JPH08106101A - Liquid crystal display panel manufacturing method - Google Patents

Abstract

(57) [Abstract] [Purpose] A method of manufacturing a liquid crystal display panel, in which a liquid crystal material is dropped on a substrate and the liquid crystal material is sealed between opposing substrates, and a liquid crystal is sealed between the substrates by a vacuum dropping method. When doing so, distribute the spacers evenly over the entire liquid crystal panel to prevent sealing failure. A maximum diameter of a spacer 5 attached and fixed between a pair of substrates 1 and 4 is at least 0.2 to 0.6 μm smaller than a thickness of a liquid crystal layer sandwiched between the substrates 1 and 4,
In addition, the spacer 5 is covered with an adhesive, and the viscosity of the sealing material 2 for sealing the liquid crystal is set to 50000 cp or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display panel, and more particularly, to manufacturing a liquid crystal display panel in which a liquid crystal material is dropped on a substrate and the liquid crystal material is sealed between opposed substrates. Regarding the method.

[0002]

2. Description of the Related Art Liquid crystal display devices are widely used as display devices because of their thinness, light weight, and low power consumption. A liquid crystal panel for displaying characters and images, which is a main part of a liquid crystal display device, has a first substrate on which a transparent electrode is formed and a second substrate on which a driving circuit such as a TFT is formed. A liquid crystal material is enclosed between the substrates.

As a method of enclosing the liquid crystal between a pair of substrates, there are, for example, a vacuum injection method and a vacuum dropping injection method. In the vacuum injection method, an empty cell is formed by stacking two substrates at a predetermined interval with a frame-shaped sealing member having an opening part in between.
Put this empty cell in the chamber to reduce the pressure inside,
Then, immersing the opening of the empty cell in the liquid crystal material, and then introducing nitrogen or the like into the chamber to increase the pressure inside the chamber, the liquid crystal material becomes empty due to the difference between the internal pressure of the empty cell and the pressure inside the chamber. It is sucked and filled in the cell. For example, it is proposed in JP-A-62-89025.

However, according to this method, it takes a long time to exhaust the inside of the chamber to a vacuum when a large-sized liquid crystal panel is manufactured. In addition, a large amount of liquid crystal material is required to immerse the empty cell, which increases the cost. Further, it takes time and effort to seal the opening after the liquid crystal is sealed and to clean the liquid crystal attached around the opening. On the other hand, the vacuum drop injection method has many advantages. FIG. 6 is a perspective view schematically showing a liquid crystal sealing process in the vacuum dropping injection method,
FIGS. 6A to 6C show respective steps.

In FIG. 6A, a sealing material 22 made of a photo-curing resin is attached in a frame shape on a first substrate 21 on which pixel electrodes, TFT elements, an alignment film and the like are formed. Liquid crystal 23 is dropped inside the frame of the sealing material 22.
A transparent electrode and an alignment film are also formed on the second substrate 24, and the surface on the transparent electrode formation side faces the pixel electrode formation surface of the first substrate 21. Spacers (not shown) are uniformly dispersed on the alignment film of the second substrate 24. The spacers are substantially spherical fine particles made of a resin and having a diameter of several μm, and when the first and second substrates 21 and 24 are bonded together, a gap between the substrates 21 and 24 is formed over the entire panel. Used to even out across.

Next, as shown in FIG. 6 (b), a second substrate 24 having spacers attached thereto is superposed on the first substrate 21 on which the liquid crystal 23 has been dropped in a vacuum. And the sealing material 22
Contact the second substrate 24, and the first and second substrates 21, 2
When a closed space is formed by the frame of the sealing material 22 between the four, when the pressure is changed from vacuum to atmospheric pressure, the first and second substrates 21 and 24 are attracted by the pressure difference inside and outside the cell. At this time, the first and second electrode substrates 21, 2
As the interval of 4 becomes narrower, the liquid crystal 23 spreads laterally between the first and second substrates 21 and 24.

As a result, as shown in FIG. 6 (c), the liquid crystal 23 is completely filled in the frame of the seal material 22 between the first and second substrates 21 and 24. Here, the gap between the first and second substrates 21 and 24 is made uniform over the entire panel by the spacer. Further, at this point, realignment for precisely aligning the mutual positions of the first and second substrates 21 and 24 at the pixel level is performed. This is done by moving the first substrate 21 or the second substrate 24 laterally. After the realignment is completed, the sealing material 22 is cured by irradiating with ultraviolet rays, and the sealing of the liquid crystal is completed.

[0008]

However, the manufacturing method of such a liquid crystal display panel has the following problems. First, when the liquid crystal is dropped on one of the substrates and the two substrates are bonded together, a rapid flow of the liquid crystal occurs between the two substrates. For this reason, the spacers that have been uniformly attached in advance may move due to a sudden flow of liquid crystal and spread radially from the center of the panel to be biased in an annular shape or biased near the sealing material at the end of the panel. When the spacer distribution becomes uneven in this way, the gap between the substrates on the panel surface becomes non-uniform and the performance of the liquid crystal panel may be deteriorated.

Further, depending on the relationship between the diameter of the spacer and the thickness of the gap between the substrates, the spacer and the substrate surface may contact with each other more than necessary. Therefore, when the substrate is moved for realignment, the spacer may come into strong contact with the surface of the substrate to damage the alignment film or the electrode film, or hinder the movement of the substrate. Moreover, when the liquid crystal is filled in the cells between the substrates, the pressure difference between the inside and the outside of the frame of the sealing member is used, but at the time of filling, the sealing member is still in an uncured and soft state. Therefore, the pressure may cause cracks in the sealing member, resulting in defective sealing.

FIG. 7 shows a liquid crystal display panel in which such a sealing defect has occurred. Two kinds of cracks 22a and 22b are generated in the sealing member 22 sandwiched between the first and second substrates 21 and 24. ing. One of the cracks 22a is generated by the pressure of the atmosphere working from the outside to the inside of the frame of the sealing member 22 when the inside of the frame of the sealing member 22 is in vacuum. The other crack 22b is a liquid crystal material 23 that works from the inside to the outside of the frame 22.
It is often caused by the pressure of the liquid or the compatibility of the liquid crystal and the sealant. When such cracks 22a and 22b are formed in the sealing member 22, the liquid crystal material leaks from the cell or air enters the cell, which deteriorates the display characteristics of the liquid crystal display panel.

Contamination of the liquid crystal is one of the factors related to the display performance of the liquid crystal display panel. The contamination of the liquid crystal can be obtained by measuring the voltage holding ratio between the counter electrodes sandwiching the liquid crystal. The higher the voltage holding ratio, the higher the ability to maintain the potential difference between the counter electrodes and the higher the ability to drive the liquid crystal. The graph of FIG. 8 shows changes in the voltage holding ratio with time of irradiation of ultraviolet rays for curing the sealing member, which were measured at the center and the edge of the liquid crystal display panel. In this graph, the horizontal axis represents the ultraviolet irradiation time and the vertical axis represents the voltage holding ratio of the liquid crystal. In the graph line, A is the center of the display panel and B is the vicinity of the sealing member of the display panel. As you can see from this graph,
The voltage holding ratio of the liquid crystal in the central part of the liquid crystal display panel hardly changes even when irradiated with ultraviolet rays for a long time, but the voltage holding ratio of the liquid crystal near the sealing member of the liquid crystal display panel decreases as the ultraviolet irradiation time increases. There is. The UV irradiation conditions were within the range of the manufacturer's recommended conditions.

This is because when the liquid crystal in the vicinity of the sealing member is irradiated with ultraviolet rays, the liquid crystal and the sealing member react with each other, and the reaction product dissolves in the liquid crystal and contaminates the liquid crystal. Although this liquid crystal contamination occurs near the sealing member, it spreads over time and deteriorates the performance of the entire liquid crystal display panel. The present invention has been made in view of the above conventional problems, and when the liquid crystal is sealed between the substrates by a vacuum dropping injection method, the spacers are uniformly distributed over the entire liquid crystal panel. (EN) A method for manufacturing a liquid crystal display panel, in which the gaps between the liquid crystal display panels are made uniform to improve the display performance of the liquid crystal display panel, the substrate surface is prevented from being damaged by spacers, and the substrate for realignment is easily moved. To aim.

Further, according to the present invention, when the liquid crystal is sealed between the substrates by the vacuum dropping injection method, the sealing failure due to the cracking of the sealing member can be prevented, and the yield of the liquid crystal display panel can be improved. An object is to provide a method for manufacturing a liquid crystal display panel. A further object of the present invention is to provide a method for manufacturing a liquid crystal display panel, which can reduce liquid crystal contamination caused by irradiation of ultraviolet rays for curing a sealing member and improve the display performance of the liquid crystal display panel.

[0014]

As illustrated in FIG. 1, the above-mentioned problems include a step of applying a sealing material 2 in a frame shape on a surface of at least one of the pair of substrates 1 and 4 on which an electrode is formed, The thickness of the liquid crystal layer to be formed and controlled between the pair of substrates 1 and 4 is 0.2 to 0.6 μm or 4 to 1
Fine particles 5 having a diameter smaller than 2% are formed on the pair of substrates 1, 4
A step of adhering and fixing to one surface of the electrode forming side, a step of dropping the liquid crystal material 3 on the surface of the electrode forming side surrounded by the sealing material 2, the pair of substrates 1, Four
The surfaces on which the electrodes are formed face each other and are superposed on each other under reduced pressure, and the liquid crystal material 3 is spread to expand the pair of substrates 1 and 4.
And a step of forming the liquid crystal layer between the two.

Alternatively, the fine particles are covered with an adhesive and fixed to the surface on the one electrode forming side, which is solved by the method for manufacturing a liquid crystal display panel. Alternatively, a step of applying a seal material 2 having a viscosity of 50,000 cp or more in a frame shape on at least one of the pair of substrates 1 and 4 on the electrode formation side, and the surface on the electrode formation side surrounded by the seal material 2. The step of dropping the liquid crystal material 3 on the substrate and the surfaces of the pair of substrates 1 and 4 on the side where the electrodes are formed face each other and are superposed under reduced pressure, and the liquid crystal material 3 is spread to spread the liquid crystal material 3 on the pair of substrates 1 and 4. And a step of forming the liquid crystal layer in between, which is solved by a method for manufacturing a liquid crystal display panel.

Alternatively, at least one of the pair of substrates 1 and 4 has a frame 2 made of a sealing material 21 on the surface on which the electrodes are formed.
a) and 2b are formed at least twice along the surface, and a step of dropping the liquid crystal material 3 into the innermost frame 2a of the sealing material on the electrode formation side of the substrates 1 and 4, And forming a liquid crystal layer between the pair of substrates 1 and 4 by spreading the liquid crystal material 3 so that the surfaces of the pair of substrates 1 and 4 on the side where the electrodes are formed face each other and overlap each other under reduced pressure. This is achieved by a method of manufacturing a liquid crystal display panel characterized by having.

Alternatively, after sealing the liquid crystal material 3,
The liquid crystal display panel manufacturing method is characterized in that at least one of the pair of substrates 1 and 4 is cut off while leaving at least the innermost side of the frames 2a and 2b made of the sealing material. Alternatively, as illustrated in FIGS. 1 and 3, at least one of the pair of substrates 1 and 4 is coated with a frame made of a photo-curing sealing material 2 on the surface on which the electrodes are formed, and the inside of the frame is coated. A step of disposing a light shielding means 8 in the vicinity and dropping the liquid crystal material 3 on the surface of the electrode forming side surrounded by the frame made of the sealing material 2, and the pair of substrates 1, 4
Of the liquid crystal display panel, comprising: a step of facing the respective electrodes forming surfaces to each other and superposing them under reduced pressure; and a step of irradiating the sealing material 2 with light to cure the sealing material 2. It is solved by the manufacturing method.

Alternatively, as illustrated in FIG. 2 (a), a liquid crystal material container 11 having a liquid crystal supply hole 13 on the lower side and having a constant internal pressure, and a liquid crystal material container 11 disposed inside the liquid crystal material container 11. The liquid crystal material 3 is dropped by using a dispenser having a needle 14 that opens and closes the liquid crystal supply hole 13 to solve the liquid crystal panel manufacturing method.

[0019]

According to the present invention, the maximum diameter is at least 0.2 to 0.6 μm or 4 to 12% smaller than that of the liquid crystal layer formed in the pair of substrates constituting the liquid crystal display panel, and the adhesive material is used. By attaching and fixing the covered fine particles to one of the substrates, it is possible to reliably move the substrate for realignment without damaging the inner surface of the substrate. This is experimentally confirmed.

Further, a frame of a sealing material is formed on the electrode forming side of the substrate, fine particles with an adhesive are attached to the inside of the opposing substrate, the liquid crystal is dropped in the frame of the sealing material, and the liquid crystal is sealed under reduced pressure. By stopping, the fine particles can be surely attached to the substrate. Therefore, it is possible to prevent fine particles from flowing unevenly on the substrates due to a sudden liquid crystal flow when filling the liquid crystal between the substrates, and to make the liquid crystal thickness uniform between the substrates on the panel surface. Can be increased. In particular, since fine particles having the above-mentioned diameter are easily washed away, it is necessary to cover these fine particles with an adhesive.

Further, the viscosity is 5000 on the electrode formation side of the substrate.
A sealing material of 0 cp or more is attached in a frame shape, and the liquid crystal is dropped in the frame and sealed by reducing the pressure, so that the sealing material is less likely to be damaged by an external force. Therefore, the liquid crystal is filled between the substrates. In this case, defective sealing of the sealing material can be reduced.
Also, a frame of sealing material is provided at least twice along the plane of the substrate on the electrode formation side of the substrate, and liquid crystal is dropped on the innermost side of the frame and sealed under reduced pressure to seal the liquid crystal. The pressure difference between the inside and the outside of the sealing material at the time of the operation is alleviated, and the occurrence of defective sealing can be reduced. Further, by removing the substrate while leaving at least the innermost side of the frame of the sealing material, the unnecessary sealing frame is finally removed and the liquid crystal display panel is simplified.

Further, a light-shielding means is provided in the vicinity of the inside of the frame of the photocurable sealing material attached to the electrode formation side of the substrate, and the liquid crystal material is dropped and sealed in the frame of the sealing material and irradiated with ultraviolet rays. By curing the sealing material, it is possible to prevent the liquid crystal from contaminating due to the reaction between the liquid crystal and the sealing material when irradiated with ultraviolet rays. Thereby, the display performance of the liquid crystal display panel can be improved.

The dropping of the liquid crystal material in the present invention uses a dispenser which is opened and closed by a needle. According to this, it was experimentally confirmed that the dropping amount can be made uniform with high accuracy and the reproducibility is good.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1A to 1E are sectional views schematically showing a method of manufacturing a liquid crystal display panel according to a first embodiment of the present invention.

In these drawings, the first substrate 1 is made of, for example, glass, and a transparent electrode such as ITO or an alignment film is formed on one surface thereof, and circuits such as TFT elements and bus lines are patterned. The liquid crystal is supplied onto the TFT elements and the like, but the transparent electrodes, TFTs and the like are omitted in the figure for the sake of clear explanation. First,
As shown in FIG. 1 (a), a sealing material 2 made of an ultraviolet curable resin or the like is formed in a frame shape on the surface of the first substrate 1 on which the electrodes are formed, and the sealing material 2 is provided inside the frame. A predetermined amount of liquid crystal 3 is dropped by a known method. Also, the first substrate 1
The surface of the second substrate 4 on which the liquid crystal 3 is dropped is arranged to face the surface of the second substrate 4 to which the spacer 5 is attached.

The second substrate 4 is made of a transparent material such as glass or quartz. Further, a black matrix, a color filter, a common transparent electrode, and an alignment film are sequentially formed on the side of the second substrate 4 facing the first substrate 1, but they are omitted for simplicity of description. ing.
Next, the sealing material and the spacer used in this embodiment will be described.

(About Sealing Material) The sealing material 2 is, for example, a UV-curable type, and in a later step, the first and second substrates 1 and 1 are formed.
It serves as the adhesive of No. 4 and is for partitioning the space for enclosing the liquid crystal 3 between the substrates, so that the sealing material 2 does not cause a sealing failure due to the pressure difference inside and outside the cell when the liquid crystal 3 is filled. It is important to select a sealing material with an appropriate viscosity.

[0028]

[Table 1]

Table 1 is a table showing the relationship between the viscosity of the sealing material and the sealing failure rate. As can be seen from this table, when the viscosity of the sealing material is 20,000 cp or less, the sealing failure rate is extremely high, and when the viscosity is 50,000 cp or more, the sealing material failure occurrence rate is extremely low. Therefore, the sealing material 2
It is preferable to use a material having a viscosity of 50,000 cp or more.

(Regarding Spacer) Spacers 5 are uniformly scattered and attached on the alignment film (not shown) on the second substrate 4 side. The spacers 5 are fine particles of uniform size, and are made of substantially spherical plastic or the like. The diameter of the spacer 5 is determined so as to make the thickness of the liquid crystal layer between the substrates uniform throughout when the first and second substrates 1 and 4 are bonded with the sealing material 2. It must also be taken into consideration that the diameter of the spacer 5 does not hinder the movement of the substrate when realigning the first and second substrates 1 and 4 performed in a later step.

[0031]

[Table 2]

Table 2 is a table showing how the difference between the liquid crystal thickness between the substrates and the spacer diameter relates to the movement of the substrate and the liquid crystal thickness unevenness. The liquid crystal thickness unevenness indicates an error in the thickness of the liquid crystal layer actually formed between the substrates. Here, a spacer 5 having a diameter of 5 μm (made by Hayakawa Rubber) is used,
Moreover, when the thicknesses of the liquid crystal layers of the first and second substrates 1 and 4 are different, the state of substrate movement due to substrate realignment and the liquid crystal thickness unevenness in the entire panel are shown. Here, the substrate movement test was performed by fixing one substrate with a vacuum chuck, fixing the other substrate with another vacuum chuck, and applying a force of 50 kg in the lateral direction.

As is clear from Table 2, with respect to the movement of the substrate, the movement of the substrate was impossible when the liquid crystal thickness was 5.0 μm or less, that is, when it was the same as or smaller than the spacer diameter. On the other hand, when the liquid crystal thickness was 5.2 μm or more, the liquid crystal was movable. Regarding the liquid crystal thickness unevenness, it was found that the liquid crystal thickness became large when the liquid crystal thickness was 5.8 μm and did not change when the liquid crystal thickness was 5.6 μm or less.

Taking these into consideration, when a spacer having a diameter of 5 μm is used, the liquid crystal thickness is 5.2 to 5.6 μm.
Is preferred. That is, it is preferable that the maximum diameter of the spacer is smaller than the thickness of the liquid crystal layer between the substrates by 0.2 to 0.6 μm. That is, it is preferable that the thickness of the liquid crystal layer between the substrates and the diameter of the spacer are larger by about 4 to 12%. Therefore, in this embodiment, the spacer 5 having a diameter of 5 μm is used, and the liquid crystal thickness between the first and second substrates 1 and 4 is set to 5.2 μm.

By the way, in order to attach the spacer 5 to the surface of the second substrate 4, for example, a method of mixing the spacer 5 with a solvent or the like and spraying it on the surface of the second substrate 4 in an atmosphere of 80 to 90 ° C. is used. Adopted. According to this method, the solvent evaporates before the spacer 5 reaches the second substrate 4,
Only the spacers 5 adhere to the surface of the second substrate 4 in the form of particles. At this time, the spacer 5 is attached to the surface of the second substrate 4 by electrostatic or chemical adsorption. As another spacer attachment method, a dry spray method or the like may be used.

As the spacer, it is preferable to use, for example, a spacer whose surface is coated with an adhesive. As a result, the spacers 5 are surely attached to the second substrate 4, and it is possible to prevent the spacers 5 from flowing due to a liquid crystal flow or the like to cause uneven distribution of the spacers 5. Therefore, the uniformity of the thickness of the liquid crystal layer of the entire liquid crystal panel is improved.

Needless to say, such an effect is produced by fixing the spacer with a strength that is sufficient to resist the flow of liquid crystal or higher, and the surface is not necessarily treated with an adhesive. It doesn't have to be. For example, a spacer formed by processing a bank or the like having the same level difference as the diameter of the spacer naturally produces the effect.

In this embodiment, in order to attach the spacer (made by Hayakawa Rubber) coated with the adhesive to the surface of the second substrate 4, the conventional spacer attachment treatment is performed by heat treatment at 150 ° C. for 30 minutes. did. After the sealing material is formed in this way, the spacer is attached, and the first and second substrates 1 and 4 are bonded together, as shown in FIG. 1 (b), the first and second substrates 1 and 4 are
The cell 6 between 4 is filled with the liquid crystal 3.

When filling the liquid crystal, the substrates 1 and 4 are placed in a vacuum and the second substrate 4 is placed and pressed on the first substrate 1 on which the liquid crystal 3 is dropped, and the sealing material 2
When is in close contact with the surface of the second substrate 4, the atmosphere is returned from vacuum to atmospheric pressure. At this time, the inside of the cell 6 sealed by the sealing material 2 is in vacuum, and the outside of the cell 6 is at atmospheric pressure, so that the pressure difference causes the second substrate 4 to be drawn toward the first substrate 1. As a result, the liquid crystal 3 spreads along the surfaces of the first and second substrates 1 and 4.

In this case, since the liquid crystal 3 rapidly spreads inside the cell when the ambient atmosphere is returned to the atmospheric pressure, a sharp flow occurs in the liquid crystal 3. However, in this embodiment, a spacer with an adhesive is used. Therefore, the spacers 5 are not pushed by the flow of the liquid crystal 3 and the spacer distribution is not biased.
Can be maintained in a uniformly distributed state. Also,
At this time, there is a large atmospheric pressure difference between the inside and the outside of the cap 6, and the sealing material 2 receives a large pressure, but since the sealing material 2 is still uncured, a sealing failure is likely to occur. However, in this embodiment, since a material having a viscosity of 50,000 cp is used as the sealing material 2, it is less likely to be damaged by the pressure, and the occurrence of defective sealing can be greatly reduced.

A state in which the liquid crystal 3 is completely filled in the gap 6 between the first and second substrates 1 and 4 is as shown in FIG. 1 (c), and the liquid crystal thickness becomes a predetermined value d. . Here, the liquid crystal thickness d is 5.2 μm. Although not shown in detail in the drawing, the spacer 5 is not actually in uniform contact with the surface of the first substrate 1. Since an alignment film made of resin is formed on the electrode formation side of each of the first and second substrates 1 and 4, there is unevenness instead of flatness, and since the glass substrate itself also has a curvature, the liquid crystal thickness The value of d is larger than the diameter of the spacer 5.

At this point of time, since the sealing material 2 is not cured, the position of the first substrate 1 or the second substrate 4 is shifted and realignment is performed. This step is performed under atmospheric pressure. At this time, since the diameter of the spacer 5 is 0.2 μm smaller than the thickness of the liquid crystal layer between the first and second substrates 1 and 4, mutual movement of the first and second substrates 1 and 4 is hindered. Realignment can be performed easily and surely.

After re-alignment, as shown in FIG. 1 (d),
The sealing material 2 is irradiated with ultraviolet rays 7 by a high pressure mercury lamp to be cured, and the first and second substrates 1 and 4 are fixed. Next in FIG.
In (e), a portion of the second substrate 4 outside the sealing material 7 is cut to remove unnecessary spacers 5 and liquid crystals 3 between the first and second substrates 1 and 4 outside the sealing material 2. Remove with. Therefore, the liquid crystal display panel is simplified and easy to handle.

As described above, in this embodiment, by using the spacer with the adhesive, it is possible to maintain the uniform distribution of the spacer over the entire panel.
Work that took over an hour in the inch class can be completed in minutes. Further, by using a spacer having a diameter smaller than the thickness of the liquid crystal layer between the substrates by 0.2 μm, it is possible to surely move the substrate for repositioning the substrate. further,
Since a sealing material having a viscosity of 50,000 cp or more is used as the sealing material, the occurrence of sealing defects can be reduced and the yield of liquid crystal panels can be improved.

It is not always easy to make a liquid crystal panel so as to satisfy the above conditions. Regarding the spacer diameter, various diameters are commercially available and easily available, but the point of this technology is to supply a certain amount of liquid crystal to the transfer tube with high accuracy and reproducibility. . As a result of investigating and using various dispensers, the present inventor has found that the electromagnetic opening / closing type needle type is the best and only applicable.

Table 3 shows the results of examining the accuracy of various dispensers.

[0047]

[Table 3]

The electromagnetic opening / closing needle type dispenser has a structure as shown in FIG. 2 (a), for example. In FIG. 2A, a pointed cap 12 is attached to the lower end of a liquid crystal container 11 for housing the liquid crystal 3, and one liquid passage hole 13 is formed in the center of the cap 12.
An electromagnetically movable needle 14 is arranged above the liquid passage hole 13 of the cap 12, and the lower end of the needle 14 closes or opens the upper hole of the liquid passage hole 13 by the vertical movement of the needle 14. Is configured. Further, the inside of the liquid crystal container 11 is adjusted so as to always have a constant pressure.

Next, the liquid crystal dropping supply performance is shown in the figure using an electromagnetic opening and closing needle type dispenser. For example, Acura Jetta manufactured by Nordon was used. Also, the liquid crystal is ZLI
-4792 (manufactured by Merck) was used. The internal pressure of the liquid crystal container 11 is, for example, 4 kgf / cm ² , and the thickness of the needle 14 is, for example, 26G.

The relationship between the dispense time (opening time of the needle valve) and the liquid crystal dropping amount and the experimental result of the liquid crystal dropping amount per unit time at each time of the dispensing time are shown in FIG. 2 (b). According to this experiment, there is a good linear relationship between the dispense time and the liquid crystal dropping amount, and the liquid crystal dropping amount per unit time is constant with high accuracy.

Next, when the accuracy and reproducibility of the liquid crystal dropping amount with the increase in the number of liquid crystal shots were tested by the electromagnetic opening / closing needle type dispenser, the results shown in FIG. 3 were obtained. According to this, the liquid crystal is continuously used for 1 day in 2 days.
After 00 shots, the error of the dispenser amount is ±
Within 1%, high precision and high reproducibility were obtained. In addition,
The conditions for the shots on the first day and the second day were set to be the same.

Since the electromagnetic opening / closing tip needle type dispenser can be used in a vacuum because of its structure, it can be seen that it is also suitable for a dropping injection method for dropping liquid crystal in a vacuum atmosphere. Liquid crystal is generally dropped at atmospheric pressure. (Second Embodiment) In the present embodiment, in order to prevent the reaction between the sealing material 2 and the liquid crystal 3 due to the ultraviolet rays 7 and to prevent the contamination of the liquid crystal 3 caused by the reaction, the second sealing material 2 along the inner vicinity is formed. A light-shielding film is provided on the lower surface of the substrate 4. The details are described below.

FIG. 4A is a plan view of the light shielding film 8 formed on the second substrate 4, and FIG. 4B is a sectional view thereof. FIG.
In (a), the light shielding film 8 formed on the back side of the transparent second substrate 4 is shown. The light-shielding film 8 is an area along the inside of the frame-shaped seal material 2 and is formed outside the display area 9, and is determined so as not to overlap the seal material 2 and the display area 9. If the region where the light-shielding film 8 is formed overlaps or is too close to the sealing material 2, a part of the sealing material 2 that is not cured will occur. Therefore, it is preferable to provide a slight gap between the light-shielding film 8 and the sealing material 2. The light-shielding film 8 is
Although it may be formed on the upper side of the second substrate 4, the lower side of the second substrate 4 is preferable in terms of light shielding accuracy.

The light-shielding film 8 is formed by patterning a film (for example, a chrome film) forming a black matrix film formed on the second substrate 4 in order to improve display quality.
It does not complicate the manufacturing process. When irradiating ultraviolet rays to cure the sealing material 2, a light-shielding mask 10 as shown in FIG. 4B is placed outside the first and second substrates 1.4 to irradiate the display area 9 with ultraviolet rays. To prevent. This is because the light-shielding area of the light-shielding film 8 is limited between the display area 9 and the area where the sealing material 2 is formed.

When the sealing material 7 is cured by irradiating it with ultraviolet rays from the side of the first substrate 1, a light-shielding film may be provided on the side of the first substrate 1. Since the wiring such as the bus line is formed of a metal such as Al, the light shielding film is preferably formed of an insulating material. By providing the light-shielding film 8 in this manner, the amount of ultraviolet rays irradiated to the liquid crystal 3 in the vicinity of the seal material 2 can be significantly reduced, so that the reaction between the seal material 2 and the liquid crystal 3 due to the irradiation of ultraviolet rays can be reduced. Therefore, the contamination of the liquid crystal 7 can be extremely reduced. Moreover, the external light-shielding mask 10 prevents the liquid crystal in the display region from reacting with a small amount of molecules of the sealing material 2 to suppress the contamination of the liquid crystal 7.

As described above, in this embodiment, since the liquid crystal in the vicinity of the sealing material is prevented from being irradiated with ultraviolet rays, the sealing material 2 is cured when the sealing material is cured by the irradiation of ultraviolet rays.
The liquid crystal can be prevented from being contaminated by the reaction between the liquid crystal 4 and As a sealing material, T-470 (cationic polymerization type, manufactured by Nagase Ciba, 1
As a result of evaluating the voltage holding ratio by reducing the liquid crystal electric resistance as described above using 0,000 cp), almost no decrease in the liquid crystal holding ratio was observed. As the liquid crystal 3, ZLI-4792 (manufactured by Merck) was used, and the sealing material 2 was used.
The irradiation condition of the ultraviolet ray was 5000 mJ / cm ² .

It should be noted that ultraviolet rays may be made into a beam shape and applied only to the frame-shaped sealing material 2, and in this case, it is not necessary to use a light shielding film. (Third Embodiment) A method of manufacturing a liquid crystal display panel according to a third embodiment of the present invention has the same general flow as that described in the first embodiment, but has two substrates facing each other. The method of forming the sealing material for sealing the is different.

5 (a) and 5 (b) are a plan view and a sectional view of a liquid crystal display panel in a state where liquid crystal is sealed. Figure 5
In (a), the sealing material 2b is formed outside the sealing material 2a in the panel, and the liquid crystal 3 is sealed inside the sealing material 2a. The space between the sealing materials 2a and 2b is vacuum, and the outside of the sealing material 2b is the atmosphere. In order to form such double sealing materials 2a and 2b, the sealing materials 2a and 2b are attached to the first substrate 1 in vacuum before the first and second substrates 1 and 4 are stacked. . Then, when the first and second substrates 1 and 4 are overlapped and bonded to each other and the atmosphere is brought to atmospheric pressure, the first and second substrates 1 and 4 are attracted and the liquid crystal 3 is filled in the sealing material 2a. It At this time, the outside of the sealing material 2b is at atmospheric pressure, but a vacuum remains between the sealing material 2a and the sealing material 2b.

When the liquid crystal 3 is sealed between the substrates by setting the ambient atmosphere to atmospheric pressure, the inside of the seal material 2a is substantially vacuum until the liquid crystal 3 is completely filled inside the seal material 2a. However, the double provision of the sealing material in this way makes it possible to bring the outside of the sealing material 2a into a vacuum state. Therefore, it is possible to prevent a sudden pressure difference between the inside and the outside of the sealing material 2a, and it is possible to avoid the occurrence of defective sealing of the sealing material 2a.

After the liquid crystal 3 is completely filled and at least the sealant 2a is cured, the outer side of the sealant 2a of the second substrate 4 is cut and removed. Therefore, the material of the sealing material 2b is not so limited and various materials can be used. By thus providing the frame of the sealing material twice, it is possible to reduce defective sealing and improve the yield of the liquid crystal panel.

[0061]

As described above, according to the present invention, a frame having a sealing material is formed on a substrate having a transparent electrode, liquid crystal is dropped in the frame, and another substrate to which a spacer is attached is formed. In a liquid crystal display panel and a method for manufacturing the same in which liquid crystal is sealed between substrates by superimposing them in a vacuum and returning the atmosphere to atmospheric pressure, and a sealing material is hardened, the diameter of the spacer is smaller than the thickness of the liquid crystal layer between the substrates. At least 0.2μ
By using a small m, it is possible to reliably move the substrate during realignment while maintaining the thickness uniformity of the liquid crystal layer between the substrates.

Further, by using the spacer with the adhesive as the spacer, it is possible to prevent the spacer from flowing due to the liquid crystal flow and the distribution of the spacer being biased. This improves the uniformity of the thickness of the liquid crystal layer between the substrates over the entire panel. The sealing material has a viscosity of 5000.
By using a material of 0 cp or more, the sealing material becomes strong against external force, so that defective sealing can be reduced. Furthermore, since the frame of the sealing material is provided twice, the pressure difference between the inside and the outside of the frame that seals the liquid crystal can be relaxed, so that the sealing failure can be reduced. Thereby, the yield of the liquid crystal display panel can be improved.

Even when a UV curable material is used as the sealing material and is irradiated with ultraviolet rays when it is cured, the liquid crystal and the sealing material react with each other by providing a light shielding film in the vicinity of the sealing material on the substrate. Since it is possible to prevent the liquid crystal from being contaminated, it is possible to enhance and stabilize the display performance of the liquid crystal display panel. Since a dispenser that opens and closes by a needle is used for dropping the liquid crystal material in the present invention, the dropping amount can be made uniform with high accuracy and the reproducibility can be improved.

[Brief description of drawings]

1A to 1E are sectional views schematically showing a method of manufacturing a liquid crystal display panel according to a first embodiment of the present invention.

FIG. 2 (a) is a sectional view showing the outline of an electromagnetic opening / closing needle type liquid crystal dispenser used in the first embodiment of the present invention, and FIG. 2 (b) shows the relationship between the dispensing time and the dispensing amount. It is a graph which shows and the graph which shows the change of the amount of dispenses per unit time with progress of dispense time.

FIG. 3 is a graph showing the relationship between the number of shots and the amount of dispense by a liquid crystal dispenser of the electromagnetic opening / closing needle type.

4A and 4B show in detail one step of a method of manufacturing the liquid crystal display panel shown in FIG. 1, FIG. 4A being a plan view and FIG. 4B being a sectional view.

FIG. 5 shows one step of a method of manufacturing a liquid crystal display panel according to a second embodiment of the present invention, FIG. 5 (a) is a plan view, and FIG.
Is a sectional view.

FIG. 6 schematically shows a method for manufacturing a liquid crystal display panel, and FIGS. 6 (a) to 6 (c) are perspective views showing respective steps.

FIG. 7 is a plan view showing a sealing failure of a sealing material caused by a conventional liquid crystal display panel manufacturing method.

FIG. 8 is a graph showing changes in the voltage holding ratio of liquid crystals at different positions in the panel in the conventional method for manufacturing a liquid crystal display panel.

[Explanation of symbols]

 1, 4, 21, 24 Substrate 2, 2a, 2b, 22 Sealing material 3, 23 Liquid crystal 5 Spacer 6 Cell 7 Ultraviolet 8 Light shielding film 9 Display area 10 Light shielding member 11 Liquid crystal container 12 Cap 13 Liquid passage hole 14 Needle

Claims (7)

[Claims] 1. A step of applying a sealing material in a frame shape on at least one electrode formation side surface of a pair of substrates, and a thickness of a liquid crystal layer to be formed and controlled between the pair of substrates. And adhering and fixing fine particles having a diameter of 0.2 to 0.6 μm or 4 to 12% smaller on one electrode forming side of the pair of substrates, and the electrode surrounded by the sealing material. A step of dropping a liquid crystal material on the surface on the formation side, and a surface on the electrode formation side of the pair of substrates facing each other and superposed under reduced pressure, and spreading the liquid crystal material to form a space between the pair of substrates. And a step of forming the liquid crystal layer, the manufacturing method of the liquid crystal display panel. 2. The method for manufacturing a liquid crystal display panel according to claim 1, wherein the fine particles are covered with an adhesive and fixed to the surface on the one electrode forming side. 3. A step of applying a sealing material having a viscosity of 50,000 cp or more in a frame shape on at least one surface of the pair of substrates on which the electrode is formed, and a liquid crystal on the surface of the electrode which is surrounded by the sealing material. A step of dropping a material, and a step of forming the liquid crystal layer between the pair of substrates by spreading the liquid crystal material by causing the surfaces of the pair of substrates on the electrode formation side to face each other and overlapping under reduced pressure; A method of manufacturing a liquid crystal display panel, comprising: 4. A step of forming at least double a frame made of a sealing material on at least one electrode formation side surface of a pair of substrates along the surface, and the sealing material on the electrode formation side of the substrate. A step of dropping a liquid crystal material in the innermost frame of the pair of substrates, the surfaces of the pair of substrates on which the electrodes are formed face each other and are superposed under a reduced pressure, and the liquid crystal material is spread to spread between the pair of substrates. And a step of forming the liquid crystal layer, the manufacturing method of the liquid crystal display panel. 5. The method according to claim 4, wherein after sealing the liquid crystal material, at least one of the pair of substrates is cut off, leaving at least the innermost one of the frames made of the sealing material. A method for manufacturing a liquid crystal display panel according to. 6. A frame made of a photo-curing sealing material is applied to at least one surface of the pair of substrates on which electrodes are formed,
A step of arranging a light shielding means near the inside of the frame and dropping a liquid crystal material on a surface of the electrode forming side surrounded by the frame made of the sealing material; A method for manufacturing a liquid crystal display panel, comprising: a step of making the surfaces face each other and superposing them under reduced pressure; and a step of irradiating the sealing material with light to cure the sealing material. 7. A liquid crystal material container having a liquid crystal supply hole on the lower side thereof, the internal pressure of which is kept constant, and a dispenser having a needle arranged in the liquid crystal material container for opening and closing the liquid crystal supply hole. 7. The method of manufacturing a liquid crystal panel according to claim 1, wherein the liquid crystal material is dropped.