JPS62267720A - Manufacture of liquid crystal element - Google Patents

Abstract

PURPOSE:To obtain a liquid crystal element having excellent element characteristics at a high yield, by using a flexible substrate for at least one of the substrates which hold a liquid crystal substance in between and continuously carrying out a series of processes which form a film of a bonding agent and another layer of the liquid crystal substance containing a spacer on the flexible substrate and harden the bonding agent by pressing after the other substrate is put on the flexible substrate in a pressure-reduced atmosphere. CONSTITUTION:A glass substrate 3 is placed on rollers 5 and a flexible substrate 1 is held by short rollers 6 provided under a condition where the rollers 6 are not contacted with a bonding agent film. Leading edges of both base plates 3 and 1 are inserted into the space between press rollers 7 and a liquid crystal substance 9 containing a spacer is extruded through a slit-like nozzle 10 under a condition where the pressure is reduced to about 30 mmTorr. As the rollers rotate, the film of a bonding agent 2 is formed between the two substrates 3 and 1 and the substrates 3 and 1 are pressed 7 against each other after they are put together. Under this state, a layer 11' of the liquid crystal material is caused to have a thickness which is almost the same as that of the spacer and temporarily bonded by the bonding agent 2. Then the temporarily bonded substrates are heated by a heater 12 and properly bonded to each other by thermally setting the bonding agent 2. thereafter, the liquid crystal element thus manufactured is taken out from a pressure-reduced chamber 8 after returning the pressure in the chamber 8 to a normal pressure and each final liquid crystal element is obtained when it is cut off from the others and a polarizing plate is glued to it.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a liquid crystal element having a structure in which a liquid crystal substance is sandwiched between two substrates via a spacer, and more specifically relates to a method for manufacturing a liquid crystal element having a structure in which a liquid crystal substance is sandwiched between two substrates, and more specifically, it relates to a method for manufacturing a liquid crystal element having a structure in which a liquid crystal substance is sandwiched between two substrates. The present invention relates to a method of manufacturing a liquid crystal element using a flexible substrate such as the above.

(Prior Art) Liquid crystal displays that utilize the electro-optic effect and thermo-optic effect of liquid crystals are widely used. Further, electrophotographic liquid crystal printers using liquid crystal optical shutter arrays are being developed, and some of them have been commercialized. In this way, liquid crystal elements such as liquid crystal display panels and liquid crystal optical shutters are widely used because they can be driven with low voltage and low current. This is largely due to its low cost structure, which allows it to be constructed by simply sandwiching a fluid-like liquid crystal material between two electrode-equipped substrates. First, a conventional method for manufacturing a liquid crystal element will be explained using drawings. According to the conventional method, two substrates constituting a liquid crystal element are placed one on top of the other with a spacer interposed therebetween, and the periphery is bonded and sealed, leaving a liquid crystal injection hole, and then liquid crystal is injected.

FIG. 3 is a cross-sectional view showing the device structure before liquid crystal injection, during the manufacturing process of a liquid crystal device using a conventional manufacturing method. In FIG. 3, 21 and 22 are substrates on which electrodes, etc. are formed on the inner surface, and spacers such as alumina particles are used to form a gap 2.
The periphery except for 3 is sealed with adhesive 24. 25
is an injection hole for injecting liquid crystal into the gap 23;
In order to simplify the explanation, the figure shows an example in which an injection hole is formed by making a hole in one of the substrates, but there are many examples in which a cutout is provided in the peripheral sealing part to form an injection hole. In either structure, according to the conventional manufacturing method, first, the element with the structure shown in FIG. Alternatively, the device having the structure shown in FIG. 3 is immersed in a liquid crystal reservoir until the injection hole is immersed in the liquid crystal. In this state, the liquid crystal fills the gap 23 in Fig. 3 using the capillary principle, but if the gap 23 is extremely narrow or the element surface 4/( is wide), it will take a long time to fill the liquid crystal. , a method is used in which the reduced pressure state is broken with the injection hole blocked with liquid crystal, and the pressure difference is used to accelerate the filling of the liquid crystal into the gap 23. After filling the gap 23 with liquid crystal in this way, the injection is performed. Hole 25 is sealed with adhesive.

The conventional manufacturing method of the liquid crystal element described above is detailed in, for example, Chapter 11 of ``Latest Technology of F-Crystal'' (1983, Kogyo Kenkyutoku), written by Atsushi Matsumoto and Ichiyoshi Kakuda.

(Problems to be Solved by the Invention) In recent years, in response to demands for larger display capacities and larger areas of display elements, for example, liquid crystal elements have also tended to have larger areas. Furthermore, in order to improve the performance of liquid crystal elements, the thickness of the liquid crystal layer, that is, the gap between the substrates mentioned above, tends to become thinner.For example, liquid crystal elements suitable for large-capacity display elements and shutter array elements for liquid crystal printers are being actively developed. In the case of a liquid crystal element using a ferroelectric liquid crystal, an extremely thin layer of 1 to 2 microns is required compared to the conventional liquid crystal layer thickness of 6 to 8 microns.

As described above, the current situation is that as liquid crystal elements become larger in area and liquid crystal layers become thinner, conventional manufacturing methods are no longer able to cope with the problem. That is, the conventional manufacturing method is particularly unsuitable for increasing the area of a liquid crystal element and reducing the thickness of a liquid crystal layer in the following two respects. First, it is difficult to keep the gap between two substrates as thin as a few microns, especially in large areas. Although the spacer has the function of keeping the thickness constant, it is clear that in such a situation, the spacer has no function of keeping the gap at a constant thickness because the internal and external pressures of the gap are equal in the conventional manufacturing method. As described above, if the thickness of several layers becomes thick or non-uniform, the device characteristics may be insufficient or may vary. Secondly, in the method of injecting liquid crystal through the injection hole, the gap is narrow, and when the area becomes large, it is extremely difficult to completely fill the gap with liquid crystal, and even if it were possible, it would take an extremely long time. , leading to high manufacturing costs.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a liquid crystal element with good device characteristics at a high yield and at low cost even if the liquid crystal element has a large area and a thin liquid crystal layer.

(Means for Solving the Problems) In order to solve the above-mentioned problems and achieve the above objects, the present invention provides means in which at least one of the two substrates sandwiching the liquid crystal material is flexible. A method for manufacturing a liquid crystal device that is a flexible substrate, the method comprising forming an adhesive film on at least one of the substrates, and then forming a layer of liquid crystal material containing spacers on one of the substrates. a second step of superimposing the other substrate on the substrate on which the liquid crystal material layer is formed; and a third step of temporarily adhering the two superimposed substrates by applying pressure to each other. and a fourth step of curing the adhesive and performing main bonding, and are characterized in that the steps of curing the adhesive and performing main bonding are performed successively in the order from the first step to the fourth step in a reduced pressure atmosphere.

(Function) According to the manufacturing method of the present invention, two substrates are overlapped with the liquid crystal material layer sandwiched between them under reduced pressure, and the adhesive is cured under pressure, so that even after the liquid crystal material is sealed, the external pressure of the liquid crystal element remains Since the distance between the two substrates, that is, the layer thickness of the liquid crystal material, is approximately maintained at the spacer thickness by external pressure, it is maintained uniform even if the area is large. In addition, since the liquid crystal material is placed in the gap between two substrates before they are pasted together, even if the liquid crystal element has a large area and a narrow gap between the substrates, it may not be possible to fill the liquid crystal material or it may take a long time. Nothing happens. In addition, since the liquid crystal material is installed under reduced pressure,
A so-called degassing process is performed, and problems such as air bubbles remaining in the liquid crystal material do not occur.

(Example) An example of the method for manufacturing a liquid crystal element of the present invention will be described in detail below with reference to the drawings. Figure 2(a).

(b) is a plan view showing two substrates in a liquid crystal element produced by the manufacturing method of the present invention. One substrate 1 is a flexible polyester substrate, and first, an epoxy adhesive film 2 is formed by screen printing.

Of course, the substrate has already been subjected to necessary treatments such as electrodes and an alignment treatment film. The other substrate 3 is a glass substrate.

These two substrates are bonded together using an apparatus having the structure schematically shown in FIG. 1 to manufacture a liquid crystal element. That is, first, as shown in FIG. 1(a), the substrate 3 is placed on the roller 5, the substrate l is held by the short roller 6 provided so as not to contact the adhesive film, and the tip of the side substrate is It is inserted into the gap between the pressure rollers 7. In this state, the pressure in the chamber 8 is reduced to about 30 m Torr, and then the pressure shown in Fig. 1 (
As in 1)), the liquid crystal substance 9 containing spacers is extruded from the slit-shaped nozzle IO and placed on the substrate 3. In this state, the layer 11 of liquid crystal material is exposed to a reduced pressure atmosphere, and the minute bubbles contained therein disappear. Thereafter, as shown in FIG. 1(C), an adhesive film is formed on the two substrates by the rotation of the roller, and the two substrates are gradually overlapped in the area where the liquid crystal material layer is installed, and the pressure roller 7
are mutually pressurized by In this state, layer 1 of liquid crystal material
1' is approximately the same thickness as the spacer, and the two substrates are temporarily bonded with adhesive 2. The two substrates bonded together in this manner are heated by a heater 12 as shown in FIG. 1(d), and the adhesive 2 is thermally cured to be permanently bonded. In this state, the chamber 8 returns to normal pressure, and the liquid crystal element is taken out. Thereafter, unnecessary portions of the substrate are cut off as necessary, polarizing plates are attached, etc., and the liquid crystal element is completed.

It was confirmed that the liquid crystal element manufactured in this way has good layer thickness uniformity even when the liquid crystal layer is large in area and thin, and liquid crystal elements with excellent characteristics can be manufactured at a high yield, leading to cost reduction. It was confirmed that this is an effective manufacturing method.

Although this example describes the case of manufacturing one liquid crystal element, it is also possible to use a large substrate to form multiple liquid crystal elements on the large substrate and then cut the liquid crystal elements into individual liquid crystal elements. Needless to say, it is.

(Effects of the Invention) As described above, according to the present invention, even if the liquid crystal element has a large area and a liquid crystal layer thickness of T, it is possible to manufacture a liquid crystal element with good element characteristics at a high yield and at low cost. is obtained.

[Brief explanation of drawings]

FIGS. 1(a) to (d) are schematic diagrams of an apparatus showing the main steps of the manufacturing method of the present invention, and FIGS. 2(a) and (b) are two substrates in a state where the previous process has been carried out. FIG. 3 is a plan view showing a liquid crystal element in the process of being manufactured by a conventional manufacturing method. 1 is a flexible substrate, 2F'i adhesive, 3 is a glass substrate, 5
．． 6 is a support roller, 7 is a pressure roller, 8 is a decompression chamber,
9 is a liquid crystal material containing a spacer; 10 is a slit-like nozzle; 11 is a layer of liquid crystal material disposed on a substrate; 11'
12 is a layer of liquid crystal material approximately equal to the spacer thickness; 12 is a heater; 21. 22 is a substrate, 23 is a gap filled with a liquid crystal material, 24 is an adhesive, and 25 is a hole for press-fitting a liquid crystal material. Agent Patent Attorney Nobu Honjo Figure 1 (a) Figure 1 (b) Figure 1 (c) Figure 1 (d)

Claims (1)

[Claims] In a method for manufacturing a liquid crystal device in which at least one of two substrates that sandwich a liquid crystal material is a flexible substrate, after forming an adhesive film on at least one of the substrates,
a first step of forming a layer of a liquid crystal material containing a spacer on one of the substrates; a second step of superimposing the other substrate on the substrate on which the liquid crystal material layer is formed;
A third step in which the two substrates stacked on top of each other are temporarily bonded by applying pressure to each other, and a fourth step in which the adhesive is cured and permanently bonded are performed from the first step to the second step in a reduced pressure atmosphere. 4
A method for manufacturing a liquid crystal element, characterized in that the steps are performed successively in the order of.