JPH0481889A - Method for inspecting active matrix array substrate - Google Patents

Abstract

PURPOSE:To improve the efficiency of an inspection operation and to reduce the production cost of a liquid crystal display panel by pinching a polymer dispersion type liquid crystal formed in the form of a film between an active matrix array substrate and a counter electrode substrate to form a laminate for inspection, impression prescribed voltages to scanning signal lines, data signal lines and a counter electrode, irradiating the laminate with light from one side thereof, and observing the transmitted light from the other side. CONSTITUTION:A transparent plastic film 52 is laminated on the surface of the active matrix array substrate 31 and further, the film-shaped polymer dispersion type liquid crystal 53, the transparent counter electrode 11, transparent rubber 54, and a glass substrate 5 are successively laminated thereon. An inspector thereafter inputs a scanning signal to the gates of all TFTS 10, thereby impressing the prescribed voltages between driving electrodes 9 of all the picture elements and the counter electrode 11. The inspector visually observes, from above the light which is irradiated to the active matrix array substrate 31 from below this substrate and is transmitted therethrough. The polymer dispersion type liquid crystal 53, etc., are then detached from the active matrix array substrate 31 after the inspection.

Description

[Detailed description of the invention] <Industrial application field> The present invention uses a film-like polymer-dispersed liquid crystal.
The present invention relates to a method for inspecting an active matrix array substrate of a liquid crystal display panel.

<Prior Art> Currently, liquid crystal display panels are broadly classified into simple matrix type and active matrix type.

Among these methods, the active matrix method is
A switching element is added to each display pixel. Switching elements include three-terminal elements such as thin film transistors and two-terminal elements such as diodes.

FIG. 4 is a schematic diagram showing an enlarged part of a thin film transistor active matrix type liquid crystal display panel as an example of a three-terminal element.

In this figure, 1 is a liquid crystal display panel.

This liquid crystal display panel 1 is constructed between two glass substrates 5.6 each provided with a polarizing plate 2.3.
This is a structure in which a liquid crystal 4 (sted nematic) is enclosed.

Further, on the glass substrate 6, data signal lines 7 and scanning signals tIA8 are arranged in a matrix.

In addition, near these intersections there is a thin film transistor (TFT).
: Th1n Film Transistor)
10 are arranged. Further, the drain electrode side of the TFT 10 is electrically connected to a transparent drive electrode (also called a pixel electrode) 9. Below, this drive electrode 9 and TP
The glass plate 3 on which T10 etc. are arranged is called an active matrix array substrate.

On the other hand, a transparent counter electrode 11 is arranged on the glass substrate 5.

By the way, there is a method for inspecting the active matrix array substrate 6 in the liquid crystal display panel 1 having the above configuration.
That is, as methods for inspecting short circuits and disconnections in the data signal line 7, scanning signal line 8, etc. and defects in the TFT 10, there have conventionally been inspection methods using a probe, inspection methods using visual inspection, and the like.

The inspection method using a probe is a method for determining the presence or absence of defects in the active matrix array substrate 6 by sequentially inspecting all signal lines 7.8 and all drive electrodes 9 using a probe (prober).

- As an example, first, the signal line 7.8 or the drive electrode 9
Press the probe against it. Next, the signal line 7 is passed through this probe.
．． 8 or drive electrode 9 is energized.

Then, the presence or absence of a short circuit or disconnection, and whether the thin film transistor is good or bad, is determined based on the manner of conduction.

After that, if the defective part could be corrected, it was corrected, and if it could not be corrected, it was discarded.

For example, this method is published in ``Proceedings of the 1989 Autumn National Conference of the Institute of Electronics, Information and Communication Engineers J, 5-32.

The visual inspection method is to assemble the active matrix array substrate 6, TNM crystal 4, glass substrate 5, etc. as a liquid crystal display panel, and then visually observe the display condition to determine whether there are any defects in the active matrix array substrate 6. This is to determine the For more information,
First, predetermined voltages are applied or not applied to all data signal lines 7, scanning signal lines 8, and counter electrodes 11. Then, light is irradiated from the active matrix array substrate 6, and the transmission state of the light is observed from the glass plate 5 side. Then, it is examined whether the orientation of the TN liquid crystal 4 changes as expected and the light transmission state changes. That is, for example, if a certain scanning signal line 8 is disconnected and the corresponding TPTlo does not operate normally, the drive electrode (pixel electrode) 9 connected to that TPT10
It is known that there is a defect because the voltage is not properly applied to the pixel and the amount of light passing through the corresponding display pixel does not respond to the signal applied to the scanning signal line 8.

Next, FIG. 5 shows an example of the case of a two-terminal element.
(Meta 1-Insu lator-Metal
) is shown, and FIG. 6 shows a pixel pattern diagram thereof.

In these figures, 21 is a liquid crystal display panel using MIM elements. This liquid crystal display panel 21 has a structure in which a liquid crystal 26 is sealed between two glass substrates 24 and 250, and polarizing plates 22 and 23 are provided above and below, respectively. On this glass substrate 25, a drive electrode 27,
A timing signal line 28 and an MIM element 29 are provided. Further, a counter electrode 30 is provided on the glass substrate 24 .

The inspection method for the liquid crystal display panel 21 using this MIM element is substantially the same as that for a three-terminal element. In other words, in the inspection method using a probe, the timing signal line 2
By applying a probe to the MIM element 8 and the drive electrode 27 and inspecting the relationship between the applied voltage and current, the quality of the MIM element 29 is determined and a defective location is detected. In the visual inspection method, the liquid crystal display panel 21 is assembled in the same manner as in the case of the three-terminal element, and the quality of the MIM element 29 is determined by actually operating the liquid crystal display panel 21.

<Problems to be Solved by the Invention> However, in such a conventional inspection method using a probe, all signal lines or 10,000 to 10
Approximately 1,000,000 drive electrodes were sequentially inspected to determine the presence or absence of defects in the active matrix array substrate. For this reason, the inspection work was extremely complicated and the work efficiency was low.

In addition, in such conventional visual inspection methods, an inspector assembles an active matrix array substrate, TN liquid crystal, glass substrate, etc. as a liquid crystal display panel in the morning, and then visually observes this liquid crystal display panel. The presence or absence of defects in the active matrix array substrate was determined by this. Even if a defect in an active matrix array substrate was found, it was difficult to replace only the active matrix array substrate of that liquid crystal display panel, so if it could not be repaired externally, the liquid crystal display panel was discarded.

This is because TN liquid crystal is a liquid, and it is necessary to firmly seal the area around the glass substrate when it is sealed, making it difficult and difficult to disassemble the erected panel. Since it is difficult to correct the problem without removing it, the correction work is extremely time-consuming.

As a result, the manufacturing cost of liquid crystal display panels has increased.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an active matrix array substrate inspection method that improves the efficiency of inspection work and reduces the manufacturing cost of liquid crystal display panels.

<Means for Solving the Problems> The present invention is a method for inspecting an active matrix array substrate for a liquid crystal display, which includes a polymer dispersion type formed in the form of a film between the active matrix array substrate and a counter electrode substrate. By sandwiching a liquid crystal as a test stack, applying a predetermined voltage to the scanning signal line, data signal line, and counter electrode, and emitting light from one side of the stack, observing the transmitted light from the other side. This active matrix array substrate inspection method is characterized by determining whether or not the active matrix array substrate operates normally.

Effect> The method for inspecting an active matrix array substrate according to the present invention is to first sandwich a film-like polymer dispersed liquid crystal between an active matrix array substrate and a counter electrode to form a laminate, and then apply a voltage as uniformly as possible. Apply pressure evenly to the laminate so that the

For example, this laminate is held in place at four locations using clips to form a liquid crystal display panel. This method is significantly simpler than the conventional method of enclosing liquid TN liquid crystal.

Next, as in the conventional method, a voltage is applied between the drive electrode and the counter electrode, and light is irradiated from one side of the stack.
From the other side, the transmitted light is observed visually or by means such as a TV camera.

If a defective part of the liquid crystal display panel is to be repaired after being inspected by the above-described method, it must be dismantled, but it is much simpler than conventional methods because it is only necessary to remove the clips, for example. Furthermore, even if the active matrix array substrate cannot be modified and is to be discarded, only the active matrix array substrate needs to be discarded.

<Example> Hereinafter, an active matrix array substrate according to the present invention,
For example, a method for inspecting a TPT active matrix substrate will be explained. Note that the same parts as in the conventional example described above are given the same reference numerals, and redundant explanation will be omitted.

FIG. 1 is a block diagram schematically showing the structure of a TFT type active matrix drive element.

In FIG. 1, 31 is an active matrix array substrate. As shown in FIG. 4, this active matrix array substrate 31 has data signal lines 7 and scanning signal lines 8 arranged in a matrix on a glass substrate 6 which is a support.

Moreover, TPTIO is arranged near these intersection points. Specifically, as shown in FIG. 1, a drive electrode 9 is connected to the drain 41 of the TFTlo, a data signal line 7 is connected to its source 42, and a scanning signal line 8 is connected to its gate 43. Therefore, when a scanning signal is input to the gate 43, TFTlo is turned on.

Disconnection or short-circuiting of the data signal line 7 or scanning signal line 8 on the active matrix array substrate 31,
The inspection method for inspecting whether the TPT is good or bad is shown below.

FIG. 2 is a cross-sectional view of a laminate for explaining a method of inspecting an active matrix array substrate according to an embodiment of the present invention.

First, the inspector laminates a transparent plastic film 52 on the surface of the active matrix array substrate 310 as shown in FIG.
are sequentially stacked. Then, each layer of this laminate is fixed with a fixing device such as a clip so that each layer is in close contact with each other. At this time, if each layer of the laminate is brought into close contact with each other by simply stacking the glass substrates 5, there is no need to use a fixing device to fix them.

It is desirable to use a film with a high dielectric constant (for example, polyvinylidene chloride) for the transparent plastic film 52 so as not to weaken the strength of the electric field from the drive electrode 9.

The film-like polymer-dispersed liquid crystal δ3 is a film having a structure in which liquid crystal spheres 55 are dispersed in a polymer matrix.

A film-like polymer-dispersed liquid crystal 53 having such a structure
When no voltage is applied to the liquid crystal molecules 56, the liquid crystal molecules 56 are arranged along the outer wall of the liquid crystal sphere 55, as shown in FIG. 3(a). If light is irradiated from one electrode surface at this time,
This light is transmitted to the liquid crystal sphere 5 due to the birefringence of the liquid crystal molecules 56.
5 Scattered inside. As a result, this film-like polymer-dispersed liquid crystal 53 appears milky white.

On the other hand, when a voltage is applied to the film-like polymer-dispersed liquid crystal 53, as shown in FIG. 3(b), the liquid crystal molecules 56
are aligned in the electric field direction (arrow E direction in the figure). As a result, when light is irradiated from one electrode surface, the light travels straight without being scattered inside the liquid crystal sphere 55, so this polymer-dispersed liquid crystal 5
3 looks transparent like glass.

The details of such a polymer-dispersed liquid crystal 53 can be found in the December 1987 reprint of the monthly magazine "Electronic Materials J" and in the article EID89-89 published on February 15, 1990 in the Institute of Electronics, Information and Communication Engineers. Published.

The transparent counter electrode 11 is a transparent plastic film 57 on which a metal oxide is deposited.

The transparent rubber 54 is made of silicone rubber, for example, and is used to connect the active matrix array substrate 31, the plastic film 52, and the polymer-dispersed liquid crystal 5.
3 and the counter electrode 11 are laminated to improve adhesion between them.

In order to facilitate handling of the laminated product, it is preferable that the plastic film 52, polymer-dispersed liquid crystal 53, counter electrode 11, and transparent rubber 54 be integrally formed. Furthermore, it is preferable that the glass substrate 5 is also formed integrally with the above-mentioned laminated structure.

Next, the inspector applies a predetermined voltage between the drive electrode 9 and the counter electrode 11 of all pixels by inputting a scanning signal to the gates 43 of all TPTIOs. That is, all pixels are set in a state where light can pass through them. Note that the applied voltage at this time varies depending on the characteristics and thickness of the polymer-dispersed liquid crystal, but is approximately 15 V to 50 V.

Then, the inspector checks the active matrix array substrate 31
Light is irradiated from below in Figure 2, and the transmitted light is visually observed from above in the figure.

At this time, if a voltage cannot be applied between some of the drive electrodes 9 and the counter electrode 11 due to a break in the scanning signal line 8, for example, only the pixel corresponding to that drive electrode 9 appears dark. Therefore, the inspector can determine that this active matrix array substrate 31 is defective.

After the inspection, the active matrix array substrate 31
The polymer dispersed liquid crystal 53 and the like are separated from the active matrix array substrate 31 and then laminated on the next active matrix array substrate 31 for inspection.

Therefore, the inspector can easily inspect the active matrix array substrate 31 visually, for example, thereby improving the efficiency of inspection work.

Further, the active matrix array substrate 31 can be inspected simply by fixing the polymer dispersed liquid crystal 53, the counter electrode 11, etc. to the active matrix array substrate 31 using a fixing device. Therefore, if the active matrix array board 31 is defective, the active matrix array board 31 can be easily taken out by simply removing the fixing device, which improves the efficiency of inspection work whether it is repaired or discarded. The manufacturing cost of the laminated liquid crystal display panel can be lowered.

Furthermore, since the liquid crystal used for inspection is a film-like polymer-dispersed liquid crystal 53, it is easy to handle.

Further, although the above embodiment is a method for inspecting a TPT active matrix type active matrix array substrate, the method can also be applied to the above-mentioned MIM active matrix type active matrix array substrate.

In the above embodiment, the plastic film 52 and the transparent rubber 54 are laminated, but these may be omitted depending on the type of film-like polymer dispersed liquid crystal 53 and the structure of the active matrix array substrate. in this case,
A transparent counter electrode 11 is formed on the glass substrate 5.

<Effects of the Invention> According to the method for inspecting an active matrix array substrate of the present invention, an active matrix array substrate can be inspected simply by sandwiching a polymer-dispersed liquid crystal or the like between the active matrix array substrate and a counter electrode. can. That is, for example, an active matrix array substrate can be inspected visually without sealing a liquid crystal in a liquid crystal display panel.

Therefore, active matrix array substrates can be inspected easily and in a short time, which improves the efficiency of active matrix array substrate inspection work.
If the active matrix array board is defective,
Since the active matrix array substrate can be easily disassembled and only the active matrix array substrate removed from the laminate for modification or disposal, the manufacturing cost of the liquid crystal display panel can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the structure of a TFT type active matrix drive element, FIG. 2 is a cross-sectional view of a laminate for explaining a method of inspecting an active matrix array substrate according to an embodiment of the present invention, and FIG. A schematic diagram to explain the operation of a polymer-dispersed liquid crystal. Figure 4 is a schematic diagram showing an enlarged part of an active matrix type liquid crystal display spring. Figure 5 is a liquid crystal display panel using MIM elements. FIG. 6 is a pixel pattern diagram showing an enlarged view of the MIM element. 8...Scanning signal line, 9.27...Drive electrode, 10...TFT (switching element)
, 11.30... Counter electrode, 28... Timing signal line, 29.◆◆
・・・・◆・MIM element, 31・・・・・・Active matrix array substrate, 53・・・φ・・・Full-shaped polymer dispersed liquid crystal.

Claims (1)

[Claims] A method for inspecting an active matrix array substrate for a liquid crystal display, comprising: forming a laminate by sandwiching a film-like polymer dispersed liquid crystal between the active matrix array substrate and a counter electrode substrate; By applying a voltage between the upper driving electrode and the counter electrode, irradiating light from one side of the stack, and observing the light transmitted from the other side, it is possible to determine whether this active matrix array substrate operates normally. 1. A method for inspecting an active matrix array substrate, the method comprising determining whether or not the active matrix array substrate is present.