JP2000258782A - Production of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly cut a plastic transparent electrode substrate in a good state without producing cracks in a surface hardened layer. SOLUTION: When a plastic mother substrate having a surface hardened layer such as a hard coating layer and an oxygen barrier coating layer is cut into a specified size to obtain a liquid crystal display element in the production process, reinforcing dummy seals 5 are formed on the outside of each corner of a peripheral seal 3. The cutting grooves are formed to pass over the reinforcing dummy seals 5 to cut the plastic substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly to a technique for designing and cutting a seal for a display device cell using a plastic substrate as a transparent electrode substrate.

[0002]

2. Description of the Related Art In a liquid crystal display device, a pair of substrates having a transparent electrode formed on one surface is pressure-bonded with the transparent electrode forming surfaces facing each other with a peripheral seal interposed therebetween. It is constituted by injecting a display active substance such as a liquid crystal into a cell gap between the substrates.

When actually manufacturing a liquid crystal display element, a plurality of display element cells are formed at a time on a so-called mother substrate (multi-substrate) in consideration of productivity, and then the mother substrate is mounted on the display element. Each of the display cells is divided along a column or a row into a stick substrate. After a display active substance is injected into each display element cell, individual liquid crystal display elements are cut out from the stick substrate.

Thus, by the time the final product is obtained,
For example, the substrate is cut twice, but when the substrate is a glass substrate, the glass substrate is fixed to a cutting table, and a marking line is drawn with a carbide wheel cutter or the like to relatively easily cut or cut. Can be divided.

However, in the case of a glass substrate, not only is there a drawback that the glass substrate is easily broken when housed in a thin case such as a pocket calculator, but in the case of a reflection type, if the substrate is thick, the display surface and the display surface will not be formed. A double image will occur on the reflecting surface. In order to prevent this, for example, the thickness of the substrate may be reduced. However, as the thickness of the glass substrate decreases, the price increases and the glass substrate is more easily broken.

On the other hand, a plastic substrate is advantageous in that it is less likely to break and is lighter than a glass substrate, but a plastic substrate is more flexible and easier than a glass substrate. However, the method of cutting a glass substrate cannot be applied as it is due to its property of being difficult to break.

A plastic substrate for a liquid crystal display element can be made of either a thermoplastic resin or a thermosetting resin. Typical examples of the thermoplastic resin include polyethylene terephthalate and polyether. There are sulfone, polycarbonate, and the like, and thermosetting resins include acrylic and epoxy resins.

[0008]

Therefore, in order to cut the plastic substrate, the cutting of the mother substrate into the stick substrate and the cutting of the stick substrate into the individual liquid crystal display elements are performed first. Along the line, e.g.
A cut groove is formed at a depth of ~ 95% (so-called half cut), and then the remaining uncut portion of 50-5% is cut off, that is, forcedly bent or torn. There were challenges.

That is, a plastic substrate for a liquid crystal display element includes, for example, an acrylic hard coat layer for improving chemical resistance and an oxygen barrier coat layer made of an organic or inorganic material for preventing oxygen permeability. A surface hardened layer is formed on which is formed, for example, ITO (In)
A transparent electrode made of Dn Tin Oxide is formed.

[0010] This type of surface hardened layer is harder and easier to crack than a plastic substrate. Therefore, excessive stress is applied to the peripheral seal and the plastic substrate when the cut groove is formed or when the uncut portion is separated, and cracks are particularly generated in the hard coat layer and the oxygen barrier coat layer of the hardened surface layer during the sealing. May occur. Once such cracks occur, the cracks progress further,
The life of the liquid crystal display element may be shortened.

If the plastic substrate is completely cut at once instead of half-cutting, the above-described crack generation rate is reduced, but the gap between the substrates is extremely small, so that the mating substrate is damaged. It is virtually impossible to cut without cutting.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a first object of the present invention is to cut a plastic substrate serving as a transparent electrode substrate by half-cutting. It is another object of the present invention to provide a method of manufacturing a liquid crystal display element in which an excessive stress is not applied at the time of sealing the periphery, so that a crack is not generated in a surface hardened layer or the like.

It is a second object of the present invention to provide a method of manufacturing a liquid crystal display element in which liquid crystal does not crawl on a terminal portion when liquid crystal is injected into each cell in a stick substrate state. It is in.

According to the present invention, the first object is to allocate a plurality of cell forming regions in a predetermined arrangement to each of a first mother substrate and a second mother substrate formed of a plastic substrate having a surface hardened layer. After forming display electrodes on the display portion of each cell formation region, a peripheral seal is applied in a square frame shape having a liquid crystal injection hole on one side around each display portion on one of the mother substrates. After the first and second mother substrates are pressure-bonded through the peripheral seal to form a plurality of display element cells simultaneously, cut grooves having a predetermined depth are formed along the outline of each display element cell. Then, by forcibly cutting off the cut groove portion, each mother substrate is divided into a stick substrate, and an injection hole for injecting liquid crystal into each display element cell, and each display is formed from the stick substrate. In the method of manufacturing a liquid crystal display element in which a terminal portion of a child cell is provided, when the peripheral seal is applied to the one mother substrate side, reinforcing dummy seals are provided at four locations outside each corner of the mother substrate. This is achieved by applying a coating so as to be connected to the peripheral seal after crimping, and inserting the cut groove so as to pass over the reinforcing dummy seal when performing the injection hole and the terminal section.

As described above, by providing the reinforcing dummy seal at each corner of the peripheral seal, the two mother boards are more firmly connected to each other, and the reinforcing dummy seal acts as a kind of support. This means that the fulcrum of the stress at the time of division becomes the reinforcing dummy seal portion, and the stress applied at the time of peripheral sealing is suppressed, thereby preventing the occurrence of cracks at the time of sealing.

[0016] In addition, when the cut groove is formed in the plastic substrate relatively softly, the uncut amount tends to vary. However, by inserting the cut groove so as to pass over the reinforcing dummy seal, the uncut amount is stabilized. Become.
Therefore, stress at the time of cutting does not concentrate locally.

In the present invention, the adhesion area of the reinforcing dummy seal to the mother substrate before the substrate compression bonding is 2.5 to 5.0 after the substrate compression bonding.
Preferably it is twice. More preferably, 3.5 to 4.
5 times.

If the ratio is less than 2.5 times, the bonding area (adhesive strength) is insufficient, and a reinforcing effect cannot be expected. On the other hand, if it exceeds 5.0 times, the adhesive force of the reinforcing dummy seal becomes too large, and stress is generated when the cut groove portion is forcibly torn, which is not preferable.

In the case where a terminal portion is set in the cell forming region adjacent to the display portion and an extraction electrode is formed in the terminal portion, the terminal portion between the display element cells included in the same stick substrate row is provided. The second object is achieved by providing a liquid crystal creep-up prevention seal for preventing liquid crystal from creeping up to the terminal portion between adjacent reinforcing dummy seals on the liquid crystal injection hole side.

When the peripheral seal is applied to one of the mother substrates, the liquid crystal creep-up prevention seal is applied together with the reinforcing dummy seals so as to be connected between the reinforcing dummy seals after compression bonding of each mother substrate.

The seal for preventing the liquid crystal from climbing up is formed along a cut line for the stick substrate, and a cut groove is formed thereon. That is, when the stick substrate is cut from the mother substrate, the cut grooves are formed as one line passing on the reinforcing dummy seal and the liquid crystal creep-up prevention seal.

Incidentally, also in the present invention, the cut grooves are
Carbide wheel cutter, circular rolling cutter, normal cutter blade, dicer cutting, laser cutting or die cutting method may be formed by a commonly used method, but according to the present invention, the reinforcing seal In the most preferable embodiment, the uncut amount of the cut groove is 7
Even at 0%, no cracking is observed at the time of the subsequent division.

[0023]

Next, the present invention will be described more specifically with reference to the drawings.

First, a pair of mother substrates are prepared.
FIG. 1 is a plan view showing a chamfered state of one of the mother substrates 1A, and FIG.
A cross-sectional view of a main part in a state where the other mother substrate 1B is overlapped is shown above.

Each of the mother substrates 1A and 1B is made of a plastic substrate such as polycarbonate. Although not shown, each of the surfaces is provided with an acrylic hard coat layer and an oxygen permeable layer to improve chemical resistance. A surface hardened layer composed of an organic or inorganic material and an oxygen barrier coat layer for preventing the formation of the surface is formed. For liquid crystal display devices, the substrate thickness is usually 0.1 to 0.4 m
m are selected.

According to this embodiment, one mother substrate 1
A is the rear panel (R plate) side, and the other mother substrate 1B is the front panel (F plate) side.
Cell formation regions 2 are assigned to each of A and 1B in an arrangement of two rows vertically and three rows horizontally. That is, each mother substrate 1A, 1B is a multi-substrate with six chamfers.

In the motherboard 1A on the rear panel side,
In each cell formation region 2, a display unit 21 and a terminal unit 22 are set, and although not shown, display electrodes made of, for example, ITO are formed in the display unit 21 in a predetermined pattern. Also, a lead electrode group 221 made of ITO is formed on the terminal portion 22.

On the other hand, although not shown, display electrodes made of, for example, ITO are also formed in a predetermined pattern on the display portion of each cell formation region of the mother substrate 1B on the front panel side. In this embodiment, the mother substrate 1
Although no terminal section is provided on the B side, the display section 21 of the mother board 1A and the display section of the mother board 1B correspond in a positional relationship of 1: 1. Each of these ITO patterns is formed on the hardened surface layer.

When bonding the mother substrates 1A and 1B, a sealing material is applied to one of them by, for example, a screen printing method. In this embodiment, as shown in FIG. Mother board 1
A is coated with a sealing material.

That is, the motherboard 1A on the rear panel side
The peripheral seal 3 is applied in a rectangular frame shape along the outline of each display section 21 of FIG. In this case, a liquid crystal injection hole 31 is provided at the center of one side of each peripheral seal 3 in FIG.

In this embodiment, the mother substrates 1A,
Since 1B is a plastic substrate, it can be used for maintaining the distance between the substrates along the four sides of each cell formation region 2 from the viewpoint of securing the workability at the time of cutting and the gap width between the mother substrates 1A and 1B. The spacer seal 4 is applied simultaneously with the peripheral seal 3.

According to the present invention, when the peripheral seal 3 is applied to the mother substrate 1A on the rear panel side as described above, at the same time, the reinforcing dummy seals 5 are applied to the four outer sides of each corner of the peripheral seal 3. In order to clarify this point, FIG. 3 shows one cell formation region 2 in an enlarged manner.

Here, of the cut lines for cutting the stick substrate from the mother substrate, the cut line on the liquid crystal injection hole 31 side is S1, the cut line on the opposite side is S2, and the individual liquid crystal panels are cut from the stick substrate. Out of the cut lines for cutting out the terminal part, the cut line for extracting the terminal portion to be put on the front panel side (mother board 1B side) is T1, and the cut line for separating the panel that is put in the same position with respect to the front panel and the rear panel T2, a cut line cut along the edge of the terminal portion 22 of the rear panel is T3.

Each of the reinforcing dummy seals 5 is connected to a corner of the peripheral seal 3, and is provided with cutting lines S1 and S2 for cutting the stick substrate and cutting lines T1 and T for cutting the panel.
2 so as to cover each intersection. The shape is not particularly limited, such as an ellipse, a circle, and a bar (square shape), but an ellipse is preferred if it is used.

Further, according to the present invention, the liquid crystal crawling prevention seal 6 for preventing the liquid crystal from crawling to the terminal portion 22 at the time of liquid crystal injection is provided on the motherboard 1A on the rear panel side together with the peripheral seal 3 and the reinforcing dummy seal 5. It is applied at the same time.

That is, as shown in FIG. 3, the liquid crystal creeping up prevention seal 6 is provided between two display element cells included in the same stick substrate row on the side of the liquid crystal injection hole 31 as shown in FIG. Dummy seal 5 (A),
5 (B) are arranged along the cutting line S1 for cutting out the stick substrate.

For the peripheral seal 3, the spacer seal 4, the reinforcing dummy seal 5, and the liquid crystal crawling prevention seal 6, for example, an epoxy resin is used. These seals 3 to 6 are crushed and spread when the mother substrates 1A and 1B are pressed.

Here, assuming that the ratio of the adhesion (application) area of the sealing material to the mother substrate before the substrate compression bonding and the bonding area after the substrate compression is the sealing magnification, as for the reinforcing dummy seal 5, the sealing magnification. Is 2.5 to 5.0
Preferably it is twice. More preferably, 3.5 to 4.
It is good to be 5 times.

That is, if the sealing magnification of the reinforcing dummy seal 5 is less than 2.5 times, the bonding area (adhesive strength) is insufficient and the reinforcing effect cannot be expected. On the other hand, if it exceeds 5.0 times, on the contrary, the adhesive force of the reinforcing dummy seal 5 becomes too large, and stress is generated when the cut groove portion is forcibly cut (teared), which is not preferable.

For reference, FIG. 4 shows a state of application of each of the seals 3 to 6 before the substrate is pressed, and FIG. 5 shows a state in which each of the seals 3 to 6 is expanded 4.2 times by the substrate compression. Thus, each of the seals 3 to 6 is connected in series by the pressure bonding of the substrate.

Each mother board 1A, 1B is attached to each of the seals 3-6.
After forming the six display element cells at the same time by pressing through a substrate, along a cutting line S1, S2 for cutting out the stick substrate by a carbide wheel or the like, for example, the substrate thickness of 50 to 50
Cut grooves with a depth of up to 95%. In this case, since the cut groove passes over each reinforcing dummy seal 5, the uncut amount can be made substantially constant.

Thereafter, the cut groove is forcibly bent or torn, whereby the mother substrate 1 is cut.
The stick substrate is separated from A and 1B. According to the present invention, since the mother substrates 1A and 1B are firmly connected by the reinforcing dummy seal 5, even at the time of this division,
The stress applied at the time of peripheral sealing is suppressed, and the occurrence of cracks at the peripheral seal 3 is prevented.

Next, liquid crystal is injected into each display element cell in the state of the stick substrate. This liquid crystal injection is performed by immersing the liquid crystal injection hole 31 side in a liquid crystal bath. According to the present invention, the liquid crystal injection hole 31 of the terminal portion 22 is formed.
Since the liquid crystal creep-up prevention seal 6 is provided on the side, the liquid crystal does not creep up to the terminal portion 22.

A notch is formed on the seal 6 for preventing the liquid crystal from rising, and the stick substrate is separated from the mother substrate.
In FIG. 5, it is necessary to set the width of the liquid crystal crawling prevention seal 6 so that the right half is left on the stick substrate side.

After injecting the liquid crystal, as shown in FIG.
Cutting lines T1 to T3 for cutting out panels on a stick substrate
As in the case of the stick substrate described above, a notch groove having a predetermined depth is formed so as to pass over the reinforcing dummy seal 5, and then each liquid crystal panel is divided by forcible bending or tearing. Therefore, even at the time of this division, there is no possibility that cracks will occur near the peripheral seal 3.

[0046]

Example: 0.4 m thick made of polycarbonate resin
m plastic substrate was prepared, and a hard coat layer (thickness 5.0 μm) made of an acrylic resin and an oxygen barrier coat layer (thickness 0.1 μm) made of silicon oxide were formed on the surface of the plastic substrate to form a mother substrate. . Next, a peripheral seal was formed on one mother substrate with a sealing material made of epoxy resin, and a reinforcing dummy seal was formed outside each corner thereof. In addition, the reinforcing dummy seal has a sealing magnification of 4.0 times after press-bonding the substrate.
It was designed to have an elliptical shape of 4 mm and short axis of 2.0 mm. The other mother substrate was pressure-bonded to the mother substrate so that the cell gap became 6.0 μm, thereby forming a display element cell. Then, the uncut amount is set to 40% of the thickness of the plastic substrate and 5% by a normal cutter blade so as to pass over the reinforcing dummy seal along the outline of the display element cell.
Cut grooves were made at 0%, 60%, and 70%, and cut by forced bending. As a result, the uncut amount is 70
%, No cracking was observed at the time of peripheral sealing. By the way, when the reinforcing dummy seal is not provided,
Cracks occurred when the uncut amount was 60%.

[0047]

As described above, according to the present invention,
When using a plastic substrate having a hardened layer such as a hard coat layer or an oxygen barrier coat layer, a reinforcing dummy seal is formed outside each corner of the peripheral seal, and a cut groove is formed so as to pass over the reinforcing dummy seal. By separating the substrate, when cutting out the stick substrate from the mother substrate, and when cutting out individual liquid crystal display elements from the stick substrate, it is possible to smoothly and smoothly generate cracks in the surface hardened layer. The substrate can be cut cleanly.

Further, according to the present invention, the work margin of the uncut amount is widened, the work management width at the time of cutting and cutting is expanded, the work management is facilitated, and the initial quality is maintained for a long time in terms of display quality. Is done.

On the other hand, between the display element cells included in the same stick substrate row, between the reinforcing dummy seals adjacent to the liquid crystal injection hole side, a liquid crystal creep-up prevention seal is provided, so that the liquid crystal at the time of liquid crystal injection is filled. Crawling to the terminal portion side can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a plan view showing one chamfered state of a mother substrate used in an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part of a mother board pressed through a seal.

FIG. 3 is an enlarged plan view showing one cell formation region from FIG. 1;

FIG. 4 is a plan view showing an application pattern of each seal before the substrate is pressed.

FIG. 5 is a plan view showing each seal shape after pressure bonding of the substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1A, 1B Mother substrate 2 Cell formation area 21 Display part 22 Terminal part 221 Leader electrode group 3 Peripheral seal 31 Liquid crystal injection hole 4 Spacer seal 5 Reinforcement dummy seal 6 Liquid crystal rise prevention seal

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 FA06 FA07 FA10 FA26 2H089 LA42 LA46 MA04Y NA24 NA28 NA39 NA55 NA58 PA15 QA04 QA12 SA17 TA01 2H090 JA07 JB03 JC01 LA02 LA03

Claims (3)

[Claims] 1. A plurality of cell formation regions are allocated to each of a first and a second mother substrate formed of a plastic substrate on which a surface hardened layer is formed, with a predetermined arrangement,
After forming display electrodes on the display section of each cell formation area,
A peripheral seal is applied in a rectangular frame shape having a liquid crystal injection hole on one side around each display section on one of the mother substrates, and the first and second mother substrates are crimped through the peripheral seal. After simultaneously forming a plurality of display element cells, a notch groove having a predetermined depth is formed along the outline of each display element cell, and then the notch groove portion is forcibly cut off, thereby forming each of the mother devices. A method for manufacturing a liquid crystal display element, in which a substrate is divided into a stick substrate and an injection hole for injecting liquid crystal into each display element cell, and a terminal portion of each display element cell from the stick substrate, is provided. When the seal is applied to the one mother substrate side, a reinforcing dummy seal is applied to four places outside each corner so as to be connected to the peripheral seal after the mother substrate is pressed. A method for manufacturing a liquid crystal display element, wherein the incision is made to pass over the reinforcing dummy seal when the injection hole and the terminal are exposed. 2. The liquid crystal according to claim 1, wherein the bonding area of the reinforcing dummy seal to the mother substrate before the substrate compression bonding is 2.5 to 5.0 times the bonding area after the substrate compression bonding. A method for manufacturing a display element. 3. In a case where a terminal portion is set in the cell formation region adjacent to the display portion and an extraction electrode is formed in the terminal portion, the display device cells are included between the display element cells included in the same stick substrate row. 3. The liquid crystal display element according to claim 1, wherein a liquid crystal creep-up prevention seal for preventing liquid crystal from creeping up to the terminal portion is provided between the reinforcing dummy seals adjacent on the liquid crystal injection hole side. Production method.