JPH03245125A - Pretreatment for inspecting disconnection of liquid crystal display element - Google Patents

Abstract

PURPOSE:To allow checking of even electrodes having a partial breakage defect by impressing a high voltage between the electrodes of both substrates of a liquid crystal display element before an inspection is made for the disconnection of the electrodes. CONSTITUTION:The high voltage of about 5kV is impressed between the electrodes 3 and 4 of the liquid crystal display element A prior to the disconnection inspection of the electrodes 3, 4. This voltage impression is executed by changing over a charge/discharge changeover switch 12 to a power source 11 side, previously charging a capacitor 13, connecting element connecting cables 14a, 14b respectively to the terminals of the electrodes 3, 4 of the liquid crystal display element A and changing over the charge/discharge changeover switch 12 in this state to an element connecting cable 14a side to instantaneously release the charges charged in the capacitor 13. Thus, the electrodes 3, 4 having the partial breakage defect are checked as the disconnection and all of the liquid crystal display elements A having the possibility of the disconnection of the electrodes 3, 4 by a secular change are discarded as defective elements.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a pretreatment method for inspecting disconnection of liquid crystal display elements.

[Conventional technology]

A liquid crystal display element is a pair of transparent substrates that face each other with a liquid crystal layer in between, and alignment films that align transparent electrodes and liquid crystal molecules for display are formed on the opposing surfaces of each substrate. There are those that display a color image, and those that display a color image by providing a color filter on one substrate surface.

FIG. 2 shows a cross section of a liquid crystal display element that displays a color image. In FIG. 2, 1.2 is a pair of transparent substrates made of glass or the like, the upper substrate 1 has a large number of striped transparent electrodes (signal electrodes) 3 formed thereon, and the lower substrate 2 has an upper substrate 1 formed thereon. A large number of striped transparent electrodes (scanning electrodes) 4 are formed perpendicular to the side electrodes 3 . Also, 5R5
G.

5B, one of the pair of substrates 1.2, for example, the upper substrate 1,
This is a striped color filter of red, green, and blue formed corresponding to each electrode 3 on the upper substrate 1 side,
The color filters 5R15G and 5B are provided below the electrode 3. And this color filter 5R, 5G
, 5B are covered with a transparent protective film (insulating film) 6, and the electrode 3 is formed on this protective film 6. In addition,
In this liquid crystal display element, the electrode 3 is replaced by a color filter 5.
The reason why the color filter is formed on R, 505B is that when the color filter is formed on the electrode (on the liquid crystal layer side), the voltage applied to the electrode 3 will drop at the color filter, and as described above, the voltage applied to the electrode 3 will drop at the color filter. By forming them on the color filters 5R, 5G, and 5B, it is possible to reduce the loss of the applied voltage and apply a high electric field to the liquid crystal layer. Reference numerals 7 and 8 denote alignment films made of polyimide resin or the like formed on the electrode formation surfaces of the pair of substrates 1.2. And this pair of substrates 1,
2 are bonded together via a rod-shaped sealant (not shown) with their electrode forming surfaces facing each other, and both substrates 1
．． A liquid crystal 9 is sealed between the two.

The liquid crystal display element for displaying a black and white image has the same structure as in FIG. 2 except that the color filters 5R, 5G, 5B and their protective film 6 are not provided.

By the way, since a liquid crystal display element is driven to display by applying a display drive voltage between the electrodes on its side substrate surface, if there is a disconnection in any of the electrodes on the side substrate surface, the displayed image may be a defective image. becomes.

This electrode disconnection mainly occurs in the electrode formed on the color filter. That is, the color filters 5R, 5G, 5 in the liquid crystal display element shown in FIG.
The electrode 3 on B is a color filter 5 formed on one surface of the substrate.
After forming a protective film 6 on R, 5G, and 5B, a transparent conductive film such as ITO is applied to the soil of this protective film 6 by sputtering method, and this transparent conductive film is patterned by photoetching method. In this case, the transparent conductive film is sputtered by heating the substrate 1 to about 200°C, so when the substrate is cooled to room temperature, the protective film 6 and the film formed thereon are formed. Due to the difference in coefficient of thermal expansion between the transparent conductive film and the transparent conductive film, cracks occur partially in the transparent conductive film.

When a crack occurs in the transparent conductive film in this way, among the electrodes 3 formed by patterning this transparent conductive film, the electrode formed in the part passing through the crack occurrence point of the transparent conductive film will crack. The electrode will be cut off in some parts.

Note that this cut defect of the electrode 3 becomes even larger due to side etching when patterning the electrode 3.

FIG. 3 shows an electrode 3 with such a cut defect, and the cut defect a of this electrode 3 includes one with a length smaller than the electrode width as shown in FIG. There is a case where the cut defect a extends over the entire width of the electrode as shown in FIG.

Note that cut defects in the electrodes of the liquid crystal display element are caused by electrodes other than the electrodes formed on the color filter (electrode 4 on the lower substrate 2 surface in Figure 2, or on the side substrate surface of the liquid crystal display element that displays a black and white image). In this case, the cutting defects in the electrodes are caused by dirt on the photoresist exposure mask used in patterning the electrodes by photoetching.

When an electrode is disconnected due to such a cut defect, an electric field is not applied to the liquid crystal from the disconnected electrode, so it becomes impossible to control the transmitted light in this area, resulting in a display defect.

For this reason, after manufacturing the liquid crystal display element, the electrodes on both substrates are inspected for disconnections, and only those with no disconnections in any of the electrodes are considered to be non-defective and incorporated into equipment products. This test for disconnection of the electrodes of the liquid crystal display element is generally carried out by displaying a test image on the liquid crystal display element and visually checking the display state.

[Problem to be solved by the invention]

However, in the past, the electrodes of liquid crystal display elements were
If the wire is broken as shown in B), this can be checked by the above-mentioned wire breakage inspection, but if the electrode cut defect a is a partial defect as shown in Figure 3 (A), ,
Since a voltage was applied to the entire electrode, partial breakage defects in this electrode could not be checked by the above-mentioned disconnection inspection.

For this reason, in the past, even if there was a cut defect in the electrode, a liquid crystal display element that was only partially defective was considered to be a good product.
Even if the electrode is partially cut, the cut may progress over a long period of time and eventually cause the electrode to break. Since the element has no reliability over its lifespan, there is a problem in incorporating such a liquid crystal display element into a device product as a non-defective item.The present invention was made in view of these circumstances, and An object of the present invention is to provide a pretreatment method for disconnection inspection of a liquid crystal display element so that electrodes having partial breakage defects can also be checked during disconnection inspection.

[Means to solve the problem]

The present invention provides, prior to inspecting disconnection of electrodes of a liquid crystal display element,
This device is characterized in that a high voltage is applied between the electrodes of the side substrates of this liquid crystal display element.

[For production]

In this way, when a high voltage is applied between the electrodes of a liquid crystal display element, a high voltage is simply applied to the electrode without a cut defect, but when the electrode has a cut defect, electric charge is concentrated on the defective part. Since this cut defect progresses, even in an electrode where the cut defect is only partial, the cut defect can progress to the entire width of the electrode and become disconnected. Therefore, if the electrodes are inspected for disconnection after this pretreatment, all electrodes with breakage defects can be checked as disconnections.
It is possible to exclude all liquid crystal display elements whose electrodes may be disconnected due to aging as defective products.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, A is a liquid crystal display element. Incidentally, since this liquid crystal display element A is the same as that shown in FIG. 2, a description thereof will be omitted by assigning the same reference numerals to the figure. Further, in FIG. 1, 10 is a preprocessing device, and this preprocessing device 10 is connected to a high voltage power source (DC power source) 11 and connected in parallel to this high voltage power source 11 via a charge/discharge changeover switch (manual switch) 12. and two element connection cables 14 for applying voltage to the liquid crystal display element A.
a, 14b, and this cable 14a, 1
One cable 13a of the cable 4b is connected to one electrode of the capacitor 13 via the charge/discharge switch 12, and the other cable 14b is connected to the other electrode of the capacitor 13. Further, 15 is a current adjustment resistor interposed between one cable 14a and the capacitor 13, and the electric charge churned from the high voltage power supply 11 to the capacitor 13 is adjusted to a voltage of about 5KV by the current adjustment resistor 15. The voltage is applied to the liquid crystal display element A.

This pretreatment method involves applying a high voltage of approximately 5 KV between the electrodes 3 and 4 of the liquid crystal display element A, prior to inspecting the electrodes 3 and 4 of the liquid crystal display element A for disconnection. Switch the charge/discharge selector switch 12 to the power supply 11 side, leave the capacitor] 3 on the charger 5', and connect the element connection cable 1.
．． 4a and 14b are electrodes 3 and 4 of liquid crystal display element A, respectively.
This is done by switching the charge/discharge changeover switch 12 to the element connection cable 14a side while the capacitor 13 is connected to the terminal of the capacitor 13, and instantly discharges the charge in the capacitor 13. Note that this voltage application applies to all electrodes 3 and 3 to the liquid crystal display element.
Do this for 4 at the same time.

When a high voltage is applied between the electrodes 3 and 4 of the liquid crystal display element A in this way, the high voltage is simply applied to the electrodes 3 and 4 with no cut defects, but on the electrodes 3 and 4 with cut defects,
Since high-voltage charges are concentrated on the defective portion, the electrode portion around the defective portion is electrochemically destroyed, and the cut defect progresses. Therefore, even in the electrodes 3 and 4, which are partial cut defects as shown in FIG. 3(a), the cut defects can extend over the entire width of the electrode and become disconnected. This is true not only when the cut defect is on one side edge of the electrode as shown in FIG. 3(a), but also when the cut defect is at the center in the width direction of the electrode.

Therefore, after performing this preprocessing, if the disconnection of the electrodes 3 and 4 of the liquid crystal display element A is inspected by a method such as displaying a test hook image on the liquid crystal display element and visually checking the display state, the disconnection can be detected. Since all defective electrodes 34 can be checked as disconnections, electrodes 3.4 due to changes over time can be checked.
All liquid crystal display elements A that are likely to be disconnected can be rejected as defective products.

Note that this preprocessing method is of course applicable not only to liquid crystal display elements in which a color filter is provided on one substrate, but also to the case of performing disconnection inspection on liquid crystal display elements that display black and white images.

〔Effect of the invention〕

According to the present invention, even if an electrode has a partial cut defect, the cut defect can progress to the entire width of the electrode and cause a disconnection. Therefore, the electrode can be inspected for disconnection after being pretreated according to the present invention. For example, electrodes with partial breakage defects can be checked as disconnections, and all liquid crystal display elements in which there is a risk of electrode disconnection due to aging can be excluded as defective products.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of preprocessing showing one embodiment of the present invention, and FIG.
The figure is a cross-sectional view of a liquid crystal display element, and FIG. 3 is a diagram showing a cut defect in an electrode. A...Liquid crystal display element, 1, 2...Substrate, 3, 4...
・Electrode, 5R, 5G, 5B... Color filter, 6・
... Protective film, 7, 8 ... Alignment film, 9 ... Liquid crystal, 10
...Pretreatment device, 11...High voltage power supply, 12...
Charging/discharging switch, 13... Capacitor, 14a,
14b...Element connection cable, 15...Voltage adjustment resistor.

Claims (1)

[Claims] 1. A pretreatment method for inspecting disconnection of a liquid crystal display element, which comprises applying a high voltage between electrodes of both substrates of the liquid crystal display element prior to inspecting an electrode of the liquid crystal display element for disconnection.