JPS6113209B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining a liquid crystal cell by hermetic sealing.

A method for manufacturing a liquid crystal layer holding structure (hereinafter referred to as a liquid crystal cell) of a liquid crystal display element is generally carried out as follows.

A transparent conductive film is formed on a smooth first glass substrate by vapor deposition or spraying of a thin film of indium oxide or tin oxide, and the thin film is etched into an arbitrary pattern to obtain a transparent electrode.

Furthermore, in the case of a reflective type, a metal thin film such as aluminum or palladium, and in the case of a transmissive type, a transparent conductive film as described above is formed in an arbitrary pattern on a smooth second glass substrate by mask vapor deposition or etching. , we get the opposite.

After performing various treatments on the two glass substrates obtained as described above, they are glued together at an appropriate distance (hereinafter referred to as liquid crystal cell thickness) using epoxy adhesive or low melting point glass to form a liquid crystal cell. get.

Here, the matters that the container obtained as described above must have as a liquid crystal cell will be described below.

Uniform liquid crystal cell thickness: This is an important factor that determines the power consumption and response characteristics of liquid crystal display elements.

Preventing the penetration of water molecules: The incorporation of water molecules into the liquid crystal material causes an increase in the conductivity of the liquid crystal material. In addition, for Schiff-based mixed liquid crystals (the general formula is shown in the formula), which is a typical liquid crystal material, As shown in the equation, since there is an equilibrium relationship with water molecules, the composition of the liquid crystal substance changes through the intermediary of the water molecules that have entered, causing a serious problem in that the transition temperature of the liquid crystal changes. It should be noted here that para-alkylaniline and para-alkoxybenzaldehyde generated in the formula can also be a cause of increasing the conductivity of the liquid crystal material.

Chemically stable against liquid crystal materials Mechanical strength Epoxy resin seals that meet the above conditions can be easily produced.
It is considered that it is essentially impossible to prevent the penetration of water molecules. On the other hand, hermetic seals using low melting point glass meet the above conditions.
, is relatively easy to satisfy, but considerable effort is required to control the liquid crystal cell thickness, which is the condition for . The conventional methods are shown below.

[Method] Low melting point glass is pasted by taking advantage of the fact that it has a fairly high viscosity near the temperature at which two glass substrates are sealed, and there is little lateral elongation when the pressure is applied to the extent necessary for sealing. A method of controlling the printing thickness using a screen is being used. Although this method is simple, a good sealing yield cannot be expected unless sufficient pressure is applied when sealing with low-melting point glass.
The screen printing thickness largely depends on the viscosity of the low-melting point glass paste, which has a basic property of constantly changing during the printing process.
Controlling the liquid crystal cell thickness using this method requires considerable effort in mass production.

[Method] A low-melting glass that crystallizes easily (once crystallized glass has a property that it does not soften near that temperature) is screen printed on a glass substrate to form columnar spacers. Next, glass paste is screen printed in a frame shape on the glass substrate including the spacer, and the two glass plates are brought together and sealed together by applying sufficient pressure and heat.

This is the method for obtaining the desired cell thickness. At this time, the glass paste used has a slightly lower melting point than the above-mentioned low melting point glass.

Although this method allows for much more accurate control than the previously described method, it has the disadvantage that the manufacturing process is complicated.

The present invention eliminates these drawbacks and provides a simple method for controlling the thickness of a liquid crystal cell in a hermetic seal.

In place of the pillars of crystallized glass in the method, the present invention crushes and forms a large number of glass fiber particles from glass fibers with a uniform wire diameter, and utilizes the uniformity of the original glass fiber wire diameter to use this as a spacer. In addition, by selecting a glass fiber with a thermal expansion coefficient close to that of the glass paste, the generation of thermal stress between the glass paste and the spacer can be suppressed even when there is a large thermal change during the pressurization and heating operation. The object of the present invention is to provide a technology for manufacturing a liquid crystal display cell with good quality and operating characteristics, which maintains strong adhesive force of a hermetic seal and eliminates the occurrence of distortion in electrode plates.

Examples will be described below and explained in detail.

A glass fiber with a diameter of 9 μm (manufactured by Nittobo) was added to 100 parts of commercially available low melting point glass paste #5816-73 (manufactured by DuPont, USA) or #4017C (manufactured by ESL, USA) or glass 101 (manufactured by EMCA, USA). Add 1 part of the mixture crushed into small pieces in a mortar and stir well.

LS-
10mm× using a 20-inch printing machine (manufactured by New Long Co., Ltd.)
Screen printing is performed on the periphery of a 10 mm glass substrate to a width of 0.5 mm, the two glass substrates are glued together, and a load of 100 g is applied to each cell.
Firing was carried out at a temperature of about °C.

The cell thickness of the liquid crystal cell obtained by the above method is 9μ
A liquid crystal cell having a desired cell thickness of 10 μm to 10 μm was obtained in good yield.

As described above, according to the present invention, by selecting the particle size of the glass fiber particles mixed into the low melting point glass, it has become possible to obtain a desired liquid crystal cell thickness with good yield.

In the present invention, the small pieces of material to be mixed into the glass paste are glass fibers crushed into granules, but these are selected from materials whose thermal expansion coefficient is very similar to that of the glass frit constituting the glass paste. However, even when the process is performed under high pressure and high temperature as in the above embodiments, the generation of stress caused by the difference in expansion coefficient between the glass paste and the spacer is suppressed. That is, in the present invention, by mixing small pieces of a heat-resistant material with a similar coefficient of thermal expansion into the glass paste and sealing two glass plates with this glass paste, the thermal stability of the sealed part is improved.
This has established a liquid crystal cell that has high adhesive strength, suppresses the occurrence of distortion in the glass plate, and has high reliability, display operation characteristics, and a long cell life.

This is due to the following reasons. In other words, when sealing glass plates, they are heated to a temperature of 400 to 500°C, but if the paste contains foreign matter with a different coefficient of thermal expansion, the glass plates may break during the cooling process. However, with the method of the present invention, this does not occur and the manufacturing yield is high. Furthermore, a seal made with a paste mixed with small pieces having different coefficients of thermal expansion is vulnerable to mechanical and thermal shock, but the seal according to the present invention is excellent in this respect as well.

Claims (1)

[Claims] 1. In a method for manufacturing a liquid crystal cell in which a cell is manufactured by bonding two electrode plates via an adhesive mainly composed of glass paste and forming a certain gap for encapsulating liquid crystal, the method described above A glass fiber having a constant diameter determined corresponding to a constant gap and a coefficient of thermal expansion close to that of the glass paste is cut to form a spacer group, and the spacer group is dispersed in the glass paste to achieve the bonding. 1. A method of manufacturing a liquid crystal cell, comprising the steps of forming an agent, applying the agent to the electrode plate by screen printing, and hermetically sealing the two electrode plates by applying pressure and heating.