JPH0731324B2 - Liquid crystal electro-optical device - Google Patents
Liquid crystal electro-optical deviceInfo
- Publication number
- JPH0731324B2 JPH0731324B2 JP60000679A JP67985A JPH0731324B2 JP H0731324 B2 JPH0731324 B2 JP H0731324B2 JP 60000679 A JP60000679 A JP 60000679A JP 67985 A JP67985 A JP 67985A JP H0731324 B2 JPH0731324 B2 JP H0731324B2
- Authority
- JP
- Japan
- Prior art keywords
- liquid crystal
- ferroelectric
- layer
- electric field
- substrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
- G02F1/133711—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by organic films, e.g. polymeric films
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- Physics & Mathematics (AREA)
- Liquid Crystal (AREA)
- Nonlinear Science (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Mathematical Physics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、記憶効果、高速応答、急峻なしきい特性を有
する強誘電性液晶を使用した液晶電気光学装置における
基板表面処理法に関する。TECHNICAL FIELD The present invention relates to a substrate surface treatment method in a liquid crystal electro-optical device using a ferroelectric liquid crystal having a memory effect, a high-speed response, and a steep threshold characteristic.
従来の液晶電気光学装置における基板表面処理法には、
上下の基板それぞれにポリイミド等の同種の表面処理層
を設ける方法、全く処理を施さない方法、第10回液晶討
論会予稿14A17のように上基板と下基板にそれぞれ表面
の極性の異なる表面処理層を設ける方法、あるいはネマ
チック液晶の配向処理と同様に基板表面にポリイミドを
塗布し、さらにラビング処理を施す方法がある。The substrate surface treatment method in the conventional liquid crystal electro-optical device includes
A method of providing the same type of surface treatment layer of polyimide or the like on each of the upper and lower substrates, a method of not performing any treatment, and a surface treatment layer having different surface polarities on the upper substrate and the lower substrate as in the 10th Liquid Crystal Conference Proceedings 14A17 Or a method of applying polyimide to the surface of the substrate and then rubbing the same as in the nematic liquid crystal alignment treatment.
カイラルな分子からなるスメクチックC*液晶は強誘電性
を示し、第1図に示すように液晶分子11はZ軸方向から
常にθ傾いた状態で円錐上に位置しており、液晶分子11
に対して垂直かつスメクチック層(X-Y平面)と平行な
方向に永久双極子12を持っている。したがって電界を印
加して永久双極子12の向きを変えることによって液晶分
子11の円錐上での位置(方位角φ)を制御することがで
きる。ただし、13は液晶分子11のX-Y平面への射影であ
る。The smectic C * liquid crystal composed of chiral molecules exhibits ferroelectricity, and as shown in FIG. 1, the liquid crystal molecule 11 is always located on a cone with a tilt of θ from the Z-axis direction.
Has a permanent dipole 12 in a direction perpendicular to and parallel to the smectic layer (XY plane). Therefore, the position of the liquid crystal molecules 11 on the cone (azimuth angle φ) can be controlled by applying an electric field to change the direction of the permanent dipole 12. However, 13 is a projection of the liquid crystal molecule 11 on the XY plane.
厚さ数μmのセルのX-Y断面における液晶分子の配向は
第2図のように表わされる。第2図(a),(b),
(c)はそれぞれ無電界時、下基板から上基板に向かっ
て電界+Eを印加した時および電界−Eを印加した時の
液晶分子の配向を示している。ただし、第2図は基板表
面にポリイミド15を塗布したセルにおける配向を示して
ある。無電界時には永久双極子12が基板表面からセルの
内部に向かう配列をとっているが、基板表面の処理剤の
種類を変えることによって、無電界時の永久双極子がセ
ルの内部から基板に向かうような配向も得ることができ
る。記憶効果の良否は無電界時の配向状態によって評価
され、電界除去後も第2図(b),(c)に示された電
界印加時と同じ配向が保持されていれば、記憶効果がす
ぐれていると評価される。The orientation of liquid crystal molecules in the XY cross section of a cell having a thickness of several μm is represented as shown in FIG. 2 (a), (b),
(C) shows the alignment of liquid crystal molecules when no electric field is applied, when an electric field + E is applied from the lower substrate to the upper substrate, and when an electric field -E is applied. However, FIG. 2 shows the orientation in a cell in which polyimide 15 is applied to the substrate surface. The permanent dipoles 12 are arranged from the substrate surface to the inside of the cell when there is no electric field.By changing the type of treatment agent on the substrate surface, the permanent dipoles from the inside of the cell to the substrate when there is no electric field. Such an orientation can also be obtained. The memory effect is evaluated by the orientation state when no electric field is applied. If the same orientation as when the electric field is applied as shown in FIGS. 2B and 2C is maintained after the electric field is removed, the memory effect is excellent. Is evaluated.
無電界時の配向状態はセルの厚さに強く影響され、第3
図に示したようにセルの厚さによって種々の配向をとる
と思われる。第3図(a)〜(c)の配向状態はtwist
状態と呼ばれ、第3図(d)はuntwist状態と呼ばれて
いる。The orientation state in the absence of an electric field is strongly influenced by the thickness of the cell.
As shown in the figure, it is considered that various orientations are obtained depending on the cell thickness. The orientation states of FIGS. 3 (a) to 3 (c) are twist.
The state is called, and FIG. 3 (d) is called the untwist state.
ここで、セル厚によっては電界除去後に電圧印加時のun
twist状態を保持することができなくなる理由は次のよ
うに考えられる。液晶分子が基板表面から受ける力は2
種類あり、液晶分子を基板表面に対して平行に保持しよ
うとする力(アンカリング力)と、液晶分子が持ってい
る永久双極子と基板表面の極性との間の相互作用(クー
ロン力)がある。アンカリング力のみを考慮すれば第4
図(a),(b)に示した2つの配向状態はいずれも安
定であり、電界除去後も電界印加時と同じuntwist状態
が保持されるはずである。しかし、クーロン力を考慮す
れば、第4図(a),(b)の配向が持つエネルギーは
異なり、基板表面の極性が正ならば第4図(a)の配向
が最も安定となる。したがってこの場合は電界印加によ
って第4図(b)のように配向させた後、電界を除去す
れば、液晶分子は第4図(a)に示す配向状態へ反転し
ようとする。Here, depending on the cell thickness, un
The reason why the twist state cannot be maintained is considered as follows. The force that liquid crystal molecules receive from the substrate surface is 2
There are different types, the force that tries to keep the liquid crystal molecules parallel to the substrate surface (anchoring force) and the interaction between the permanent dipole possessed by the liquid crystal molecules and the polarity of the substrate surface (Coulomb force). is there. 4th if only anchoring force is considered
The two orientation states shown in FIGS. (A) and (b) are both stable, and the same untwisted state as when the electric field is applied should be maintained after the electric field is removed. However, considering the Coulomb force, the energies of the orientations of FIGS. 4 (a) and 4 (b) are different, and the orientation of FIG. 4 (a) is most stable if the polarity of the substrate surface is positive. Therefore, in this case, if the electric field is removed after the liquid crystal molecules are aligned as shown in FIG. 4 (b) by applying an electric field, the liquid crystal molecules tend to be inverted to the alignment state shown in FIG. 4 (a).
配向に及ぼすクーロン力の影響の大きさは分極反転電流
の測定によって推測することができる。第5図に三角波
状の電界を厚さ4μmのセルに印加した時の分極反転電
流を示す。永久双極子の配向が電界に応答して反転した
時に分極反転電流が流れ、第5図(b)のようにピーク
が現われるが、この図からわかるように、電界の方向が
逆転する以前から永久双極子の反転が始まっている。す
なわち、電界強度がある値より小さくなると、電界に逆
らって第4図(b)の状態から第4図(a)のエネルギ
ー的に有利な状態へ移るために永久双極子の反転が始ま
るわけであり、永久双極子と基板表面の極性との相互作
用は非常に強いものと考えられる。The magnitude of the influence of the Coulomb force on the orientation can be estimated by measuring the polarization reversal current. FIG. 5 shows the polarization reversal current when a triangular electric field is applied to a cell having a thickness of 4 μm. When the orientation of the permanent dipole is reversed in response to an electric field, a polarization reversal current flows and a peak appears as shown in FIG. 5 (b). As can be seen from this figure, the direction of the electric field is permanent before it is reversed. The dipole reversal has begun. That is, when the electric field strength becomes smaller than a certain value, the inversion of the permanent dipole starts in order to move from the state of FIG. 4 (b) to the energetically favorable state of FIG. 4 (a) against the electric field. Therefore, the interaction between the permanent dipole and the polarity of the substrate surface is considered to be very strong.
液晶分子が第4図(b)から(a)の状態へ反転するた
めには、基板表面と平行な面内で反転するのではなく、
第1図に示した円錐上でZ軸を中心にして回転して反転
するため、最初基板表面と平行に配向していた液晶分子
の一端が基板表面から浮き上がらなければならない。
(第3図参照)液晶分子の一端が基板表面から浮きあが
ることのできる量は、液晶分子が受けるアンカリング力
とクーロン力とのバランスで決まると考えられる。液晶
分子が受けるアンカリング力は基板表面との距離が長い
ほど小さく、セルが厚くなるにしたがって一方の基板表
面からある距離に位置する液晶分子と他方の基板表面と
の距離が長くなり、その液晶分子が双方の基板表面から
受けるアンカリング力は薄いセルの場合に比べて小さく
なる。したがって、セルが厚くなると液晶分子が受ける
アンカリング力よりもクーロン力が優勢となって、セル
の厚さに応じて第3図に示したような種々のtwist状態
が安定となる。In order to invert the liquid crystal molecules from the state shown in FIG. 4B to the state shown in FIG. 4A, the liquid crystal molecules are not inverted in a plane parallel to the substrate surface,
Since the light is rotated about the Z axis on the cone shown in FIG. 1 so as to be inverted, one end of the liquid crystal molecules that are initially aligned parallel to the substrate surface must be lifted from the substrate surface.
(See FIG. 3) It is considered that the amount by which one end of the liquid crystal molecule can float up from the substrate surface is determined by the balance between the anchoring force and the Coulomb force that the liquid crystal molecule receives. The longer the distance between the liquid crystal molecules and the substrate surface, the smaller the anchoring force, and as the cell becomes thicker, the distance between the liquid crystal molecules located at a certain distance from one substrate surface and the other substrate surface becomes longer. The anchoring force that the molecule receives from both substrate surfaces is smaller than in the case of a thin cell. Therefore, as the cell becomes thicker, the Coulomb force becomes more dominant than the anchoring force received by the liquid crystal molecules, and various twist states shown in FIG. 3 become stable depending on the cell thickness.
ここまで、上下の基板に同種の表面を使用したセルにお
ける現象について説明したが、上基板と下基板に極性の
異なる表面を使用した場合は、第6図(a)に示したun
twist状態が安定となる。たとえば、上基板表面にはSiO
2層16を設け、下基板表面にはポリイミド層15を設けた
セルにおいては、第6図(a)に示した配向状態のエネ
ルギーが最小であり最も安定となるが、第6図(b)に
示した配向状態は非常に不安定となる。Up to this point, the phenomenon in the cell using the same kind of surface for the upper and lower substrates has been described. However, when the surfaces having different polarities are used for the upper substrate and the lower substrate, the un shown in FIG.
The twist state becomes stable. For example, the upper substrate surface is SiO
In the cell in which the two layers 16 are provided and the polyimide layer 15 is provided on the surface of the lower substrate, the energy of the alignment state shown in FIG. 6 (a) is the smallest and the most stable, but FIG. 6 (b). The orientation state shown in 1 becomes very unstable.
この他、基板表面にポリイミド層などを設け、さらにラ
ビング処理を施す処理方法がある。この場合、アンカリ
ング力とクーロン力の他に液晶分子の配向をラビング方
向に規制しようとする配向力が加わるため、記憶効果は
さらに得にくくなる。In addition to this, there is a treatment method in which a polyimide layer or the like is provided on the surface of the substrate and further rubbing treatment is performed. In this case, in addition to the anchoring force and the Coulomb force, the alignment force for controlling the alignment of the liquid crystal molecules in the rubbing direction is added, so that the memory effect is further difficult to obtain.
従来の基板表面処理法を用いて電界除去後もuntwist状
態が保持されるようにするためには、いずれの処理法に
おいてもセル厚を十分薄くしなければならない。電界除
去後、twist状態が現われなくなる臨界セル厚は基板表
面処理法によって異なり、上下基板とも同じ極性の表面
処理層を設け、ラビング処理は施さない場合が最も厚
い。しかし、その種の表面処理法においても臨界セル厚
は非常に薄く1μm以下であるため、このような薄い均
一性の良いセルを作成することは実験室レベルでも非常
に困難であり、量産性は極めて之しいのが現状である。In order to maintain the untwisted state even after the electric field is removed by using the conventional substrate surface treatment method, the cell thickness must be sufficiently thin in any treatment method. The critical cell thickness at which the twist state does not appear after the electric field is removed depends on the substrate surface treatment method, and is the largest when the surface treatment layers of the same polarity are provided on both the upper and lower substrates and no rubbing treatment is performed. However, even in such a surface treatment method, the critical cell thickness is very thin and 1 μm or less, so it is very difficult to make such a thin cell with good uniformity even at a laboratory level, and mass productivity is low. The reality is that it is extremely uncertain.
そこで本発明はこのような問題を解決するもので、その
目的とするところは、量産的な数μmの厚さのセルにお
いてもすぐれた記憶効果を表わす液晶電気光学装置を提
供することにある。Therefore, the present invention solves such a problem, and an object of the present invention is to provide a liquid crystal electro-optical device exhibiting an excellent memory effect even in a mass-produced cell having a thickness of several μm.
本発明の液晶電気光学装置は、内面に電極を有する一対
の基板間に強誘電性液晶を封入し、前記一対の基板の外
側に互いの偏光軸がほぼ直交するように偏光板が配置さ
れた液晶電気光学装置において、前記各々の基板上に
は、電極、白金層、強誘電体層の順に積層形成されてな
り、且つ前記強誘電体層の厚みは前記白金層の厚みより
厚く形成されていることを特徴とする。In the liquid crystal electro-optical device of the present invention, a ferroelectric liquid crystal is enclosed between a pair of substrates having electrodes on the inner surfaces, and polarizing plates are arranged outside the pair of substrates so that their polarization axes are substantially orthogonal to each other. In the liquid crystal electro-optical device, an electrode, a platinum layer, and a ferroelectric layer are laminated in this order on each substrate, and the thickness of the ferroelectric layer is thicker than that of the platinum layer. It is characterized by being
なお、上記強誘電体層として高分子強誘電体を使用する
場合は、その表面に平行な溝をラビング又はエッチング
によって作成するか、あるいはいずれの場合も無処理の
ままとする。When a polymer ferroelectric is used as the ferroelectric layer, grooves parallel to the surface of the ferroelectric layer are formed by rubbing or etching, or in any case, it is left untreated.
従来の方法では、電界除去後の基板表面の極性を任意に
制御することができないが、本発明の上記の構成によれ
ば、液晶分子が持つ永久双極子の、電界印加時の方向に
応じて基板表面の極性が反転し、しかも強誘電性である
ためにその極性が電界除去後も保持されるため、量産性
のある厚さ数μmのセルにおいてもすぐれた記憶効果を
得ることができる。With the conventional method, the polarity of the substrate surface after the electric field is removed cannot be arbitrarily controlled, but according to the above configuration of the present invention, the permanent dipole possessed by the liquid crystal molecules is changed depending on the direction when the electric field is applied. Since the polarity of the surface of the substrate is reversed and the polarity is maintained even after the electric field is removed because of its ferroelectricity, an excellent memory effect can be obtained even in a mass-producible cell having a thickness of several μm.
(実施例−1) 第7図に本実施例における液晶電気光学装置の断面図を
示す。17は透明電極、18白金層、19は強誘電体層、20は
スペーサー、21は液晶層であり、強誘電体19と液晶21は
図示したように接している。強誘電性液晶21としてp-de
cyloxybenzyliden-p′‐amino-2-methylbutylc-innamat
e(DOBAMBC)を使用し、強誘電体19としてPLZT(9/65/3
5)を使用し、その表面は無処理のままである。透明電
極17はSnO2である。液晶層21,強誘電体層19,白金層18の
厚さはそれぞれ4.5μm,0.35μm,0.01μmとした。(Embodiment 1) FIG. 7 is a sectional view of a liquid crystal electro-optical device according to this embodiment. Reference numeral 17 is a transparent electrode, 18 is a platinum layer, 19 is a ferroelectric layer, 20 is a spacer, 21 is a liquid crystal layer, and the ferroelectric 19 and the liquid crystal 21 are in contact with each other as shown in the drawing. Ferroelectric liquid crystal 21 p-de
cyloxybenzyliden-p′‐amino-2-methylbutylc-innamat
Using e (DOBAMBC), PLZT (9/65/3
5) is used and its surface remains untreated. The transparent electrode 17 is SnO 2 . The thicknesses of the liquid crystal layer 21, the ferroelectric layer 19 and the platinum layer 18 were 4.5 μm, 0.35 μm and 0.01 μm, respectively.
PLZTの薄膜は高周波スパッタによって作製した。基板温
度は約500℃,スパッタガスは酸素とアルゴンの25/75混
合ガス、ターゲットはPbOを約8%過剰に含むPLZT粉末
である。The PLZT thin film was prepared by high frequency sputtering. The substrate temperature is about 500 ° C., the sputtering gas is a 25/75 mixed gas of oxygen and argon, and the target is PLZT powder containing PbO in an excess of about 8%.
この方法によって作成した厚さ0.5μmのPLZT薄膜のヒ
ステリシス特性(60Hz)を第8図に示す。横軸は8.5v/
μm/divである。単結晶強誘電体が持つヒステリシス特
性と比較すると、薄膜の場合、矩形性がやや劣っている
が、それは強誘電体層19と下地(白金層18)との境界に
おける結晶性が悪いためである。すなわち、境界層は強
誘電性を示さず、電界強度の変化に応じて分極の大きさ
が変化するために第8図に示したような特性となる。し
かし、本発明においては、少なくとも強誘電体の表面層
さえ強誘電性を示せばよいわけであるから、強誘電体の
厚さを結晶性の悪い境界層よりも厚くして強誘電体の表
面層に強誘電性を持たせれば本発明の目的に使用するこ
とができる。ただし、この境界層の厚さはスパッタする
時の基板温度に左右される。Fig. 8 shows the hysteresis characteristics (60 Hz) of the PLZT thin film with a thickness of 0.5 µm prepared by this method. The horizontal axis is 8.5v /
μm / div. Compared with the hysteresis characteristic of a single crystal ferroelectric, the thin film is slightly inferior in rectangularity because the crystallinity at the boundary between the ferroelectric layer 19 and the base (platinum layer 18) is poor. . That is, the boundary layer does not exhibit ferroelectricity, and the magnitude of polarization changes in accordance with the change in electric field strength, resulting in the characteristics shown in FIG. However, in the present invention, at least the surface layer of the ferroelectric material only needs to exhibit the ferroelectricity. Therefore, the thickness of the ferroelectric material is made thicker than that of the boundary layer with poor crystallinity, and the surface of the ferroelectric material is made thicker. If the layer has a ferroelectric property, it can be used for the purpose of the present invention. However, the thickness of this boundary layer depends on the substrate temperature during sputtering.
第9図に本実施例における各電界強度に対する液晶分子
の配向モデルを示す。18は白金層、19は強誘電体層であ
り、矢印22は強誘電体表面層の永久双極子を表わしてい
る。第9図(a)〜(e)はそれぞれ電界強度が+3E,
O,−E,−3E,Oに対応している。第9図より、強誘電体層
19を上下基板上に設けたことによって電界除去後も電界
印加時と同じ2つのuntwist状態(第9図(a),
(d))が安定となることがわかる。FIG. 9 shows an alignment model of liquid crystal molecules with respect to each electric field strength in this example. 18 is a platinum layer, 19 is a ferroelectric layer, and an arrow 22 is a permanent dipole of the ferroelectric surface layer. 9 (a) to 9 (e), the electric field strength is + 3E,
It corresponds to O, −E, −3E, O. From FIG. 9, the ferroelectric layer
By providing 19 on the upper and lower substrates, the same two untwisted states as when the electric field is applied (FIG. 9 (a),
It can be seen that (d)) becomes stable.
第10図は記憶効果の良否を表わす図である。第10図
(a)は印加パルス電圧、(b),(c)はいずれも印
加パルス電圧に対する透過光強度の変化である。印加パ
ルス電圧の波高値V1,V2はいずれも第9図(a),
(d)に示した2つのuntwist状態の間を完全にスイッ
チすることができる値である。記憶効果の良否はパルス
電圧印加時と電圧除去後の明るさの差ID-ID′,IB-IB′
によって評価することができ、ID-ID′,IB-IB′の値が
小さいほど記憶効果がすぐれている。第10図(b)は本
実施例における透過光強度の変化であり、比較のために
第10図(c)に従来の方法によって作成した厚さ1.5μ
mのセルにおける透過光強度の変化を示した。両者を比
較すれば、本実施例において得られた記憶効果が非常に
すぐれていることがわかる。FIG. 10 is a diagram showing whether the memory effect is good or bad. FIG. 10A shows the applied pulse voltage, and FIGS. 10B and 10C show changes in the transmitted light intensity with respect to the applied pulse voltage. The peak values V 1 and V 2 of the applied pulse voltage are both shown in FIG. 9 (a),
It is a value that can completely switch between the two untwist states shown in (d). The memory effect is determined by the difference in brightness between when the pulse voltage is applied and when the voltage is removed. ID-ID ', IB-IB'
The smaller the value of ID-ID ′ and IB-IB ′, the better the memory effect. FIG. 10 (b) is a change in transmitted light intensity in this example. For comparison, FIG. 10 (c) shows a thickness of 1.5 μm formed by the conventional method.
The change in transmitted light intensity in the m cell was shown. Comparing the two, it can be seen that the memory effect obtained in this example is very excellent.
パルス幅100μsecのパルス電圧に対するしきい特性は非
常に急峻でありV90/V10=1.1(Vα:透過光強度がα%
変化するために必要な電圧)であり、従来技術による急
峻性と同程度であった。またコントラスト(ID′:I
B′)は白色光を用いて1:20が得られた。The threshold characteristic for a pulse voltage with a pulse width of 100 μsec is extremely steep, and V90 / V10 = 1.1 (Vα: transmitted light intensity is α%
The voltage required to change) was about the same as the steepness of the prior art. Also, the contrast (ID ′: I
B ') was obtained 1:20 using white light.
(実施例−2) 第1の実施例と同じ構成とし、液晶層と強誘電体層の厚
さをそれぞれ3.0μm,0.8μmとした。本実施例において
も記憶効果がすぐれており、V90/V10=1.2,コントラス
トは1:23が得られた。(Example-2) With the same configuration as the first example, the thicknesses of the liquid crystal layer and the ferroelectric layer were 3.0 μm and 0.8 μm, respectively. Also in this example, the memory effect was excellent, and V90 / V10 = 1.2 and the contrast was 1:23.
(実施例−3) 第1の実施例と同じ構成とし、液晶層と強誘電体層の厚
さをそれぞれ1.5μm,1.0μmとした。本実施例において
も記憶効果がすぐれており、V90/V10=1.1,コントラス
トは1:35が得られた。(Embodiment 3) With the same configuration as in the first embodiment, the thicknesses of the liquid crystal layer and the ferroelectric layer were 1.5 μm and 1.0 μm, respectively. Also in this example, the memory effect was excellent, and V90 / V10 = 1.1 and the contrast of 1:35 were obtained.
(実施例−4) 本実施例では、液晶層の厚さを5.2μm,強誘電体層とし
て厚さ1.0μmのBaTiO3スパッタ薄膜を使用した。液晶
材料S−4−0−(2−methyl)butyl−resorcylidene
−4′−alk-ylaniline(MBRA−8)である。BaTiO3薄
膜は基板温度約650℃でスパッタし、約850℃で4時間熱
処理した。本実施例においても記憶効果がすぐれてお
り、V90/V10=1.15,コントラストは1:23が得られた。Example 4 In this example, a BaTiO 3 sputtered thin film having a liquid crystal layer thickness of 5.2 μm and a ferroelectric layer thickness of 1.0 μm was used. Liquid crystal material S-4-0- (2-methyl) butyl-resorcylidene
-4'-alk-ylaniline (MBRA-8). The BaTiO 3 thin film was sputtered at a substrate temperature of about 650 ° C and heat-treated at about 850 ° C for 4 hours. Also in this example, the memory effect was excellent, and V90 / V10 = 1.15 and the contrast was 1:23.
(実施例−5) 本実施例では液晶材料としてp−decyloxybe-nzylidene
−p′−amino−1−methylbutylc-innamate(DOBA−1
−MBC)を使用し、強誘電体といてフッ化ビニリデン/
三フッ化エチレン(VDF/TrFE)共重合体を使用した。厚
さはそれぞれ3.5μm,0.3μmである。VDF/TrFEの薄膜は
組成74/26の共重合体をメチルエチルケトンに溶解し、
スピンコートすることによって作成した。成膜後、ラビ
ング処理を施し、さらに100℃で150MV/mの電界を印加し
てポーリングを行なった。第11図に本実施例で使用した
VDF/TrFE薄膜のヒステリシス特性(60Hz)を示す。横軸
は40V/μm/divである。本実施例においても記憶効果が
すぐれており、V90/V10=1.1,コントラストは1:25が得
られた。(Example-5) In this example, p-decyloxybe-nzylidene was used as the liquid crystal material.
-P'-amino-1-methylbutylc-innamate (DOBA-1
-MBC) is used as a ferroelectric and vinylidene fluoride /
An ethylene trifluoride (VDF / TrFE) copolymer was used. The thickness is 3.5 μm and 0.3 μm, respectively. VDF / TrFE thin film is a copolymer of composition 74/26 dissolved in methyl ethyl ketone,
It was created by spin coating. After film formation, rubbing treatment was performed, and poling was performed by applying an electric field of 150 MV / m at 100 ° C. Used in this example in FIG.
The hysteresis characteristic (60Hz) of VDF / TrFE thin film is shown. The horizontal axis is 40V / μm / div. Also in this example, the memory effect was excellent, V90 / V10 = 1.1, and the contrast was 1:25.
以上述べたように、1μm以上の厚いセルにおいてもす
ぐれた記憶効果が得られた。強誘電体材料はPLZT,BaTiO
3,VDF/TrFEに限定されず、その他の強誘電体材料を用い
ても同様な結果が得られ、その膜厚も限定されない。強
誘電体薄膜を作成する時、基板温度が低すぎると生成し
た薄膜が強誘電性を示さないが、その臨界温度は下地基
板の種類に左右され、下地基板として白金を使用すれ
ば、臨界温度は比較的低くなる。したがって上記実施例
では第7図に示したように白金層18を設けてあるが、白
金層は必ずしも必要ではない。また、マトリクスアドレ
ス装置として応用する場合、電極はストライプ状となっ
ているが、強誘電体層を電極と同じ形状にパターン化す
る必要はなく、第7図に示したように上下の基板全面に
設ければよい。As described above, an excellent memory effect was obtained even in a thick cell of 1 μm or more. Ferroelectric material is PLZT, BaTiO
Not limited to 3 , VDF / TrFE, similar results can be obtained by using other ferroelectric materials, and the film thickness is not limited. When creating a ferroelectric thin film, if the substrate temperature is too low, the resulting thin film does not show ferroelectricity, but the critical temperature depends on the type of the underlying substrate, and if platinum is used as the underlying substrate, the critical temperature Is relatively low. Therefore, in the above embodiment, the platinum layer 18 is provided as shown in FIG. 7, but the platinum layer is not always necessary. Further, when applied as a matrix addressing device, the electrodes have stripe shapes, but it is not necessary to pattern the ferroelectric layer into the same shape as the electrodes, and as shown in FIG. It should be provided.
以上述べたように本発明によれば、従来約1μm以下の
薄いセルにおいてのみ得られていた記憶効果が厚さ数μ
mのセルにおいても得られるので、従来技術では不可能
であった強誘電性液晶を用いた大面積の液晶電気光学装
置を容易に作製することができるという効果を有する。As described above, according to the present invention, the memory effect which has been obtained only in a thin cell having a thickness of about 1 μm or less is several μm.
Since it can be obtained also in the cell of m, there is an effect that it is possible to easily manufacture a large-area liquid crystal electro-optical device using a ferroelectric liquid crystal, which was impossible in the conventional technique.
第1図は液晶分子,永久双極子とZ軸の位置関係を示す
図、第2図(a)〜(c)は厚さ数μmのセルのX-Y断
面における液晶分子配向を示す図、第3図(a)〜
(d)は種々の厚さのセルにおける液晶分子の配向を示
す図、第4図(a),(b)は液晶分子が持つ永久双極
子と基板表面の極性との相互作用を示す図、第5図
(a),(b)は三角波状電界を印加した時の分極反転
電流を示す図、第6図(a),(b)は上基板と下基板
に極性の異なる表面を使用した時の配向状態を示す図、
第7図は本発明による液晶セルの構成を示す図、第8図
はスパッタによって作成したPLZT薄膜のヒステリシス特
性を示す図、第9図(a)〜(e)は強誘電体層を使用
した場合の各印加電界に対する液晶分子および強誘電体
の分極の配向状態を示す図、第10図(a)〜(c)は印
加パルス電圧に対する液晶の透過光強度の変化を示す
図、第11図はフッ化ビニリデン/三フッ化エチレン共重
合体のヒステリシス特性を示す図である。 11……液晶分子 12……永久双極子 13……液晶分子のX-Y平面への射影 14……ガラス基板 15……ポリイミド 16……SiO2 17……透明電極 18……白金 19……強誘電性 20……スペーサー 21……液晶 22……強誘電体表面層の分極FIG. 1 is a diagram showing a positional relationship between liquid crystal molecules, a permanent dipole and the Z axis, and FIGS. 2 (a) to 2 (c) are diagrams showing liquid crystal molecule alignment in an XY cross section of a cell having a thickness of several μm. Figure (a)-
(D) is a diagram showing the orientation of liquid crystal molecules in cells of various thicknesses, and FIGS. 4 (a) and 4 (b) are diagrams showing the interaction between the permanent dipole of the liquid crystal molecules and the polarity of the substrate surface, FIGS. 5 (a) and 5 (b) are diagrams showing polarization reversal currents when a triangular wave electric field is applied, and FIGS. 6 (a) and 6 (b) use surfaces having different polarities for the upper substrate and the lower substrate. Diagram showing the alignment state at the time,
FIG. 7 is a diagram showing the structure of a liquid crystal cell according to the present invention, FIG. 8 is a diagram showing the hysteresis characteristics of a PLZT thin film prepared by sputtering, and FIGS. 9 (a) to 9 (e) are diagrams showing a ferroelectric layer. FIG. 10 is a diagram showing an alignment state of polarization of liquid crystal molecules and a ferroelectric with respect to each applied electric field in each case, FIGS. 10 (a) to 10 (c) are diagrams showing changes in transmitted light intensity of the liquid crystal with respect to an applied pulse voltage, and FIG. FIG. 4 is a diagram showing hysteresis characteristics of a vinylidene fluoride / ethylene trifluoride copolymer. 11 …… Liquid crystal molecule 12 …… Permanent dipole 13 …… Projection of liquid crystal molecule on XY plane 14 …… Glass substrate 15 …… Polyimide 16 …… SiO 2 17 …… Transparent electrode 18 …… Platinum 19 …… Ferroelectric 20 Spacer 21 Liquid crystal 22 Polarization of ferroelectric surface layer
Claims (1)
性液晶を封入し、前記一対の基板の外側に互いの偏光軸
がほぼ直交するように偏光板が配置された液晶電気光学
装置において、前記各々の基板上には、電極、白金層、
強誘電体層の順に積層形成されてなり、且つ前記強誘電
体層の厚みは前記白金層の厚みより厚く形成されている
ことを特徴とする液晶電気光学装置。1. A liquid crystal electro-optical device in which a ferroelectric liquid crystal is sealed between a pair of substrates having electrodes on the inner surfaces, and polarizing plates are arranged outside the pair of substrates so that their polarization axes are substantially orthogonal to each other. In, on each of the substrate, an electrode, a platinum layer,
A liquid crystal electro-optical device comprising a ferroelectric layer laminated in this order, and the thickness of the ferroelectric layer is larger than that of the platinum layer.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP60000679A JPH0731324B2 (en) | 1985-01-07 | 1985-01-07 | Liquid crystal electro-optical device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP60000679A JPH0731324B2 (en) | 1985-01-07 | 1985-01-07 | Liquid crystal electro-optical device |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS61159627A JPS61159627A (en) | 1986-07-19 |
JPH0731324B2 true JPH0731324B2 (en) | 1995-04-10 |
Family
ID=11480438
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP60000679A Expired - Lifetime JPH0731324B2 (en) | 1985-01-07 | 1985-01-07 | Liquid crystal electro-optical device |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0731324B2 (en) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS61282882A (en) * | 1985-06-07 | 1986-12-13 | 日本電気株式会社 | Liquid crystal element |
JPS62124525A (en) * | 1985-11-25 | 1987-06-05 | Semiconductor Energy Lab Co Ltd | Liquid crystal device |
JP2537349B2 (en) * | 1986-08-06 | 1996-09-25 | 日本真空技術株式会社 | Method for forming liquid crystal alignment film |
JP2562585B2 (en) * | 1986-12-02 | 1996-12-11 | 株式会社 半導体エネルギ−研究所 | Liquid crystal device and method for manufacturing liquid crystal device |
JPH0792563B2 (en) * | 1986-12-04 | 1995-10-09 | 株式会社半導体エネルギー研究所 | Liquid crystal display |
JPS63301024A (en) * | 1987-05-30 | 1988-12-08 | Ricoh Co Ltd | Liquid crystal element |
JP2610141B2 (en) * | 1987-10-06 | 1997-05-14 | キヤノン株式会社 | Ferroelectric liquid crystal device |
JPH01267516A (en) * | 1988-04-20 | 1989-10-25 | Idemitsu Kosan Co Ltd | Liquid crystal optical element and its production |
JP2561603B2 (en) * | 1992-12-04 | 1996-12-11 | 株式会社半導体エネルギー研究所 | Liquid crystal device |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS54155795A (en) * | 1978-05-30 | 1979-12-08 | Seiko Instr & Electronics Ltd | Electro-optical display unit |
JPS59214824A (en) * | 1983-05-20 | 1984-12-04 | Seiko Epson Corp | Liquid-crystal electrooptic device |
-
1985
- 1985-01-07 JP JP60000679A patent/JPH0731324B2/en not_active Expired - Lifetime
Also Published As
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JPS61159627A (en) | 1986-07-19 |
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