JPH04243221A - Production of liquid crystal display element - Google Patents

Abstract

PURPOSE:To inexpensively produce the liquid crystal display device by effectively injecting and packing a liquid crystal compsn. in an injection stage into an enclosure for which a plastic film substrate is used. CONSTITUTION:A pattern of a shape consisting of two pieces of lines extending from an injection port 22 of an ordinary rectangular pattern toward the peripheral part of the substrate is formed by an adhesive 23 on one electrode substrate. Another sheet of electrode substrate is superposed thereon and after the substrates are stuck to each other, the electrode substrates are cut on the slightly outer side of the pattern of the adhesive 23 thereby the enclosure 25 formed with a projecting part 24 is produced on the outer side of an injection port 22. This enclosure 25 is held by directing the open end of the projecting part 24 upward and spreading this part in a funnel shape. After the inside of such enclosure is evacuated to a reduced pressure, a prescribed amt. of the liquid crystal compsn. is dropped into the projecting part 24 and is stored thereon. This liquid crystal compsn. is injected into the enclosure by a pressure difference between the inside and the outside and after the injection port is sealed, the projecting part 24 is cut away.

Description

[Detailed description of the invention]

0001

[Purpose of the invention]

0002

[Industrial Application Field] The present invention relates to a method for manufacturing a liquid crystal display element, and in particular, in the manufacture of a liquid crystal display element in which a plastic film substrate is used as a sandwiching member for the liquid crystal composition, the liquid crystal composition is injected without waste. The present invention relates to a method of filling and manufacturing inexpensive liquid crystal display elements.

0003

2. Description of the Related Art In recent years, many liquid crystal display devices have come onto the market as displays for televisions, word processors, personal computers, etc., taking advantage of their light weight and low power consumption. Glass substrates have traditionally been used as substrates for such liquid crystal display elements, but as liquid crystal display elements become more widespread, there is a growing demand for lighter, thinner and higher display quality substrates. There is. In order to achieve such reduction in weight and thickness, it is effective to use a plastic film as a substrate, and one with a relatively small display area has already been put into practical use.

FIG. 4 shows the structure of a liquid crystal display element using a plastic film as a substrate. That is, in the figure, numerals 1 and 2 indicate two transparent plastic film substrates arranged parallel to each other, and these substrates 1
, 2 are formed with transparent electrodes 3 and 4, respectively, and alignment films 5 and 6, which have been subjected to alignment treatment such as rubbing, are formed thereon, respectively. Further, these two electrode substrates are bonded and sealed with an adhesive 7 such as an epoxy resin, and a liquid crystal composition 8 is sandwiched between them in contact with the alignment films 5 and 6. There is. Note that the reference numeral 9 in the figure indicates a gap material for keeping the distance between the substrates constant.

Generally, in the production of liquid crystal display elements, the following vacuum immersion injection method has been conventionally used to inject and fill a liquid crystal composition between two electrode substrates.
This method is also effective in manufacturing the liquid crystal display element using a plastic film as a substrate. That is, as shown in FIG.
The envelope 13 which is laminated and sealed and the boat 14 containing the liquid crystal composition 8 to be injected are placed inside a vacuum chamber 15, and the inside of the vacuum chamber 15 is vacuumed and depressurized for a certain period of time. After evacuating the inside of the envelope 13, the inlet 12 of the envelope 13 is immersed in the liquid crystal composition 8 in the boat 14. Next, in this state, air or the like is leaked into the vacuum chamber 15 to return it to normal pressure or pressurized state, thereby removing the envelope 13.
Create a pressure difference between the inside and outside. Then, after injecting and filling the liquid crystal composition 8 into the envelope 13 using this differential pressure, the injection port 1
2 from the outside using an adhesive or the like.

[0006]

However, in such an injection method, it is necessary to make the amount of liquid crystal composition 8 to be injected into the boat 14 considerably larger than the amount that just fills the void in the envelope 13. Furthermore, there is a limit to the repeated use of such a liquid crystal composition 8, so there is a problem that a large amount of the liquid crystal composition 8 is wasted. Also,
Since the liquid crystal composition 8 adheres not only to the inner circumferential surface of the envelope 13 but also to the outer circumferential surface, after the liquid crystal composition 8 is injected and the injection port 12 is sealed, the liquid crystal composition 8 adheres to the outer circumferential surface of the envelope 13, etc. There is a problem in that a cleaning step is required to remove the liquid crystal composition 8, which increases the manufacturing cost of the liquid crystal display element.

The present invention was made to solve these problems, and an object of the present invention is to provide a method for manufacturing a liquid crystal display element at low cost by reducing waste of liquid crystal composition in the injection process.

[0008]

[Structure of the invention]

[0009]

[Means for Solving the Problems] The method for manufacturing a liquid crystal display element of the present invention includes two electrode substrates each having an electrode and an alignment layer formed on the surface of a plastic film in parallel so that the alignment layers face each other. After evacuating and evacuating the interior of the envelope, which is placed in a container and sealed with an adhesive except for the injection port, the liquid crystal composition is injected and filled from the injection port, and then the liquid crystal composition is injected and filled from the injection port. In the method of manufacturing a liquid crystal display element, after sealing with an adhesive the sides of the connecting portion of the two electrode substrates extending outward from the injection port to form a protrusion. , holding the envelope with the open end of the protrusion facing upward and expanded into a funnel shape;
Dropping and storing a predetermined amount of the liquid crystal composition in the protrusion,
The liquid crystal composition is then injected and filled into the envelope.

0010

[Function] In the method for manufacturing a liquid crystal display element of the present invention,
By extending the two electrode substrates constituting the envelope and sealing the sides of their connecting parts with adhesive,
A protrusion is formed on the outside of the injection port. Since the electrode substrate is formed based on a plastic film, this protrusion can be easily deformed into a funnel shape by widening the gap between the substrates on the open end side opposite to the injection port. As a reservoir for the liquid crystal composition to be injected, the liquid crystal composition can be efficiently injected and filled.

[0011] That is, after holding the envelope so that the open end of such a protrusion faces upward and expanding the protrusion into a funnel shape, the inside of the envelope is evacuated and evacuated. ,
A predetermined amount of liquid crystal composition corresponding to the volume of the cavity inside the envelope is dropped onto the protrusion and stored therein. Next, for example, air or the like is leaked outside the envelope to create a higher pressure than inside the envelope, creating a pressure difference between the inside and outside. Due to this pressure difference, all of the liquid crystal composition stored in the protrusion flows into the envelope through the injection port. Then, after the entire amount of the liquid crystal composition stored in the protrusion flows in and fills the envelope, the injection port is sealed with an adhesive or the like.

[0012] In this way, an amount of the liquid crystal composition approximately equal to the volume of the cavity in the envelope is dripped and stored in the protrusion, and this entire amount is injected and filled into the envelope, so that the liquid crystal composition is You can eliminate waste. In addition, in the present invention, after sealing the injection port, the protrusion on which the liquid crystal composition has adhered to the inner peripheral surface is cut and removed from immediately outside the injection port.
A liquid crystal display element can be manufactured without contaminating the outside of the envelope, and a cleaning step after injecting the liquid crystal composition is not required.Furthermore, in the present invention, the liquid crystal composition fills the inside of the envelope and the protruding parts are removed. It is also possible to drop a sealing adhesive into the protrusion when it is almost empty, allow it to harden immediately after entering the injection port, and finally cut and remove the protrusion. According to this method, the liquid crystal display element can be manufactured efficiently and at low cost without contaminating the outside of the envelope. In the present invention, it is desirable that the liquid crystal composition to be injected be defoamed in advance so that unfilled portions of the liquid crystal composition, so-called low-temperature bubbles, do not occur even if left at low temperatures.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the method for manufacturing a liquid crystal display element of the present invention will be described below with reference to the drawings. In the example, first, as shown in FIG.
, 0.1 mm thick polyether sulfone resin (
An ITO (indium-tin oxide) film is formed on the surfaces of the substrates 16 and 17 made of PES) film by sputtering, and then etched by a normal method to form a 0.65 mm width and 0 pitch in the center. 200 strip-shaped transparent electrodes 18 and 19 were formed with a diameter of .70 mm and a length of 150 mm. Next, after forming a polyimide thin film on the strip electrodes 18 and 19, a rubbing treatment is performed, and the alignment films 20 and 2
1 was formed. At this time, the polyimide thin film is 147 mm except for 6.5 mm on one end side of the strip electrodes 18 and 19.
It was formed in an area of mm x 147 mm, and the rubbing direction was A=120 degrees for the substrate 16 and A=30 degrees for the substrate 17 with respect to the strip electrodes 18 and 19.

Next, plastic beads having a particle size of 6 μm were uniformly scattered on the alignment film 20 of one of the electrode substrates as a gap material. Furthermore, as shown in FIG. 2, on the other electrode substrate, an epoxy adhesive 23 is applied and printed along the periphery of the alignment film 21, except for the injection port 22 provided on the opposite side of the exposed side of the strip electrode 19. did. In addition, with the same adhesive 23, a 2
The linear pattern of the book was printed and formed.

Next, the alignment films 20 and 21 are opposed to each other, the strip electrodes 18 and 19 are perpendicular to each other, and the rubbing direction is 24.
Two electrode substrates are placed one on top of the other so that they form an angle of 0 degrees.
They were bonded together by applying pressure and heating to harden the adhesive 23. Next, the electrode substrate was cut slightly outside the pattern of the adhesive 23 to produce an envelope 25 in which a protrusion 24 was connected and formed outside the injection port 22, as shown in FIG. At this time, the length of the protrusion 24 was 40 mm.

Next, the envelope 25 produced in this way is
The open end of the protruding portion 24 was held in a vacuum chamber with the open end facing upward and the opening diameter of this portion expanded into a funnel shape, and the inside of the envelope 25 was evacuated by suctioning and reducing the pressure inside the chamber. Next, a liquid crystal composition is placed in the funnel-shaped protrusion 24.
S-81, a counterclockwise chiral agent, is added to ZLI-2293.
After dropping 0.13 ml of 0.7 wt % of 1 (both manufactured by E. Merck & Co.), the liquid crystal composition was flowed into the envelope 25 by leaking nitrogen gas into the vacuum chamber. . Then, when the inside of the envelope 25 is almost filled with the liquid crystal composition, an ultraviolet curable resin is dripped into the protrusion 24, and when this resin reaches the injection port 22 and slightly enters the envelope 25, The resin is cured by irradiating it with ultraviolet rays,
The injection port 22 was completely sealed. Finally, the protrusion 24 was cut to obtain a liquid crystal display element.

[0017] In the manufacturing method of the embodiment configured as described above, the amount of liquid crystal composition required for injection is small, and the cleaning process of the liquid crystal display element after the injection process is not required, so that the liquid crystal display element can be manufactured at low cost. I was able to do that.

Note that the method for manufacturing a liquid crystal display element of the present invention is not limited to the above-described embodiments, and as shown in FIG. A shape forming portion 2201 may be formed. By doing so, the cell thickness at the injection port 22 portion can be controlled to be thinner.

[0019]

As explained above, according to the present invention, waste of the liquid crystal composition in the injection process is reduced, and the cleaning process of the liquid crystal display element after injection is unnecessary, so that the liquid crystal display element can be manufactured at a low cost. can be manufactured.

Note that the method for manufacturing a liquid crystal display element of the present invention is not limited to the above-described embodiment, and as shown in FIG.
Alternatively, the injection port 22 may be formed using the same method. By doing so, the cell thickness at the injection port 22 portion can be controlled to be thinner.

[Brief explanation of the drawing]

[Fig. 1] A diagram illustrating the manufacturing process of an electrode substrate in an example.

[Fig. 2] A diagram illustrating the adhesive forming process in the example,

[Fig. 3] A diagram illustrating the manufacturing process of the envelope in the example,

[Figure 4] A cross-sectional view showing the structure of a general liquid crystal display element,

[Fig. 5] A diagram illustrating a conventional injection filling method of a liquid crystal composition.

FIG. 6 is a diagram illustrating a manufacturing process of an envelope in another example.

[Explanation of symbols]

16, 17...PES film substrate 18, 19...Strip electrode 20, 21...Alignment film 22... Inlet 23...Adhesive 24... Protruding part 25……Envelope

Claims (1)

[Claims] 1. Two electrode substrates each having an electrode and an alignment layer sequentially formed on the surface of a plastic film are arranged in parallel so that the alignment layers face each other, and are bonded together and sealed with an adhesive except for the injection port. In the method for manufacturing a liquid crystal display element, the method of manufacturing a liquid crystal display element comprises: after evacuating the inside of an envelope formed by a vacuum cleaner, injecting and filling a liquid crystal composition through the injection port, and then sealing the injection port. After sealing the connecting portion sides of the two electrode substrates extending outward from each other with an adhesive to form a protrusion, the open end of the protrusion is turned upward and expanded into a funnel shape. A liquid crystal display element characterized in that the envelope is held in a state where the envelope is held, a predetermined amount of liquid crystal composition is dropped and stored in the protrusion, and then this liquid crystal composition is injected and filled into the envelope. manufacturing method.