JP4054506B2 - Liquid crystal light modulator and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the alignment of a liquid crystal without using a high temperature calcining process so that a plastic substrate can be used as a transparent substrate and to attain a light and large-sized device. SOLUTION: A fluorocarbon resin is applied to transparent electrodes 3a, 3b formed on transparent substrates 4a, 4b to form fluorocarbon resin alignment films 1a, 1b which control the alignment of the liquid crystal. A voltage outputted from a voltage supply 7 is applied to the transparent electrodes 3a, 3b to control the molecular arrangement of the liquid crystal 2.

Description

【００２８】
請求項２では、請求項１に記載の液晶光変調器を用いることを特徴としている。
【００２９】
上記の構成において、本発明では、高分子の側鎖に―Ｒ_１―（ＣＦ_２）_ｎ―Ｒ_２という化学構造（但し、ｎは１以上の整数を表し、Ｒ_１は直接結合または１つ以上のメチレン基を表し、Ｒ_２はＣＦ_３、ＣＨＦ_２、ＣＨ_２ＦまたはＣＨ_３を表す）を合むフッ素樹脂を配向膜として用いることにより、高温焼成過程が不要な液晶光変調器の作製を可能とした。
【００３０】
なお、本発明のフッ素樹脂配向膜は、分子構造に合まれるＣ−Ｆ結合の高い安定性から、以下に示すような特徴を示す。
【００３１】
上記フッ素樹脂は透明であり、透明基板上へ塗布した後に高温焼成処理を施さなくても、耐熱性、耐溶剤性に非常に優れ、さらに膜が透明基板から剥離することはない（▲２▼の問題点を解決）。
【００３２】
上記フッ素樹脂は、高温焼成過程を必要としないため、カラーフィルターの特性を劣化させることが無い（▲１▼の問題点を解決）。
【００３３】
さらに、熱に弱いプラスティックフィルムを透明基板に用いることも可能となり、計量化、大型化が可能なフラットディスプレイヘの応用もできる（▲１▼、▲２▼の問題点を解決）。
【００３４】
【発明の実施の形態】
図１は、本発明を適用した液晶光変調器の実施の形態を模式的に示す構造断面図である。
【００３５】
この図に示す液晶光変調器１３では、透明電極３ａ，３ｂ付き透明基板４ａ，４ｂ上に付着したフッ素樹脂配向膜１ａ，１ｂで、液晶２を挟みこんだ構造をしており、液晶２はフッ素樹脂配向膜１ａ，１ｂにより配向制御される。透明電極３ａ，３ｂは透明基板４ａ，４ｂ上に付着され、リード線５ａ，５ｂとスイッチ６を介して、電圧源７に接続される。液晶層の厚みは、液晶２中に分散されたスペーサー８により一定に保たれ、液晶２はシール剤９ａ，９ｂにより封止してある。入射光１０は、偏光板１１ａにより偏光された後、一方の透明基板４ａから入射し、液晶２で偏光状態が制御され、透明基板４ｂ、ついで出射側の偏光板１１ｂを通過した後、出射光１２となる。この液晶光変調器１３のスイッチ６を入れて透明電極４ａ，４ｂに電界を印加すると、液晶の配列が変化し出射光１２の強度が変化するため、本液晶光変調器１３の制御は電圧源７により行われる。
【００３６】
フッ素樹脂配向膜１ａ，１ｂとして用いることのできるフッ素樹脂は、メタクリル樹脂、アクリル樹脂、ウレタン樹脂、ポリ塩化ビニル、酢酸ビニル、フェノール樹脂、エポキシ樹脂、セルロース樹脂、ポリエチレン、ポリプロピレン、メラニン樹脂、ポリエステル、ポリビニルブチラール、ポリビニルカルバゾール、ポリビニールアセテート、ポリカーボネート、ポリスチレン、シリコーン樹脂、またはこれらの共重合体である樹脂の側鎖に、―Ｒ_１―（ＣＦ_２）_ｎ―Ｒ_２という構造を持つ基（但し、ｎは１以上の整数を表し、Ｒ_１は直接結合または１つ以上のメチレン基を表し、Ｒ_２はＣＦ_３，ＣＨＦ_２，ＣＨ_２ＦまたはＣＨ_３を表す）を合む樹脂である。
【００３７】
このフッ素樹脂の成膜は、最初にスピンコーティング、ロールコーティング、ディッピング、スプレー、ブレード、ワイヤーバーコーティング、凸版印刷、フレキソ印刷またはシルク印刷などにより、透明電極３ａ，３ｂ付き透明基板４ａ，４ｂ上に塗布した後、溶媒蒸発、光硬化、熱硬化または反応硬化により行うことが可能である。
【００３８】
なお、上記透明基板４ａ，４ｂと透明電極３ａ，３ｂの間に、カラーフィルターやブラックマトリクスなどが設けられていても良く、従来の液晶光変調器に用いられる構造はすべて適用することが可能である。
【００３９】
上記の成膜方法では、フッ素樹脂の塗布後の高温焼成過程を必要としないため、透明基板４ａ，４ｂとして薄くて柔軟なプラスティックフィルムや厚みが０．６ｍｍ以下の薄いガラス板を用いることが可能となり、軽量で柔軟な液晶光変調器が実現できる。
【００４０】
また、上記透明基板４ａ，４ｂとして、薄いガラス板やプラスティックフィルムを用いる場合には、液晶層の厚みを保持するために、液晶層に球状のスペーサー８を分散させる方法が有用である。
【００４１】
上記の方法により成膜したフッ素樹脂配向膜１ａ，１ｂに、ラビング処理もしくは偏光紫外光の照射による配向処理を施すことにより、液晶２の分子配列をホモジニアス配向、ホメオトロピック配向または捩れ配向とすることが可能なため、偏光板１１ａ，１１ｂとの組み合わせを変えることにより、種々の光変調器を作製することができる。
【００４２】
また、液晶２の材料には、強誘電性液晶を含むスメクティック液晶、ネマティック液晶、コレステリック液晶を用いるが、それらの液晶材料に微細な樹脂を分散して液晶層に導入した液晶光変調器の作製も可能である。
【００４３】
また、透明基板４ａ，４ｂの一方に、反射板あるいは電極を兼用できる伝導性の反射板を付加することにより、低消費電カの反射型の液晶光変調器を作製することもできる。
【００４４】
さらに上記の液晶光変調器を表示装置に応用すると、軽量で柔軟なディスプレー装置を実現できる。
【００４５】
一例として試作した実施例では、メタクリル型フッ素樹脂（アスカ電子社ＨＦ−２）を用いた。このフッ素樹脂配向膜１ａ，１ｂを構成する材料は、以下の構造式で記載することができる。
【００４６】
【化３】

【００４７】
上述した構造式のメタクリル型フッ素樹脂をスピンコーティングにより、透明電極３ａ，３ｂ（Ｉｎ２０３：Ｓｎ、厚み１５０ｍｍ）付きプラスティックフィルム透明基板４ａ，４ｂ（厚み１００μｍ）上に塗布する。そのまま室温で溶媒を揮発させて１００ｎｍの配向膜１ａ，１ｂを成膜し、微細なレーヨンロールで一方向に擦る（ラビング処理）。この配向膜付きプラスティック透明基板４ａ，４ｂの一方となる透明基板４ｂに、シール剤９ａ，９ｂを塗布し、さらに６μｍの球状スペーサー８を散布したネマティック液晶（メルクジャパン社ＢＬ−００８、誘電率異方性△ε＝１７．３、屈折率異方性△μ＝０．２８）を塗布して、もう一方の透明基板４ａをラビング方向が互いに９０度ずれた方向になるように張り合わせ、液晶２を捩れ配向させた。
【００４８】
そして、偏光板１１ａと偏光板１１ｂを偏光軸が互いに平行になるように配置すると、スイッチ６に印加する交流電圧が小さい場合には、入射光１０は偏光板１１ａにより直線偏光された後、液晶２で偏光軸が９０度回転するため、出射側の偏光板１１ｂを通過することができず、出射光１２は観測されなかった。
【００４９】
次にスイッチ６に印加する交流電圧を大きくすると、液晶の長軸が基板に垂直に立ち上がるため、入射光が出射側の偏光板１１ｂを通過できるようになり、出射光１２が観測された。
【００５０】
以上の測定結果を図２に示す。同図では、ツイストネマティック効果が示され、フッ素樹脂配向膜の配向機能が確認された。
【００５１】
【発明の効果】
以上説明したように本発明によれば、請求項１の液晶光変調器では、配向膜として、側鎖にフロロメチレン基を合むフッ素樹脂を導入することにより、高温焼成過程を行わなくても配向制御が可能となるため、透明基板にプラスティックフィルム基板などを使用した軽量な液晶光変調器を提供することができる。
【００５２】
請求項２の表示装置では、大型フラットディスプレイ等の軽量化が期待できる。
【図面の簡単な説明】
【図１】本発明による表示装置で使用される液晶光変調器の実施の形態を模式的に示す構造断面図である。
【図２】本発明よる液晶光変調器に印加する交流電庄と透過率の関係を示す模式図である。
【符号の説明】
１ａ，１ｂ…フッ素樹脂配向膜
２…液晶
３ａ，３ｂ…透明電極
４ａ，４ｂ…透明基板
５ａ，５ｂ…リード線
６…スイッチ
７…電圧源
８…スペーサー
９ａ，９ｂ…シール樹脂
１０…入射光
１１ａ，１１ｂ…偏光板
１２…出射光
１３…液晶光変調器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal light modulator that modulates light intensity using liquid crystal and a display device using the liquid crystal light modulator.
[0002]
[Summary of Invention]
The present invention relates to a liquid crystal light modulator and a display device capable of controlling the transmittance of incident light by an applied voltage. By using a fluororesin that does not require a high-temperature baking process for an alignment film, the use of a lightweight plastic film substrate is possible. It is possible to apply to a liquid crystal light modulator and a display device which can be made light and can be enlarged.
[0003]
[Prior art]
The liquid crystal light modulator applies an electro-optic effect in which the alignment state of liquid crystal molecules is changed by an electric field, and is widely used in display devices and the like. In a liquid crystal light modulator, it is necessary to control the alignment of liquid crystal molecules, and an alignment film is generally used to regulate the alignment of liquid crystal molecules.
[0004]
Conventionally, polyimide has been widely used as an alignment film for liquid crystal. Since polyimide is a polymer whose main chain is an imido acid bond, it has a feature of being extremely excellent in heat resistance and solvent resistance. Furthermore, it is transparent and has good adhesion to the substrate and various electrode films, and the liquid crystal can be easily aligned by a process such as rubbing or irradiation with polarized ultraviolet rays.
[0005]
In addition, as a film-forming method of the said polyimide alignment film, the following are mentioned.
[0006]
(1) A polyimide alignment film is formed by dissolving polyamic acid, which is a precursor of polyimide, in an organic solvent and applying it to a substrate by spin coating or the like, followed by baking at 200 to 300 ° C. to cause an imidization reaction. .
[0007]
(2) A soluble polyimide solution obtained by chemically imidizing the polyamic acid in an organic solvent is applied onto a substrate by spin coating or the like, and then the solvent is evaporated at about 180 ° C. to form a polyimide alignment film. .
[0008]
[Problems to be solved by the invention]
However, the polyimide alignment film has the following problems.
[0009]
The polyimide alignment film formed by the method (1) requires a baking process at a very high temperature of 200 to 300 ° C., so that the glass which is a transparent substrate is deformed by heat or is weak to heat. There is a problem that a plastic film substrate cannot be used. Further, when producing a color filter type color liquid crystal element by the above method, there is a problem that the color filter is deteriorated by being heated at a high temperature.
[0010]
The polyimide alignment film formed by the method (2) can be formed at a lower temperature than the method (1). However, when the film is formed on a plastic film substrate which is vulnerable to heat. However, since it is necessary to lower the firing temperature, the solvent remains in the alignment film and the mechanical strength of the film becomes weak, and the problem arises that the film peels off from the substrate during rubbing.
[0011]
In view of the above circumstances, in the present invention, a plastic film substrate can be used in claim 1 by using an alignment film that does not require a high-temperature baking process, thereby facilitating weight reduction and enlargement. An object is to provide a liquid crystal light modulator.
[0012]
In the second aspect of the present invention, a plastic film substrate can be used by using an alignment film that does not require a high-temperature firing process, and thereby an object is to provide a display device that can be easily reduced in weight and size. Yes.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, in claim 1, a transparent substrate to which a transparent electrode is attached, a fluororesin alignment film applied to the transparent electrode on the transparent substrate, and the fluororesin alignment film are provided. a liquid crystal which is oriented control, and a voltage source for applying a voltage to the transparent electrode and organic,
A resin represented by the following structural formula (where n represents an integer of 1 or more) is used for the fluororesin alignment film.
[0027]
[Chemical 2]

[0028]
According to claim 2, characterized by using a liquid crystal light modulator of claim 1.
[0029]
In the above structure, in the present invention, the side chain of the polymer has a chemical structure of —R ₁ — (CF ₂ ) _n —R ₂ (where n represents an integer of 1 or more and R ₁ is a direct bond or one A liquid crystal light modulator that does not require a high-temperature baking process by using a fluororesin that combines the above methylene groups and R ₂ represents CF ₃ , CHF ₂ , CH ₂ F, or CH ₃ as an alignment film. Made possible.
[0030]
In addition, the fluororesin alignment film of the present invention exhibits the following characteristics from the high stability of the C—F bond matched to the molecular structure.
[0031]
The fluororesin is transparent, and it is very excellent in heat resistance and solvent resistance without being subjected to a high-temperature baking treatment after being applied onto a transparent substrate, and the film does not peel from the transparent substrate ((2) To solve the problem.
[0032]
Since the fluororesin does not require a high-temperature baking process, the characteristics of the color filter are not deteriorated (the problem (1) is solved).
[0033]
Furthermore, it becomes possible to use a heat-sensitive plastic film as a transparent substrate, and it can be applied to a flat display that can be scaled and enlarged (solves the problems (1) and (2)).
[0034]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a structural sectional view schematically showing an embodiment of a liquid crystal light modulator to which the present invention is applied.
[0035]
The liquid crystal light modulator 13 shown in this figure has a structure in which liquid crystal 2 is sandwiched between fluororesin alignment films 1a and 1b attached on transparent substrates 4a and 4b with transparent electrodes 3a and 3b. The orientation is controlled by the fluororesin orientation films 1a and 1b. The transparent electrodes 3a and 3b are attached on the transparent substrates 4a and 4b, and are connected to the voltage source 7 via the lead wires 5a and 5b and the switch 6. The thickness of the liquid crystal layer is kept constant by the spacers 8 dispersed in the liquid crystal 2, and the liquid crystal 2 is sealed with sealants 9a and 9b. The incident light 10 is polarized by the polarizing plate 11a, then enters from one transparent substrate 4a, the polarization state is controlled by the liquid crystal 2, passes through the transparent substrate 4b, and then the output-side polarizing plate 11b, and then the emitted light. 12 When the switch 6 of the liquid crystal light modulator 13 is turned on and an electric field is applied to the transparent electrodes 4a and 4b, the alignment of the liquid crystal changes and the intensity of the emitted light 12 changes. Therefore, the liquid crystal light modulator 13 is controlled by a voltage source. 7 is performed.
[0036]
The fluororesin that can be used as the fluororesin alignment films 1a and 1b are methacrylic resin, acrylic resin, urethane resin, polyvinyl chloride, vinyl acetate, phenol resin, epoxy resin, cellulose resin, polyethylene, polypropylene, melanin resin, polyester, A group having a structure of —R ₁ — (CF ₂ ) _n —R ₂ on the side chain of polyvinyl butyral, polyvinyl carbazole, polyvinyl acetate, polycarbonate, polystyrene, silicone resin, or a copolymer thereof (provided that , N represents an integer of 1 or more, R ₁ represents a direct bond or one or more methylene groups, and R ₂ represents CF ₃ , CHF ₂ , CH ₂ F, or CH ₃ ).
[0037]
The fluororesin film is first formed on the transparent substrates 4a and 4b with the transparent electrodes 3a and 3b by spin coating, roll coating, dipping, spraying, blade, wire bar coating, letterpress printing, flexographic printing or silk printing. After application, it can be carried out by solvent evaporation, photocuring, heat curing or reaction curing.
[0038]
In addition, a color filter, a black matrix, or the like may be provided between the transparent substrates 4a and 4b and the transparent electrodes 3a and 3b, and all structures used in a conventional liquid crystal light modulator can be applied. is there.
[0039]
Since the above film forming method does not require a high-temperature baking process after application of the fluororesin, it is possible to use a thin and flexible plastic film or a thin glass plate having a thickness of 0.6 mm or less as the transparent substrates 4a and 4b. Thus, a lightweight and flexible liquid crystal light modulator can be realized.
[0040]
Further, when a thin glass plate or plastic film is used as the transparent substrates 4a and 4b, a method of dispersing spherical spacers 8 in the liquid crystal layer is useful in order to maintain the thickness of the liquid crystal layer.
[0041]
The fluororesin alignment films 1a and 1b formed by the above method are subjected to a rubbing process or an alignment process by irradiation with polarized ultraviolet light, so that the molecular alignment of the liquid crystal 2 is set to a homogeneous alignment, homeotropic alignment, or twisted alignment. Therefore, various optical modulators can be manufactured by changing the combination with the polarizing plates 11a and 11b.
[0042]
The liquid crystal 2 is made of a smectic liquid crystal containing a ferroelectric liquid crystal, a nematic liquid crystal, or a cholesteric liquid crystal, and a liquid crystal light modulator in which a fine resin is dispersed in the liquid crystal material and introduced into a liquid crystal layer. Is also possible.
[0043]
Further, a reflective liquid crystal light modulator with low power consumption can be produced by adding a conductive reflector that can also serve as a reflector or an electrode to one of the transparent substrates 4a and 4b.
[0044]
Furthermore, when the liquid crystal light modulator is applied to a display device, a light and flexible display device can be realized.
[0045]
As an example, a methacrylic fluororesin (Asuka Electronics HF-2) was used in the prototype. The material constituting the fluororesin alignment films 1a and 1b can be described by the following structural formula.
[0046]
[Chemical 3]

[0047]
The methacrylic fluororesin having the structural formula described above is applied onto the plastic film transparent substrates 4a and 4b (thickness 100 μm) with transparent electrodes 3a and 3b (In203: Sn, thickness 150 mm) by spin coating. The solvent is volatilized as it is to form 100 nm alignment films 1a and 1b and rubbed in one direction with a fine rayon roll (rubbing treatment). A nematic liquid crystal (Merck Japan BL-008, different dielectric constant) in which a sealant 9a, 9b is applied to a transparent substrate 4b, which is one of the plastic transparent substrates 4a, 4b with an alignment film, and a 6 μm spherical spacer 8 is dispersed. Is applied to the other transparent substrate 4a so that the rubbing directions are shifted from each other by 90 degrees, and the liquid crystal 2 is bonded. Were twisted.
[0048]
When the polarizing plate 11a and the polarizing plate 11b are arranged so that the polarization axes are parallel to each other, when the alternating voltage applied to the switch 6 is small, the incident light 10 is linearly polarized by the polarizing plate 11a, and then the liquid crystal 2, the polarization axis was rotated by 90 degrees, so that it could not pass through the exit-side polarizing plate 11b, and the emitted light 12 was not observed.
[0049]
Next, when the AC voltage applied to the switch 6 is increased, the major axis of the liquid crystal rises perpendicularly to the substrate, so that incident light can pass through the polarizing plate 11b on the emission side, and the emission light 12 is observed.
[0050]
The above measurement results are shown in FIG. In the figure, the twisted nematic effect was shown, and the alignment function of the fluororesin alignment film was confirmed.
[0051]
【The invention's effect】
As described above, according to the present invention, in the liquid crystal light modulator according to the first aspect of the present invention, the introduction of the fluororesin having a fluoromethylene group in the side chain as the alignment film eliminates the need for a high-temperature baking process. Since the orientation can be controlled, a lightweight liquid crystal light modulator using a plastic film substrate or the like as the transparent substrate can be provided.
[0052]
In the display device according to the second aspect , weight reduction of a large flat display or the like can be expected.
[Brief description of the drawings]
FIG. 1 is a structural cross-sectional view schematically showing an embodiment of a liquid crystal light modulator used in a display device according to the present invention.
FIG. 2 is a schematic diagram showing a relationship between AC voltage applied to a liquid crystal light modulator according to the present invention and transmittance.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1a, 1b ... Fluorine resin alignment film 2 ... Liquid crystal 3a, 3b ... Transparent electrode 4a, 4b ... Transparent substrate 5a, 5b ... Lead wire 6 ... Switch 7 ... Voltage source 8 ... Spacer 9a, 9b ... Seal resin 10 ... Incident light 11a , 11b ... Polarizing plate 12 ... Emission light 13 ... Liquid crystal light modulator

Claims (2)

A transparent substrate having a transparent electrode attached thereto, a fluororesin alignment film applied to the transparent electrode on the transparent substrate, a liquid crystal controlled in alignment by the fluororesin alignment film, and a voltage source for applying a voltage to the transparent electrode It has a door,
A liquid crystal light modulator, wherein a resin represented by the following structural formula (where n represents an integer of 1 or more) is used for the fluororesin alignment film.

A liquid crystal light modulator according to claim 1 is used.

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