JPH024226A - Ferroelectric liquid crystal element - Google Patents

Abstract

PURPOSE:To improve not only the impact resistance but also the display quality by distributing an adhesive body to the inside surface of a substrate under a specific condition. CONSTITUTION:The ferroelectric liquid crystal element is provided with a pair of substrates 102, 103 which are placed at an interval, a ferroelectric liquid crystal 104 which is placed between a pair of substrates, and an adhesive body 106 for sticking a pair of substrates, and the adhesive body 106 is distributed to the inside surface of the substrates 102, 103, and when an average adhesion area per one piece of the adhesive body 106, distribution density of the adhesive body 106, a total adhesion area of the adhesive body 106 and a display part area are set to <=1.25X10<-3>mm<2>, <=100pieces/mm<2> <=50 pieces/mm<2> desirably, SA (mm<2>), and SB(mm<2>), respectively, (SA/SB)X100% is set to 2.5X10<-2>-1.0%. In such a way, the generation of a sanded texture caused by an impact can be prevented, and furthermore, the generation of a zigzag or wavy black line for deteriorating the display quality can be suppressed.

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention relates to a liquid crystal element used in a liquid crystal display element, a liquid crystal-light shutter, etc., particularly a liquid crystal element using ferroelectric liquid crystal, and more specifically relates to a liquid crystal element using ferroelectric liquid crystal. This invention relates to a ferroelectric liquid crystal element with excellent properties.

[Conventional technology]

C1ark and Lage are display devices that utilize the refractive index anisotropy of ferroelectric liquid crystal molecules to control transmitted light in combination with polarizing elements.
rwall) (Japanese Patent Laid-Open No. 56-10
7216), U.S. Pat. No. 4,367,924, etc.). This ferroelectric liquid crystal generally has a chiral smectic C phase (SmC") or an H phase (
In this state, it takes either the first optically stable state or the second optically stable state in response to an applied electric field, and maintains that state when no electric field is applied. It has the property of maintaining its stability, that is, bistability, and also has a quick response to changes in electric field, and is expected to be widely used as a high-speed and memory-type display element.

In order for a ferroelectric liquid crystal device to have the above-mentioned high-speed response and memory properties, vertical molecular layers that produce a chiral smectic phase with a suppressed helical alignment structure are ordered in one direction in a plane. It is necessary. When an external stress such as an impact is applied to the orientation state of a plurality of vertical molecular layers that are orderly arranged in one direction within a plane, there is a problem in that they break or sag, resulting in a so-called sanded texture.

Therefore, in order to improve the impact resistance of large liquid crystal cells of A5 size or larger, the present inventors used adhesive materials such as silica beads and alumina beads as spacer materials to bond between a pair of substrates within the cell. By placing it on a hard body,
An attempt was made to solve the above problems.

However, according to experiments conducted by the present inventors, a ferroelectric liquid crystal compound with equal blades is completely injected into the above-mentioned cell in which a pair of substrates are fixed with an adhesive, and then the compound is cooled to a chiral smectic phase. When a liquid crystal cell prepared by this method is held between a pair of crossed Nicol polarizers and the cell surface is observed, there is a problem in that zigzag or wavy lines are produced which can be visually identified. This zigzag or wavy line causes a problem of deteriorating display quality.

Such zigzag or wavy lines are caused by volume contraction in the chiral smectic liquid crystal when the phase transition from the equi-edge or cholesteric phase fully injected into the cell to the smectic A phase or chiral smectic phase occurs by cooling. This is due to the formation of zigzag or wavy void lines. This zigzag or wavy gap line is visually observed with a crossed Nicol polarizer.

[Summary of the invention]

An object of the present invention is to provide a ferroelectric liquid crystal element that solves the above-mentioned problems.

Another object of the present invention is to provide a ferroelectric liquid crystal element that simultaneously improves impact resistance and display quality.

The present inventors repeatedly conducted experiments in accordance with the above-mentioned objectives, and found that there is a correlation between the occurrence of the above-mentioned zigzag or wavy lines and the distribution state of the adhesive, and achieved the present invention. This is what I did.

That is, the present invention provides a ferroelectric liquid crystal element having a pair of substrates spaced apart from each other, a ferroelectric liquid crystal disposed between the pair of substrates, and an adhesive bonding the pair of substrates. The adhesive bodies are distributed on the inner surface of the substrate, and the average adhesive area of each adhesive body is 1.25 x 10-''
m rd or less, the distribution density of the adhesive is 100 pieces/mrr
? Hereinafter, preferably 50 pieces/mm2 or less and the total adhesive area of the adhesive body is sA (m%), and the display area is 5s (
rnr+? ), (SA/5s)X100% is 2
．． The ferroelectric liquid crystal element has a characteristic of 5XIO-'' to 1.Q%.

[Detailed description of aspects of the invention]

The first part (A) is a cross-sectional view of the ferroelectric liquid crystal cell 101 of the present invention. A ferroelectric liquid crystal cell 101 includes a pair of substrates 1
Between 02 and 103 (glass, plastic) is a ferroelectric liquid crystal 104 and a hard body 105 that functions as a spacer.
(Glass fiber, alumina beads, silica beads, alumina beads) and an adhesive body 106 for bonding the substrates 102 and 103 are arranged.

Transparent electrodes 10 are provided on the inner surfaces of the substrates 102 and 103, respectively.
7 and 108, transparent dielectric films 109 and 110, and alignment control films 111 and 112 are provided. This orientation control film 1
It is also possible to omit either one of 11 and 112.

As the ferroelectric liquid crystal 104, for example, US Pat. No. 456
Publication No. 1726, Publication No. 4589996, Publication No. 45
Liquid crystals disclosed in U.S. Pat. No. 92858 and U.S. Pat. No. 4,614,609 can be used, and the orientation state thereof is as disclosed in U.S. Pat. No. 4,563,059 and U.S. Pat.
The suppressed or eliminated helical arrangement structure disclosed in Publication No. 3 can be used.

FIG. 2 shows the bistable alignment state of chiral smectic liquid crystal when the helical alignment structure inherent in the bulk state disappears. This bistable alignment state is achieved by keeping the distance between the pair of substrates 201 and 202 sufficiently small (10 μm or less) to cause the helical alignment structure to disappear, and in the absence of an electric field, liquid crystal molecules The liquid crystal molecules 203A and 203B are held in one of the stable states. Further, in the present invention, the liquid crystal molecules 203 are connected to the substrates 201 and 20 in the absence of an electric field.
It is also possible to use an alignment state with a pretilt angle with respect to 2. 204 in FIG. 2 represents a vertical molecular layer organized by a plurality of liquid crystal molecules, and the arrow in the figure represents the direction of the dipole moment.

Further, the adhesive body 106 used in the present invention is obtained by spraying adhesive epoxy resin particles (particle size 1 to 50 μm) onto one of the substrates in advance, superimposing the two substrates, and then applying heat treatment. obtained by Moreover, it is preferable that the hard body 105 be spread on the substrate in advance together with adhesive epoxy resin particles. At this time, the diameter of the hard body 105 maintains the distance between the pair of substrates 102 and 103, and is generally 1-10 μm.

Such a ferroelectric liquid crystal cell 101 includes a pair of polarizers 113.
and 114, the change in the orientation state is optically identified.

FIG. 1(B) is a plan view of the ferroelectric liquid crystal cell 101.
A pair of sealing members 115 for sealing the substrates 102 and 103 are arranged except for the injection port 116, and the inside of the sealing members 115 is used as a display section 1]7.

The alignment control films 111 and 112 are made of polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylerin, polyester, polycarbonate, polyvinyl acecool, polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, etc. A film of an organic insulating material such as acrylic resin that has been subjected to a uniaxial alignment treatment (e.g., rubbing treatment) can be used, and the transparent dielectric films 109 and 110 can be made of silicon oxide, silicon dioxide, aluminum oxide, etc. ,
A film of an inorganic insulating material such as zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, or borate nitride can be used.

The alignment control films 111 and 112 generally have a thickness of 50 to 1,000.
The transparent dielectric films 109 and 11 can have a thickness of about 100 mm.
0 can generally be between 100 and 3,000 people.

Hereinafter, the present invention will be explained by giving specific examples and comparative examples.

Example 1 Two glass plates with a thickness of 1 mm and 1 mm were prepared, transparent stripe electrodes of ITO (indium tin oxide) were formed on each glass plate, and SiO2 was formed as a transparent dielectric film on top of the transparent stripe electrodes of ITO (indium tin oxide). A film was formed using a 1,000-layer process sputtering method.

A polyimide forming liquid 5P710 (
By applying a 4% by weight N-methylpyrrolidone/n-butylcelloring (2:1.) solution (manufactured by Toshisha Co., Ltd.) by a printing method and baking at 300°C, a zero-thickness polyimide alignment control film was formed. did. The fired coating was subjected to a rubbing treatment using an acetate flocked cloth. after that,
Epoxy resin adhesive particles (trade name: Treval; manufactured by Toshi Co., Ltd.) having an average particle size of 5 μm were sprayed onto one substrate using the Nordson electrostatic spraying method at a distribution density of 30 particles/m rd. The other substrate has an average grain size of 5 μm.
of silica microbeads were dispersed at a distribution density of 200 beads/m rd using the Nordson electrostatic dispersion method. Next, as a sealing member 115, a liquid adhesive (trade name Nistruct Bond; manufactured by Mitsui Toatsu Co., Ltd.) was applied by printing to a film thickness of 4 μm. Next, the two glass plates were glued together and compressed by applying a pressure of 4 kg/crrr for 5 minutes at a temperature of 70°C, and then a pressure of 1 kg/cI was applied at a temperature of 150°C.
While applying a pressure of T1', the two types of adhesives were cured over 2 hours to produce a cell. At this time, the average adhesion area per bonded body by the adhesive particles is 5 x 10-'mr
It was d. After that, the pressure inside the liquid crystal cell was reduced to 10-', and the ferroelectric liquid crystal was used as C31014 (manufactured by Chisso Corporation).
(trade name) was injected at 90°C (equal blade set). Thereafter, the mixture was cooled to 25° C. to form a chiral smectic C phase through a cholesteric phase and a smectic A phase.

This liquid crystal sail was subjected to an impact durability test using a drop durability tester (manufactured by Yoshihichi Seiki Co., Ltd., DT-50). In the test, the drop impact was increased from 20G by IOG. The alignment of the liquid crystal element described above did not deteriorate even when subjected to a drop impact of 80 G.

Examples 2 to 9 Instead of the particulate adhesive used in Example 1, UV (ultraviolet) adhesive (product name: XLC) was applied onto the substrate surface using a letterpress printing plate.
-1 (manufactured by Wakitachi Kagaku) was printed with 3 μm thick and 28 μm diameter dots at the distribution density shown in Table 1 below. At this time, the same UV adhesive was used as the sealant. However, the sealant is 4μm
Printed with a film thickness of Thereafter, in the same manner as in Example 1, two pieces of glass were placed on top of each other, and the upper and lower substrates were bonded together by UV irradiation.

Except for the above operations, an element was manufactured in the same manner as in Example 1, and the same impact durability test was conducted. The results are shown in Table 1 (in the table, "FLCJ" stands for "ferroelectric liquid crystal"). ).

Comparative Examples 1 to 4 FLC cells were created in the same manner as in Example 1, except that the average adhesion area and distribution density per adhesive particle were shown in Table 2, and the same impact durability test was conducted. Ta. The results are shown in Table 2.

Comparative Example 5 An FLC cell was prepared in the same manner as in Example 2, except that the distribution density of the UV adhesive used in Example 2 was shown in Table 2, and the same impact durability test was conducted. The results are shown in Table 2.

FL created in Examples 1 to 10 and Comparative Examples 1 to 5 above
When the cell C was held between a pair of crossed Nicol polarizers and the state of the panel was visually observed, many zigzag and wavy black lines were observed in the cells of Comparative Examples 1 to 5, which were clearly distinguishable by visual inspection. In contrast, Example 1-10
The cells of Comparative Examples 3 and 4 had a sanded texture during the impact test.

FIG. 3 is a diagram created based on experimental data obtained in Examples 1 to 10 and Comparative Examples 1 to 5. In FIG. 3, the "poor image quality" area is the area where the above-mentioned zigzag and wavy black lines occur, and the "poor injection" area is the area where the FL is in the empty cell.
C represents a region that is not completely implanted.

In a preferred embodiment of the present invention, the average adhesive area per adhesive body 106 is 1.25×10=m rd or less, the distribution density is 100 pieces/m rd or less, and the distribution density The product with the area (y) is 2.5XIO-
'~l X 10-'', in other words, the display area Ss (
The total adhesion area S B (m r
r? ) ratio (SA/5s) x 100% to 2.5 x 1
It is set to 0=~1.0%. In particular, in a preferred example, the distribution density of the adhesive bodies 106 can be set to 50 pieces/mm 2 or less.

○ and . in the figure are actually measured values, . is a value of this example, and O is a value outside the present invention.

Further, the average bonding area per bonded body is the average value measured for about 200 bonded bodies, and the distribution density of the bonded body is the average value measured for 200 points.

〔Effect of the invention〕

According to the present invention, it is possible to prevent the occurrence of sanded texture due to impact, and at the same time, it is possible to suppress the occurrence of zigzag or wavy black lines that degrade display quality.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1(A) is a cross-sectional view of a ferroelectric liquid crystal element of the present invention, and FIG. 1(B) is a plan view thereof. FIG. 2 is a perspective view schematically showing the alignment state of ferroelectric liquid crystal molecules used in the present invention. FIG. 3 is a characteristic diagram showing the relationship between the average bonding area per bonded body and the distribution density. Condolences 2 Special 3' [Chief Minister Yoshi 1) Moon Takeshi 1. ! Display of l$i11 1988 Patent Application No. 155453 2. Name of the invention Ferroelectric liquid crystal element 3. Name to be amended 7Σ Relationship to address name case Patent applicant 3-3O-2 Shimomaruko, Ota-ku, Tokyo (100) Canon Co., Ltd. Representative Keiichi Yamaji 4, Agent 5, Specification subject to amendment 6, Contents of amendment (1) “Table 1” on page 12 and “Table 1” on page 14 of the specification of the present application Table 2 will be corrected as shown in the attached sheet. residence

Claims (6)

[Claims] (1) A ferroelectric liquid crystal element having a pair of substrates spaced apart from each other, a ferroelectric liquid crystal disposed between the pair of substrates, and an adhesive for bonding the pair of substrates, wherein the adhesive distributed on the inner surface of the substrate, and the average adhesion area per piece of the adhesive body is 1.25 × 10^-^3 mm^2 or less,
When the distribution density of the adhesive body is 100 pieces/mm^2 or less, the total adhesive area of the adhesive body is S_A (mm^2), and the display area is S_B (mm^2), (S_A/S_B)
A ferroelectric liquid crystal element characterized in that ×100% is 2.5×10^-^2 to 1.0%. (2) The ferroelectric liquid crystal device according to claim 1, wherein the distribution density of the adhesive is 50 pieces/mm^2 or less. (3) Claim (
1) Ferroelectric liquid crystal element. (4) The ferroelectric liquid crystal device according to claim (3), wherein the non-adhesive body is a granular or fibrous hard body. (5) The ferroelectric liquid crystal device according to claim 1, wherein the distance between the pair of substrates is set to be sufficiently small to suppress a helical alignment structure of the ferroelectric liquid crystal. (6) The ferroelectric liquid crystal device according to claim (1), wherein an alignment control film is disposed on at least one of the pair of substrates.