JPH01253716A - ferroelectric liquid crystal panel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a high-speed, high-contrast ferroelectric liquid crystal panel.

2. Description of the Related Art Liquid crystal display devices are used in wristwatches, calculators, etc. due to their advantages of being thin, lightweight, and capable of being driven at low voltages. However, the response speed of the currently used Nemati 7 LCD is only a few millimeters.
Since the response time is several tens of milliseconds, high-speed response is not possible, and the field of use is limited.

- Ferroelectric liquid crystals can be used as high-speed display elements, memory type displays, etc. due to their microsecond response speed and memory effect.
It can be applied to fields such as liquid crystal shutters. Currently, the rubbing method, oblique evaporation method, magnetic field application method, electric field application method, shearing method, etc. have been devised as orientation methods, and the rubbing method is the best in terms of mass production and practicality. In the rubbing orientation method, the uniaxiality is too strong, resulting in monostable or twist-stable properties, making it difficult to obtain good uniform bistable properties. In addition, the phase series from Iso phase to SmC'' phase in ferroelectric liquid crystal is ■Iso-43mA-43mC'' (IAC system)■l
5o-=N”-=SmC” (INC system) ■Tso
-N" = SmA-3mC" (INAC system) ■Is
o−=SmC” (IC system), etc. can be considered.

The orientation of ferroelectric liquid crystals depends more on the phase series on the high temperature side than the SmC" phase. Conventionally, in order to achieve uniform alignment in the SmC" phase, an N" phase is required, and the pitch of the N" phase is The longer and thinner the cell, the more the helix of the ferroelectric liquid crystal unravels, and the S
It was thought that when the mA phase is formed, the phases are properly aligned, and that good orientation can be obtained even in the SmC'' phase.

Invention tries to solve! ! l! If a ferroelectric liquid crystal exhibiting the N0 phase as described above shows good alignment and bistability in a ferroelectric liquid crystal cell aligned by SiO oblique evaporation, etc., but when aligned by rubbing, the alignment at the interface Due to the strong regulating force, the layers align properly in the SmA phase, but when the SmA phase transitions to the SmC'' phase, the molecules tilt from the layer normal, distorting the layers and causing many disclinations. If a ferroelectric liquid crystal CINC system (CINC system) (IC system) without an SmA phase is used, the orientation will be poor because the layer direction is not regulated, and even if an IAC system liquid crystal is used, the INC system will be unstable. Although it is not as bad as in the case of or IC systems, it becomes difficult to align the layer directions.

Means for Solving the Problem A ferroelectric liquid crystal having a spontaneous force pole of 20 nC/- or more and 100 nC/- or less and having triple points of an isotropic phase, a chical nematic phase, and a smectifuku A phase in a phase transition series is produced by a rubbing method. Orient by.

Function: By using this ferroelectric liquid crystal, it is possible to fabricate a uniform-shaped, bistable ferroelectric liquid crystal cell with high speed and high contrast even in the rubbing arrangement method.

Example Below, regarding a ferroelectric liquid crystal panel according to an example of the present invention,
This will be explained with reference to the drawings.

As shown in Figure 1, ITO films 3 and 4 were formed as transparent electrodes on transparent glass substrates [1 and 2], and polyimide resin was applied thereon as an alignment film using a spinner. A rubbing process is performed on the substrate, and the alignment film surfaces of the substrates are bonded together. The thickness of the panel is 21JITl due to the spacer mixed in the sealing resin 7. A ferroelectric liquid crystal 8 was sealed in this panel. The phase and series of this ferroelectric liquid crystal were changed as shown in FIG. 2, and the contrast in each of the A, B, and C states is shown in Table 1.

Table 1 〉 As is clear from these results, in Type A 1 (IAC system), l
During the transition from the so phase to the SmA phase, the orientation of the long axes of molecules and the formation of layers occur simultaneously, making it difficult to align the layer directions. In addition, in C-like fLi (INAC system), the orientation in the SmA phase is good, but the regulating force in the SmA phase is too strong, so the Sm
The layer is distorted when transitioning from the A phase to the SmC'' phase.On the other hand, in the B state, the orientation is better in the SmA phase than in the A state, and in the C state, the regulating force is not strong, so the Sm
Even in the transition from the A phase to the SmC'' phase, the layer did not bend and exhibited good orientation, resulting in high contrast and bistable properties.

In addition, if the spontaneous polarization is smaller than 20 nC/aj, the contrast will deteriorate due to the twist stability, and if the spontaneous polarization is smaller than 100 nC/aj,
Table 2: In the above invention, at least one of the substrates is transparent, and although polyimide was used as an example for the alignment film, other materials may be used. This is possible even without surface treatment using an alignment film.

Effects of the Invention As is clear from the above explanation, according to the present invention, the spontaneous polarization is 20 nC/aj or more and 100 nC/csl or less, and there are three points in the phase transition series: an isolaboratory phase, a chiral nematic phase, and a chiral smectic phase. By using ferroelectric liquid crystal, conventional rubbing can
Whereas only twist-stable alignments could be obtained, it is now possible to obtain high-speed, high-contrast, uniform-type, bistable ferroelectric liquid crystal panels.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a ferroelectric liquid crystal panel according to an embodiment of the present invention, and FIG. 2 is a graph showing the phase series of ferroelectric liquid crystal. 1...Top glass substrate, 2...Bottom glass substrate, 3゜4...ITO electrode, 5, 6...
...Alignment film, 7...Seal resin, 8...
・Ferroelectric liquid crystal. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1
1- Upper glass board Figure 2

Claims (3)

[Claims] (1) A ferroelectric liquid crystal panel characterized by using a ferroelectric liquid crystal having triple points of an isotropic phase, a chiral nematic phase, and a smectic A phase in a phase transition series. (2) The ferroelectric liquid crystal panel according to claim (1), wherein the ferroelectric panel is aligned by rubbing. (3) The ferroelectric liquid crystal panel according to claim (1), wherein the ferroelectric liquid crystal has a spontaneous polarization of 20 nC/cm^2 or more and 100 nC/cm^2 or less.