gate wiring 11 is broken as indicated by the symbol Q, by applying a positive voltage to the gate wiring and a negative voltage to the source wiring, the pixel electrodes on the right side of the broken portion .. does not change as shown by the black-painted portion in FIG. 22, and a corresponding voltage is obtained such that the pixel electrodes 13 of other normal pixels are all darkened as shown by the diagonal lines. (m) Next, when the source line 10 is disconnected as indicated by the reference symbol R as shown in FIG. 23, by applying a positive voltage to the gate line and a negative voltage to the source line, the pixels in a row below the disconnection part The electrodes 13 ... Do not change as shown by the black-painted portions in FIG. 23, and the pixel electrodes 13 of other normal pixels are all brightened as shown by the hatched lines.

In this way, the equivalent voltage distribution corresponding to each pixel is observed, and the number of defective portions and the position of the defective portion of the active matrix liquid crystal display substrate 5 can be determined by the change in the generated position and number. Although the defect can be detected by applying the steady voltage as described above, the defect inspection can be performed by applying the voltage in the pulse mode as shown below. For example,
A point defect due to a short circuit as shown in FIGS.
If a voltage is applied in the mode shown in 4 (a) (b), it can be distinguished from a normal pixel. That is, a so-called blinking state in which light and dark are repeated only in the defective pixel is brought about. On the other hand, in the case of the disconnection defect as shown in FIGS. 20 to 23, when a voltage is applied in the mode as shown in FIGS. 24A and 24B, the normal pixel becomes bright, but when there is the disconnection defect, it changes. Not appear as lines or dots.

Further, in the case of a short circuit defect, in order to distinguish the short circuit between the source and the drain from the short circuit between the gate and the drain, a voltage may be applied in a mode as shown in FIGS. 25 (a) and 25 (b). .. At this time, due to a short circuit between the source and the drain, only the defective pixel becomes bright or becomes in a blinking state. Moreover, when detecting only the short circuit defect between the gate and drain,
The voltage may be applied in the modes of FIGS. 26 (a) and 26 (b). At this time, only the short-circuit defect between the gate and the drain becomes bright or becomes a blinking state.

However, when the resistance of these short-circuited portions is high, it may appear normal even if a pulse voltage is applied. In that case, a defect can be detected by applying a sufficiently long pulse width. Further, the degree of short-circuit resistance can be known by combining with the mode in which pulse voltage is applied to both the gate and the source in FIGS. 24 (a) and 24 (b). That is, the determination can be made by appropriately modulating the pulse voltage, the pulse width and the period in the modes of FIGS. 24A and 24B and detecting the decay time constant of the brightness of the pixel. The present invention reproduces a state close to the conventional final inspection in the state of the active matrix liquid crystal display substrate 5 before the liquid crystal panel is assembled, and detects a defect, and the defect is also repaired before the liquid crystal panel is assembled. It ’s relatively easy to do,
This is useful for improving the in-line yield because it is not necessary to put a defective substrate in the subsequent process.

When the inspection method of the present invention is applied, inspection can be performed regardless of which short-circuit electrode shown in FIG. 18 to FIG. 23 is installed, and an effect of preventing static electricity can be obtained in a process where static electricity is particularly generated, such as when assembling a liquid crystal panel later. Can be handed over while holding. In addition, it is possible to inspect even a substrate mounted with a drive IC instead of the short-circuit electrode, a substrate mounted with a drive circuit, a substrate having a drive circuit, or a substrate having no short-circuit electrode, which has versatility. ..

Further, the electro-optical element can be set without being restricted by the size of the pixel electrode on the active matrix liquid crystal display substrate to be inspected, has versatility, high reliability, and low manufacturing cost. It has the advantage of If the active matrix liquid crystal display substrate 5 is inspected as described above, the position, number, and type of defects of the active matrix liquid crystal display substrate 5 can be electrically displayed. An inspection can be done.

Further, since the reflected light from the electro-optical element 2 is collectively converted into a corresponding voltage to judge the defect, the inspection can be carried out quickly in a short time. For example, the present inventors used an inspection device that was actually prototyped using a liquid crystal sheet as an electro-optical element,
When a 10-inch active matrix liquid crystal display substrate was inspected, the resolution of the liquid crystal sheet was 50.
It was possible to perform the inspection including the handling of the active matrix liquid crystal display substrate 5 (including mechanical rate control) at a rate of 12 μm or less per hour and at a rate of 12 or more per hour. However, if the photodetector 3 (CCD camera) is additionally installed to inspect a plurality of active matrix liquid crystal display substrates 5 at a time, the number of processed substrates can be easily increased.

[0052]

As described above, according to the present invention, the electro-optical element is installed on the active matrix liquid crystal display substrate to be inspected, and the pixel electrode of the active matrix liquid crystal display substrate and the thin film transparent electrode on the upper surface of the electro-optical element are arranged. Change the optical property of the electro-optical element by energizing,
By detecting a change in the intensity of light that has passed through the electro-optical element in that state with a photodetector and converting it into an equivalent voltage, it is possible to detect defects in the active matrix liquid crystal display substrate, so the active matrix liquid crystal is detected by the detection output of the photodetector. There is a feature that a defect of the display substrate can be electrically detected and an accurate and quick inspection can be performed.

If a liquid crystal sheet is used as the electro-optical element, a defective portion can be detected by the transmittance of light passing through the liquid crystal sheet, and if a Pockels crystal plate is used, the defective portion can be detected due to a change in the polarization amount of reflected light. Can be detected. Further, as an electro-optical element used in the inspection apparatus, in which a light reflector is provided at the bottom of a transparent case enclosing a liquid crystal, the light radiated from the light source to the liquid crystal is reflected by the light reflector to receive the light. You can get it at
It is suitable as an electro-optical element for the inspection device. Further, in the case of an electro-optical element using this liquid crystal, the transmissivity changes minutely according to the minute electric field emitted from the minute pixel electrode, so that the resolution is excellent and the active matrix liquid crystal display having the minuter pixel electrode. It is suitable for inspection of substrates.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a schematic configuration of a main part of an inspection device used for carrying out a method of the present invention.

FIG. 2 is a partially enlarged view of an active matrix liquid crystal display substrate tested by the device.

FIG. 3 is a plan view showing a configuration example of a shorting bar.

FIG. 4 is a plan view showing a configuration example of a shorting bar.

FIG. 5 is a plan view showing a configuration example of a shorting bar.

FIG. 6 is a plan view showing a configuration example of a shorting bar.

FIG. 7 is a plan view showing a configuration example of a shorting bar.

FIG. 8 is a configuration diagram showing an example of a voltage applying device.

FIG. 9 is a configuration diagram showing the entire inspection apparatus.

FIG. 10 is an internal configuration diagram of an inspection head of the inspection apparatus.

FIG. 11 is a detailed view of the inside of the inspection head.

FIG. 12 is a side view showing a state of alignment between a holder used in the inspection device and an active matrix liquid crystal display substrate.

FIG. 13 is an explanatory diagram showing a state in which the active matrix liquid crystal display substrate is taken out from the substrate housing portion.

FIG. 14 is an explanatory diagram of an active matrix liquid crystal display substrate.

FIG. 15 is a flowchart showing an example of an operation procedure.

FIG. 16 is a cross-sectional view of a liquid crystal sheet in a state where no electric field is applied.

FIG. 17 is a cross section of a liquid crystal sheet with an electric field applied.

FIG. 18 is an enlarged view for explaining a defective portion of the active matrix liquid crystal display substrate.

FIG. 19 is an enlarged view for explaining a defective portion of the active matrix liquid crystal display substrate.

FIG. 20 is an enlarged view for explaining a defective portion of the active matrix liquid crystal display substrate.

FIG. 21 is an enlarged view for explaining a defective portion of the active matrix liquid crystal display substrate.

FIG. 22 is an enlarged view for explaining a defective portion of the active matrix liquid crystal display substrate.

FIG. 23 is an enlarged view for explaining a defective portion of the active matrix liquid crystal display substrate.

FIG. 24 is a graph for explaining an example of voltage applied during inspection.

FIG. 25 is a graph for explaining an example of voltage applied during inspection.

FIG. 26 is a graph for explaining an example of voltage applied during inspection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light source 2 electro-optical element 3 light receiver 4 monitor 5 active matrix liquid crystal display substrate 8 liquid crystal sheet 9 reflector 10 source wiring 11 gate wiring 13 pixel electrode 14 switching element 15,16 shorting bar 20 bed 21 substrate housing 22 scanning Head 23 Operation Panel 25 Guide Rail 26 Table 30 Beam Splitter 31, 32 Lens 33 Holder 35 Zoom Lens 40 Control Unit

Claims (4)

[Claims] 1. An apparatus for inspecting a liquid crystal display substrate having a thin film transistor including a plurality of gate wirings, a plurality of source wirings, and a plurality of pixel electrodes formed on a substrate, wherein the active matrix liquid crystal display substrate comprises: An electro-optical element, which is arranged facing each other with a minute gap therebetween and whose optical properties change when an electric field is applied, a light source that irradiates the electro-optical element with light, and an electro-optical element that irradiates the electro-optical element. A light receiver that captures the emitted light, a power supply that applies a voltage between the pixel electrode on the active matrix liquid crystal display substrate and the electro-optical element, and a measuring unit that measures a change in the light captured by the light receiver. An apparatus for inspecting an active matrix liquid crystal display substrate, comprising: 2. A polymer-dispersed liquid crystal is used as the electro-optical element, and the measuring means measures the intensity of the light captured by the light receiver.
An inspection device for an active matrix liquid crystal display substrate as described above. 3. The inspection of the active matrix liquid crystal display substrate according to claim 1, wherein the electro-optical element is a Pockels crystal, and the measuring means measures the polarization amount of the reflected light from the Pockels crystal. apparatus. 4. A transparent case in which liquid crystal is enclosed,
The electro-optical element for an inspection device of an active matrix liquid crystal display substrate according to claim 1, comprising a light reflector provided on a bottom portion of the transparent case.