JPS6278531A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To improve fastening strength against strain stress by bringing a pair of substrates into close contact to each other through liquid crystal and sealing outer periphery of the substrates with hardenable resin. CONSTITUTION:Liquid crystal 2 is provided on a face 8 to be filled separated from each other, keeping a space between a pair of substrates 1, 1', and liquid crystal material is liquefied by heating. Further, the two are brought close to each other, and a face 8' to be filled of another substrate 1' is brought into close contact on the liquid crystal 2, and the pair of substrates are pressed from outside to specified mutual position, and the liquid crystal material is spread over whole face to be filled. Then, hardenable resin 18, 18' is placed to cover the periphery of the pair of substrates 1, 1' which are in close contact through the liquid crystal 2 and a lead terminal connected to existing substrates at a junction, and the whole is made vacuous again. Further, organic resin in the periphery and junction is hardened, and peripheral part of the pair of substrates is sealed with resin.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention relates to a liquid crystal device including a liquid crystal display device that is modularized. It is intended that the terminals will also be integrated. The present invention is effective when a high viscosity liquid crystal material such as a smectic liquid crystal (hereinafter referred to as Sm liquid crystal) is used as a liquid crystal material, particularly when a ferroelectric liquid crystal (hereinafter referred to as FLC) is used. By using this liquid crystal and providing a guest-host type or birefringence type display panel, the present invention relates to a liquid crystal display device for a display section of a microcomputer, a word processor, a television, etc., or to modularization thereof.

``Prior Art'' For solid-state display panels, a system in which each picture element is controlled independently is effective for large-area displays. 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 is driven by multiplexing in a simple matrix configuration of 14-size size with 400 elements in the horizontal direction and 200 elements in the vertical direction. Display devices using this method are known.

Does it take TN? f9. If you do not want to make a product, this TN
Taking advantage of the low viscosity of liquid crystal, a pair of glass substrates
The glass substrates are placed against each other with a gap of ~10 μm, and after scattering spacers between the glass substrates, a sealant for sealing is applied to the periphery of the pair of glass substrates to bring them into close contact with each other. At this time, a portion of the surrounding seal portion is not sealed, and the injection port remains. 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. The peripheral area was to be sealed by bringing the substrates into close contact with each other on the "inside" of the substrates. For this reason, it has been completely impossible to simultaneously use this sealing material to reinforce the leads connected to each panel.

[Problems to be Solved by the Invention] This method is excellent when a liquid crystal having a low viscosity at room temperature, such as a TN liquid crystal, is filled between substrates. However, (1) the mechanical attachment strength of the connection between the IC circuit board connected to the liquid crystal display panel and the lead terminals of the electric circuit or the printed electric circuit is weak (and tends to cause low reliability).

(2) Manufacturing takes time due to the sealing work of the connection terminals of the electric circuit and the periphery of the display panel.

(3) The distance between the electrodes of the cell is 4μ or less, preferably 0.5 to 3μ
When using a high viscosity liquid crystal material that requires the use of a narrow gap, filling takes an extremely long time.

(3) When filling a large area, e.g., A4 size, with liquid crystal material, the temperature is high for a long period of time, e.g., 120°C, for 8 to 10 hours.
Requires filling work. Therefore, the sealing material in the peripheral area deteriorates, and this sealing material tends to mix into the liquid crystal as an impurity.

(4) Liquid crystal material that is not used effectively during filling accounts for 9
It's close to 0%, which means there's a lot of waste.

etc. have many disadvantages.

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 ( A liquid crystal is placed thereon, and the pair of substrates, one substrate and the other substrate, are brought into close contact with each other with the liquid crystal interposed therebetween.

Furthermore, after this step, the outer periphery of the pair of substrates is sealed with a curable resin. Furthermore, when sealing this outer periphery, a lead terminal (640X
(For a panel with 400 pixels, there are 1040 pixels) covered with this organic resin to improve reliability.
A vacuum is maintained between the pair of substrates and the liquid crystal material is liquefied by heating. Furthermore, a lamination method (meaning to make a thin layer or to spread it into a thin layer) method is used, in which the two substrates are brought close to each other, the filling surface of the other substrate is brought into close contact with the liquid crystal, and the pair of substrates is pressed from the outside to a predetermined mutual position. to spread the liquid crystal material over the entire surface to be filled. The liquid crystal material is thus spread over the entire surface to be filled. After that, the liquid crystal is again used to cover the periphery of the pair of substrates that are in close contact with each other and the lead terminals connected to the already installed substrate (glass substrate) at the connection part using a hardening resin (thermosetting or light curing) is installed,
Vacuum the whole thing again. Further, at least the organic resin in the peripheral portions and the contact areas is cured, and the peripheral portions of the pair of substrates are sealed with the resin, resulting in a second lamination step.

In the present invention, a highly adhesive liquid crystal such as 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 generally 4 μm or less. is 0.5~3μ
By setting m, a state in which the helical structure disappears can be obtained.

``Effect'' By doing this, (1) each substrate is fixed with the sealing material around the cell periphery, and the bonding area is increased compared to the conventional case where the adhesive area is only around the ``inside'' side of the substrate. It is possible to obtain a strong fixing strength against strain stress caused by twisting a pair of substrates with respect to each other.

(2) At the same time as sealing the periphery of the display panel, in order to cover the connection part with the lead terminal or printed electric circuit terminal of another electric circuit made at the same time on the periphery of this board, the electrical connection at this connection part is sealed. Additionally, mechanical connection and integration can be achieved with higher reliability.

(3) The work can be completed in a short time by simultaneously performing the first laminating process for the liquid crystal and the subsequent sealing process by the second laminating process for the peripheral area.

(4) The liquid crystal is spread over the entire surface to be filled by a first lamination step, and then the pair of substrates are precisely aligned with each other at a microscopic level. Furthermore, since the outer periphery is sealed in the second lamination step after this, the positions of the pair of substrates can be precisely positioned relative to each other at the finished level.

(5) Since liquid crystal is filled between a pair of substrates through lamination, even a thin cell with a gap (cell thickness) of 4 μm or less can be made to have a large area (equivalent to A4 size).

(6) The liquid crystal material provided on the substrate can be effectively utilized by 100χ.

(7) Even if a highly viscous liquid crystal material is used, the lamination and sealing operations do not require more than 2 hours.

(8) A liquid crystal material can be laminated in the same process with an active structure in which an active element and an electrode connected thereto are provided on one substrate side, or a passive structure in which no active element is used at all.

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(A) has two substrates (1), (1°). Electrodes are respectively provided on the opposing filling surfaces (8) and (8'). Also, to display in color,
A color filter is provided on one side between the electrode and the substrate or between the electrode and the filled liquid crystal. Further, the upper surface of this electrode is subjected to a known 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 (for example, an asymmetric alignment treatment layer) was provided on the electrode on this substrate, and its upper surface was used as the filling surface. Then, on this surface, FLC such as S8 (P-octyl oxy benzylidene-Po-amino-methyl gatyl henzoate and B-8 (9-ocluoxy-4''=biphenylcarboxylic acid-2-methylbutyl ester) We have provided branded LCDs with blended LCDs, etc. In addition to this,
It may be filled with FLC such as BOBAMBC or FCC with multiple blends. Regarding these FLCs, for example, JP-A-56-107216. Japanese Unexamined Patent Publication 1983
-118744. Japanese Patent Publication No. 59-118745. Japanese Patent Application Publication No. 5
9-98051 etc. may be used.

The liquid crystal (2) was dropped onto the filling surface (8) of one of the pair of substrates (1) (1°).

A pair of substrates provided with such liquid crystals were sealed in a vacuum container (100) as shown in FIG. 1(B). This vacuum container (100) has a first space (4) on the container side (10) and a second space (5) on the lid side (10'). A heater (3) is provided below the first space (4), and a sink (heat sink) is formed between the heater and the substrate to enable slow cooling and gradual temperature rise and fall. . This heater (
3) One of the substrates (1) was placed on top, and this substrate was heated to a predetermined temperature within the range of room temperature to 170°C, for example, 80"C. Then, the surface to be filled on the substrate (1) was already heated. The liquid crystal (3) provided on the substrate is heated and spreads over the surface to be filled.Before or after dropping this liquid crystal, spacers with a particle diameter of 2μ were placed on the substrate at a predetermined interval.This spacer was completely You may also adopt a method that does not use this method.

Furthermore, the other substrate (I゛) facing above is 0.1
~10 mm, for example, 3 mm Q (they were placed in partial contact with each other).

After this, the lid side container (10) having this second space (5)
°) was fitted to 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 pressure, it expands downward, and when the pressure in the first space is negative pressure, it is pulled upward. This rubber is not limited to silicone rubber as long as it can withstand a temperature of 170°C.

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

(11') was simultaneously evacuated. That is, these two outlets are connected to the vacuum pump (14) via the pulp (12), (12'). And this pulp (12).

(12') are opened together, pulp (13) and (13'
) are both closed, the first and second spaces (4),
(5) were both made into vacuum spaces.

Furthermore, as shown in FIG. 1(C), the other substrate was placed at a predetermined position on this upper surface.

That is, the upper and lower substrates were aligned with each other to ensure that there was no misalignment of the upper and lower electrodes. Then, the pulp (12°) is closed so that the other second space (5) has a positive pressure compared to the first space (4) from a vacuum state, and the pulp (13'') is gradually opened. Air or nitrogen was leaked to create atmospheric pressure.

Then, as shown in Figure 1 (C), the silicone rubber (6)
expands downward and presses the other opposing substrate (1゛) to the side of one base +7i (1). At atmospheric pressure, a pressure of I kg/cm2 can be applied.

Further, when nitrogen is supplied from (13') and further pressurized, it is also possible to set the pressure to 2 to 5 kg/cm2, which is 1 atm or more.

In this way, it is possible to apply uniform pressure to the entire surface of the pair of substrates, and due to this pressure, liquid crystals were initially provided at one or more points in the form of dots or planes, but the liquid crystals were placed flat on the surface of the substrate (1). It spreads laterally and is laminated.

Thereafter, the first space is also brought to atmospheric pressure, the lid-side container (10) of this container (100) is opened, and the first lamination step is completed.

Furthermore, this pair of substrates is precisely aligned under a high temperature condition where the viscosity of the liquid crystal is low. This precise alignment may be performed within the container (100) or on the hot plate at another location.

Next, lead terminals of an electric circuit or terminals of a printed electric circuit, particularly, for example, FPC (Flexible Printed Circuit, hereinafter referred to as FPC for brevity) are connected to the peripheral portions of the pair of substrates by soldering. For this connection, P-1000 or CP-2000 sold by Sony Chemical Company was used. This connection is shown, for example, in Electronic Technology (June 1984 issue). The outer periphery of the pair of substrates with the lead terminals connected in this way was fixed with an organic resin.

That is, inside the container (100) of FIG. 1(B), there is a pair of substrates to which an electric circuit (21) such as an FPC is connected, and on the outer periphery of the substrate there are curable resins (1B) and (1B') and on the outside thereof. Protective organic resins (19) and (19'') are arranged. That is, the structure shown in Fig. 1 (D) is arranged in the container shown in Fig. 1 (B), and the lid (10') is closed. Furthermore, as in the first lamination step, the entire container is evacuated.Furthermore, if a thermosetting resin is used as the hardening resin, it is heated to a predetermined temperature, for example, 120°C.Then, the thermosetting resin becomes a primary It becomes soft and wraps around the sides of the pair of substrates.In order to improve the adhesion between this surrounding debris and the outer periphery of the substrate and the outer periphery of the substrate, the vacuum step and the valve (13") are opened and the first As shown in Figure (C), a pair of curable resins (18) are placed through a rubber (6).

The step of pressurizing (18') is important. Then, the thermosetting reaction is further completed.

Thus, the outer periphery including the outer periphery of the pair of substrates (cells) that are in close contact with each other via the liquid crystal (2) to which the FPC is connected is coated with a curable resin (20
) is fixed. For example, the hardening resin is EVA (ethylene vinyl alcohol), and this EV is placed on the top surface.
A uses PE as a protective resin to withstand subsequent actual use.
Cover with S (polyether sulfone) thin film. Thus, as shown in FIG. 1(E), a pair of substrates and an FPC
terminals can be fixed to each other and integrated.

Thus, one of the pair of electrodes/leads (for example, the lower side)
If one direction is a simple matrix electrode/lead structure in which the other direction is only the Y direction, this alignment accuracy can even allow an accuracy of 1 to 3 mm. However, in a configuration in which one electrode is a rectangular electrode with a width of 400 μm and the other electrode is a striped electrode in the Y direction with a width of 400 μm, the accuracy error is required to be less than ±30 μm. In this case, as mentioned above, in Figure 1 (D
) Perform precise positioning during the process. This positioning accuracy is determined by its use.

Further, 120℃ (30 minutes), pressurization (5 minutes), 160℃ (
10 minutes) to crosslink and stabilize the curable resin by heat curing to obtain the image shown in FIG. 1(E).

In this way, by performing two independent lamination processes, the central part of the pair of substrates is filled with liquid crystal, and the liquid crystal is sealed in the outer peripheral part and the FPC is integrated with the glass substrate by fixing the organic resin. Ta. This sealing had a width of 2 to 10 mm, for example 5 mm, to strengthen the adhesion between the substrates. It is preferable to cover the connection portion of the FPC with an organic resin (18). However, just covering a portion of it with material is effective for mechanical security.

Figure 2 corresponds to (^) in Figure 1, (A-1), (
A-2).

(A-3) is shown, and B-1) corresponds to Fig. 1 (E).
, (B-2) is shown. That is, FIG. 2 (A-3) is shown corresponding to FIG. 1 (8). A plan view of the upper substrate is shown in (A-1), and a plan view of the lower substrate is shown in (A-2). FIG. 2 (B-2) corresponds to FIG. 1 (E). This plan view is shown in (B-1). As is clear from these, each has an electrode external connection region (17), (17') provided on one side of the substrate. This external connection area has an FP for electrical connection from other external sources.
C (flexible printed electronic circuit). Therefore, in FIG. 2 (B-1), the sealing organic resin was connected to the FPC. It is effective to cover this external connection area as well to increase the adhesion strength in this connection area.

In this embodiment, in the state shown in FIG. 1(A), the FPC may be placed continuously on each board. In that case, during the steps in Figure 1 (B) and (C), the FPC
Since the laminates 1 and 2 are also held in the container, there is a drawback that the container becomes unnecessarily large.

Example 2 This example is the same as Example 1 except for the following steps.

That is, a curable resin is placed in advance on the outside of the surface to be filled with respect to the upper substrate (1') in FIG. 1(A), as shown in FIG. 1(D). This pair of substrates (1).

At (lo), the FPC is already connected at the connection part.

Further, a pair of substrates (IL (1') and sealing resin (18), (1
8') is placed in a container (100) as shown in FIG. 1(B), and a liquid crystal (2) is laminated thereon as shown in FIG. 1(C). That is, the first lamination process and the second lamination process are performed simultaneously.

In this way, FIG. 1(E) can be obtained.

The rest is the same as in Example 1 except for the above.

In this process, all can be done at the same time, so the working time can be reduced. However, it has the disadvantage that the accuracy of aligning the pair of substrates is poor.

``Effect'' By doing this, when trying to make a 20cm x 30cm plate, the connection part, which is the most problematic in terms of reliability, is covered with the remaining resin, making it possible to achieve high reliability.

In addition, this process has another feature in that it does not require any extra steps. The liquid crystal used in one piece is 0.3cc.
is sufficient, and liquid crystal, which is more expensive than gold at 3000 yen/g, can be used very effectively.

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

The entire area of the substrate can be used as a display section.

That is, in the conventionally known TN liquid crystal filling operation,
The feature is that no stress is applied to the liquid crystal. Therefore, the effect of the sealant in the peripheral area is to 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, on the other hand, in the filling operation of the smectic liquid crystal having a high viscosity used in the present invention, the inventors have found that even if this stress is applied to the liquid crystal itself, there is no problem with regard to alignment and reliability. By utilizing this property of withstanding pressure, it has become possible to create a manufacturing method of the present invention, which is completely different from conventional methods.

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 10 μm of 1 μ or more) along the rubbed surface under high temperature conditions.
It is effective to shift the liquid crystal by 4 μm) and apply stress to the liquid crystal to align it.

In the liquid crystal display device of the present invention described above, a polarizing plate can be provided on the outside of one or both of the substrates to make it a guest-host type or a birefringent type. When this liquid crystal display device is used as a reflective type, one polarizer is used, and the electrode on the incident light side is made transparent, and the other is made a reflective type electrode. This can be achieved by using a guest-host type liquid crystal material and adding, for example, 3% by weight of an anthraquinone dichroic dye to FLC. At this time, if an FLC having a tilt angle of about 45 degrees is used, the contrast ratio can be increased.

On the other hand, in the case of a birefringent type, which is a transmissive type or a reflective type using two polarizing systems, the two polarizers are oriented on the outside of each substrate, and the tilt angle of the FLC is set to approximately 22.5 degrees. This can be achieved by doing this. In the case of a translucent type, a display can be obtained by illuminating the backlight with an EL (electroluminescence) fluorescent lamp or natural light and controlling the amount of transmitted light. In the case of a reflective type, a reflection plate is disposed outside the polarizer on the back surface and the incident light is reflected back to the incident surface side, thereby displaying information.

In the present invention, if the polarizing plate has heat resistance, it can be fixed to the surface of the glass substrate at the same time as sealing the outer periphery. Further, if a photocuring method is used, it is possible to fix the polarizing plate as well as sealing the liquid crystal.

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, 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 NTN type can be used 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 liquid crystal device of the present invention is effective not only for liquid crystal display devices but also for other applied products using liquid crystals. Examples of applied products include disk memory devices, speakers, infrared sensor links, and the like.

[Brief explanation of drawings]

FIG. 1 shows a method for manufacturing a liquid crystal device of the present invention. FIG. 2 shows a plan view and a longitudinal sectional view of the liquid crystal device of the present invention.

Claims (1)

[Claims] 1. In a liquid crystal device in which a pair of substrates are opposed with the surfaces to be filled inside and liquid crystal is filled between the surfaces to be filled, the outer periphery of the pair of substrates is covered and the liquid crystal is A liquid crystal device characterized by being sealed. 2. In a liquid crystal device having electrodes and leads, a pair of substrates facing each other with the surfaces having the electrodes and leads inside, and liquid crystal filled between the electrodes, an electric circuit connected to the electrodes and leads. Lead terminals or terminals of printed electrical wiring are connected to each other at a connecting portion, the outer periphery of the pair of substrates is covered to seal the liquid crystal, and an organic resin film is provided to cover the connecting portion. A liquid crystal device characterized by: 3. A liquid crystal device according to claim 1 or 2, characterized in that the organic resin presses the outer peripheries of the pair of substrates from the upper and lower surfaces to bring them into close contact with each other.