JPH03150530A - Formation of oriented film of liquid crystal display device - Google Patents

Abstract

PURPOSE:To easily obtain the oriented film which slants and orients liquid crystal slantingly a little bit from the vertical direction by pressing a die against the surface of the oriented film at specific temperature and thus forming slanting surfaces which slant in the specific direction in the surface of the oriented film. CONSTITUTION:The die 1 which has many slanting surfaces on the surface at a necessary angle theta is pressed against the oriented film 2 with necessary pressure and then heated to transfer the surface shape of the die 1 to the orienting film 2. After cooling, the die 1 is removed and then the oriented film 2 whose surface consists of the slanting surfaces 6 which slant at the specific angle theta is formed. The liquid crystal 4 is oriented by using this oriented film 2 and then molecules of the liquid crystal 4 are oriented at right angles to the slanting surfaces 6 of the oriented film 2 to slant at the angle theta to a glass substrate 3 eventually. Consequently, the liquid crystal can easily be oriented in the same directly slantingly a little bit from the vertical direction.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for forming a vertical alignment type alignment film used in a liquid crystal display device, the present invention relates to a method for forming a vertical alignment type alignment film used in a liquid crystal display device. The aim is to achieve stable results even on large screens.The liquid crystal is sandwiched between two substrates, at least one of which is transparent, and each substrate has transparent electrodes and vertical panels made of polymer material. When creating a liquid crystal display device in which a polarizing member is formed on the outside of each of the substrates by laminating an oriented alignment film,
The alignment film is formed on the surface of the substrate on which the electrode is formed, and the alignment film surface is pressed with the pressure die at a predetermined temperature. The structure includes a step of forming the surface of the alignment film into a surface consisting of a plurality of inclined surfaces facing in a predetermined direction.

[Industrial application field]

The present invention relates to a method for forming a vertical alignment type alignment film used in a liquid crystal display device.

In recent years, liquid crystal display devices have been required to display large amounts of information. For this purpose, a liquid crystal display system with a fast response speed is required. Therefore, display devices in which liquid crystal molecules are oriented in the homeotropic direction are attracting attention as a method that can increase capacity using a simple matrix method.

However, in this display method, if the liquid crystal is aligned completely perpendicular to the substrate, the direction in which the liquid crystal tilts will vary when a voltage is applied. Therefore, for example, even if you try to make the entire screen uniformly pale white, as shown in Figure 3,
White and black (hatched areas) are mixed together, resulting in uneven display.

To prevent this display unevenness, it is necessary to tilt the liquid crystal molecules in the same direction slightly from the vertical direction in advance.

Conventional technology] Conventionally, in order to obtain an orientation that is slightly tilted from the vertical direction, a method has been used in which SiO is directly vapor-deposited onto a substrate from an oblique direction, a large number of inclined surfaces are created, and then a vertical alignment agent is applied. [For example, see co-authored by Matsumoto and Tsunoda: Latest Technology of Liquid Crystals (Industrial Research Institute, 11983) pp. 61-162].

[Problem to be solved by the invention]

However, the SiO oblique vapor deposition method has problems in that it is difficult to apply to large screens due to the nature of the process, and mass productivity is also extremely low.

An object of the present invention is to stably obtain an alignment film for aligning liquid crystal by slightly tilting it from the vertical direction, even for large screens, by a more convenient method.

[Failure to solve the problem]

The present invention will be explained below with reference to FIGS. 1(a) to 1(d).

In the figure, reference numeral 1 denotes a pressing mold having a large number of inclined surfaces having the required angle θ on the surface. The inclined surface 5 on the surface of the pressing mold 1 is required to have greater mechanical strength than the alignment film 2 described later. As this pressing mold 1, a glass substrate having grooves in the shape of a diffraction grating, or a glass substrate on which SjO is obliquely vapor-deposited to form an inclined surface 5 on the entire surface can be used.

Further, 2 is an alignment film with vertical alignment property, and 4 is a liquid crystal molecule.

First, as shown in FIG. 1(a), a vertically aligned polymer material is applied onto a glass substrate 3 serving as a transparent insulating substrate to form an alignment film 2. As shown in FIG.

Next, as shown in FIG. 1(b), the pressing mold 1 is placed on the alignment film 2.
By pressing and heating the alignment film 2 with uniform pressure,
The shape of the surface of the pressing mold 1 is transferred to the surface of the pressing die 1.

Next, as shown in FIG. 1(C), after cooling, the pressing die I is removed to form an alignment film 2 whose surface is composed of an inclined surface 6 inclined at a predetermined angle θ.

When the liquid crystal 4 is aligned using the alignment film 2 formed in this way, the molecules of the liquid crystal 4 are aligned with the alignment film 2 as shown in FIG. 1(d).
is oriented in a direction perpendicular to the inclined surface 6 of the glass substrate 3, and as a result is tilted at an angle θ with respect to the glass substrate 3.

[For production]

In the present invention, the polymer material used as the alignment film 2 is, for example, polytetrafluoroethylene having vertical alignment. Since this resin has thermoplasticity, by pressing it with the press die 1 without heating it, the shape of the surface of the press die 1 can be transferred onto the alignment film. Since the molecules of the liquid crystal 4 are aligned perpendicularly to the inclined surface 6 of the alignment film 2, they are consequently aligned slightly inclined from the perpendicular direction to the substrate 3.

In this way, by using the method of transferring the inclined surface using the pressing die 1, not only can many alignment films be molded from one die, but also the time for forming the alignment films can be shortened.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

The liquid crystal display device created in this example has a glass substrate 22.
After forming transparent electrodes 23 and 27 and alignment films 24 and 26 on the opposing surfaces of the electrodes 28, a nematic liquid crystal 25 was filled between the two plates. Furthermore, the side substrate 22
．． Linear polarizing plates 21 and 29 whose polarization directions are perpendicular to each other are disposed outside of 28.

-h To create the liquid crystal display device, first, transparent electrode films are formed on the surfaces of the pair of glass substrates 22 and 28 by sputtering, and then patterned to form transparent electrodes 23 and 27.

A polytetrafluoroethylene film of vertically aligned polymeric material is then formed by sputtering.

Then, a pressing die 1 having a surface shape corresponding to the required slope is pressed against the surface of the polytetrafluoroethylene membrane with uniform pressure and heated to 250°C. An inclined surface 6 inclined at a predetermined angle is formed over the entire surface of the alignment film 24.degree. 26 thus obtained. At this time, the press die used is a glass substrate having grooves in the shape of a diffraction grating.

Through the above steps, a large number of inclined surfaces 6 are formed on the surfaces of the alignment films 24 and 26. The liquid crystal molecules are aligned perpendicular to the inclined surface. Therefore, the molecules of the liquid crystal 25 have an orientation slightly tilted from the perpendicular direction with respect to the surfaces of the glass substrates 22 and 27.

Therefore, by bonding the pair of substrates 22 and 28 together, injecting the liquid crystal 25, and sealing it, a liquid crystal display device is obtained.
A liquid crystal display panel is obtained in which the molecules of the liquid crystal 25 are slightly inclined from the vertical direction with respect to the surface of the glass substrate 22°28.

Next, another embodiment of the present invention will be described.

In the above-mentioned embodiment, a glass substrate having a groove in the shape of a diffraction grating was used as the pressing mold 1 for forming inclined surfaces on the surfaces of the alignment films 24 and 26, but the pressing mold 1 was formed by obliquely vapor-depositing SiO on the glass substrate. It can be anything. Further, the structure of the suppressing mold 1 does not have to be planar, but may be a roll-shaped mold having grooves in the shape of a diffraction grating on the surface, or one having SiO deposited obliquely.

In the liquid crystal display devices manufactured in the above-mentioned example and other examples, the liquid crystal molecules are tilted in a certain direction by a predetermined angle θ, so when a voltage is applied, the tilt direction of the liquid crystal molecules is uniform, and the display is No unevenness occurs.

Moreover, in the present invention, by preparing the pressing mold in advance,
A desired alignment film can be created through an extremely simple manufacturing process.

〔Effect of the invention〕

As explained above, according to the present invention, in a liquid crystal display device in which liquid crystal molecules are aligned in the homeotropic direction, it is possible to easily produce a liquid crystal alignment that is slightly tilted from perpendicular to the same direction in order to prevent display unevenness. becomes possible. This has greatly improved the productivity of homeotropically aligned liquid crystal display devices with high display quality.

[Brief explanation of the drawing]

1(a) to 1(d) are diagrams illustrating the configuration of the present invention, FIG. 2 is a diagram illustrating an embodiment of the present invention, and FIG. 3 is a diagram illustrating the problems of the prior art. In the figure, 1: Press mold with angle θ 2: Vertical alignment film 3 Ni glass substrate 4: Liquid crystal molecules 5: Slanted surface of the pressing mold surface 6: Slanted surface of the alignment film surface 21. 29: Linear polarizing plate 22. 28 Ni glass Substrate 23.27: Transparent electrode 24.26: Vertical alignment film 25: Liquid crystal layer.

Claims (3)

[Claims] (1) A liquid crystal (4) is sandwiched between two substrates (3), at least one of which is transparent, and each substrate is provided with a transparent electrode and a vertical alignment film (2) made of a polymer material. When producing a liquid crystal display device having a polarizing member on the outside of each of the substrates by laminating the substrates, a pressing die (1) consisting of a plurality of inclined surfaces whose surfaces face in a predetermined direction is provided, and the substrates on which the electrodes are formed; Forming the alignment film on the surface, pressing the alignment film surface with the pressing die at a predetermined temperature to form a plurality of inclined surfaces (6
) A method for forming an alignment film for a liquid crystal display device, the method comprising the step of forming an alignment film on a surface consisting of: (2) A glass substrate having a diffraction grating-like groove on the surface is used as the pressing mold (1).
A method for forming an alignment film for a liquid crystal display device as described above. (3) The method for forming an alignment film for a liquid crystal display device according to claim 1, characterized in that the pressing die (1) is a glass substrate on which SiO is obliquely vapor-deposited.