JPS6370228A - Ferroelectric liquid crystal element - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to liquid crystal elements such as liquid crystal display elements and liquid crystal-light shutter arrays. The present invention also relates to a ferroelectric liquid crystal element with improved driving characteristics.

[Summary of the Disclosure] This specification and drawings describe a method in which a gap agent sandwiched between substrates is inserted into a color filter on a substrate in a ferroelectric liquid crystal element used for a liquid crystal display element, a liquid crystal-optical shutter array, etc. The present invention discloses a technology for improving cell gap variation and preventing alignment defects by forming a ferroelectric liquid crystal element in which a ferroelectric liquid crystal element can fully exhibit the characteristics of a ferroelectric liquid crystal. .

[Prior Art] Conventionally, in a color liquid crystal display panel, in order to maintain the gap between a filter substrate and a counter substrate (cell gap), a gap agent is sprayed on the first layer of the filter formed on the substrate and then attached to the counter substrate. The cell gap was obtained by pressing the filters together with a pressure that did not allow the gap agent to sink into the filter layer.

[Problems to be Solved by the Invention] However, the accuracy of the gap agent sprayed between the substrates decreases as the particle size decreases, and not all of the gap agent is necessarily in uniform contact with one layer of the filter. In other words, some of them are floating in the liquid crystal, and some are embedded in the filter. For example, when the gap interval is set to IJLm, it is actually 1
The accuracy was only about 1.5km ± 0.5km.

Conventionally, alignment defects in liquid crystal were thought to be caused by unevenness on the filter surface caused by the gap agent sinking into the filter. However, as a result of research conducted by the present inventors, it has become clear that alignment defects in liquid crystals are mainly caused by the above-mentioned variations in cell gap precision rather than by the unevenness of the filter surface caused by the gap agent. That is, in order to eliminate alignment defects in liquid crystal, a highly accurate cell gap is required.

An object of the present invention is to provide a ferroelectric liquid crystal element that can prevent the occurrence of the above-mentioned alignment defects and fully exhibit the high-speed response and memory effect characteristics inherent in ferroelectric liquid crystal elements. This is the purpose.

[Means for Solving the Problems] and [Operation] The present inventors particularly focused on the initial orientation during the cooling process in which the liquid crystal transitions from the isokyoshi phase (high temperature state) to the liquid crystal phase (low temperature state), and We have discovered a liquid crystal element having a structure that allows both the operating characteristics of the element based on bistability and the monodomain property of the liquid crystal layer. The liquid crystal element of the present invention is based on such knowledge, and more specifically, the thickness of the liquid crystal layer is uniform on the inner surface of the liquid crystal element, that is, the thickness of the liquid crystal layer does not change rapidly. By eliminating this, the initial orientation during the temperature cooling process is maintained in a good state, and monodomains with no orientation defects are formed.

That is, in the present invention, a gap agent that maintains the distance between the ferroelectric liquid crystal and the parallel substrates is sandwiched between a pair of parallel substrates on which transparent electrodes are formed, and between at least one of the transparent electrodes and the substrates, A ferroelectric liquid crystal element with a cell structure having a color filter with the same film thickness for each pixel, and a gap agent used to maintain the cell gap of the element.
This is a ferroelectric liquid crystal element characterized by being formed by being sunk into a filter that constitutes a pixel.

Particularly suitable liquid crystal materials for use in the present invention are liquid crystals with bistability and ferroelectricity, specifically chiral smectic C phase (SIII
C* phase), H phase (SmH phase), I phase (SmI° phase),
J phase (SmJ' phase), K phase (Sw, K phase), G phase (
A liquid crystal of Sa+G phase) or F phase (S++F phase) can be used.

Regarding this ferroelectric liquid crystal, Le Journal de...
Physique Rutile (“LE JOURNALICE”
P) IYsIQUE LETTER3'') 1975
Year, No. 1 (L-69), “Ferroelectric Liquid Crystals J (rFerroelectri
cliquid GrystalsJ); “Applied Physics Letters” (AppliedPhys
sics Letters'') 1980, 36 (
No. 11), “Submicro Second Bistiple”
electroobtic switching in liquid
Crystals (rsubmicro 5econdB
istableElectroopticSwit
changing in Liquid CrystalsJ)
``Solid State Physics'', 1981, No. 16 (141), ``Liquid Crystal'', etc., and the ferroelectric liquid crystal disclosed in these can be used in the present invention.

A specific example of the ferroelectric liquid crystal compound is decyloxybenzylidene-p'-amino-2-methylbutylcinnamate (DOBA)! BC), hexyloxybenzylidene-p'-amino-2-chloropropylcinnamate (
HOBACPC), 4-o-(2-methyl)-butylresol silidan-4-fuoctylaniline (MBRA
8).

When constructing an element using these materials, the element can be supported by a block or the like in which a heater is embedded, if necessary, in order to maintain the temperature at which the liquid crystal compound becomes a chiral smectic phase.

Materials for the alignment control film used in the present invention include, for example, polyvinyl alcohol, polyimide, polyamideimide, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, and urea resin. , resins such as acrylic resin, photosensitive polyimide, photosensitive polyamide, cyclized rubber photoresist, phenol novolac photoresist, or electron beam photoresist (polymethylmethacrylate-1, epoxidized-1,4- polybutadiene, etc.).

Color filters used in the present invention include vapor deposition types, dyed types, resin types, electrodeposition types, etc., and may be formed by any method.

In addition, the pigment materials for color filters used in the present invention include azo-based, anthraquinone-based, phthalocyanine-based, quinacridone-based, isoindolinone-based, dioxazine-based, perylene-based, perinone-based, thioindigo-based, pyrocholine-based, and fluorobin-based. , quinophthalone series, etc.

Examples of the material for the gap agent used in the present invention include glass, alumina, and plastic, and the gap agent may have a spherical shape.

FIG. 1 is a cross-sectional view schematically showing the cell structure of a ferroelectric liquid crystal device according to the present invention. In FIG. 1, the liquid crystal element consists of a pair of parallel substrates 1 arranged above and below, a color filter 2 formed on one of the substrates, a gap agent 3 and a ferroelectric liquid crystal 4 sandwiched between these substrates. It is composed of a sealant 5 for sealing the surroundings.

As shown in the figure, the diameter of each gear gap agent is the sum of the penetration depth lr of the gap agent 3 into the color filter 2 and the cell gap lG, which is larger than the gap agent used in conventional elements. A diameter gap agent will be used. As mentioned above, it is difficult to make a gap agent with high precision when the diameter is around 1 gm, but if the diameter is as large as this, it becomes possible to make a gap agent with high precision relatively easily. In addition, the bonding pressure of the upper and lower substrates in the present invention varies depending on the material (hardness) of the color filter, but is usually about 3 times the bonding pressure in the conventional method.
It will be a premium. Therefore, the gap agent is pressed with a higher pressure than before, and is formed in a state in which it is sunk into the filter to a certain depth. Therefore, the cell gap can be maintained with extremely high precision, and monodomains without orientation defects can be obtained.

[Example] FIG. 3 shows an example of forming a color filter on a substrate, and is a diagram showing a process of forming a color filter using a photosensitive colored resin.

In FIG. 3, a blue colored resin agent [Heliogen Blue L7080 (trade name, manufactured by BASF, C, 1, No. 74160, manufactured by BASF Corporation) that can obtain desired spectral characteristics is placed on a glass substrate 1.
) in PA-1000c (trade name, manufactured by Ube Industries, Ltd., polymer content 10%, solvent - N-methyl-2-pyrrolidone, pigment: polymer = 1:2 blend) Photosensitive colored resin material 2 ] by spinner coating method, 2.0
It was applied to a film thickness of JLra (see FIG. 3(a)). Next, this colored resin layer 2 was subjected to blebbing at 80° C. for 30 minutes, and then exposed to light using a high-pressure mercury lamp through a photomask 10 having a pattern corresponding to the pattern shape to be formed (see Fig. 3(b). )reference). After the exposure, the colored resin layer 2 is developed using an ultrasonic wave with a special developer (a developer whose main component is N-methyl-2-pyrrolidone) that dissolves only the unexposed areas, and a special rinse solution ( After treatment with a rinsing liquid whose main component is 1,1,1,-)lichloroethane,
Post-baking was performed at 150°C for 30 minutes to form a blue colored resin layer 7 having a patterned shape (see Fig. 3 (C)).
), see (d)).

Next, a green colored resin material [Lionol Green] was applied as a second color onto the glass substrate on which the blue colored pattern was formed.
7 (Lionol Green) 6YK (Product name.

Manufactured by Toyo Ink Co., Ltd., C, L No. 74265)
A-+000c (product name, manufactured by Ube Industries, polymer content: 1)
A green colored resin layer was prepared in the same manner as above, except that a photosensitive colored resin material prepared by dispersing it in 0, '6, solvent 2N-methyl-2-pyrrolidone, pigment:polymer = 1:2 ratio) was used. 7 was formed at a predetermined position on the substrate.

Furthermore, on the substrate on which the blue and green patterns are formed, a red colored resin material [Irgazin Red (trade name) BPT (trade name,
Manufactured by Ciba-Gsigy, C, I
.

No. 71127) is dispersed in PA-+000c (trade name, manufactured by Ube Industries, Ltd., polymer content 10%, solvent = N-methyl-2-pyrrolidone, pigment: polymer = 1 = 2 combination). Photosensitive colored resin. material]
In the same manner as above, the red colored resin layer 8 is shaped at a predetermined position on the substrate, and three layers of L, R (red), G (green), and B (blue) are formed.
A colored pattern of colored stripes was obtained (see FIG. 3(e)).

A sealant (DNM-2110, manufactured by Dainippon Toyo Co., Ltd.) was printed on the outer periphery of the filter substrate obtained in this way, and then a spherical gap agent (2.0 km in diameter) was printed on the filter.
(made of glass) was sprayed. Then, attach it to the counter board,
A ferroelectric liquid crystal element was obtained by crimping with a pressure of 1.8 kg/cm2 and betaening at 180°C for 30 minutes.

The ferroelectric liquid crystal device obtained by the above method is as follows:1.
Since it is crimped with a force of 8Kg/cm2, it is 2.0 JLm.
The filter is exactly 1. Op-rs sinking, cell gap 1. Ogm±0.051. I was able to obtain Lm.

FIG. 2 is a perspective view showing the measurement positions of the cell gap in the liquid crystal element, and the cell gap measurements at the measurement positions of ■ to ■ in the figure are shown in the table below - IK 75 f.
Table 1 In the above embodiment, an example was explained in which the gap agent was directly sprayed on the color filter, but as shown in FIG. The agent may be sunk into this protective layer 9.

[Effects of the Invention] As explained above, according to the present invention, by sinking a highly accurate gap agent into a filter to a certain depth, it is possible to maintain a uniform cell gap with high accuracy. can. Therefore, alignment defects in the initial alignment state 7G of the liquid crystal can be prevented, and a ferroelectric liquid crystal that can fully exhibit the characteristics of a ferroelectric liquid crystal can be provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a ferroelectric liquid crystal element according to the present invention, and FIG.
The figure shows the cell gap measurement position, and FIG. 3 shows the process of forming a color filter. 1...Substrate, 2...Color filter. 3...Gap agent. Figure 1. Full A's and one tube in the present position. Figure 2.

Claims (1)

[Claims] 1) A gap agent that maintains the distance between the ferroelectric liquid crystal and the parallel substrates is sandwiched between a pair of parallel substrates on which transparent electrodes are formed, and a gap agent for each pixel is placed between at least one of the transparent electrodes and the substrate. 1. A ferroelectric liquid crystal element having a cell structure having color filters having the same film thickness, characterized in that the gap agent is formed by sinking into the color filter.