JPS6278526A - Manufature of liquid crystal device - Google Patents

Abstract

PURPOSE:To improve strength of electrical and mechanical connection at junctions by providing the first laminating process, a process that connects terminals of electric circuits to each other and the second laminating process. CONSTITUTION:Liquid crystal 2 is dropped on one of face to be filled 8 of a pair of substrates 1, 1' and uniform pressure is applied to whole surface of the pair of substrates. Thereby, liquid crystal is spread laterally along the surface of the substrate 1 and laminated. Then a lead terminal of an electric circuit or a terminal of a printed electric circuit is connected to peripheral parts of substrates. Then, hardening resin 18, 18' is placed in the pair of substrates in which an electric circuit 21 is connected in the container 100 and their outer periphery, and protective organic resin 19, 19' is placed its outside. The whole container is made vacuous as in the case of the first laminating process, and heated to specified temperature. The thermosetting resin becomes soft temporarily, and goes round to the sides of the pair of substrates.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a method for manufacturing a liquid crystal device including a liquid crystal display device that is modularized, and relates to a method for manufacturing a liquid crystal device including a liquid crystal display device that is modularized. The aim is to integrate the terminals of the electric circuit. 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 modularization of liquid crystal display devices in display units of microcomputers, word processors, televisions, etc.

``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 has a simple matrix configuration of 4-size size with 400 elements in the horizontal direction and 200 elements in the vertical direction. Display devices using a multiplexing drive method are known.

If such a TN liquid crystal is not to be manufactured, the low viscosity of this TN liquid crystal can be utilized to prepare a pair of glass substrates for 5 to 10 minutes.
After spacers are spread between the glass substrates, which are opposed to each other with a gap of .mu., a sealing agent is applied to the periphery of the pair of glass substrates, and the glass substrates are brought into close contact with each other. At this time, a portion of the surrounding seal portion is not sealed, and the injection port remains. After that, the pair of substrates whose peripheries have been sealed are held in a vacuum container, and the whole is evacuated. Furthermore, after this, this hole part is TN? g. By immersing the liquid crystal in a crystal solution and bringing the inside of the vacuum container to atmospheric pressure, the liquid crystal was filled into a gap between 5 and 10 μm between a pair of substrates using capillarity. 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 this 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 terminal of the electric circuit or the printed electric circuit is weak, and reliability tends to be lowered.

(2) It takes time to manufacture the electrical circuit connection terminals and the sealing work around the display panel. (3) Use a narrow gap between cell electrodes of 4μ or less, preferably 0.5 to 3μ. If a high viscosity liquid crystal material is used, it takes an extremely long time to fill the liquid crystal material.

(4) 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.

(5) Liquid crystal material that is not effectively used during filling accounts for 9
It's close to 0%, which means there's 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 instead seals the periphery of the pair of substrates with liquid crystal. A liquid crystal is placed on the substrate, 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 achieve high 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 connecting portions is cured, and the peripheral portions of the pair of substrates are sealed with the resin, thereby providing a second lamination step.

In the present invention, the liquid crystal material is a highly adhesive liquid crystal, such as a smectic C phase, particularly preferably a smectic C phase (
A ferroelectric liquid crystal that exhibits the characteristics of SmC" is used. In other words, the cell spacing is 4 μm or less, generally 0.5 to 3 μm.
By doing so, a state in which the helical structure has disappeared 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. Furthermore, mechanical coupling 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 liquid crystal material with high viscosity is used, its lamination,
It does not require more than 2 hours for the mounting and sealing work.

(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) and (1'). Electrodes are provided on the opposing filling surfaces (8) and (8°), respectively. 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 N (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-P'-amino-methyl gatyl benzoate) and B-8 (9-ocluoxy-4'-biphenylcarboxylic acid-2-methylbutyl ester) are added. We have provided branded LCDs with blended LCDs, etc. In addition to this,
FLCs such as BOBAMBC or blends of FLCs may be filled. 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 volume 1 (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 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 having a particle size of 2 μm 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 substrate (1°) facing above is 0.1
~10 mm, for example 3 mm apart, 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 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 valves (12) and (12').
12).

(12') are both opened, valves (13) and (13'
) are both closed, and the first and second spaces (4)
, (5) are both 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 valve (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 valve (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) against the one substrate (1). At atmospheric pressure, a pressure of 1 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/cm'', 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.

After this, the space in the cylinder 1 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, an IJ terminal of an electric circuit or a terminal of a printed electric circuit, particularly, for example, a terminal of an FPC (flexible printed circuit, hereinafter referred to as FPC for brevity) is connected to the peripheral portions of the pair of substrates by soldering. For this connection, use the P-1000 or CP-2000 sold by Sony Chemical.
were connected using. 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 outside thereof, curable resins (18) and (18') are placed. Protective organic resins (19) and (19') are provided. That is, the structure shown in FIG. 1(D) is placed in the container shown in FIG. 1(B), and the lid (10') is closed. Furthermore, the entire container is evacuated as in the first lamination step. Further, if a thermosetting resin is used as the curable resin, it is heated to a predetermined temperature, for example, 120°C. The thermosetting resin temporarily softens and wraps around the sides of the pair of substrates. In order to improve the adhesion between this surrounding debris and the outer periphery and outer periphery of the board, a vacuum drawing process and a valve (1
3') and open the rubber (6') as shown in Figure 1 (C).
) through a pair of curable resins (18).

The step of pressurizing (1B') 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, if the hardening resin is EVA (ethylene vinyl alcohol), this EVA is applied to the top surface.
should withstand subsequent actual use (using PES as a protective resin)
Cover with a thin film (polyether sulfone). In this way, as shown in FIG. 1(E), the pair of substrates and the terminals of the FPC 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 the case where 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 ±30 μm or less. 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 was made to have 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 (A) in Figure 1, (8-1), (
A-2).

(A, 3), corresponding to Fig. 1 (E) 84)
, (B-2) is shown. That is, FIG. 2 (A-3) is shown corresponding to FIG. 1 (A). The plan view of the upper board is shown in (A-1), and the plan view of the lower board is shown in (A-2).
Shown below. FIG. 2 (8-2) corresponds to FIG. 1 (E). This plan view is shown in (B-1). As is clear from these, each has an electrode external connection area (17), (17'') provided on one side of the substrate.This external connection area is provided with 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 laminate is also held within the laminating container, it has the disadvantage 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).

(1″) is already connected to the FPC at the connecting part.

Furthermore, a pair of substrates (1), (1') on which such printed circuits are connected at a connecting part, and a sealing resin (18), (
18') 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 so, A4 size (20cm x 30cm
When trying to make a new device (area), high reliability was achieved by covering the connection part, which is the most problematic area in terms of reliability, with organic resin.

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.
'μm) It is effective to apply stress to the liquid crystal and distribute 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, when using two polarizing systems to create a transmissive or reflective birefringent type, the two polarizers are oriented on the outside of each substrate, and the tilt angles of Fl and C are set to about 22. This can be accomplished by making it five degrees. In the translucent type, a display can be produced by irradiating the hack light with an EL (electroluminescence) fluorescent lamp or natural light and controlling the amount of light transmitted. 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 NrN type can be used as the nonlinear element.

In the liquid crystal display device of the present invention, display and reading can be improved 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 printers, 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. A first laminating step in which a liquid crystal material is provided on a surface to be filled of a substrate, the other substrate is opposed to form a pair, and the two substrates are brought into close contact with each other via the liquid crystal; At the same time or after this step, a step of connecting lead terminals of an electric circuit or terminals of a printed electric circuit to external connection terminals provided on the substrate, and curing the peripheral portions of the pair of substrates and the continuous terminals. a second laminating step of disposing a rubber resin, evacuating the entire structure, applying pressure to at least the outer peripheral portions of the pair of substrates, and sealing the peripheral portions of the pair of substrates with the resin; 1. A method for manufacturing a liquid crystal device, characterized by comprising: 2. In claim 1, the step of connecting lead terminals of an electric circuit or terminals of a printed electric circuit to external connection terminals of a substrate, and providing a liquid crystal material on the surface to be filled of the substrate, A first laminating step in which the substrates are formed into pairs facing each other and brought into close contact with each other via the liquid crystal, and simultaneously with or after this step, the peripheral portions of the pair of substrates and the connected terminals are cured. a second laminating step in which the outer peripheral portions of the pair of substrates are sealed with the resin by applying pressure to at least the peripheral portions of the pair of substrates; 1. A method for manufacturing a liquid crystal device, characterized by comprising: 3. A method for manufacturing a liquid crystal device according to claims 1 and 2, characterized in that a thermosetting resin is provided covering the connected terminals, and heat treatment is performed under pressurized conditions. .