JPH06214247A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To decrease problems, such as crosstalks, degradation in contrast or nonuniform display, by providing the lower parts of the drawing around parts of wiring electrodes or pixel electrodes with wiring conductive films which are respectively in contact therewith. CONSTITUTION:The front surface of a substrate 21 is provided with a conductive film and is etched, by which the conductive films 25 acting as light shielding films, the wiring conductive films 30, 31 and lining part of an inspecting electrode 29 are formed. The front surface of the substrate is then provided with an insulating film and is formed by etching to required shapes in such a manner that the wiring conductive films 30, 31 and the lining part of the inspecting electrode 29 are exposed. A transparent conductive film is then provided over the entire surface of the substrate and is etched, by which the wiring electrodes 26, the inspecting electrode 29 and the pixel electrodes 23 are formed. The pixel electrodes 23 are partly lined with the wiring conductive films 31 and the resistance value is decreased by the wiring electrodes 26 and the wiring conductive films 30. Since the inspecting electrode 29 is connected to the conductive film 25, the shorting inspection of the pixel electrodes 23 and the conductive film 25 is thereafter executed at all times by testing the conduction between the respective pixel electrodes 23 and the inspecting electrode 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a liquid crystal display device. In a liquid crystal display device, basically, two substrates on which transparent electrodes (hereinafter, referred to as pixel electrodes) for forming a plurality of pixels are formed, and the surfaces on which the pixel electrodes are formed face each other, and are sealed with a sealing material. Then, a liquid crystal material is injected into this. The structure may be different depending on the mode such as monochrome, color, segment type, matrix type, active type, passive type or TN, STN or other modes, but the present invention is applicable to any of them.
In the following description, STN and passive matrix type monochrome liquid crystal display devices will be described as representatives.

[0002]

2. Description of the Related Art A conventional technique will be described below with reference to the drawings. FIG. 3 is a cross-sectional view showing the structure of a conventional passive matrix array monochrome liquid crystal display device using a chip-on-glass (hereinafter referred to as COG) technique. First substrate 1
The 1st and 2nd board | substrate 21 is sealed by the sealing material 24, and the liquid crystal 14 is inject | poured in this sealing area | region. The spacer 15 regulates the distance between both substrates (hereinafter referred to as the substrate distance). The pixel electrode 13 is provided on the first substrate 11. A conductive film 25 is provided on the second substrate 21, an insulating film 28 is provided on the conductive film 25, and a pixel electrode 23 is provided on the insulating film 28. An alignment film is actually provided on the pixel electrodes 13 and 23, but the illustration is omitted for simplicity. A polarizing plate 1 is provided outside the substrates 11 and 21, respectively.
2, 22 are provided.

The pixel electrodes 13 and 23 are arranged orthogonally to each other in a grid pattern, and the intersections of the two serve as pixels.
The pixel electrode 23 is outside the encapsulant 24, and the driving integrated circuit 40
Of the output terminal 41. The input terminal 42 of the driving integrated circuit 40 is independent of the pixel electrode 23 and
3 is connected to a transparent electrode (hereinafter referred to as a wiring electrode) 26 having the same quality as that of the wiring 3, and the wiring electrode 26 is connected to a wiring member 32 such as a flexible sheet.

The liquid crystal in the pixel portion is applied with a voltage which is the difference between the driving voltages applied to the pixel electrode 13 and the pixel electrode 23, and the liquid crystal changes its state in relation to its effective voltage and participates in display. Since a normal voltage is not applied to the liquid crystal in the parts other than the pixels, it may cause a display inconvenient state and lower the display contrast. There are cases. This film may be either non-conductive or conductive, but a conductive film is often used in consideration of the effect of the light-shielding property and the film thickness on other properties.

FIG. 3 shows a case where the conductive film 25 is used as a light-shielding film. The conductive film 25 is arranged in a non-pixel portion in a portion where pixels are arranged as described above (hereinafter referred to as a display portion). In addition to the above-mentioned structure, it may be extended to a portion other than the display portion as a parting near the sealing material 24 or for the purpose of matching the substrate interval of the sealing portion with that of the display portion. In FIG. 3, the conductive film 25 extends below the sealing material 24 for the purpose of matching the substrate spacing of the sealing portion with the substrate spacing of the display portion, and further, the transparent electrode for adjusting the substrate spacing in the sealing portion of the substrate 11. 1
An example in which 6 is provided will be shown.

[0006] The COG technique described above uses a particularly fine pixel electrode 1
This is effective for the display device having 3, 23. Further, in the display device having such fine pixel electrodes 13 and 23, the effective pixel area tends to decrease and the contrast tends to decrease, and a light shielding film is often required.

[0007]

One of the problems of the COG technique is that the drive integrated circuit 40 is provided on the substrate 21, so that the resistance of the power supply line tends to increase.
That is, the connection resistance between the wiring member 32 and the wiring electrode 26,
The wiring resistance of the wiring electrode 26 itself, the connection resistance between the wiring electrode 26 and the input terminal 42 of the drive integrated circuit 40, etc. are the causes. Among the power supply lines of the drive integrated circuit 40, an increase in the resistance of the power supply lines particularly related to the liquid crystal drive voltage causes the waveform of the drive voltage applied to the liquid crystal to be distorted and deviates from the ideal waveform, resulting in crosstalk and contrast. It causes a decrease.

Further, since the lead-out portions of the pixel electrodes 23 to the integrated circuit 40 are concentrated together in an extremely narrow range,
In this portion, the pixel electrode 23 has an extremely narrow line width and the resistance increases, which also causes crosstalk and contrast reduction. Furthermore, since the lengths of the drawn-out portions of the pixel electrodes 23 are different from each other, the resistance value is not constant, which causes a problem that the display state is not uniform.

The first problem to be solved by the present invention is to reduce the wiring resistance of the wiring electrode 26.
The purpose is to reduce the resistance of the wiring that connects the pixel electrode 23 to the drive integrated circuit 40.

Next, the conductive film 25 used as the light-shielding film is insulated from the pixel electrode 23 by the insulating film 28, but nevertheless, an electrical short circuit often occurs between the conductive film 25 and the pixel electrode 23. , The yield will be significantly reduced. The cause thereof is, for example, a fine pinhole generated in the insulating film 28. Completely eliminating this pinhole is currently very difficult. Another cause is dust.

Due to various causes, the steps in which a short circuit occurs are not the same. If a short circuit already occurs when the pixel electrode 23 is provided on the substrate 21, or if the pixel electrode 23 is pressed during the assembly process with the substrate 11, the liquid crystal 14 is injected into the sealing region. It can be considered that this occurs when the substrates 11 and 21 are pressed to adjust the thickness of the liquid crystal layer.

Of these, a short circuit that occurs after the step of assembling the substrate 11 is often in the vicinity of the sealing material 24 in many cases. That is, as described above, when the substrate spacing of the sealing portion is extended to a portion other than the display portion for the purpose of matching it with that of the display portion, the area of the conductive film 25 in the sealing portion becomes considerably large and the probability of occurrence of short circuit is increased. This is because, in addition to rising, the stress applied to the sealing portion is generally larger than the stress applied to the display portion. Therefore, the second problem to be solved by the present invention is
The problem is to prevent the occurrence of a short circuit in the sealed portion.

When the process of generating a short circuit is expressed in the state of the substrate 21, the state of the substrate on which the pixel electrode 23 is provided, the assembly of the substrate 11 and the empty cell state in which the liquid crystal 14 is not yet injected, and the liquid crystal 14 are Injected and sealed, displayable using inspection jigs, etc., completed state after processes such as polarizing plate adhesion
Can be divided into two. In any case, if the occurrence of a short circuit is detected in the earliest possible process and the outflow to the subsequent process is not prevented, all the subsequent processes will be wasted, resulting in a large loss.

Conventionally, this short-circuit inspection can be performed only in a state where the liquid crystal 14 is injected, and an inspection jig including a polarizing plate and a drive circuit is used to bring the inspection electrodes into contact with the plurality of pixel electrodes 13 and 23, respectively. The scanning drive voltage was applied to the electrode 23 for inspection. By doing so, only the portion of the pixel electrode 23 short-circuited with the conductive film 25 exhibits a display state different from that of the other pixel electrode portions, and the abnormality can be found.

However, when the pixel electrodes 23 are fine, it is difficult to individually contact all the individual pixel electrodes 23 with the inspection electrodes, and it is possible to contact only a part of the electrodes, or a rubber connector or the like. With all pixel electrodes 23
You can only touch the same time.

In such a case, the pixel electrode 1 on the substrate 11
3 is commonly contacted by a rubber connector to be one common electrode, and the pixel electrode 23 of the substrate 21 is commonly contacted by a rubber connector to be the other common electrode. A driving voltage is applied between both common electrodes to drive the liquid crystal. It will be displayed and inspected.

However, in this inspection, the pixel electrodes 23 are not scanned, and the same voltage is applied to all the pixel electrodes 23 at the same time, so that the entire display is the same and it is difficult to detect a short-circuited portion, and the subsequent process is performed. In most cases, the abnormality was discovered only when the normal driving became possible after a certain period of time.

That is, when the COG technique is used, a failure is discovered after the drive integrated circuit 40 is mounted on the substrate 21, and an expensive integrated circuit is wasted, so that the loss is extremely large.

As the simplest method of this short-circuit inspection, in claim 1 and FIG. 1 of Japanese Patent Laid-Open No. 4-271326 (hereinafter referred to as “reference”), the entire display surface except the point where the pixel electrodes 13 and 23 intersect. There has been proposed a liquid crystal display element having a light-shielding mask (hereinafter referred to as a conductive film) 25 formed of a wide metal film and a test electrode drawn out from the conductive film 25. The proposed method is simple,
And certainly, there were the following serious drawbacks.

In the test electrode 29 in the cited invention, the conductive film 25 is extended to the outside of the insulating film 28, and the wiring member 40 is formed.
Since it is exposed at a position different from the installation position of, it is difficult to wire the test electrodes 29 in the completed state of the display device. However, if the test electrode 29 is left open, static electricity generated by various causes is taken into the conductive film 25, and the potential of the conductive film 25 changes independently of the pixel electrode 23. As a result, the state of the liquid crystal is affected. In addition to adversely affecting the display state, electric discharge may occur between the pixel electrode 23 and the conductive film 25 in some cases, damaging the pixel electrode 23.

When the conductive film is a material which is easily oxidized, the exposed portion of the test electrode 29 is oxidized and exhibits an insulating property in the course of repeating the process, and the correct inspection cannot be performed, and the defective product is flown to the completion process. I will end up.

In view of the above problems, a third problem to be solved by the present invention is to prevent alteration of the inspection electrode for inspecting a short circuit between the conductive film 25 and the pixel electrode 23, and to reduce the potential of the inspection electrode. It is to be able to easily control in the completed state of the display device.

[0023]

The first means used by the present invention to solve the above-mentioned first problem is a wiring which is independently in contact with at least a lower portion of the wiring electrode 26 or the leading portion of the pixel electrode 23. It is to provide a conductive film.

Next, the second means used by the present invention to solve the above-mentioned second problem is to extend the wiring conductive film in contact with the lower portion of the pixel electrode 23 into the inside of the sealing material 24, and instead use the pixel electrode. That is, the conductive film 25 on the lower part of 23 is retracted inside the sealing material 24.

The third means used by the present invention to solve the third problem is to provide a transparent electrode (hereinafter referred to as an inspection electrode) which is connected to the conductive film 25 and has the same quality as the wiring electrode 26. Is.

Further, the fourth means of the present invention is to provide a portion 33 having no conductive film for backing in the vicinity of the connecting portion of each transparent electrode, and the fifth means is to connect the inspection electrode to the driving integrated circuit 40. It is common to any of the wiring electrodes 26.

[0027]

According to the first means, the wiring electrode 26 or the leading portion of the pixel electrode 23 is lined with the wiring conductive film, so that the wiring resistance is reduced.

Next, according to the second means, the wiring conductive film in contact with the lower portion of the pixel electrode 23 is extended into the sealing material 24,
Instead, the conductive film 25 under the pixel electrode 23 is retracted to the inside of the encapsulant 24, so that the substrate interval of the encapsulation portion does not change, and the encapsulant 24 is pressed to cause the lower part of the encapsulant 24. Even if the pixel electrode 23 and the wiring conductive film are short-circuited, there is no problem because the wiring conductive film is originally in contact with the pixel electrode 23.

Further, according to the third means, since the inspection electrode 29 is made of the same material as the wiring electrode 26, there is no fear of alteration, the reliable inspection can be performed, and the inspection electrode 29 can be easily connected to the wiring member 32. Since the inspection electrode 29 can be easily connected to a part of the drive circuit when the display device is in use, the problem due to static electricity or the like is solved.

Further, according to the third means, it is needless to say that the inspection can be performed in each process, but the inspection electrode 29 and the wiring electrode 26 or the pixel electrode 23 are formed on the same surface and made of the same material. Since it can be installed in the vicinity, the design of the jig for inspection becomes extremely simple.

According to the fourth means, the state of the connecting portion of each transparent electrode can be visually inspected from the back surface of the substrate 21 through the portion without the conductive film, and the fifth means widens the width of the wiring member. There is no need.

[0032]

Embodiments of the present invention will now be described with reference to the drawings, but the drawings show only the structure of the substrate 21 and do not show the dimensions or the like. The same reference numerals are used for the same reference numerals as those in FIG. Further, in the present invention, the conductive film is different from the transparent electrode film.

FIG. 1 (a) is a plan view of a substrate 21 showing one embodiment of the present invention, and FIG. 1 (b) is AA 'of FIG. 1 (a).
It is a cross-sectional view and FIG. 1C is a BB ′ cross-sectional view. Figure 1
In the above, the first means and the third means of the present invention are carried out at the same time. That is, FIG. 1 (b) shows the implementation of the first means, and FIG. 1 (c) shows the implementation of the third means.

In FIG. 1, after the conductive film is provided on the entire surface of the substrate 21, the conductive film 25, the wiring conductive films 30, 31 and the inspection electrode 2 which act as a light shielding film by etching or the like.
9 backing portions are formed. Next, an insulating film is provided on the entire surface of the substrate, and the wiring conductive film 3 is formed by etching the insulating film.
It is formed so that the backing portions of 0 and 31 and the inspection electrode 29 are exposed and have a required shape. Next, after the transparent electrode film is provided on the entire surface of the substrate, the wiring electrode 26, the inspection electrode 29, and the pixel electrode 23 are formed by etching or the like.

The shape of each transparent electrode and the conductive film for lining it is preferably thicker than each transparent electrode in order to reduce the resistance value of each transparent electrode. You may make it cover with each transparent electrode so that it may not be exposed. FIG. 1 shows a case where the shape of the conductive film for backing is made to match each transparent electrode.

In this state, the wiring electrode 26 becomes the wiring conductive film 30.
As a result, a part of the pixel electrode 23 is lined with the wiring conductive film 31, and the resistance value is reduced. Further, since the inspection electrode 29 is connected to the conductive film 25, the short circuit inspection of the pixel electrode 23 and the conductive film 25 can be always performed thereafter by observing the continuity between each pixel electrode 23 and the inspection electrode 29.

As described above, according to the structure shown in FIG. 1, the inspection electrode 29 can be made to have the same surface and the same material as the pixel electrode 23, so that the inspection jig can be simplified. In FIG. 1A, the inspection electrode 29 has an example in which the width and the pitch are equal to the wiring electrode 26 and is provided at the same position as the wiring electrode 26, but of course the width, pitch and shape may be different. Good or different position. However, it is desirable to provide the wiring member 32 so that it can be easily connected.

After that, an alignment film 27 is provided in a necessary portion, and a rubbing step, an assembling step, an injecting step, etc.
In the G process, the drive integrated circuit 40 is attached and the wiring member 32 is further connected.

The wiring of the wiring member 32 is connected to the wiring electrode 26 and the inspection electrode 29, and the wiring connected to the inspection electrode 29 has a potential on the wiring member 32 or in another device in which the display device is incorporated. It is connected to a part that is not indefinite (preferably, it should represent the reference level of the liquid crystal drive voltage).

In FIG. 1, the integrated circuit 4 of the pixel electrode 23 is shown.
Although the lead-out portion to 0 is shown briefly, actually, the pixel electrodes 23 must be concentrated and gathered in an extremely narrow range. Therefore, in this portion, the pixel electrode 23 has an extremely thin line width and the resistance increases. .

Moreover, since the lengths of the lead-out portions of the respective pixel electrodes 23 are different from each other, the resistance value is not constant, and there is a problem that the display state is not uniform. According to the present invention, these problems can be solved by providing the wiring conductive film 31 also on a part of the pixel electrode 23.

FIG. 2 shows a second embodiment of the present invention.
FIG. 2A is a plan view of the substrate 21, and FIG.
2 is a sectional view taken along line AA ′ of FIG. This embodiment shows the implementation of the second, fourth and fifth means of the present invention in addition to the first embodiment.

The second means will be described with reference to FIG.
As shown in FIG. 3, the wiring conductive film 31 is extended into the sealing material 24, and instead the conductive film 25 under the pixel electrode 23 is retracted to the inside of the sealing material 24. Does not change, and the pixel electrode 23
Even if the wiring conductive film 31 and the wiring conductive film 31 are short-circuited, no problem occurs because the wiring conductive film 31 is separated from the conductive film 25 and individually contacts the individual pixel electrodes 23.

Next, in the case of FIG. 1, the shape of the conductive film for backing was made to match each transparent electrode. In that case, the wiring conductive film 3
When 0 and 31 are opaque, each transparent electrode 26, when the drive integrated circuit 40 is mounted on the substrate 21 by the COG technique,
23 and the respective terminals 41 and 42 of the drive integrated circuit 40, or the transparent member 2 when the wiring member 32 is connected.
It becomes impossible to visually inspect the connection state between 6, 29 and the wiring member 32 from the back surface of the substrate 21. Therefore, as shown in the embodiment of FIG. 2, if a portion 33 without a conductive film for backing is provided near the connection portion of each transparent electrode, the connection state of these can be visually observed. Regarding this point, in FIG.
6 shows the implementation of the inspection electrode 29, the pixel electrode 2
As a matter of course, it is possible to implement No. 3.

Further, in FIG. 2, if the inspection electrode 29 is shared with any of the wiring electrodes 26 connected to the driving integrated circuit 40, it is convenient because it is not necessary to increase the width of the wiring member 32. In this case, the wiring electrode 26 to be shared with the inspection electrode 29 does not necessarily have to be the outermost end.
Further, the wiring electrode 26 to be shared may be a power line or a signal line, but if possible, it is desirable that the wiring electrode 26 represents a reference level of a liquid crystal drive voltage.

The above description of the first and second embodiments of the present invention has been made assuming that the conductive film is a light-shielding film. However, in the present invention, the conductive film (whether transparent or non-transparent) is electrically conductive. It is obvious that it is effective even when it is used for other purposes such as heat rays, and that it is effective even if structural differences such as color panels and liquid crystal modes are different.

Although the above description has been made for the case where the COG technique is carried out, it is effective even when the COG technique is not used. For example, even when the pixel electrode 23 is directly connected to the wiring member 32, it is desirable that the resistance value of the lead-out portion from the portion forming the pixel to the wiring member 32 is as small as possible. By implementing the first means, the resistance value can be lowered, and by using the second means, the short-circuit accident can be reduced.

Further, although the above embodiment shows the case where a plurality of means are carried out at the same time, it is also possible to use only individual means. For example, the first means and the second means use the wiring conductive film 3 even if the conductive film 25 for the purpose of shielding light does not exist.
It can be implemented by providing 0 and 31.

The conductive film 25 and the wiring conductive films 30 and 31 do not necessarily have to be the same, and in order to reduce the resistance, a material having relatively good conductivity should be used. In this case, consideration of adhesion, stability, and the like to form a multilayer structure is naturally included in the present invention.

[0050]

As is apparent from the above description, according to the first means of the present invention, the resistance value of each electrode for lining a part of the wiring electrode 26 or the pixel electrode 23 with the conductive film is set. Therefore, it is possible to reduce problems such as crosstalk, lowering of contrast, and uneven display.

Next, according to the second means, in the substrate 21 having the conductive film 25, the pixel electrode 23 and the conductive film 25 are formed with the height of the sealing material portion and the height of the display portion being the same. The occurrence of short circuit accidents can be reduced.

According to the first and second means, the sealing material 24
Even if the wiring electrode 26 and the pixel electrode 23 are damaged outside the device and the wire is broken, the wiring conductive film 3 is lined.
It is not important because the electrical connection is maintained by 0 and 31.

Further, according to the third means of the present invention, since the inspection electrode 29 connected to the conductive film 25 is of the same quality as the wiring electrode 26, it is possible to eliminate the risk of defective inspection due to the alteration of the inspection electrode 29. Since the inspection in the process can be easily performed using a simple jig and can be easily connected to the wiring member 32, it is possible to easily apply a non-constant electric potential to the inspection electrode 29, so that an accident due to static electricity can be prevented. I can do things.

The fourth means enables visual inspection of the connection state of each transparent electrode in the practice of the first and second means of the present invention, and the fifth means changes the size of the wiring member 32. Since it is not given, conventional members can be used as they are.

As described above, the present invention greatly solves the serious problems of the prior art and contributes to provide a liquid crystal display device with high display quality and reliability.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, in which FIG.
2A is a plan view of the first embodiment of the present invention, and FIG. 7B is a cross-sectional view of the first means of the present invention, and FIG.

2A and 2B are views showing another embodiment of the present invention, in which FIG. 2A is a plan view of a substrate 21 and FIG. 2B is a sectional view taken along the line AA ′, showing an implementation of the second means.

FIG. 3 is a cross-sectional view of a liquid crystal display device having a conventional conductive film and using COG technology.

[Explanation of symbols]

 21 Substrate 23 Pixel Electrode 25 Conductive Film 28 Insulating Film 29 Inspection Electrode 30 Wiring Conductive Film 31 Wiring Conductive Film 32 Wiring Member

Claims (6)

[Claims] 1. A liquid crystal display device characterized in that a wiring electrode having the same quality as the pixel electrode and separated from the pixel electrode is in contact with a conductive film provided on a substrate. 2. A liquid crystal display device, wherein the pixel electrode is in contact with a conductive film provided on a substrate, at least outside the sealing material. 3. The liquid crystal display device according to claim 2, wherein the pixel electrode is in contact with the conductive film provided on the substrate in the sealing portion. 4. A liquid crystal display device comprising one or more wiring electrodes which are connected to a conductive film provided on the substrate inside the encapsulating material and which are of the same quality as the pixel electrodes and are separated from the pixel electrodes. 5. A wiring electrode, which is connected to a conductive film provided on the substrate inside the encapsulating material, and which is of the same quality as the pixel electrode and is separated from the pixel electrode is connected to a portion having a non-constant potential outside the substrate. The liquid crystal display device according to claim 4, wherein the liquid crystal display device is provided. 6. The method according to claim 1, wherein a portion where the conductive film is not in contact is provided in a portion where the wiring electrode or the pixel electrode is connected to another member. Liquid crystal display device.