JPH01147518A - Production of liquid crystal cell and glass substrate for liquid crystal cell - Google Patents

Abstract

PURPOSE:To obtain a good-quality liquid crystal cell having no unequal colors or the like by forming the opposite surface of one of glass substrates which face each other to a shape symmetrical surface to which the opposite surface of the other glass substrate is transferred. CONSTITUTION:Flat plate-shaped soda lime glass (550 deg.C transition point) 4 is imposed on a stand 2 made into a cylindrical recess the front face 31 of which is formed to 1,000mm radius of curvature in a heating furnace 1. The glass 4 is heated for 2hr at 600 deg.C and is brought into contact with the front face 31 of the stand to form the curved glass 4a. This glass 4a is placed on the front face 31 of the stand and further, the flat plate-shaped low melting point glass (120 deg.C transition point) 5 is imposed thereon and is heated at 300 deg.C heating temp. to form the glass 5a. The opposite surface 51a of the glass 5a comes into tight and close contact with the opposite surface 41a of the glass 4a. An ITO film is then deposited by evaporation on the projecting face of the glass 4a and the concave face of the glass 5a is subjected to a sputtering treatment; thereafter, the liquid crystal cell is formed by an ordinary method, by which the good liquid crystal cell having no domains and unequal colors is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a liquid crystal cell used for a liquid crystal mirror, etc., and a method for manufacturing a glass substrate for a liquid crystal cell.

[Prior Art] Conventionally, curved glass substrates for liquid crystal mirrors used in automobile door mirrors, etc., are made by placing flat glass on a pedestal made of fireproof material, softening it by heating, and deforming it along the pedestal. It is made using a method of molding.

[Problem to be Solved by the Invention 1] When a curved glass substrate formed by such a self-weight bending method is used for a liquid crystal cell, there are variations in the curvature of the curved glass substrate, so two of the curved glass substrates are separated at a predetermined interval. If they are separated and faced, the gap between them will be uneven.

For example, when a flat glass substrate is bent by its own weight, the curvature is reduced to half t! 1
When processed as 00011 m, there is a variation of about ±50 m1 in the radius of curvature. On the other hand, in order to make a good liquid crystal cell, it is necessary from experience that the difference in the radius of curvature of the two curved glass substrates used be about ±10 mm. Therefore, in order to obtain a good liquid crystal cell, it is necessary to measure the curvature of each curved glass substrate and to combine two curved glass substrates whose curvatures are within an acceptable range, which complicates the manufacturing process. There is a problem.

Furthermore, even when two curved glass substrates with a difference in curvature within the allowable range are combined, there are local differences in curvature, so there is a limit to improving the uniformity of the gap between the substrates of the liquid crystal cell. Ta.

[Means for solving the problem] The liquid crystal cell of the present invention has two glass substrates and a liquid crystal layer sealed between the glass substrates, in which the opposing surfaces of one of the glass substrates are opposite to each other. is characterized in that the opposing surface of the other glass substrate is a transferred mold symmetry surface.

The liquid crystal cell having the above-mentioned two glass substrates and a liquid crystal layer is a known guest host (GH) type liquid crystal cell equipped with a transparent electrode, a twisted nematic (TN) type liquid crystal cell, a dynamic scattering (DS) type liquid crystal cell, etc. It can be any of the following.

The opposing surface of the other glass substrate, which defines the surface shape of the opposing surface of one of the mutually opposing glass substrates, is given a certain shape in advance depending on the intended use of the liquid crystal cell, such as a liquid crystal mirror.

Furthermore, when the opposing surface of one glass substrate is transferred to the opposing surface of another glass substrate, for example, the opposing surface of one glass substrate is transferred to the opposing surface of one glass substrate by a mechanical method as shown in the method for manufacturing a glass substrate for a liquid crystal cell described later. This refers to copying the same surface shape onto the opposite surface of another glass substrate and deforming this other glass substrate to make a mold. For example, contact may be used.

The fact that the opposing surfaces of the two glass substrates are mold-symmetric surfaces means that because they were formed by the above-mentioned transfer, the opposing surfaces have the same shape and differ only in direction.

Further, the method for manufacturing a glass substrate for a liquid crystal cell of the present invention includes placing a low melting point glass having a softening point temperature below the first glass substrate on one surface of the first glass substrate; heated above the softening point of low melting point glass,
The present invention is characterized in that one surface of the low-melting point glass is deformed so as to come into close contact with one surface of the first glass substrate, thereby forming a second glass substrate having a mold-symmetrical surface onto which one surface of the first glass substrate is transferred.

Here, the softening point temperature refers to the mlf temperature at which glass behaves like rubber before it becomes a viscous liquid when heated above its transition point temperature.
This refers to the lower limit temperature of the range, and refers to the temperature at which the viscosity corresponds to approximately 106.8 Pa-8.

The two glass substrates use glass materials having different melting points due to their characteristics. As the first glass substrate, commonly used soda lime glass (transition point: 500 to 600° C.) or the like can be used. Further, the low melting point glass used for the second glass substrate can be, for example, one having a proportion of tin, phosphorus, lead, oxygen and monofluorine. Further, to give an example, if these compositional element components are expressed in parts by weight in order, 64
Composition of ゜0-34.0-6.4-121.5-60.4 (transition point 95℃), 56.7-37゜0-6.2
-130.7-49.5 composition (transition point 125℃
), also 56.5-38.7-4.7-131.6-5
A composition having a composition of 2.8 (transition point: 120° C.) can be used.

The first glass substrate used is one that has been given a necessary surface shape depending on the application by, for example, a self-weight bending method.

This first glass substrate is placed and supported on a pedestal made of metal, refractory material, etc. installed in a heating furnace equipped with a heater. Here, the first glass substrate may be placed on a pedestal installed in the heating furnace and heated to a temperature higher than the softening point of the first glass substrate, thereby forming the first glass substrate and using the first glass substrate as it is. A second glass substrate is placed on top of this first glass substrate. In this state, it is heated with a heater.

Here, the heating temperature is set to be below the softening point temperature of the first glass substrate and above the softening point temperature of the second glass substrate.

Since the first glass substrate has a temperature below its softening point, it does not deform and maintains its rigidity. On the other hand, since the second glass substrate is heated above its softening point temperature, it gradually bends downward due to its own weight, and eventually the facing surfaces of the first glass substrate and the second glass substrate come into close contact with each other.
Transfer on the opposing surface is completed.

The two glass substrates obtained in this way can be made into a liquid crystal cell through normal steps such as sealing to form an empty cell container, injection of liquid crystal material, and sealing of liquid crystal injection holes.

[Example] The present invention will be explained below with reference to Examples.

Schematic cross-sectional views of the manufacturing method used in this example are shown in FIGS. 1 and 2. A heating heater 2 is provided in the heating furnace 1 . A pedestal 3 made of refractory material is installed inside the heating furnace 1, and the top surface 31 of this pedestal 3 has a radius of curvature of 10.
A cylindrical recess with a diameter of 0.00 mm is formed. A flat plate of soda lime glass (transition point 550°C) 4 is placed on top of this pedestal 3.
Place. In this state, soda lime glass 4 is heated at a heating temperature of 660° C. for 2 hours to soften it, and the lower surface 41 of this soda lime glass 4 is brought into contact with the upper surface 31 of pedestal 3 to form soda lime glass 4a.

The soda lime glass 4a obtained at this time had a radius of curvature of 9601 to 1 when 50 samples were measured.
It was 040mm.

The soda lime glass 4a thus formed is placed and supported on the upper surface 31 of the pedestal 3 as shown in FIG. 2, and a flat plate-like low melting point glass (transition point 120° C.) 5 is placed thereon. In this state, heating is performed at a heating temperature of 300° C. for a heating time of 1 hour to soften the flat low melting point glass 5 and form the low melting point glass 5a.

A cross-sectional view after molding is shown in FIG. Here, the opposing surface 51a of the low melting point glass 5a after molding and the opposing surface 41a of the soda lime glass 4a are in close contact with each other without any gaps.

An ITO film is deposited on the convex surface of the soda lime glass 4a formed by the IjIf manufacturing method of the embodiment, and the concave surface of the low melting point glass 5a is subjected to sputtering treatment, after which a liquid crystal cell is fabricated by a conventional method. The cell gap between the substrates of the liquid crystal cell at this time was 7 μm, the liquid crystal used was a phase transition guest-host mode liquid crystal, and a chiral substance (08-15) was added to the nematic liquid crystal so that the pitch number was 1. This is what I did.

Liquid crystal cell obtained by the above process (external dimension: 150Il)
As a result of inspecting 10 samples of 11×70111 m), all were found to be in good condition with no domains, uneven color, etc.

[Comparative Example] A liquid crystal cell was produced in the same manner by combining two pieces of soda lime glass 4a formed by the manufacturing method of the above example, and as a result of inspecting 10 samples, domains were generated in 8 of them. Color unevenness was also observed for the two domains without domains.

[Effect] In the liquid crystal cell of the present invention, the opposing surfaces of the two glass substrates are symmetrical in shape, so the cell gap between the substrates of the liquid crystal cell becomes uniform, resulting in a high-quality liquid crystal cell without domains, color unevenness, etc. It can be done.

In particular, when the glass substrate is made of curved glass, the radius of curvature can be made constant and it is also possible to cope with local changes in curvature.

In addition, the method for manufacturing a glass substrate for a liquid crystal cell of the present invention can easily manufacture a glass substrate for a liquid crystal cell in which the opposing surfaces of the 211M glass substrate as described above are symmetrical in shape, and the cell gap between the substrates for a liquid crystal cell can be reduced. It is possible to manufacture high-quality cells that are uniform and free of domains, color unevenness, etc.

Therefore, the process of measuring the curvature of each curved glass substrate and assembling two appropriate glass substrates can be omitted, saving labor in the manufacturing process and improving product yield.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the process of forming soda lime glass 4 before heating in the manufacturing method of the embodiment. FIG. 2 is a schematic explanatory sectional view showing the process of forming the low melting point glass 5 before heating in the manufacturing method of the embodiment. FIG. 3 is a schematic explanatory sectional view showing changes after heating in FIG. 2. 1... Heating furnace 2... Heater 3... Frame 4.4a... Soda lime glass 5.5a... Low melting point glass Figure 1, Figure 2, Figure 3.

Claims (3)

[Claims] (1) In a liquid crystal cell having two glass substrates facing each other at a predetermined interval and a liquid crystal layer sealed between the glass substrates, the facing surface of one of the glass substrates facing each other is the same as that of the other glass substrate. A liquid crystal cell characterized in that the facing surface is a pattern-symmetrical surface that has been transferred. (2) The liquid crystal cell according to claim 1, wherein the two glass substrates are curved glass. (3) A low melting point glass having a softening point temperature below the first glass substrate is placed on one surface of the first glass substrate, and the softening point temperature of the low melting point glass is below the softening point temperature of the first glass substrate. or more, one surface of the low melting point glass is heated to
Deform the glass substrate so that it comes into close contact with one surface of the glass substrate, and
A method for manufacturing a glass substrate for a liquid crystal cell, characterized in that a second glass substrate has a mold symmetry plane onto which one surface of the glass substrate is transferred.