JPS62111236A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To obtain the ferroelectric liquid crystal element having a good orientation and an excellent contrast property by combining an orientation layer composed of a polyimide resin and effected a rubbing treatment, and an orientation layer composed of an org. compd. contg. a mercapto group or an epoxy group and effected a rubbing treatment. CONSTITUTION:Transparent electrodes 3 and 4 having a prescribed shape and composed of a NESA film are provided on each one surface of substrates 3 and 4 respectively. The orientation layer 5 is formed by coating the substrate 1 formed the electrode 3 thereon with the polyimido resin by means of a spinner followed by rubbing it at an axial direction 7 by a rubbing machine. The orientation layer 6 is formed by coating the surface 2 formed the electrode 4 thereon with a silan compd. having the mercapto group followed by rubbing it at an axial direction 8 by the rubbing machine. And then, the substrate 1 and 2 are sticked with each other in such a way that the angle between the rubbing directions 7 and 8 makes 180 deg., and the orientation layers 5 and 6 face with each other. The mixed composition of the DOBANBC type is sealed between the substrate as the ferroelectric liquid crystal 9, thereby forming the liquid crystal element 10. And a polarizing plate 11 which shifts a polarizing axis from the rubbing direction 7 and an another polarizing plate 12 which meets the polarizing axes at right angle are arranged on the upper and the lower substrates 1 and 2 of the liquid crystal element 10 respectively.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a liquid crystal element using a ferroelectric liquid crystal.
In particular, it relates to the alignment of liquid crystals.

(Technical background of the invention and its problems) Liquid crystal elements are widely used in electro-optical devices such as wristwatches, calculators, personal computer displays, and pocket color televisions. However, the nematic liquid crystals currently in use are Since the optical response time is slow at about 50 msec, its use in fields where high-speed response is required is limited.

In addition, we are reaching the limit in terms of display capacity.

On the other hand, since ferroelectric liquid crystals exhibit high-speed response on the microsecond scale, their practical use is expected to dramatically expand the applications of liquid crystal elements.

A technical problem when using ferroelectric liquid crystals is the difficulty of alignment. The emergence of electro-optical properties of ferroelectric liquid crystals is due to
Uniform alignment of liquid crystal molecules parallel to the substrate is required. However, the conventional rubbing method used for homogeneous alignment of nematic liquid crystals cannot achieve a sufficiently good alignment of 1':I. Examples include the magnetic field 1)11 method, the electric field application method, the shearing method, and the Sveza Edge method.However, each method has the following drawbacks.The magnetic field application method has several to dozens of Because it requires a Gaussian magnetic field, a large magnetic field generator is essential, making it impractical.The electric field application method causes a current to flow through the liquid crystal molecules, causing deterioration of the liquid crystal molecules.The shearing method Uniform alignment cannot be obtained.The spacer edge method has difficulty in producing large panels.For reasons of practicality, it is difficult to employ any of the above methods as an alignment method.

On the other hand, an alignment method that is an improved version of the conventional rubbing method has also been proposed. 5ID85 DIGEST page 131,
An attempt was made to achieve alignment by applying a single layer of polymer to one substrate and then rubbing it, and applying a silane compound to the other substrate.
j, has been done. The types of alignment layers on the two substrates are different,
It is also said that by rubbing only one layer of polymer, the alignment of chiral smectic liquid crystals can be improved and good alignment can be achieved.

However, many of the silane compounds tend to form vertical alignment with respect to the ferroelectric liquid crystal, and if rubbing is not performed, many defects will occur, leading to a reduction in contrast.

Moreover, an attempt to make the rubbing directions parallel to each other, that is, in the same direction, is described in Japanese Patent Application Laid-Open No. 59-131911@. According to this, the alignment of chiral smectic liquid crystal can be improved by applying polyimide resin to two glass substrates, rubbing it after curing, and then combining the rubbing directions on the two glass substrates so that they are parallel to each other in the upper and lower directions. It is said that it is possible to improve contrast characteristics.

However, in this method, a smectic liquid crystal layer is formed perpendicularly between the upper and lower glass substrates, whereas each rubbing on the upper and lower glass substrates restricts the molecular layers, resulting in many defects between the molecular layers.

[Purpose of the invention]

The present invention eliminates the drawbacks of the prior art and aims to improve contrast by realizing uniform alignment of ferroelectric liquid crystals.

[Summary of the invention]

The liquid crystal element of the present invention is a liquid crystal element in which a ferroelectric liquid crystal is sandwiched between a pair of substrates, at least one of which is transparent.
This is a liquid crystal element characterized in that one of the substrates has an alignment layer made of a rubbed polyimide resin, and the other substrate has an alignment layer made of a rubbed organic compound having a mercapto group or an epoxy group.

Thereby, good homogeneous alignment is obtained from the δ-polarity of the mercapto group or epoxy group in the organic molecule alignment layer and the rubbing effect, and the contrast of the liquid crystal element is improved.

[Embodiments of the invention]

Embodiment 1 FIG. 1 shows an embodiment of the invention, in which two substrates 1.2 made of transparent glass are placed opposite each other.

Electrodes 3.4 are formed on the opposing surfaces of each substrate, and alignment layers 5.6 made of polyimide resin and an organic compound containing mercapto or epoxy groups are deposited on these electrodes 3.4, respectively. has been done. The alignment layer 5 of the lower substrate 1 is subjected to a horizontal alignment treatment in one direction horizontal to the substrate as indicated by an arrow 7, that is, in a -axial direction. Also, the upper board 2
The alignment layer 6 is subjected to a uniaxial horizontal alignment treatment in one direction horizontal to the substrate as indicated by an arrow 8. A ferroelectric liquid crystal 9 is sandwiched between these substrates 1.2 in contact with alignment layers 5 and 6 to form a liquid crystal element 10.

The method for manufacturing this liquid crystal element will be described below.

Transparent electrodes 3.4 made of Nesa film and having a predetermined shape were provided on each one side of the substrate 1.2. On the substrate 1 on which the electrodes 3 were formed, polyimide resin was applied to a thickness of 500 mm using a spinner at a rotational speed of 3000 rpm to form an alignment layer 5, and this was rubbed in a uniaxial direction 7 using a rubbing machine.

Further, on the substrate 2 on which the electrode 4 was formed, the following molecular structure formula A
A silane compound having a mercapto group showing
I rubbed it.

8: H3CH2CH2CII2Si (OCH3).

At this time, the substrates 1 and 2 were bonded together with an interval of 1 to 3 μm such that the angle formed by the rubbing directions 7 and 8 was 180 degrees, and the alignment layers 5 and 6 were facing each other. A DOBANBC-based mixed composition was sealed between these substrates as a ferroelectric liquid crystal 9 to form a liquid crystal element 10.

Next, as shown in FIG. 2, the upper and lower substrates 1,
A polarizing plate 11 whose polarizing axis was shifted by about 22 degrees from the rubbing direction 7 and another polarizing plate 12 whose polarizing axis was orthogonal to the polarizing plate 11 were installed on the substrate 2.

When contrast characteristics were measured using the above liquid crystal element, the contrast was 8:1 to 10:1.

Example 2 The silane compound used in Example 1 was replaced with a silane compound having an epoxy group represented by the following molecular structure B, and the contrast characteristics were measured, and the contrast properties were 9:1 to 11:1.

Comparative Example When contrast characteristics were measured by replacing the silane compound used in Example 1 with a silane compound having the molecular structure shown in C to F below, vertically aligned portions appeared in a part of the liquid crystal element, and the contrast All properties were 5:1 or less.

C: N112C11,, C112NHCII□CH2
Cl1□Si (OCH3), 3D: C H,,
NHcj116 si (octl,).

E: CIC, H5Si(OCH,)3 (Effects of the Invention) As described in the examples above, according to the present invention, each layer has an alignment layer made of a polyimide resin that has been subjected to a rubbing treatment, and has a mercapto group or an epoxy group. By combining it with an alignment layer made of an organic compound, a ferroelectric liquid crystal element with good alignment and contrast characteristics can be realized.

Note that at least one of the substrates needs to be transparent for visual recognition, and it goes without saying that various types of ferroelectric liquid crystal such as HOBACPC type can be selected as the ferroelectric liquid crystal.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of the invention, and FIG. 2 is a schematic diagram illustrating details of the invention. 1...lower board, 2...upper board,
3.4... Electrode, 5... Polyimide alignment layer, 6... Silane compound alignment layer, 9... Ferroelectric liquid crystal, 10... ...Liquid crystal element, ii, 12...Polarizing plate. Agent Patent Attorney Noriyuki Chika Yudo Norito Ogo Figure 1! Figure 2

Claims (2)

[Claims] (1) In a liquid crystal element in which a ferroelectric liquid crystal is sandwiched between a pair of substrates, at least one of which is transparent, one of the substrates has an alignment layer made of a rubbed polyimide resin,
A liquid crystal element characterized in that the other substrate has an alignment layer made of a rubbed organic compound having a mercapto group or an epoxy group. (2) The liquid crystal element according to claim 1, wherein the organic compound having a mercapto group or an epoxy group is an organic silane compound.