JPH01120535A - Ferroelectric liquid crystal element - Google Patents

Abstract

PURPOSE:To increase an apparent tilt angle and the quantity of transmitted light and to improve optical quality in an extinction position by providing an oriented film formed with a diagonally vapor deposited film on one electrode and a different oriented film on the other electrode, respectively. CONSTITUTION:ITO electrodes 2 are patterned and formed on a glass substrate 1 and an insulating film 3 is formed on the electrodes 2 to obtain a substrate A. SiO is projected on and deposited by evaporation on the insulating film 3 in the same manner as for the substrate A and the diagonally vapor deposited film 6 of SiO is formed thereon to obtain the substrate B. The substrates A and B are disposed to face each other in such a manner that the incident direction is in counter parallel. The particles of SiO2 are uniformly sprayed as a sealing member 5 in the cell. The upper and lower substrates are stuck to each other and a ferroelectric liquid crystal 4 is injected into the cell. After the cell is heated up to the isotropic phase of said liquid crystal, the cell is subjected to adequate slow cooling at the time of a phase transition, by which the orientation uniform over the entire part is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a ferroelectric liquid crystal device, and particularly to a liquid crystal display device that forms bright and dark areas by controlling the orientation of ferroelectric liquid crystal molecules. be.

[Prior Art] Conventional 1 A method for aligning ferroelectric liquid crystal in a ferroelectric liquid crystal element is a method in which a temperature gradient is formed within the cell to form sequential alignment as phase transition occurs (wet layer gradient method). However, these methods lack mass productivity and stability, and are inappropriate for industrial use.

On the other hand, as an industrially advantageous method, conventionally, TN (Twisted Nematic)
The rubbing method and the oblique evaporation method, which are the methods used for liquid crystal cells of the tic) type, are useful.

In the rubbing method, PI (polyimide), PV
Organic fermentation 11i (400
~2000λ), and on top of that, a flocked fabric such as nylon, acetate, cotton etc.
．． 0mm) (rubbing: Rubbi)
This is a method that attempts to align the molecular long axes of nematic liquid crystals in the rubbing direction on average by
There is a track record for liquid crystal elements such as N and SBE.

However, when trying to apply this method directly to the alignment of ferroelectric liquid crystals, molecules (directors) occur between the upper and lower substrates.
Since there is no need to twist the directions, unlike the case of TN element orientation, the rubbing process is performed in the same direction or in opposite directions.

When ferroelectric liquid crystal molecules are aligned using such an alignment treatment method, it is easy to obtain a SPLAY orientation in the S■C1 phase.In this spray orientation, the direction of the molecules is twisted in the cell thickness direction. As a result, the apparent tilt angle θa is small, and the amount of transmitted light is reduced to about 5%, compared to over 30% for TN elements, resulting in lower contrast and more defects such as zigzag defects. This results in an orientation state that is undesirable for a display, as it is difficult to control.

In addition, when using an obliquely vapor-deposited SiO film as an alignment film, the dark value of switching may be increased in boat fishing, and there may be many other stable states.

On average, an orientation state with an extinction position in the layer direction becomes dominant,
There were problems such as difficulty in matrix driving.

[Problems to be Solved by the Invention] As mentioned above, the rubbing treatment of the aWI provided on both sides of the two electrode substrates provided oppositely, or the oblique evaporation of SiO provided on both sides, etc. When alignment treatment is performed using this method, the following problems occur: ■ The apparent tilt angle θa is small and the amount of transmitted light is small. ■ The leakage light at the extinction position is large and the contrast is low. ■ Other defects such as zigzag defects. There were drawbacks such as a large number of occurrences and poor display quality.

The present invention has been made to improve the drawbacks of the prior art, and provides a ferroelectric liquid crystal element with a large apparent tilt angle θa, a large amount of transmitted light, and improved optical quality at the extinction position. The purpose is to provide

[Means for Solving the Problems] That is, the present invention provides a liquid crystal element in which a ferroelectric liquid crystal is sandwiched between two opposing electrodes.
A ferroelectric liquid crystal element characterized in that an alignment film made of an obliquely evaporated film of iO is provided, and an alignment film different from that of the one electrode is provided on the other electrode.

The present invention will be explained in detail below.

In the ferroelectric liquid crystal element of the present invention, an alignment film made of an obliquely evaporated SiO film is provided on one of two opposing electrodes, and an alignment film made of an obliquely vapor-deposited film of SiO is provided on the other electrode. An alignment film is provided, and a ferroelectric liquid crystal is sandwiched between the two electrodes.

In this way, an alignment film is provided on the two electrodes,
One of the electrodes is formed by forming an SiO oblique evaporation film as described above, but the other alignment film may be different from that provided on one electrode, and is not particularly limited. , preferably as shown below.

■Those made of a non-directional organic film■-Those made of aWi subjected to a chemical treatment■No aII
Examples include those consisting of.

In the present invention, the thickness of the SiO obliquely vapor-deposited film provided on one electrode is usually 400 to 2000, preferably 5
00 to 1000 people is desirable.

The organic film in the present invention includes polyimide, polyvinyl alcohol (PVA), polyacrylonitrile (PA).
N) or polyethylene oxide (PEG), etc., and the film thickness is usually 20 to 2000, preferably <2
Preferably 0 to 500 people.

Also, 5to2. Tiltschoa20
5 or AlzOx, etc., and the film thickness is usually 40
0 to 6000 people, preferably 400 to 1000 people.

In the present invention, the alignment film provided on one electrode is
After forming an insulating film on the electrode, it can be easily formed by obliquely depositing SiO. When SiO is deposited obliquely, it is preferable to deposit the film at an angle of 70 to 88° C. from the normal to the substrate.

[Function] The ferroelectric liquid crystal element of the present invention is a liquid crystal element in which a ferroelectric liquid crystal is sandwiched between two opposing electrodes, and an alignment film made of an obliquely evaporated SiO film is provided on one electrode. is provided, and an alignment film different from that of the one electrode is provided on the other electrode. Although the details are unknown, the apparent tilt angle θa is large due to the different alignment film. , it is possible to increase the amount of transmitted light, reduce leakage light at the extinction position, increase contrast, and improve optical quality.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 FIG. 1 is a sectional view showing an example of the ferroelectric liquid crystal element of the present invention. The device shown in the figure was created by the following method.

First, an ITO electrode 2 with a thickness of about 1000 wafers was patterned on a glass substrate 1 by EB evaporation method.Next, an ITO electrode 2 with a thickness of about 1000 yen thick was formed on the ITO electrode 2 by sputtering method.
A substrate A was obtained by forming an insulation@3 consisting of a 5in2 film of 0 people.

Next, the insulating film 3 of the substrate was formed in the same manner as the substrate A.
SiO was deposited thereon at an angle of 82° from the normal to the substrate in a vacuum of about 10-'torr to form an obliquely deposited SiO film 6 to obtain substrate B. Well, the length of the columnar crystals composed of SiO in the direction of the evaporation source was about 2000.

The thus obtained one substrate B and the other substrate A were made to face each other so that the incident directions were antiparallel, and used as a sealing member 5 using LIXONBOND 100 manufactured by Chisso Corporation.
2AB was used, and for the purpose of controlling the cell gap, particles of diametral IILs of Sin were uniformly scattered within the cell, and the upper and lower substrates were bonded together so that the distance between them was about 1.1 gm. As the ferroelectric liquid crystal 4, Chisso Corporation @ (:S-1
014 was injected into the cell.

After heating the cell created in this way through the Toyoshi phase,
Appropriate slow cooling (~10°C/hr) was performed during the phase transition from ch phase to SmA phase to Sac''' phase.

Observation of the alignment state of the ferroelectric liquid crystal element obtained in this way under crossed nicol conditions revealed uniform black/white domains, and alignment abnormalities such as zigzag defects seen in normal rubbing cells. However, a more uniform alignment was obtained. The apparent tilt angle was Is@.

In addition, in the above example, when forming the oblique evaporation H6 of SiO on the substrate, SiO is evaporated by being incident in a range of 82° from the normal line of the substrate, but these ranges can be changed, for example, to the direction of incidence. The same tendency as above was observed even when the column length of the columnar crystal composed of SiO was 600 Å or more.

In addition, the insulating film (dielectric w2) of the opposing layer of the obliquely deposited SiO film
Similar results were obtained even when processing such as rubbing was performed.

Example 2 In the cell configuration shown in Example 1 (Fig. 1), SiO
The configuration of the opposing substrate A of the obliquely deposited film was changed as follows.

On insulation 123 (5ift layer, 1000 people thick),
3% solution of polyimide (manufactured by Toshisha 5P-710)
Coating at a rotation speed of 500 pl (spinner method)
After that, a substrate was used which was baked at 300°C to form a polyimide thin film.

The cell thickness is controlled by scattering 5in2 beads with a particle size of 1.0 gm, making it a ferroelectric liquid crystal manufactured by Chisso! I! cs-1014 was used.

In such a configuration, the orientation of the ferroelectric liquid crystal molecules is not microscopically aligned and there are defects, but overall a bistable pulse response is achieved, and the apparent tilt angle described above is It was wide at about 15 degrees. Therefore, it was recognized that the transmittance was significantly improved.

Example 3 In the cell configuration shown in Example 2, rubbing was performed in parallel to the incident direction of oblique evaporation on the organic film.

The rubbing process was performed using an acetate cloth at a rotation speed of 1000 rpm for 10 seconds. The bristles of acetate cloth are approximately 0.
．． 15■ Made contact with the shoe board surface. Cell gap is 1.2
1L ■, C8-1014 manufactured by Chisso Corporation as ferroelectric liquid crystal
was used.

In the cell constructed in this manner, the orientation was regular although there were homogeneous defects in one direction, and a good blue-white optical response was exhibited. The apparent tilt angle was approximately 12.5@.

[Effects of the Invention] According to the present invention, as a ferroelectric liquid crystal alignment film, by using an obliquely deposited SiO film for one alignment film and using an organic or inorganic film or a rubbing film thereof for the other, The apparent tilt angle θa is large.

A ferroelectric liquid crystal element with a large amount of transmitted light and improved optical quality at the extinction position can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the ferroelectric liquid crystal element of the present invention. l...Glass substrate 2-ITO electrode 3...Insulating film 4...Ferroelectric liquid crystal 5...Sealing member 6...SiO oblique evaporation film A, B-...
substrate

Claims (6)

[Claims] (1) In a liquid crystal element in which a ferroelectric liquid crystal is sandwiched between two opposing electrodes, an alignment film made of an obliquely vapor-deposited SiO film is provided on one electrode, and an alignment film made of an obliquely vapor-deposited film of SiO is provided on one electrode, and 2. A ferroelectric liquid crystal device, characterized in that an alignment film different from the one electrode is provided. (2) The ferroelectric liquid crystal element according to claim 1, wherein the alignment film provided on the other electrode is a non-directional organic film. (3) The ferroelectric liquid crystal element according to claim 1, wherein the alignment film provided on the other electrode is an organic film subjected to uniaxial treatment. (4) A ferroelectric liquid crystal device according to claim 2 or 3, wherein the organic film is made of polyimide, polyvinyl alcohol, polyacrylonitrile, or polyethylene oxide. (5) The ferroelectric liquid crystal element according to claim 1, wherein the alignment film provided on the other electrode is an inorganic film. (6) The inorganic film is SiO_2, TiO_2, Ta_2O_
5. The ferroelectric liquid crystal element according to claim 5, which is Al_2O_3.