JPS6254229A - Manufacturing method for liquid crystal display - Google Patents

Abstract

PURPOSE:To execute filling work of the liquid crystal for a short time by filling the smectic liquid crystal between filled surfaces of a substrate, and simultaneously, sealing the peripheral part of a pair of substrates. CONSTITUTION:After the liquid crystal is provided on the filled surface of one side substrate, the filled surface of other substrate is tightly connected on the liquid crystal, and further, a pair of substrates are arranged to the pre scribed mutual position. Further, as the same process as the process, the laminat ing system is used which executes the sealing for sealing to the peripheral part, especially, to the corner part of the square or rectangular substrate. As the liquid crystal material, the smectic liquid crystal, especially preferably, the ferroelectric liquid crystal to show a smectic C phase (SmC*) is used. Name ly, the interval of the cell is made into 4mum or the interval below it is made into 0.5-3mum, and thereby, the bistable condition can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for manufacturing a liquid crystal display device, and particularly relates to a method for manufacturing a liquid crystal display device. The present invention relates to a method for manufacturing a liquid crystal display device, which aims to reduce the thickness of the display section of a microcomputer, word processor, television, etc. by providing a display panel using the .C).

``Prior Art'' For solid-state display panels, a method in which each picture element is controlled independently is effective for use in large areas. Conventionally, such a panel uses a dual-frequency liquid crystal, such as a twin-stick nematic liquid crystal (hereinafter referred to as TN liquid crystal), and has a simple 71 to 4-inch structure with 400 elements in the horizontal direction and 200 elements in the vertical direction. Display devices using a multiplexing drive method are known.

However, if such a TN liquid crystal is not manufactured, this T
Because the viscosity of N liquid crystal is low, a pair of glass substrates is
Apply a sealing agent mixed with a spacer to the periphery of the pair of glass substrates, making them face each other with a gap of μ,
bring each other into close contact. At this time, a portion of the surrounding seal portion is not sealed, and an open hole is left. Thereafter, the pair of substrates whose peripheries have been sealed are held in a vacuum container, and the whole is evacuated. Furthermore, by immersing this hole in a TN liquid crystal solution and bringing the inside of this vacuum container to atmospheric pressure, liquid crystal is filled into the gap between 5 to 10μ between the pair of substrates using capillary action. It was something I wanted to do.

"Problems to be Solved by the Invention" However, this method is excellent when filling a space between substrates with a liquid crystal having a low viscosity at room temperature, such as a TN liquid crystal.

However, (1) it is extremely difficult to work with FLCs that use smectic liquid crystals with high viscosity, such as SmC''layers;

(2) The gap between the electrodes of the cell should be 4 lt or less, preferably 0.
．． Fl, which assumes the use of a narrow gap of 5 to 3 μ;
When C is used, filling takes a very long time.

(3) When filling Fl and C into a large area, e.g.
Requires filling operation at °C. Therefore, the sealing around the periphery is likely to deteriorate. Moreover, this sealing material is likely to be mixed into the liquid crystal as an impurity.

(4) As the liquid crystal is filled, the spacer (commonly known as a scallop) that determines the cell gap tends to be biased to one side.

'(5) During filling, nearly 90% of the liquid crystal material is not effectively used, resulting in a lot of waste.

It has many disadvantages such as.

The present invention solves this problem.

"Means for Solving the Problem" In order to solve this problem, the present invention does not seal the periphery of the pair of substrates before filling the pair of substrates with liquid crystal, but rather After the liquid crystal is provided on the surface, the surface to be filled of the other substrate is brought into close contact with the liquid crystal, and then the pair of substrates are disposed at predetermined mutual positions. Furthermore, as a simultaneous process with this process, we basically use a so-called lamination (making it into a thin layer, spreading it into a thin layer) method that seals the periphery, especially the corners of square or rectangular substrates. .

In addition, in the present invention, a smectic liquid crystal, particularly preferably a ferroelectric liquid crystal exhibiting a smectic C phase (SmC"), is used as the liquid crystal material. That is, the cell spacing is 4 μm.
A bistable state can be obtained by setting the thickness to 0.5 to 3 μm or less.

That is, (isotropic) liquid crystal is dropped, sprinkled, or coated on one or more points on the filling surface on the electrode of one of the substrates. Furthermore, a small amount of sealing resin is dropped onto the corner portion of one or the other substrate. After this, the other substrate is placed on top of this.

Furthermore, these are evacuated, heated before and after, and the pair of substrates are pressurized to each other, so that the surfaces to be filled installed inside each substrate are kept in close contact with each other with a gap of 4μ or less. In addition, at least a portion of the periphery is simultaneously sealed.

Furthermore, the temperature of this thin Fl, C-filled and laminated substrate is lowered to obtain SmA, and further bistable Sm
C" is obtained. Then, the Tora-U structure can be removed.

Thereafter, after storing it at room temperature, the peripheral edges are sealed with a plastic sealant.

In the method of the present invention, the contact area between the substrates can be increased at this corner portion, and the substrates can be firmly fixed to each other.

In addition, the operating temperature range, which is a problem that remains even with the present invention, is currently limited by combining (blending) multiple different PLCs.
It can be used at ~50°C. Therefore, it does not pose much of a problem in practice, and as far as gradations are concerned, if the number of colors is up to eight, gradations are not necessary, and it has been found that it is fully usable as a display for microcomputers and the like.

"Function" By doing this, (1) Since the cells are dispersed with spacers and the minimum gap is determined by the size of the spacers, there is no variation in the gaps formed between Fl and C.

(2) Even if the cells are thin with a gap (cell thickness) of 4μ or less or have a large area (equivalent to A4 size), lamination work can be performed in a short time.

(3) FLC provided on the substrate can be effectively utilized by 100χ.

(4) Even if FLC with high viscosity is used, the lamination and sealing operations do not require more than one hour.

(5) Even if an active element and an electrode connected thereto are provided on one substrate side, FLC can be laminated in the same process as a passive structure that does not use any active element.

Furthermore, due to these characteristics, the liquid crystal lamination method of the present invention (indicating that the gap between two substrates is gradually narrowed and a thin layer of liquid crystal is interposed between them) is used, and in addition, nonlinear elements (NF, ) and ferroelectric liquid crystals (Fl, C) in series to form each pixel, crosstalk between each pixel is removed and driven in a large-area matrix of A4 size or larger. I was able to accomplish this for the first time.

The present invention will be explained below according to examples.

"Example 1" FIG. 1 shows the manufacturing process of a liquid crystal display device of the present invention.

FIG. 1 (8) has two substrates (1) and (1').

Each of the opposing surfaces (8) and (8") has an electrode. In addition, in order to display color, it is necessary to fill in the space between the electrode and the substrate on the one □ side, or between the electrode and the electrode. A color filter is provided between the liquid crystal and the liquid crystal.

Further, the upper surface of this electrode is subjected to a known asymmetric alignment treatment.

In these drawings, for the sake of simplicity, illustration is omitted and it is simply referred to as a substrate. However, it is effective to perform these electrodes, filters, alignment treatment, formation of a black matrix masking treatment (mask), production of active elements, etc. on opposite sides of a pair of substrates, as necessary.

The substrate is generally a glass substrate such as Corning 70
59 is used. However, it is effective to use a flexible substrate for one or both of the substrates. The flexible substrate is a chemically strengthened glass substrate with a thickness of 0.3 to 0.6 mm, or polyimide.

It is effective to use a light-transmitting heat-resistant organic resin substrate such as PAN or PET.

An alignment treatment layer (asymmetric alignment treatment layer) was provided on the electrode on this substrate, and its upper surface was used as the surface to be filled. Then, on this surface, an FLC, for example, S8 (octyl oxy benzylidene amino methyl butyl benzoate) was provided. In addition to this, FLC such as BOB static BC or FLC blended with a plurality of FLCs may be filled. For example, here, a blended liquid crystal of S8 and 87 was used.

Furthermore, a liquid crystal (2) is placed on the filling surface of one of the pair of substrates.
was dripped.

Furthermore, epoxy-based sealing resin (19) is applied to a plurality of peripheral parts, especially corner parts, with the other filling surface oriented downward.
(19') was added dropwise in a small amount. This used thermosetting resin.

A pair of substrates provided with such liquid crystals were sealed in a vacuum container (1,00) as shown in FIG. 1(B). This vacuum container (1,00) has a first space on the container side (10),
A second space (5) is provided on the lid side (10'). A heater (3) is provided within the first space (4). One of the substrates (1) is placed on this heater (3), and the substrate is heated and controlled to a predetermined temperature within the range of room temperature to 150°C, for example, 70 to 150°C, such as 120°C, at which the viscosity of the liquid crystal is sufficiently low. Ta. Then, the liquid crystal (3) already provided on the surface to be filled on the substrate (1) is heated and spreads to the surface to be filled. Spacers were placed on the substrate at predetermined intervals before or after dropping the liquid crystal.

A method may also be adopted in which this spacer is not used at all.

Furthermore, the other board (1゛) facing above this
They were arranged at a distance of 0 mm or slightly in contact with each other.

After this, the lid side container (10) having this second space (5)
') was fitted onto the container (10) side using an O-ring.

Below the second space, the first space and the second space are shielded from each other by a layer having elasticity (hereinafter referred to as silicone rubber (6) for simplicity). Regarding the pressures in the second space and the first space, when the pressure in the first space is positive, the lower side expands, and when the pressure is negative, the lower side is pulled upward. This rubber is not limited to silicone rubber, as long as it can withstand a temperature of at least 150°C.

Align these with each other using an O-ring (11).

(11') was simultaneously evacuated. That is, these two outlets are connected to a vacuum pump (14) via valves (12) and (12'). Then open both valves (12L (12'), valve (13),
(13') are both closed, and the first and second spaces (
4) and (5) are both vacuum spaces.

Further, as shown in FIG. 1(C), the other substrate was precisely placed on the upper surface of the substrate at a distance.

Then, the liquid crystals (3) are filled into the upper and lower filling surfaces. In addition, corner sealing, +h material (1,9), (19
”) comes into contact with the heated substrate side and raises the temperature.

Then, air or nitrogen is gradually leaked from the valve (13°) to bring the other second space (5) from a vacuum state to atmospheric pressure so that the pressure is positive compared to the first space (4). Ta.

Then, as shown in Figure 1 (C), the silicone rubber (6)
expands downward and presses the other opposing substrate (1") toward the one substrate (1). At atmospheric pressure, a pressure of 1 kg/cm" can be applied.

In addition, when further pressurizing with nitrogen, 1 atm or more
A pressure of ~5 kB7 cm" is also possible.

In this way, it is possible to apply uniform pressure to the entire surface of the pair of substrates, and due to this pressure, the liquid crystal, which was provided at one or more points, spreads laterally along the surface of the substrate (1). Laminated 1~.

In addition, the sealing material also spread at its corners, bringing the respective substrates into close contact with each other over an opening area of 1 to 15 mm.

At this time, to prevent one liquid crystal or the other sealing material from mixing with each other or spreading beyond a predetermined position, a barrier (18) made of fibers of 1 to 3 μm (1B
') is effective. Further, this barrier may be provided not only at the corner portion but also over the entire peripheral area.

Further, the gap between the pair of substrates on the electrode side can have a uniform thickness of 4 μm or less, for example, 2 μm.

This thickness can be 2μ if spacers with a size of 2μ are provided in advance, and 1μ if spacers with a size of 1μ are distributed.

Of course, it is also possible to laminate to a predetermined thickness by precisely controlling only this pressure and heating temperature without using any spacers.

As a result, excess liquid crystal is moved to the periphery. However, because this outer periphery is covered with silicon rubber, or because the barriers (18) and (18') block like an embankment, this prevents the liquid crystal from overflowing beyond the outer periphery of a part of the substrate. Virtually preventable. In addition, overflowing the liquid crystal from all the outer peripheries or running out of the liquid crystal without covering the entire desired area can be prevented by precisely controlling the initial supply amount of the liquid crystal.

By overlapping two substrates in the X and Y directions, they can be moved and rearranged when the substrates (1), (1') and liquid crystal (3) that are brought into close contact with each other are heated and in a low viscosity state. .

After this, the heater was gradually lowered to room temperature in FIG. 1(C). Furthermore, the first space (5) is also set to atmospheric pressure and the vacuum container (1
00) was removed. A cell with a liquid crystal laminated between a pair of substrates is removed from the container as shown in Figure 1 (
D).

This figure shows a corner part, and the sealing material is also interposed between the two substrates to bring them into close contact with each other.

Thus, as shown in FIG. 1(D), the two opposing substrates (1,), (1°) cause the liquid crystals (3) to be substantially superimposed on each other.

In FIG. 1(E), a sealing agent (9) (generally a plastic material) is applied from the outside to the peripheral side portion in a subsequent step to fix the substrates to each other.

Of course, in Figure 1 (8), sealing +, I' (19)
, (19') may be simultaneously dropped not only on the corner portions of a square or rectangular substrate but also on the side portions, and the entire outer periphery may be sealed at the same time as the liquid crystal is laminated.

In this way, we were able to establish a method for filling and laminating liquid crystals having high viscosity, such as the smectic liquid crystal of the present invention, between substrates, especially FLC.

"Effect" By doing so, A4 size (20cm x 30cm
0.2 cc of liquid crystal is sufficient for one sheet (area), and liquid crystal, which is more expensive than gold at 3,000 yen/g, can be used very effectively.

One liquid crystal filling operation can be completed in a short time of about one hour.

It has the characteristic that even if the area is large, the working time does not become long.

That is, in the conventionally known filling operation for TNt& products, it is important to prevent stress from being applied to the liquid crystal. Therefore, the sealants in the peripheral areas support each other's forces so that pressure that may be applied from the outside to each substrate is not applied to the liquid crystal itself.

However, in the case of smectic liquid crystals, the inventors have found that even if this force is applied to the liquid crystal itself, the viscosity thereof is large and there is no problem. By utilizing this characteristic, a manufacturing method such as the present invention, which is completely different from conventional methods, has been made possible.

In the liquid crystal filling method of the present invention described above, the alignment treatment layers constituting the surface to be filled are subjected to an asymmetric alignment treatment, one of which is subjected to a rubbing treatment, and the other is subjected to a non-rubbing treatment. At this time, after laminating as in the present invention, this substrate is subjected to slight movement (1 to 1
It is effective to apply stress to the liquid crystal to align it.

In the liquid crystal display device of the present invention described in 2 below, when a polarizing plate is provided on the outside of one or both of the substrates to make it a reflective type, the electrode on the incident light side is made transparent, and the other electrode is made translucent. is a reflective electrode. And the tilt angle of FLC is about 4
By setting the angle to 5 degrees, one filter can be disposed on the substrate on the incident light side.

On the other hand, when using two filters to create a transmissive or reflective type, this can be achieved by aligning two polarizing plates on the outside of each substrate and setting the tilt angle of the FLC to about 22.5 degrees. obtain. In the translucent type, the backlight is EL.
(Electroluminescence) A display can be created by irradiating with fluorescent lamps or natural light and controlling the amount of light that passes through.

In the case of colorization, a color filter may be provided above or below the electrode on the other opposing substrate side (the side visible to the human eye).

Further, in the present invention, a non-linear element arranged on a substrate and an electrode provided above the substrate can be treated as a substrate, and an active element type can be obtained. In such a case, it is possible to use a 5CLAD (space charge limited current type amorphous semiconductor device) or an insulated gate type field effect semiconductor device having a composite diode structure such as an NIN type as the nonlinear element.

In the liquid crystal display device of the present invention, display and reading can be performed by forming a dot-shaped photosensor using a light pen.

The manufacturing process shown in FIG. 1 of the present invention has a matrix structure of 100 x 100 (100 x 300 for color).

However, this number of dots can also have 640 x 400 (1920 x 400 in color), 720 x 400 and other configurations.

[Brief explanation of the drawing]

FIG. 1 shows a method for manufacturing a liquid crystal display device of the present invention.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a liquid crystal display device in which a pair of substrates having electrodes are placed opposite each other with the surfaces to be filled inside, and liquid crystal is filled between the surfaces to be filled, wherein the surface to be filled of the substrates is A method for manufacturing a liquid crystal display device, comprising filling a space between the substrates with smectic liquid crystal, and simultaneously sealing the peripheral portions of the pair of substrates. 2. The method for manufacturing a liquid crystal display device according to claim 1, wherein the sealing is performed on at least a corner portion of a rectangular or square substrate. 3. A method for manufacturing a liquid crystal display device in which a pair of substrates having electrodes are placed facing each other with the surfaces to be filled inside, and liquid crystal is filled between the surfaces to be filled, wherein smectic liquid crystal is filled between the surfaces to be filled of the substrates. A liquid crystal display device comprising the steps of simultaneously sealing the corner portions of the pair of rectangular or square substrates, and after the step, sealing the side portions of the rectangular or square substrates. Fabrication method.