JPH06160898A - Inspection method for liquid crystal display panel - Google Patents

Abstract

PURPOSE:To accurately and easily detect a short circuit between scanning electrodes, as to an inspection method for a liquid crystal display panel for inspecting the trouble of the short circuit between the scanning electrodes. CONSTITUTION:At an inspection time, an inspection control circuit 16 for alternately supplying a driving signal having a different phase at every scanning line is connected with the scanning electrode 12c of the liquid crystal display panel 11 so as to see the brightness of the liquid crystal display panel 11. The brightness on the short-circuited part is increased, so that the presence or absence of the short circuit and the short-circuited position are recognized by seeing the brightness of the liquid crystal display panel 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display panel inspecting method, and more particularly to a liquid crystal display panel inspecting method for inspecting a short circuit between scanning electrodes.

Data electrodes and scanning electrodes are wired in a matrix in a liquid crystal display panel, and it is necessary to maintain an insulating state between the scanning electrodes forming different scanning lines. However, the pitch between adjacent scan electrodes is very short, and a short circuit is likely to occur. Therefore, it is necessary to inspect for a short circuit between the scan electrodes.

[0003]

2. Description of the Related Art FIG. 7 is a schematic block diagram of a TFT (thin film transistor) type color liquid crystal display panel. LCD panel 1
Holds the TFT substrate 2 and the common electrode substrate 3 at a predetermined interval and seals the periphery thereof with a sealing material 4.
The liquid crystal 5 is filled between the common substrate 3 and the common substrate 3.

A pixel electrode 2a for applying a voltage to the liquid crystal 5, a thin film transistor (TFT) 2b for controlling the voltage applied to the pixel electrode 2a, and a matrix for supplying a control signal to the thin film transistor 2b are formed on the TFT substrate 2. Wiring scan electrodes 2c and data electrodes 2d are formed together with the flattening layer 2e. On the common electrode substrate 3, a multicolor color filter 3a and a common electrode 3b held at a common potential are formed together with a flattening layer 3c for flattening unevenness.

The source of the thin film transistor 2b is a pixel electrode 2a, the gate is a scan electrode 2c, and the drain is a data electrode 2.
connected to d. The thin film transistor 2b is the scanning electrode 2c.
It is turned on / off according to the voltage level of 2 to control the supply of the voltage of the data electrode 2d to the pixel electrode 2a.

The liquid crystal 5 changes its state according to the voltage applied between the pixel electrode 2a and the common electrode 3b, and transmits or diffuses light. The liquid crystal display panel 1 changes the state of the liquid crystal 5 for each pixel electrode 2a by controlling the voltage applied to each pixel electrode 2a by the thin film transistor 2b, and controls the transmission of light to perform display control.

In the liquid crystal display panel 1 of this type, normally, as shown in FIG.
As shown in (B), two systems of the thin film transistor 2b and the scanning electrode 2c are prepared for the pixel electrode 2a, and when a defect occurs in one thin film transistor 2b or the scanning electrode 2c, the other thin film transistor 2b and the scanning electrode 2c are driven. The so-called redundancy is performed to make it possible and prevent the yield from decreasing. At this time, the scanning electrodes 2c for driving the pixel electrodes 2a are arranged on both sides of one pixel electrode 2a.

Therefore, the distance d between the scanning electrodes 2c adjacent to each other is as small as about 10 .mu.m, and a short circuit easily occurs between the scanning electrodes 2c. Therefore, it is necessary to inspect whether a short circuit has occurred between the scan electrodes 2c.

Conventionally, an automatic inspection device has been used for inspecting a short circuit between the scan electrodes 2c, and the actual pattern of the scan electrodes 2c is optically detected for each unit of one pixel electrode 2a, and the adjacent scan electrodes are detected. It is performed by determining whether or not a predetermined interval is maintained between 2c.

[0010]

However, the conventional method for inspecting a liquid crystal display panel uses an automatic inspection device to optically detect the pattern of the scanning electrodes pixel by pixel and inspect for a short circuit between the scanning electrodes. However, there is a problem that, for example, it takes about 20 to 30 minutes to inspect a panel of 900,000 pixels, and it takes a lot of time to inspect.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method for inspecting a liquid crystal display panel, which can inspect a short circuit between scanning electrodes with high accuracy and easily.

[0012]

According to the present invention, a common electrode substrate on which a common electrode is formed is connected to a pixel electrode and a plurality of pixel electrodes via a switching element, and a plurality of voltages are applied to the pixel electrode for each scanning line. In a liquid crystal display panel in which a liquid crystal is sandwiched between a pixel electrode substrate on which scan electrodes are formed, a method of inspecting a liquid crystal display panel for inspecting a short circuit between a plurality of scan electrodes, wherein the plurality of scan electrodes have odd scan lines By supplying signals having different phases between the scanning lines and even scanning lines to both ends of each scanning electrode and sequentially turning on the switching elements, the liquid crystal panel is driven, and by detecting the brightness of the liquid crystal display panel, Inspecting for short circuit between scan electrodes.

[0013]

In the scanning electrodes adjacent to each other, signals having different phases are supplied to both ends of each scanning electrode.

If there is an unnecessary short circuit between the adjacent scan electrodes, there is a potential difference between the adjacent scan electrodes.
The voltage at the short-circuited portion is reduced, and the brightness at the short-circuited portion is different from that at other portions. Therefore, it is possible to detect the presence or absence of a short circuit and the position by observing the brightness on the liquid crystal display panel.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic block diagram of an embodiment of the present invention. In the figure, 11 indicates a liquid crystal display panel.

The liquid crystal panel 11 holds the TFT substrate 12 and the common electrode substrate 13 at a predetermined interval and seals the periphery thereof with a sealing material 14, and the TFT substrate 12 and the common substrate 13 are sealed.
The liquid crystal 15 is filled in between.

A pixel electrode 12a for applying a voltage to the liquid crystal 15, a thin film transistor (TFT) 12b for controlling the voltage applied to the pixel electrode 12a, and a matrix for supplying a control signal to the thin film transistor 12b are formed on the TFT substrate 12. Wiring scan electrode 12c and data electrode 12d
Are formed together with the flattening layer 12e. The common electrode substrate 13 has a multicolor color filter 13a, and a common electrode 13b held at a common potential has a flattening layer 1 for flattening unevenness.
It is formed together with 3c.

FIG. 2 is a plan view of an essential part of one embodiment of the present invention,
FIG. 3 shows an operation waveform diagram of an embodiment of the present invention. As shown in FIG. 2, since the scanning electrodes 12c are redundant, each pixel electrode 12
It is bifurcated so as to sandwich a, and each is connected to the pixel electrode 12a via the thin film transistor 12b. Further, on the TFT substrate 12, a capacitor electrode (Cs) 1 for forming a capacitor between the pixel electrodes 12a below the pixel electrodes 12a.
2f is formed.

The source of the thin film transistor 12b is connected to the pixel electrode 12a, the gate is connected to the scan electrode 12c, and the drain is connected to the data electrode 12d. The thin film transistor 12b is turned on / off according to the voltage level of the scan electrode 12c, and controls the supply of the voltage of the data electrode 12d to the pixel electrode 12a.

The liquid crystal 15 includes a pixel electrode 12a and a common electrode 1
The state changes depending on the voltage applied between the light source 3b and the light source 3b, and transmits or diffuses light. The liquid crystal display panel 11 changes the state of the liquid crystal 15 for each pixel electrode 12a by controlling the voltage applied to each pixel electrode 12a by the thin film transistor 12b, and controls the transmission of light to perform display control.

At the time of inspection, the inspection control circuit 16 is connected to the liquid crystal display panel 11. The inspection control circuit 16 is connected to both ends Ta and Tb of the scan electrode 12c and the data electrode 12d, and supplies a drive signal necessary for the inspection. The inspection control circuit 16 is connected to one terminal (Ta- of the scan electrodes 12c-1).
1) and the other terminal (Tb-1), as shown in FIG. 3B, a first drive signal having a constant phase (positive / negative), frequency, and amplitude, for example, on level = 15V, off level. =-
A signal of 15 V, frequency of 30 Hz, and pulse width of 300 μs is input, and the scan electrode (1c) adjacent to the scan electrode (12c-1) is input.
2c-2) one terminal (Ta-2) and the other terminal (Tb-
As shown in FIG. 3C, the second drive signal has a phase difference from the first drive signal, for example, a phase of 30).
Input signals with a shift of 0 μs. In addition, the inspection control circuit 16
Is turned on to the data electrode 12d as shown in FIG.
Level = 5V, off level = -5V, frequency 30Hz
Input the drive signal of.

When the first and second drive signals are input,
When the scanning electrodes 12c-1 and 12c-2 are at 15V, the thin film transistor 12b is turned on, and the signal of the data electrode 12d is written in the pixel. Scan electrodes 12c-1, 12c
When -2 is -15V, thin film transistor 12b is off
Then, the voltage of the pixel is held.

Next, the inspection method will be described. FIG. 4 shows an equivalent circuit of a main part of one embodiment of the present invention, and FIG. 5 shows an operation explanatory diagram of one embodiment of the present invention.

If there is no short circuit between the scan electrode 12c-1 and the scan electrode 12c-2 adjacent thereto, as shown in FIG. 4 (A), both ends Ta-1 and Tb-1 of the scan electrode 12c-1 are connected. Is +1
A voltage of 5 V is applied and all the thin film transistors 12b-1 connected to the scan electrode 12c-1 are turned on. Thereby, the pixel electrode 12a-1 connected to the scanning electrode 12c-1
Is applied with a voltage of +5 V, and if the liquid crystal display panel 11 is normally white (white display when the liquid crystal applied voltage is 0 V), black display is performed.

At this time, a voltage of -15 V is applied to both ends Ta-2 and Tb-2 of the scanning electrode 12c-2, and the thin film transistor 12b-2 connected to the scanning electrode 12c-2 is turned off. As a result, the pixel electrode 12a-2 keeps the voltage of -5 V in the previous cycle held, and black display is performed.

Therefore, when there is no short circuit between the scanning electrodes 12c, the entire surface of the liquid crystal display panel 11 is displayed in black.

When there is a short circuit between the scan electrode 12c-1 and the scan electrode 12c-2 adjacent thereto, the equivalent circuit is as shown in FIG. 4 (B).

In the figure, r ₁ is terminals Ta-1 and Ta-2.
To the short-circuit point P ₀ , r ₂ is the terminal Tb-1, Tb-
The resistance value from 2 to the short-circuited point P ₀ , and the resistance values r ₁ , r
₂ depends on the position of the short-circuited point P ₀ .

The first and second scanning electrodes 12c-1 and 12c-2 are provided on the scanning electrodes 12c-1 and 12c-2.
When the second drive signal is input, the voltage +15 V of the scan electrode 12c-1 at the short-circuited point P ₀ is the voltage − of the scan electrode 12c-2 −.
Canceled by 15V, the voltage becomes 0V, and terminals Ta-1, T
b-1 is held at + 15V.

FIG. 5A shows the characteristics of the scanning electrode voltage with respect to the position on the scanning line direction at this time. Figure 5 (A)
As shown in FIG. ₅ , the voltage becomes the minimum at the short-circuit position P ₀ and gradually increases to +15 V toward both terminals Ta-1 and Tb-1. FIG. 5B shows the characteristic of the pixel voltage with respect to the position on the horizontal axis. FIG. 5B shows the same characteristics as FIG. 5A, and the pixel voltage at the short-circuit position P ₀ becomes the minimum. Figure 5
In (C), the liquid crystal panel 11 is normally white (voltage is 0
The white characteristic is displayed at V), and the luminance characteristics with respect to the position when the common electrode is 0 V are shown. As shown in FIG. 5C, the brightness is high at the short circuit position P ₀ .

Therefore, the first and second drive signals are applied to the electrode 12
When the change is input to c-1 and 12c-2, the change in brightness can be visually detected to determine the presence or absence of a short circuit between the scan electrodes 12c-1 and 12c-2 and the position P ₀ thereof.

According to such a method, the inspection time can be reduced to 1/2 or less of the conventional inspection time.

In this embodiment, the change in brightness is visually detected to detect the short-circuited position. However, the brightness of the display screen of the liquid crystal display panel 11 is detected by a camera or the like and image processing is performed to automate the process. You can do it easily.

FIG. 6 shows a plan view of the essential part of another embodiment of the present invention. In the figure, the same components as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, as shown in FIG. 6A, the pixel electrode 12a, the thin film transistor 12b, and the scan electrode 12 are used for short-circuit inspection of the adjacent scan electrodes 12c-1 and 12c-2.
c, scan electrodes 12c-1, 1 when forming the data electrode 12d
Insulating films 17a-1 and 17 for covering the left end and the right end of 2c-2
a-2, 17b-1, and 17b-2 are formed in advance.

At the time of inspection, as shown in FIG. 6B, the short bars 18a-1 and 18a connected to the inspection control circuit 16 are provided.
-2, 18b-1, 18b-2 drive signal to scan electrode 12
Supply to c-1, 12c-2. The short bar 18b-1 is connected to the scan electrode 12c-1 by an insulating film 17b-1 formed on the right end portion of the scan electrode 12c-1, and the scan electrode 12c-2.
It is configured not to connect to. Short bar 18b
-2 is an insulating film 17 formed on the right end of the scanning electrode 12c-2
b-2 is connected to the scan electrode 12c-2, and the scan electrode 1
2c-1 is not connected. Short bar 1
8a-1 is a scanning electrode 12c-1 formed by an insulating film 17a-1 formed at the left end of the scanning electrode 12c-2 and the Cs electrode 12f.
Is connected to the scanning electrode 12c-2 and the Cs electrode 12f. The short bar 18a-2 is connected to the scan electrode 12c-2 by the insulating film 17a-2 formed on the left end of the scan electrode 12c-1 and the Cs electrode 12f, but is not connected to the scan electrode 12c-1 and the Cs electrode 12f. It is said that.

With the above structure, the inspection can be easily performed by attaching and detaching the four short bars 18a-1, 18a-2, 18b-1, 18b-2.

[0038]

As described above, according to the present invention, the short circuit between the scanning electrodes can be inspected only by detecting the brightness of the entire surface of the liquid crystal display panel, and therefore the inspection can be easily performed.
The inspection time can be shortened, and since the phenomenon that occurs in the liquid crystal display panel due to an actual short circuit is detected, the inspection can be performed with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention.

FIG. 2 is a plan view of an essential part of an embodiment of the present invention.

FIG. 3 is a signal waveform diagram according to an embodiment of the present invention.

FIG. 4 is an equivalent circuit diagram of a main part of an embodiment of the present invention.

FIG. 5 is a diagram for explaining the operation of the embodiment of the present invention.

FIG. 6 is a plan view of an essential part of another embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a liquid crystal display panel.

[Explanation of symbols]

 11 liquid crystal display panel 12 TFT substrate 12a pixel electrode 12b thin film transistor 12c scanning electrode 13 common electrode substrate 13a color filter 13b common electrode 15 liquid crystal

Claims (2)

[Claims] 1. A common electrode substrate (13) on which a common electrode (13b) is formed, a pixel electrode (12a) and the pixel electrode (12a) connected to each other via a switching element (12b). A liquid crystal display panel (11), in which a liquid crystal (15) is sandwiched between a pixel electrode substrate (12) having a plurality of scan electrodes (12c) for applying a voltage to each scan line, and a plurality of the plurality of scan electrodes (12c). In a method of inspecting a liquid crystal display panel for inspecting a short circuit between scan electrodes (12c), drive signals having different phases between odd scan lines and even scan lines are applied to the plurality of scan electrodes (12c) at both ends of each scan electrode. (Ta, Tb) to sequentially turn on the switching elements (12b) to drive the liquid crystal display panel (11), and to drive the liquid crystal display panel (1).
A method for inspecting a liquid crystal display panel, which comprises inspecting the short circuit between the scanning electrodes by detecting the luminance of 1). 2. The both ends (Ta,
Tb) Short bars (18a-1, 18a-2, 1) that connect the odd scan lines and the even scan lines separately to each other.
8. The method for inspecting a liquid crystal display panel according to claim 1, wherein the drive signal is supplied to the scanning electrodes (12c) by 8b-1, 18b-2).