JPH08328046A - Antiferroelectric liquid crystal display element - Google Patents
Antiferroelectric liquid crystal display elementInfo
- Publication number
- JPH08328046A JPH08328046A JP7157113A JP15711395A JPH08328046A JP H08328046 A JPH08328046 A JP H08328046A JP 7157113 A JP7157113 A JP 7157113A JP 15711395 A JP15711395 A JP 15711395A JP H08328046 A JPH08328046 A JP H08328046A
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- Prior art keywords
- liquid crystal
- crystal molecules
- alignment
- antiferroelectric
- phase
- Prior art date
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Abstract
Description
【発明の詳細な説明】Detailed Description of the Invention
【０００１】[0001]
【産業上の利用分野】この発明は反強誘電性液晶（ＡＦ
ＬＣ、AntiFerroelectric Liquid Crystal）を用いた液
晶表示素子に関し、特に、階調表示が可能なＡＦＬＣ液
晶表示素子に関する。This invention relates to an antiferroelectric liquid crystal (AF)
The present invention relates to a liquid crystal display element using LC, AntiFerroelectric Liquid Crystal), and particularly to an AFLC liquid crystal display element capable of gradation display.
【０００２】[0002]
【従来の技術】強誘電性液晶を用いる強誘電性液晶表示
素子は、ネマティック液晶を用いるＴＮモードの液晶表
示素子と比較して、高速応答、広い視野角が得られる等
の点で注目されている。2. Description of the Related Art Ferroelectric liquid crystal display elements using ferroelectric liquid crystal have been noted for their high-speed response and wide viewing angle as compared with TN mode liquid crystal display elements using nematic liquid crystal. There is.
【０００３】強誘電性液晶表示素子として、強誘電性液
晶を用いた強誘電性液晶表示素子と反強誘電性液晶を用
いた反強誘電性液晶表示素子とが知られている。As a ferroelectric liquid crystal display element, a ferroelectric liquid crystal display element using a ferroelectric liquid crystal and an antiferroelectric liquid crystal display element using an antiferroelectric liquid crystal are known.
【０００４】反強誘電性液晶表示素子は、反強誘電性液
晶が備える配向状態の安定性を利用して画像を表示する
ものである。即ち、反強誘電性液晶は、液晶分子の配向
に３つの安定状態を有し、第１のしきい値以上の電圧を
該液晶に印加したとき、印加電圧の極性に応じて液晶分
子が第１の配向方向に配列する第１の強誘電相または第
２の配向方向に配列する第２の強誘電相に配向し、前記
第１のしきい値より低い第２のしきい値以下の電圧を印
加したとき、第１と第２の強誘電相の中間の配列状態で
ある反強誘電相に配向する。液晶表示素子の両側に配置
する一対の偏光板の透過軸の方向を反強誘電相の光学軸
を基準にして設定することにより、図１３にその電圧−
透過率特性を示すように、光の透過率を制御して画像を
表示することができる。The antiferroelectric liquid crystal display element displays an image by utilizing the stability of the alignment state of the antiferroelectric liquid crystal. That is, the antiferroelectric liquid crystal has three stable states in the alignment of the liquid crystal molecules, and when a voltage equal to or higher than the first threshold value is applied to the liquid crystal, the liquid crystal molecules become A voltage that is oriented in a first ferroelectric phase arranged in one orientation direction or a second ferroelectric phase arranged in a second orientation direction and is below a second threshold value lower than the first threshold value. Is applied, it is oriented in an antiferroelectric phase which is an intermediate arrangement state between the first and second ferroelectric phases. By setting the directions of the transmission axes of the pair of polarizing plates arranged on both sides of the liquid crystal display element with reference to the optical axis of the antiferroelectric phase, the voltage-
An image can be displayed by controlling the light transmittance so as to show the transmittance characteristic.
【０００５】反強誘電性液晶は、印加電圧が変化して
も、上記第１と第２のしきい値の間の範囲であれば、第
１または第２の強誘電相または反強誘電相に配向した状
態を維持するというメモリ性を有している。従来の反強
誘電性液晶表示素子は、このメモリ性を利用して単純マ
トリクス駆動されている。The antiferroelectric liquid crystal has a first or second ferroelectric phase or an antiferroelectric phase as long as it is in the range between the first and second threshold values even if the applied voltage changes. It has a memory property of maintaining the oriented state. The conventional antiferroelectric liquid crystal display device is driven by a simple matrix by utilizing this memory property.
【０００６】反強誘電性液晶の配向状態のメモリ性は、
液晶が第１または第２の強誘電相から反強誘電相に相転
移する電圧と、反強誘電相から第１または第２の強誘電
相に相転移する電圧との電圧差によって定まり、この電
圧差が大きいほど、配向状態のメモリ性が高い。即ち、
光学特性のヒステリシスが大きい程メモリ性が高い。こ
のため、従来の単純マトリクス駆動される反強誘電性液
晶表示素子では、反強誘電性液晶として、上記電圧差が
大きい液晶を用いている。The memory property of the alignment state of the antiferroelectric liquid crystal is
It is determined by the voltage difference between the voltage at which the liquid crystal phase transitions from the first or second ferroelectric phase to the antiferroelectric phase and the voltage at which the liquid crystal phase transitions from the antiferroelectric phase to the first or second ferroelectric phase. The larger the voltage difference, the higher the memory property of the alignment state. That is,
The larger the hysteresis of the optical characteristics, the higher the memory property. Therefore, in the conventional simple matrix-driven antiferroelectric liquid crystal display element, the liquid crystal having a large voltage difference is used as the antiferroelectric liquid crystal.
【０００７】[0007]
【発明が解決しようとする課題】しかし、メモリ性の高
い反強誘電性液晶を用いる従来の反強誘電性液晶表示素
子は、光の透過率を任意に制御することができず、表示
階調の制御がほとんど不可能で、階調表示を実現するこ
とはできなかった。However, the conventional anti-ferroelectric liquid crystal display device using the anti-ferroelectric liquid crystal having a high memory property cannot control the light transmittance arbitrarily, and the display gradation Since it was almost impossible to control, the gradation display could not be realized.
【０００８】この発明は上記実状に鑑みてなされたもの
で、明確な階調表示を実現できる反強誘電性液晶表示素
子を提供することを目的とする。The present invention has been made in view of the above situation, and an object thereof is to provide an antiferroelectric liquid crystal display device capable of realizing clear gradation display.
【０００９】[0009]
【課題を解決するための手段】上記目的を達成するた
め、この発明の第１の観点にかかる反強誘電性液晶表示
素子は、対向する一対の基板の一方に画素電極を、他方
の基板に前記画素電極に対向する対向電極をそれぞれ形
成し、前記一対の基板間に、２つの配向状態の液晶分子
が均一に混在する反強誘電相を有し、各液晶分子が印加
電圧に応じて電界と垂直な方向に傾くと共に印加電圧に
応じて一方の配向状態の液晶分子が他方の配向状態に変
化することにより、異なった配向状態の領域が可視光帯
域の光の波長よりも小さい距離内に複数形成されること
により、ダイレクタの平均的な方向が印加電圧に応じて
連続的に変化する反強誘電性液晶を封入し、階調表示を
可能としたことを特徴とする。In order to achieve the above object, an antiferroelectric liquid crystal display element according to a first aspect of the present invention has a pixel electrode on one of a pair of substrates facing each other and a pixel electrode on the other substrate. Opposing electrodes facing the pixel electrodes are formed respectively, and an antiferroelectric phase in which liquid crystal molecules in two alignment states are uniformly mixed is formed between the pair of substrates, and each liquid crystal molecule has an electric field depending on an applied voltage. The liquid crystal molecules in one alignment state change to the other alignment state in response to the applied voltage as well as tilting in a direction perpendicular to, and the regions of different alignment states are within a distance smaller than the wavelength of light in the visible light band. By forming a plurality of anti-ferroelectric liquid crystals in which the average direction of the director continuously changes according to the applied voltage, a gray scale display is possible.
【００１０】上記目的を達成するため、この発明の第２
の観点にかかる反強誘電性液晶表示素子は、画素電極と
画素電極に接続されたアクティブ素子がマトリクス状に
複数配列された一方の基板と、前記画素電極に対向する
対向電極が形成された他方の基板と、前記基板の間に封
入され、液晶分子がほぼ第１の配向方向に配列した第１
の強誘電相と液晶分子がほぼ第２の配向方向に配列した
第２の強誘電相と、第１の配向方向に配列した液晶分子
と第２の配向方向に配列した液晶分子が混在することに
より、ダイレクタの方向がスメクティックＣA*相の層構
造の層の法線方向にほぼ一致する反強誘電相を有し、印
加電圧に応じて、液晶分子が電界と垂直な方向に傾くと
共に第１の配向方向に配列した液晶分子と第２の配向方
向の一方に配列した液晶分子が他方の配向方向に配列す
ることにより、可視光帯域の光の波長より短い範囲で、
異なった配向状態の領域が複数形成されることにより、
ダイレクタの方向が変化し、前記強誘電相と前記反強誘
電相の間の中間の状態を有する反強誘電性液晶、を備え
たことを特徴とする。In order to achieve the above object, the second aspect of the present invention
In the antiferroelectric liquid crystal display element according to the aspect, one substrate on which a plurality of pixel electrodes and active elements connected to the pixel electrodes are arranged in a matrix, and the other on which a counter electrode facing the pixel electrode is formed. And a first liquid crystal molecule, which is enclosed between the substrate and the liquid crystal molecules and is aligned in a first alignment direction.
The second ferroelectric phase in which the ferroelectric phase and the liquid crystal molecules are aligned in the second alignment direction, and the liquid crystal molecules in the first alignment direction and the liquid crystal molecules in the second alignment direction are mixed. As a result, the director has an antiferroelectric phase in which the direction of the director is substantially aligned with the normal direction of the layer of the layer structure of the smectic CA * phase, and the liquid crystal molecules are tilted in the direction perpendicular to the electric field according to the applied voltage. In the range shorter than the wavelength of light in the visible light band, the liquid crystal molecules aligned in the alignment direction and the liquid crystal molecules aligned in one of the second alignment directions are aligned in the other alignment direction.
By forming multiple regions with different alignment states,
An antiferroelectric liquid crystal having an intermediate state between the ferroelectric phase and the antiferroelectric phase, in which the direction of the director is changed, is provided.
【００１１】[0011]
【作用】この発明の第１の観点にかかる反強誘電性液晶
表示素子によれば、反強誘電性液晶の各液晶分子は、印
加電圧に応じて、２つの配向状態の一方から他方に順次
変化する。このため、平均的な配向状態が異なった領域
が多数形成される。また、各領域内の液晶分子は電界の
印加によりその長軸回りの回転が抑制され、その為に生
ずる自発分極と電界の間の相互作用により、電界に垂直
な面内で傾く。各領域のサイズが可視光帯域の光の波長
よりも小さいため、光学的には、これらの領域の液晶分
子の平均的な配向方向が光学軸となる。このため、印加
電圧を制御することにより、液晶分子の平均的な配向方
向を変化させて強誘電相と反強誘電相の間の多数の中間
配向状態を形成することができる。According to the antiferroelectric liquid crystal display element according to the first aspect of the present invention, each liquid crystal molecule of the antiferroelectric liquid crystal is sequentially transferred from one of the two alignment states to the other in accordance with the applied voltage. Change. Therefore, many regions having different average alignment states are formed. Further, the liquid crystal molecules in each region are restrained from rotating about their major axes by the application of an electric field, and due to the interaction between the spontaneous polarization and the electric field caused thereby, the liquid crystal molecules tilt in a plane perpendicular to the electric field. Since the size of each region is smaller than the wavelength of light in the visible light band, optically, the average alignment direction of liquid crystal molecules in these regions is the optical axis. Therefore, by controlling the applied voltage, it is possible to change the average orientation direction of the liquid crystal molecules and form a number of intermediate orientation states between the ferroelectric phase and the antiferroelectric phase.
【００１２】また、この発明の第２の観点にかかる反強
誘電性液晶表示素子によれば、反強誘電性液晶の各液晶
分子は、印加電圧に応じて、第１又は第２の配向方向か
ら第２又は第１の配向方向に変化する。このため、平均
的な配向状態が異なった領域が多数形成される。また、
各領域内の液晶分子は電界の印加によりその長軸回りの
回転が抑制されて、電界に垂直な方向に傾く。各領域の
サイズが可視光帯域の光の波長よりも小さいため、これ
らの領域の光学特性が平均化される。このため、印加電
圧を制御することにより、強誘電相と反強誘電相の間の
多数の中間配向状態を形成することができる。従って、
アクティブ素子により、非選択期間も該液晶に表示階調
に対応する印加電圧を保持することにより、任意の階調
の表示が可能となる。Further, according to the antiferroelectric liquid crystal display element according to the second aspect of the present invention, each liquid crystal molecule of the antiferroelectric liquid crystal has a first or second alignment direction depending on an applied voltage. To the second or first orientation direction. Therefore, many regions having different average alignment states are formed. Also,
The liquid crystal molecules in each region are tilted in a direction perpendicular to the electric field, because rotation of the liquid crystal molecules around the major axis is suppressed by application of the electric field. Since the size of each region is smaller than the wavelength of light in the visible light band, the optical characteristics of these regions are averaged. Therefore, by controlling the applied voltage, a large number of intermediate alignment states between the ferroelectric phase and the antiferroelectric phase can be formed. Therefore,
By holding the applied voltage corresponding to the display gradation in the liquid crystal during the non-selection period by the active element, it is possible to display an arbitrary gradation.
【００１３】[0013]
【実施例】以下、この発明の実施例を図面を参照して説
明する。まず、この実施例の反強誘電性液晶表示素子の
構成を説明する。図１は反強誘電性液晶表示素子の断面
図、図２は画素電極とアクティブ素子を形成した基板の
平面図である。Embodiments of the present invention will be described below with reference to the drawings. First, the structure of the antiferroelectric liquid crystal display device of this embodiment will be described. FIG. 1 is a sectional view of an antiferroelectric liquid crystal display element, and FIG. 2 is a plan view of a substrate on which pixel electrodes and active elements are formed.
【００１４】この反強誘電性液晶表示素子は、アクティ
ブマトリクス方式のものであり、一対の透明基板（例え
ば、ガラス基板）１１、１２のうち、図１において下側
の基板（以下、下基板）１１には透明な画素電極１３と
画素電極１３に接続されたアクティブ素子１４とがマト
リクス状に配列形成されている。This antiferroelectric liquid crystal display element is of an active matrix type, and is one of a pair of transparent substrates (for example, glass substrates) 11 and 12, which is the lower substrate in FIG. 1 (hereinafter, lower substrate). In FIG. 11, transparent pixel electrodes 13 and active elements 14 connected to the pixel electrodes 13 are arranged in a matrix.
【００１５】アクティブ素子１４は、例えば、薄膜トラ
ンジスタ（以下、ＴＦＴ）から構成される。ＴＦＴ１４
は、基板１１上に形成されたゲート電極と、ゲート電極
を覆うゲート絶縁膜と、ゲート絶縁膜の上に形成された
半導体層と、半導体層の上に形成されたソース電極及び
ドレイン電極とから構成される。The active element 14 is composed of, for example, a thin film transistor (hereinafter, TFT). TFT14
Is a gate electrode formed on the substrate 11, a gate insulating film covering the gate electrode, a semiconductor layer formed on the gate insulating film, and a source electrode and a drain electrode formed on the semiconductor layer. Composed.
【００１６】さらに、下基板１１には、図２に示すよう
に、画素電極１３の行間にゲートライン（走査ライン）
１５が配線され、画素電極１３の列間にデータライン
（階調信号ライン）１６が配線されている。各ＴＦＴ１
４のゲート電極は対応するゲートライン１５に接続さ
れ、ドレイン電極は対応するデータライン１６に接続さ
れている。Further, on the lower substrate 11, as shown in FIG. 2, gate lines (scanning lines) are provided between the rows of the pixel electrodes 13.
15 are wired, and data lines (gradation signal lines) 16 are wired between the columns of the pixel electrodes 13. Each TFT1
The gate electrode of No. 4 is connected to the corresponding gate line 15, and the drain electrode is connected to the corresponding data line 16.
【００１７】ゲートライン１５は、端部１５ａを介して
行ドライバ（行駆動回路）３１に接続され、データライ
ン１６は端部１６ａを介して列ドライバ（列駆動回路）
３２に接続される。行ドライバ３１は、後述するゲート
信号を印加して、ゲートライン１５をスキャンする。一
方、列ドライバ３２は、表示データ（階調データ）を受
け、データライン１６に表示データに対応するデータ信
号を印加する。The gate line 15 is connected to a row driver (row driving circuit) 31 via an end 15a, and the data line 16 is connected to a column driver (column driving circuit) via an end 16a.
Connected to 32. The row driver 31 applies a gate signal described later to scan the gate line 15. On the other hand, the column driver 32 receives the display data (gradation data) and applies a data signal corresponding to the display data to the data line 16.
【００１８】ゲートライン１５は端部１５ａを除いてＴ
ＦＴ１４のゲート絶縁膜（透明膜）で覆われており、デ
ータライン１６は前記ゲート絶縁膜の上に形成されてい
る。画素電極１３は前記ゲート絶縁膜の上に形成されて
おり、その一端部においてＴＦＴ１４のソース電極に接
続されている。The gate line 15 is T-shaped except for the end 15a.
The FT 14 is covered with a gate insulating film (transparent film), and the data line 16 is formed on the gate insulating film. The pixel electrode 13 is formed on the gate insulating film and has one end connected to the source electrode of the TFT 14.
【００１９】図１において、上側の基板（以下、上基
板）１２には、下基板１１の各画素電極１３と対向する
透明な対向電極１７が形成されている。対向電極１７は
表示領域全体にわたる面積の１枚の電極から構成され、
基準電圧Ｖ０が印加されている。In FIG. 1, a transparent counter electrode 17 that faces each pixel electrode 13 of the lower substrate 11 is formed on the upper substrate (hereinafter, upper substrate) 12. The counter electrode 17 is composed of one electrode having an area covering the entire display area,
The reference voltage V0 is applied.
【００２０】下基板１１と上基板１２の電極形成面に
は、それぞれ配向膜１８、１９が設けられている。配向
膜１８、１９はポリイミド等の有機高分子化合物からな
る水平配向膜であり、その対向面には同一方向（後述す
る配向方向２１Ｃにほぼ等しい方向）にラビングによる
配向処理が施されている。Alignment films 18 and 19 are provided on the electrode formation surfaces of the lower substrate 11 and the upper substrate 12, respectively. The alignment films 18 and 19 are horizontal alignment films made of an organic polymer compound such as polyimide, and the facing surfaces thereof are subjected to the alignment treatment by rubbing in the same direction (almost equal to the alignment direction 21C described later).
【００２１】下基板１１と上基板１２は、その外周縁部
において枠状のシール材２０を介して接着されており、
基板１１、１２間のシール材２０で囲まれた領域には液
晶２１が封入されている。The lower substrate 11 and the upper substrate 12 are adhered to each other at their outer peripheral edges via a frame-shaped sealing material 20,
A liquid crystal 21 is sealed in a region surrounded by the sealing material 20 between the substrates 11 and 12.
【００２２】液晶２１は、スメクテッィクＣA*相の反強
誘電性液晶（以下、ＡＦＬＣ）から構成され、その層の
厚さは、透明なギャップ材２２により規制されている。
ギャップ材２２は液晶封入領域内に点在状態で配置され
ている。The liquid crystal 21 is composed of a smectic CA * phase antiferroelectric liquid crystal (hereinafter referred to as AFLC), and the thickness of its layer is regulated by a transparent gap member 22.
The gap material 22 is arranged in a scattered state in the liquid crystal filling area.
【００２３】ＡＦＬＣ２１は、十分高い電圧が印加され
た時、印加された電圧の極性に応じて、液晶分子が図３
に示す第１の配向方向２１Ａに配列した第１の強誘電相
と前記第１の配向方向と異なる第２の配向方向に配列し
た第２の強誘電相、及びダイレクタ（液晶分子長軸の平
均的方向）がスメクティックＣA*相の層構造の層の法線
方向２１Ｃに向いた状態の反強誘電相と、これらの中間
状態を呈する。In the AFLC 21, when a sufficiently high voltage is applied, the liquid crystal molecules are changed depending on the polarity of the applied voltage.
, The first ferroelectric phase arranged in the first alignment direction 21A, the second ferroelectric phase arranged in the second alignment direction different from the first alignment direction, and the director (average of long axes of liquid crystal molecules). (I.e., the target direction) has an antiferroelectric phase in a state in which the smectic CA * phase is oriented in the normal direction 21C of the layer structure, and an intermediate state between them.
【００２４】液晶表示素子の上下には、一対の偏光板２
３、２４が配置されている。偏光板２３、２４の光学軸
（以下、透過軸とする）は、ＡＦＬＣ２１の液晶分子の
配向方向に基づいて設定されている。即ち、図３に示す
ように、下側の偏光板２３の透過軸２３Ａは配向処理の
方向２１Ｃにほぼ一致するスメクティック層の法線方向
とほぼ平行に設定され、上側偏光板２４の透過軸２４Ａ
は下偏光板２３の透過軸２３Ａにほぼ直角に設定されて
いる。A pair of polarizing plates 2 are provided above and below the liquid crystal display element.
3, 24 are arranged. The optical axes of the polarizing plates 23 and 24 (hereinafter referred to as transmission axes) are set based on the alignment direction of the liquid crystal molecules of the AFLC 21. That is, as shown in FIG. 3, the transmission axis 23A of the lower polarizing plate 23 is set to be substantially parallel to the normal line direction of the smectic layer which substantially coincides with the orientation direction 21C, and the transmission axis 24A of the upper polarizing plate 24.
Is set substantially perpendicular to the transmission axis 23A of the lower polarizing plate 23.
【００２５】図３に示すように、偏光板２３、２４の透
過軸を設定した反強誘電性液晶表示素子は、液晶分子の
長軸が第１又は第２の配向方向２１Ａ、２１Ｂにほぼ配
向した強誘電相の時に透過率がほぼ最大（表示が最も明
るく）になり、液晶分子の長軸の平均的な方向が第３の
配向方向２１Ｃに向くようにほぼ配向した反強誘電相の
時に透過率がほぼ最小（表示が最も暗く）になる。As shown in FIG. 3, in the antiferroelectric liquid crystal display device in which the transmission axes of the polarizing plates 23 and 24 are set, the long axes of the liquid crystal molecules are almost aligned in the first or second alignment directions 21A and 21B. In the ferroelectric phase, the transmittance is almost maximum (the display is brightest), and when the antiferroelectric phase is substantially aligned so that the average direction of the long axes of the liquid crystal molecules is oriented in the third alignment direction 21C. The transmittance is almost minimum (the display is darkest).
【００２６】すなわち、液晶分子が第１又は第２の配向
方向２１Ａ、２１Ｂを向いた状態では、入射側の偏光板
２３の透過軸２３Ａを通過した直線偏光はＡＦＬＣ２１
の複屈折作用により非直線偏光となり、出射側偏光板２
４の透過軸２４Ａと平行な成分が出射し、表示は明るく
なる。一方、ＡＦＬＣ２１のダイレクタが第３の配向方
向２１Ｃを向いた状態では、その光学軸が層の法線方向
に向くため、入射側の偏光板２３を通った直線偏光はＡ
ＦＬＣ２１の複屈折作用をほとんど受けず、直線偏光の
ままＡＦＬＣ２１を通過し、そのほとんどが出射側の偏
光板２４で吸収され、表示が暗くなる。また、ＡＦＬＣ
２１が光学的中間状態の時は、液晶分子のダイレクタの
平均的な方向に応じた階調が得られる。That is, when the liquid crystal molecules are oriented in the first or second alignment direction 21A, 21B, the linearly polarized light passing through the transmission axis 23A of the incident side polarizing plate 23 is AFLC21.
It becomes non-linearly polarized light by the birefringence action of
The component parallel to the transmission axis 24A of 4 is emitted, and the display becomes bright. On the other hand, when the director of the AFLC 21 is oriented in the third alignment direction 21C, the optical axis thereof is oriented in the normal direction of the layer, so that the linearly polarized light passing through the incident side polarizing plate 23 is A
The birefringence effect of the FLC 21 is hardly received, the linearly polarized light passes through the AFLC 21 as it is, and most of the light is absorbed by the polarizing plate 24 on the emission side, and the display becomes dark. Also, AFLC
When 21 is in an optical intermediate state, a gradation corresponding to the average direction of the directors of liquid crystal molecules can be obtained.
【００２７】次に、ＡＦＬＣ２１についてより詳細に説
明する。ＡＦＬＣ２１は、例えば、コーンアングルが３
０゜から４５゜（望ましくは、３５゜以上）と大きく、
Ｉ、ＳｍＡ、ＳｍＣA*というシーケンスで相転移するス
メクティックＣA*相の液晶から構成され、図４に示すよ
うに、バルクの状態で分子配列の層構造と螺旋構造を有
している。通常の強誘電性液晶と異なり、隣接する液晶
分子は層毎にコーンのほぼ１８０゜シフトして螺旋を描
いた二重螺旋構造を有する。ＡＦＬＣ２１の層の厚さ
（セルギャップ）は、ＡＦＬＣ２１の螺旋構造の１ピッ
チ（ナチュラルピッチ）よりも小さく形成されている。
このため、ＡＦＬＣ２１は、図５に模式的に示すよう
に、二重螺旋構造が消失した状態で基板１１、１２間に
封止されている。なお、セルギャップをＡＦＬＣ２１の
螺旋構造の１ピッチよりも大きくし、代わりに、配向膜
１８、１９の表面を安定化することにより、表面安定化
効果により、二重螺旋構造を消失させてもよい。Next, the AFLC 21 will be described in more detail. The AFLC21 has, for example, a cone angle of 3
As large as 0 ° to 45 ° (preferably 35 ° or more),
It is composed of liquid crystal of smectic CA * phase which undergoes phase transition in the sequence of I, SmA and SmCA * , and has a layered structure of molecular arrangement and a helical structure in a bulk state as shown in FIG. Unlike ordinary ferroelectric liquid crystals, adjacent liquid crystal molecules have a double spiral structure in which a cone is shifted by about 180 ° in each layer to draw a spiral. The layer thickness (cell gap) of the AFLC 21 is formed smaller than one pitch (natural pitch) of the spiral structure of the AFLC 21.
Therefore, the AFLC 21 is sealed between the substrates 11 and 12 in a state where the double helix structure disappears, as schematically shown in FIG. The cell gap may be made larger than one pitch of the spiral structure of the AFLC 21, and instead, the surfaces of the alignment films 18 and 19 may be stabilized to eliminate the double spiral structure due to the surface stabilizing effect. .
【００２８】また、ＡＦＬＣ２１は、強誘電的相互作用
が強い、即ち、各分子が並列に平行使用とる力が比較的
強くまた、分子の自由回転力の強い液晶材料から構成さ
れている。The AFLC 21 is made of a liquid crystal material which has a strong ferroelectric interaction, that is, a force in which each molecule is used in parallel in parallel is relatively strong and a free rotational force of the molecule is strong.
【００２９】次に、図６を参照して、印加電圧による液
晶分子の配向の変化を説明する。なお、図６は液晶分子
の配置を基板面に投影して示す図である。液晶分子は、
第１の配向方向２１Ａ又は第２の配向方向２１Ｂに配列
した２つの配向状態を有する。電圧無印加の状態では、
図６（Ａ）に示すように、液晶分子は第１と第２の配向
方向２１Ａと２１Ｂに層毎に交互に配列した状態とな
る。即ち、層毎に第１の配向状態と第２の配向状態を繰
り返す状態になる。この状態では、層内では自発分極が
発生するが、隣接する層の永久双極子が互いに反対方向
を向き、双極子モーメントが互いに打ち消しあって総合
的には自発分極は存在せず、反強誘電相となる。空間的
に平均されたＡＦＬＣ２１の光学軸は液晶分子の平均的
な配向方向であるスメクティック層（スメクティック相
の層構造の層）の法線方向２１Ｃとなる。また、この状
態では、液晶分子はその長軸の回りに、反強誘電的作用
により抑制されて回転している。Next, referring to FIG. 6, the change in the orientation of the liquid crystal molecules due to the applied voltage will be described. Note that FIG. 6 is a diagram showing the arrangement of liquid crystal molecules projected on the substrate surface. Liquid crystal molecules are
It has two alignment states arranged in the first alignment direction 21A or the second alignment direction 21B. With no voltage applied,
As shown in FIG. 6A, the liquid crystal molecules are arranged alternately in the first and second alignment directions 21A and 21B for each layer. That is, the first alignment state and the second alignment state are repeated for each layer. In this state, spontaneous polarization occurs in the layer, but the permanent dipoles of adjacent layers point in opposite directions, and the dipole moments cancel each other out, so there is no spontaneous polarization overall, and antiferroelectricity is present. Be in phase. The spatially averaged optical axis of the AFLC 21 is the normal direction 21C of the smectic layer (layer of the smectic phase layer structure) which is the average alignment direction of the liquid crystal molecules. Further, in this state, the liquid crystal molecules are rotated around their major axes while being suppressed by the antiferroelectric effect.
【００３０】前述のように、ＡＦＬＣ２１は、強誘電性
的相互作用が強い。即ち、隣接する層の液晶分子が平行
になろうとする相互作用が強い。このため、飽和電圧Ｅ
ｃ未満の電圧Ｅを印加すると、図６（Ｂ）及び（Ｃ）に
示すように、印加電圧Ｅの大きさに応じて、第２の配向
状態にある液晶分子の一部が第１の配向状態に変化す
る。配向状態が変化する分子の数（割合）は、印加電圧
Ｅが大きくなるに従って多くなる。As described above, the AFLC 21 has a strong ferroelectric interaction. That is, there is a strong interaction in which the liquid crystal molecules in the adjacent layers tend to be parallel. Therefore, the saturation voltage E
When a voltage E of less than c is applied, as shown in FIGS. 6B and 6C, some of the liquid crystal molecules in the second alignment state are aligned in the first alignment depending on the magnitude of the applied voltage E. Change to state. The number (ratio) of molecules whose orientation state changes increases as the applied voltage E increases.
【００３１】また、液晶分子の長軸回りの回転が、印加
電圧の大きさに応じて抑制されて自発分極が発生する。
この自発分極と電界の相互作用により、図６（Ｂ）及び
（Ｃ）に示すように液晶分子は第１の配向方向２１Ａに
向かって傾き、その傾き角は、印加電圧Ｅの上昇に伴っ
て上昇する。The rotation of the liquid crystal molecules around the major axis is suppressed according to the magnitude of the applied voltage, and spontaneous polarization occurs.
Due to the interaction between the spontaneous polarization and the electric field, the liquid crystal molecules are tilted toward the first alignment direction 21A as shown in FIGS. 6B and 6C, and the tilt angle is increased as the applied voltage E is increased. To rise.
【００３２】印加電圧の上昇に伴う第１の配向状態の液
晶分子の増加と、回転の抑制による液晶分子の傾きの増
加との複合作用により、印加電圧の上昇に伴ってＡＦＬ
Ｃ２１のダイレクタは第１の配向方向２１Ａに向かって
連続的に変化する。Due to the combined action of the increase of the liquid crystal molecules in the first alignment state with the increase of the applied voltage and the increase of the inclination of the liquid crystal molecules due to the inhibition of the rotation, the AFL is increased with the increase of the applied voltage.
The C21 director continuously changes in the first alignment direction 21A.
【００３３】ＡＦＬＣ２１にある一定値Ｅｃ以上の電圧
（飽和電圧）を印加することにより、図６（Ｄ）に示す
ように、液晶分子は第１の配向状態になる。回転の抑制
による傾きも加わり、各液晶分子は第１の配向方向２１
Ａよりも所定角度傾いた方向に配列する。この状態で
は、隣接する層の永久双極子が互いに同一方向を向き、
自発分極が存在し、第２の強誘電相となる。この状態で
は、印加電界により液晶分子の回転は大幅に抑制されて
おり、大きな分極が現れる。By applying a voltage (saturation voltage) of a certain value Ec or more to the AFLC 21, the liquid crystal molecules are brought into the first alignment state as shown in FIG. 6 (D). The tilt due to the suppression of rotation is also added, and each liquid crystal molecule has a first alignment direction 21.
They are arranged in a direction inclined by a predetermined angle from A. In this state, the permanent dipoles of adjacent layers face each other in the same direction,
Spontaneous polarization exists and becomes the second ferroelectric phase. In this state, the rotation of liquid crystal molecules is significantly suppressed by the applied electric field, and a large polarization appears.
【００３４】また、逆極性で飽和電圧Ｅｃ未満の電圧Ｅ
をＡＦＬＣ２１に印加すると、図６（Ｅ）及び（Ｆ）に
示すように、印加電圧Ｅの大きさに応じて、第１の配向
状態にある液晶分子の一部は第２の配向状態に変化す
る。配向状態が変化する分子の数（割合）は印加電圧が
大きくなるに従って大きくなる。Further, a voltage E having a reverse polarity and less than the saturation voltage Ec
6 is applied to the AFLC 21, a part of the liquid crystal molecules in the first alignment state changes to the second alignment state according to the magnitude of the applied voltage E, as shown in FIGS. 6 (E) and (F). To do. The number (ratio) of molecules in which the orientation state changes increases as the applied voltage increases.
【００３５】また、液晶分子の長軸回りの回転が、印加
電圧の大きさに応じて抑制されて自発分極が発生する。
この自発分極と電界の相互作用により、電界と垂直な方
向に液晶分子は、図６（Ｅ）及び（Ｆ）に示すように徐
々に傾く。Further, the rotation of the liquid crystal molecules around the major axis is suppressed according to the magnitude of the applied voltage, and spontaneous polarization occurs.
Due to the interaction between the spontaneous polarization and the electric field, the liquid crystal molecules gradually tilt in the direction perpendicular to the electric field as shown in FIGS. 6 (E) and 6 (F).
【００３６】印加電圧の上昇に伴う第２の配向状態の液
晶分子の増加と、回転の抑制による液晶分子の傾きの増
加との複合作用により、印加電圧の上昇に伴ってＡＦＬ
Ｃ２１のダイレクタは第２の配向方向２１Ｂに向かって
連続的に変化する。Due to the combined action of the increase of the liquid crystal molecules in the second alignment state with the increase of the applied voltage and the increase of the inclination of the liquid crystal molecules due to the suppression of the rotation, the AFL is increased with the increase of the applied voltage.
The C21 director continuously changes in the second alignment direction 21B.
【００３７】ＡＦＬＣ２１に逆極性で一定値Ｅｃ以上の
電圧（飽和電圧）を印加することにより、図６（Ｇ）に
示すように、液晶分子は第２の配向状態になる。回転の
抑制による傾きも加わり、各液晶分子は第２の配向方向
２１Ｂよりも所定角度傾いた方向に配列する。この状態
では、隣接する層の永久双極子が互いに同一方向を向
き、自発分極が存在し、第２の強誘電相となる。この状
態では、印加電界により液晶分子の回転は大幅に抑制さ
れており、大きな分極が現れる。By applying a voltage (saturation voltage) having a reverse polarity and a constant value Ec or more to the AFLC 21, the liquid crystal molecules are in the second alignment state as shown in FIG. 6 (G). The liquid crystal molecules are arranged in a direction inclined by a predetermined angle with respect to the second alignment direction 21B due to the addition of the inclination due to the suppression of rotation. In this state, permanent dipoles of adjacent layers face each other in the same direction, spontaneous polarization exists, and a second ferroelectric phase is formed. In this state, the rotation of liquid crystal molecules is significantly suppressed by the applied electric field, and a large polarization appears.
【００３８】このように、上述のＡＦＬＣ２１では、第
１又は第２の配向状態の液晶分子の一部が印加電圧に応
じて第２又は第１の配向状態に切り替わるため、可視光
帯領の光の波長内より短い距離の中の液晶分子の平均的
配向が変化する。即ち、図７に模式的に示すように、第
１の配向状態に液晶分子が配列した微小領域と第２の配
向状態に液晶分子が配列した微小領域が、可視光帯域の
光の波長λよりも短い距離内に多数形成される。しか
も、これらの微小領域の面積又は数の割合及び各微小領
域内の液晶分子の傾き角は印加電圧に応じて変化する。As described above, in the AFLC 21 described above, a part of the liquid crystal molecules in the first or second alignment state is switched to the second or first alignment state according to the applied voltage, so that light in the visible light band is generated. The average orientation of the liquid crystal molecules within a distance shorter than within the wavelength of is changed. That is, as schematically shown in FIG. 7, the minute region in which the liquid crystal molecules are aligned in the first alignment state and the minute region in which the liquid crystal molecules are aligned in the second alignment state are closer to each other than the wavelength λ of light in the visible light band. Are formed within a short distance. Moreover, the area or the ratio of the number of these minute regions and the tilt angle of the liquid crystal molecules in each minute region change according to the applied voltage.
【００３９】各微小領域のサイズが可視領域の光の波長
よりも小さいため、光学的には、これらの微小領域の光
学特性が平均化される。従って、ＡＦＬＣ２１の光学軸
は、印加電圧の変化に伴う液晶分子の配向の変化、即
ち、第１の配向状態と第２の配向状態の液晶分子の割合
の変化に応じて連続的に変化する。Since the size of each minute region is smaller than the wavelength of light in the visible region, the optical characteristics of these minute regions are optically averaged. Therefore, the optical axis of the AFLC 21 continuously changes according to the change of the alignment of the liquid crystal molecules according to the change of the applied voltage, that is, the change of the ratio of the liquid crystal molecules in the first alignment state and the second alignment state.
【００４０】このため、偏光板２３、２４を図３に示す
ように配置し、０．１Ｈｚ程度の十分低周波の三角波電
圧を画素電極１３と対向電極１７との間に印加して得ら
れる光学特性は、図８に示すように、印加電圧０Ｖ近傍
において平坦な部分がなく、印加電圧の変化に伴って光
学特性も連続的に変化し、閾値が存在しない。さらに、
印加電圧の極性に対して透過率のカーブも対称となる。
また、絶対値が一定の値（Ｅｃ）以上の電圧が印加され
ると、ほぼ全ての液晶分子が第１又は第２の配向状態に
配向し、透過率はほぼ飽和する。さらに、ヒステリシス
が非常に小さい。For this reason, the polarizing plates 23 and 24 are arranged as shown in FIG. 3, and a triangular wave voltage having a sufficiently low frequency of about 0.1 Hz is applied between the pixel electrode 13 and the counter electrode 17 to obtain an optical signal. As shown in FIG. 8, there is no flat portion in the vicinity of the applied voltage of 0 V, the optical characteristics continuously change with the applied voltage, and there is no threshold value. further,
The transmittance curve is also symmetrical with respect to the polarity of the applied voltage.
When a voltage whose absolute value is a constant value (Ec) or more is applied, almost all liquid crystal molecules are aligned in the first or second alignment state, and the transmittance is almost saturated. Moreover, the hysteresis is very small.
【００４１】このような光学特性を示す液晶表示素子に
よれば、印加電圧に対し表示階調が一義的に定まり、し
かも、任意の階調を得ることができる。従って、上述の
ように、液晶表示素子をアクティブマトリクス型とし
て、各画素の非選択期間に、印加電圧を表示階調に対応
するほぼ一定値に維持することにより、任意の階調が表
示可能となる。ここで、透過光量が最大値の５０％とな
る位置での電圧幅（ヒステリシス幅）Δ50は、ほぼ０．
１Ｖ以下となるＡＦＬＣ２１が望ましい。According to the liquid crystal display element having such optical characteristics, the display gradation is uniquely determined with respect to the applied voltage, and further, an arbitrary gradation can be obtained. Therefore, as described above, the liquid crystal display element is of the active matrix type, and by maintaining the applied voltage at a substantially constant value corresponding to the display gradation during the non-selection period of each pixel, it is possible to display an arbitrary gradation. Become. Here, the voltage width (hysteresis width) Δ50 at the position where the amount of transmitted light is 50% of the maximum value is almost 0.
The AFLC 21 having a voltage of 1 V or less is desirable.
【００４２】次に、上記構成の液晶表示素子に階調表示
を行わせる場合の駆動方法について説明する。図９
（Ａ）は、行ドライバ３１が第１行のＴＦＴ１４に接続
されたゲートライン１５に印加するゲート信号の波形を
示し、図９（Ｂ）は、列ドライバ３２がデータライン１
６に印加するデータ信号の波形を示し、図９（Ｃ）は各
画素に保持される電圧を示す。なお、理解を容易にする
ため、第１行の画素用のデータ信号のみ示し、他の行用
のデータ信号は図示しない。Next, a driving method for causing the liquid crystal display device having the above-mentioned configuration to perform gradation display will be described. Figure 9
9A shows a waveform of a gate signal applied to the gate line 15 connected to the TFT 14 of the first row by the row driver 31, and FIG.
6 shows the waveform of the data signal applied, and FIG. 9C shows the voltage held in each pixel. Note that, for ease of understanding, only the data signals for the pixels in the first row are shown, and the data signals for the other rows are not shown.
【００４３】図９（Ａ）〜図９（Ｃ）において、ＴＦは
１フレーム期間、ＴＳは第１行の画素の選択期間、ＴＯ
は非選択期間を示す。各選択期間ＴＳは、例えば、約６
０μ秒である。この実施例においては、図９（Ｂ）に示
すように、連続する２つのフレームの選択期間Ｔｓに、
表示階調に応じ、極性が反対で絶対値が同一の電圧値Ｖ
Ｄ、−ＶＤを有する駆動パルス（書き込みパルス）をデ
ータライン１６に印加する。即ち、１つの映像信号（表
示データ）について、電圧値が＋ＶＤと−ＶＤの２つの
駆動パルスを２つのフレームの各選択期間ＴＳにそれぞ
れ１つずつＡＦＬＣ２１に印加する。駆動パルスの極性
及び電圧値は、データ信号の基準電圧Ｖ０に対する極性
と電圧である。基準電圧Ｖ０は対向電極７に印加する電
圧と同一である。In FIGS. 9A to 9C, TF is one frame period, TS is a pixel selection period of the first row, and TO is TO.
Indicates a non-selection period. Each selection period TS is, for example, about 6
It is 0 microsecond. In this embodiment, as shown in FIG. 9B, during the selection period Ts of two consecutive frames,
Voltage value V with opposite polarity but the same absolute value according to the display gradation
A drive pulse (write pulse) having D, −VD is applied to the data line 16. That is, for one video signal (display data), two drive pulses having a voltage value of + VD and −VD are applied to the AFLC 21 one by one in each selection period TS of two frames. The polarity and voltage value of the drive pulse are the polarity and voltage of the data signal with respect to the reference voltage V0. The reference voltage V0 is the same as the voltage applied to the counter electrode 7.
【００４４】この駆動方法では、書き込み電圧ＶＤの最
小値をＶ０とし、最大値Ｖmaxを透過率の飽和が起こる
電圧ＥCよりも若干低い値として、Ｖ０〜Ｖmaxの範囲で
書き込み電圧ＶＤを制御する。In this driving method, the minimum value of the write voltage VD is set to V0, the maximum value Vmax is set to a value slightly lower than the voltage EC at which the saturation of the transmittance occurs, and the write voltage VD is controlled in the range of V0 to Vmax.
【００４５】上記のような波形のゲート信号とデータ信
号とを用いて上記反強誘電性液晶表示素子を駆動する
と、各行の選択期間ＴＳに、駆動パルスの電圧（書き込
み電圧）ＶＤがゲート信号によりオンしているＴＦＴ１
４を介して画素電極１３に印加される。ゲート信号がオ
フし、非選択期間ＴＯになると、ＴＦＴ１４がオフ状態
になり、図９（Ｃ）に示すように、書き込み電圧ＶＤ
が、画素電極１３と対向電極１７とその間のＡＦＬＣ２
１とで形成される容量（画素容量）に保持される。この
ため、図９（Ｃ）に示すように非選択期間ＴＯの間、そ
の画素の透過率が、画素容量の保持電圧に対応する値に
維持される。When the antiferroelectric liquid crystal display element is driven by using the gate signal and the data signal having the above waveforms, the voltage (writing voltage) VD of the drive pulse is applied by the gate signal during the selection period TS of each row. TFT1 turned on
The voltage is applied to the pixel electrode 13 via 4. When the gate signal is turned off and the non-selection period TO is started, the TFT 14 is turned off, and as shown in FIG.
However, the pixel electrode 13, the counter electrode 17 and the AFLC2 between them are
It is held in the capacity (pixel capacity) formed by 1. Therefore, as shown in FIG. 9C, the transmittance of the pixel is maintained at a value corresponding to the holding voltage of the pixel capacitor during the non-selection period TO.
【００４６】この実施例では、ＡＦＬＣ２１として印加
電圧の変化に対する明確な閾値を有さず、透過率が連続
的に変化するものを使用し、しかも、図３に示す光学配
置を採用しているので、書き込み電圧ＶＤの絶対値に対
する透過率が一義的に定まり、書き込み電圧ＶＤの絶対
値により透過率を制御して、明確な階調表示を実現でき
る。また、連続する２つのフレームにより、１つの画素
データに対する正負逆極性の電圧＋ＶＤと−ＶＤをＡＦ
ＬＣ２１に印加しているので、正負の電圧に対する光学
特性が若干異なっていてもこれらの光学的変化の平均値
として観察されるので、正負逆極性の電圧に対する光学
的特性に差があっても明確な階調表示が可能である。In this embodiment, the AFLC 21 which does not have a clear threshold value with respect to the change of the applied voltage and whose transmittance continuously changes is used, and furthermore, the optical arrangement shown in FIG. 3 is adopted. The transmittance with respect to the absolute value of the writing voltage VD is uniquely determined, and the transmittance can be controlled by the absolute value of the writing voltage VD to realize clear gradation display. In addition, by using two consecutive frames, the voltages + VD and -VD having positive and negative reverse polarities with respect to one pixel data are AF-processed.
Since it is applied to the LC21, even if the optical characteristics with respect to positive and negative voltages are slightly different, it is observed as an average value of these optical changes. It is possible to display various gradations.
【００４７】また、連続する２つのフレームで、極性が
逆で絶対値が等しい電圧＋ＶＤと−ＶＤを各画素（ＡＦ
ＬＣ２１）に印加するので、ＡＦＬＣ２１に直流電圧成
分が片寄って印加されることがない。従って表示の焼き
付き現象やＡＦＬＣ２１の劣化を生ずることもない。Further, in two consecutive frames, voltages + VD and -VD having opposite polarities and equal absolute values are applied to each pixel (AF).
Since it is applied to the LC 21), the DC voltage component is not biasedly applied to the AF LC 21. Therefore, a display burn-in phenomenon or deterioration of the AFLC 21 does not occur.
【００４８】具体例 図１０はＡＦＬＣ２１としてＩ−ＳA転移温度が７１
℃、ＳA−ＳC*転移温度が５７℃で、自発分極が１７
６、チルト角３１．５（コーン角３３°）で、上述の特
性を有する反強誘電性液晶を使用し、配向処理方向及び
偏光板の透過軸の方向を図３に示したように設定し、各
選択期間ＴＳを６０μ秒とし、図９（Ｂ）に示すように
絶対値が同一の電圧を有する駆動パルスを２つのフレー
ムで異なった極性とし、書き込み電圧を０Ｖ〜１０Ｖの
範囲で変化させた場合の印加電圧と透過率の関係を示
す。このグラフから明らかなように、この液晶表示素子
及びこの駆動方法によれば、書き込み電圧を変化させる
ことにより、透過率が連続的に変化し、さらに、書き込
み電圧に応じて表示階調がほぼ一義的に定まり、階調表
示が可能になる。Concrete Example FIG. 10 shows an AFLC 21 having an I-SA transition temperature of 71.
℃, SA-SC * transition temperature is 57 ℃, spontaneous polarization is 17
6, tilt angle 31.5 (cone angle 33 °), antiferroelectric liquid crystal having the above-mentioned characteristics is used, and the alignment treatment direction and the transmission axis direction of the polarizing plate are set as shown in FIG. , Each selection period TS is set to 60 μs, drive pulses having voltages with the same absolute value have different polarities in the two frames as shown in FIG. 9B, and the write voltage is changed in the range of 0V to 10V. The relationship between the applied voltage and the transmittance in the case of As is clear from this graph, according to this liquid crystal display element and this driving method, the transmissivity is continuously changed by changing the writing voltage, and further, the display gradation is almost unique according to the writing voltage. The gradation display becomes possible.
【００４９】この発明は上記実施例に限定されず、種々
の変形が可能である。例えば、液晶表示素子の駆動方
法、駆動波形等は任意に変更可能である。また、偏光板
２３と２４の透過軸２３Ａと２４Ａを平行に配置しても
よい。偏光板の光学軸は吸収軸でもよい。また、一方の
偏光板の光学軸を第１又は第２の配向方向に平行又は直
角とし、他方の偏光板の光学軸を一方の偏光板の光学軸
に平行又は直交させてもよい。また、この発明はＴＦＴ
をアクティブ素子とする反強誘電性液晶表示素子に限ら
ず、ＭＩＭをアクティブ素子とする反強誘電性液晶表示
素子にも適用可能である。The present invention is not limited to the above embodiment, but various modifications can be made. For example, the driving method and driving waveform of the liquid crystal display element can be arbitrarily changed. Further, the transmission axes 23A and 24A of the polarizing plates 23 and 24 may be arranged in parallel. The optical axis of the polarizing plate may be the absorption axis. Further, the optical axis of one polarizing plate may be parallel or perpendicular to the first or second alignment direction, and the optical axis of the other polarizing plate may be parallel or orthogonal to the optical axis of one polarizing plate. In addition, this invention is a TFT
The present invention can be applied not only to the anti-ferroelectric liquid crystal display element using the active element as the active element, but also to the anti-ferroelectric liquid crystal display element using the MIM as the active element.
【００５０】[0050]
【発明の効果】以上説明したように、この発明の反強誘
電性液晶表示素子は、分子レベルで第１と第２の配向状
態を有し、印加電圧に応じて液晶分子の配向状態が第１
又は第２の配向状態から第２又は第１の配向状態にそれ
ぞれ変化する。また、印加電圧に応じて、液晶分子の回
転の抑制による液晶分子の電界に垂直な方向へ傾く。こ
のため、配向状態の異なる部分領域が可視領域の光の波
長の中に複数発生し、これらの光学特性が平均化され、
強誘電相と反強誘電相の間の多数の中間的な状態を生成
できる。従って、この中間的な状態を用いて明確な階調
表示を行うことができる。As described above, the antiferroelectric liquid crystal display device of the present invention has the first and second alignment states at the molecular level, and the alignment state of the liquid crystal molecules becomes the first alignment state depending on the applied voltage. 1
Alternatively, the second alignment state is changed to the second or first alignment state. In addition, depending on the applied voltage, the liquid crystal molecules are tilted in a direction perpendicular to the electric field of the liquid crystal molecules by suppressing the rotation of the liquid crystal molecules. Therefore, a plurality of partial regions having different alignment states are generated in the wavelength of light in the visible region, these optical characteristics are averaged,
A number of intermediate states can be created between the ferroelectric and antiferroelectric phases. Therefore, clear gradation display can be performed by using this intermediate state.
【図１】この発明の一実施例にかかる液晶表示素子の構
造を示す断面図である。FIG. 1 is a sectional view showing a structure of a liquid crystal display element according to an embodiment of the present invention.
【図２】図１に示す液晶表示素子の下基板の構成を示す
平面図である。FIG. 2 is a plan view showing a configuration of a lower substrate of the liquid crystal display element shown in FIG.
【図３】偏光板の透過軸と液晶分子の配向方向の関係を
示す図である。FIG. 3 is a diagram showing a relationship between a transmission axis of a polarizing plate and an alignment direction of liquid crystal molecules.
【図４】反強誘電性液晶の液晶分子の描く二重螺旋構造
を説明するための図である。FIG. 4 is a diagram for explaining a double helix structure drawn by liquid crystal molecules of antiferroelectric liquid crystal.
【図５】基板間に封止された液晶分子の配向状態を説明
するための図である。FIG. 5 is a diagram for explaining an alignment state of liquid crystal molecules sealed between substrates.
【図６】印加電圧と液晶分子の配向との関係を示す図で
あり、（Ａ）は電圧を印加していない時の液晶分子の配
向を説明するための図であり、（Ｂ）と（Ｃ）は第１の
極性の中間電圧を印加した時の液晶分子の配向を説明す
るための図であり、（Ｄ）は第１の極性で十分大きい電
圧を印加した時の液晶分子の配向を説明するための図で
あり、（Ｅ）と（Ｆ）は第２の極性の中間電圧を印加し
た時の液晶分子の配向を説明するための図であり、
（Ｇ）は第２の極性で十分大きい電圧を印加した時の液
晶分子の配向を説明するための図である。FIG. 6 is a diagram showing the relationship between an applied voltage and the orientation of liquid crystal molecules, (A) is a diagram for explaining the orientation of liquid crystal molecules when no voltage is applied, and (B) and ( C) is a diagram for explaining the alignment of the liquid crystal molecules when an intermediate voltage of the first polarity is applied, and (D) shows the alignment of the liquid crystal molecules when a sufficiently large voltage of the first polarity is applied. FIG. 6 is a diagram for explaining, and (E) and (F) are diagrams for explaining alignment of liquid crystal molecules when an intermediate voltage of the second polarity is applied,
(G) is a diagram for explaining the alignment of the liquid crystal molecules when a sufficiently large voltage is applied with the second polarity.
【図７】可視光帯域の光の波長λより短い距離内に配向
状態の異なる領域が形成された状態を模式的に示した図
である。FIG. 7 is a diagram schematically showing a state in which regions having different alignment states are formed within a distance shorter than the wavelength λ of light in the visible light band.
【図８】この発明の一実施例の反強誘電性液晶表示素子
に低周波の三角波電圧を印加した時の、印加電圧−透過
率特性を示すグラフである。FIG. 8 is a graph showing applied voltage-transmittance characteristics when a low-frequency triangular wave voltage is applied to the antiferroelectric liquid crystal display element of one embodiment of the present invention.
【図９】この発明の一実施例の液晶表示素子の駆動方法
を説明するためのタイミングチャートであり、（Ａ）は
ゲート信号、（Ｂ）はデータ信号、（Ｃ）は各画素に保
持される電圧を示すタイミングチャートである。FIG. 9 is a timing chart for explaining a method of driving a liquid crystal display element according to an embodiment of the present invention, in which (A) is a gate signal, (B) is a data signal, and (C) is held in each pixel. 3 is a timing chart showing the voltage applied.
【図１０】図９に示す駆動方法を用いてこの発明の一実
施例の液晶表示素子を駆動した時の印加電圧−透過率特
性を示す図である。10 is a diagram showing applied voltage-transmittance characteristics when the liquid crystal display element of one embodiment of the present invention was driven by using the driving method shown in FIG.
【図１１】従来の反強誘電性液晶表示素子に低周波の三
角波電圧を印加した時の、印加電圧−透過率特性を示す
グラフである。FIG. 11 is a graph showing applied voltage-transmittance characteristics when a low-frequency triangular wave voltage is applied to a conventional antiferroelectric liquid crystal display device.
１１・・・透明基板（下基板）、１２・・・透明基板（上基
板）、１３・・・画素電極、１４・・・アクティブ素子（ＴＦ
Ｔ）、１５・・・ゲートライン（走査ライン）、１６・・・デ
ータライン（階調信号ライン）、１７・・・対向電極、１
８・・・配向膜、１９・・・配向膜、２０・・・シール材、２１・
・・反強誘電性液晶（ＡＦＬＣ）、２２・・・ギャップ材、
２３・・・偏光板（下偏光板）、２４・・・偏光板（上偏光
板）、３１・・・行ドライバ（行駆動回路）、３２・・・列ド
ライバ（列駆動回路）11 ... Transparent substrate (lower substrate), 12 ... Transparent substrate (upper substrate), 13 ... Pixel electrode, 14 ... Active element (TF
T), 15 ... Gate line (scanning line), 16 ... Data line (gradation signal line), 17 ... Counter electrode, 1
8 ... Alignment film, 19 ... Alignment film, 20 ... Sealing material, 21 ...
..Anti-ferroelectric liquid crystal (AFLC), 22 ... Gap material,
23 ... Polarizing plate (lower polarizing plate), 24 ... Polarizing plate (upper polarizing plate), 31 ... Row driver (row driving circuit), 32 ... Column driver (column driving circuit)
Claims (5)
他方の基板に前記画素電極に対向する対向電極をそれぞ
れ形成し、前記一対の基板間に、２つの配向状態の液晶
分子が均一に混在する反強誘電相を有し、各液晶分子が
印加電圧に応じて電界と垂直な方向に傾くと共に印加電
圧に応じて一方の配向状態の液晶分子が他方の配向状態
に変化することにより、異なった配向状態の領域が可視
光帯域の光の波長よりも小さい距離内に複数形成される
ことにより、ダイレクタの平均的な方向が印加電圧に応
じて連続的に変化する反強誘電性液晶を封入し、階調表
示を可能としたことを特徴とする反強誘電性液晶表示素
子。1. A pixel electrode is provided on one of a pair of substrates facing each other.
A counter electrode facing the pixel electrode is formed on the other substrate, and an antiferroelectric phase in which liquid crystal molecules in two alignment states are uniformly mixed is formed between the pair of substrates, and each liquid crystal molecule has an applied voltage. Depending on the applied voltage, the liquid crystal molecules in one alignment state change to the other alignment state, so that the regions of different alignment states are An antiferroelectric liquid crystal, in which multiple directors are formed within a small distance so that the average direction of the director changes continuously according to the applied voltage, enables grayscale display. Ferroelectric liquid crystal display device.
ブ素子がマトリクス状に複数配列された一方の基板と、 前記画素電極に対向する対向電極が形成された他方の基
板と、 前記基板の間に封入され、液晶分子がほぼ第１の配向方
向に配列した第１の強誘電相と液晶分子がほぼ第２の配
向方向に配列した第２の強誘電相と、第１の配向方向に
配列した液晶分子と第２の配向方向に配列した液晶分子
が混在することにより、ダイレクタの方向がスメクティ
ックＣA*相の層構造の層の法線方向にほぼ一致する反強
誘電相を有し、印加電圧に応じて、液晶分子が電界と垂
直な方向に傾くと共に第１の配向方向に配列した液晶分
子と第２の配向方向の一方に配列した液晶分子が他方の
配向方向に配列することにより、可視光帯域の光の波長
より短い範囲で、異なった配向状態の領域が複数形成さ
れることにより、ダイレクタの方向が変化し、前記強誘
電相と前記反強誘電相の間の中間の状態を有する反強誘
電性液晶、を備えたことを特徴とする反強誘電性液晶表
示素子。2. A substrate between one substrate on which a plurality of pixel electrodes and active elements connected to the pixel electrodes are arranged in a matrix, another substrate on which a counter electrode facing the pixel electrode is formed, and between the substrates. And a second ferroelectric phase in which liquid crystal molecules are aligned in a first alignment direction, a second ferroelectric phase in which liquid crystal molecules are aligned in a second alignment direction, and a second ferroelectric phase in which liquid crystal molecules are aligned in a first alignment direction. Since the mixed liquid crystal molecules and the liquid crystal molecules aligned in the second alignment direction are mixed, the director has an antiferroelectric phase in which the direction of the director is substantially aligned with the normal direction of the layer of the layer structure of the smectic CA * phase, Depending on the voltage, the liquid crystal molecules are tilted in the direction perpendicular to the electric field, and the liquid crystal molecules aligned in the first alignment direction and the liquid crystal molecules aligned in one of the second alignment directions are aligned in the other alignment direction. Shorter than the wavelength of light in the visible light band A plurality of regions having different alignment states are formed in the enclosure, the direction of the director is changed, and an antiferroelectric liquid crystal having an intermediate state between the ferroelectric phase and the antiferroelectric phase is provided. An antiferroelectric liquid crystal display device characterized by the above.
の相互作用による回転の抑制により、電界と垂直な方向
に傾くことを特徴とする請求項１又は２に記載の反強誘
電性液晶表示素子。3. The antiferroelectric liquid crystal according to claim 1, wherein the liquid crystal molecules are tilted in a direction perpendicular to an electric field by suppressing rotation due to an interaction between the applied voltage and spontaneous polarization. Display element.
A*相の液晶が螺旋構造を消失された状態で前記基板間に
封止されて構成されている、ことを特徴とする請求項
１、２、又は３に記載の反強誘電性液晶表示素子。4. The antiferroelectric liquid crystal is smectic C
4. The antiferroelectric liquid crystal display element according to claim 1, wherein the liquid crystal of A * phase is sealed between the substrates in a state where the helical structure is eliminated. .
平行又は直交する方向に光学軸が配置された第１の偏光
板と、 前記液晶を介して前記第１の偏光板に対向し、前記第１
の偏光板の光学軸に平行又は直交するように光学軸が設
定された第２の偏光板を備える、 ことを特徴とする請求項２に記載の反強誘電性液晶表示
素子。5. The antiferroelectric liquid crystal display device further comprises a first polarizing plate having an optical axis arranged in a direction parallel or orthogonal to an average alignment direction of liquid crystal molecules in the antiferroelectric phase. Facing the first polarizing plate through the liquid crystal,
The anti-ferroelectric liquid crystal display element according to claim 2, further comprising a second polarizing plate having an optical axis set to be parallel or orthogonal to the optical axis of the polarizing plate.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15711395A JP3259600B2 (en) | 1995-05-31 | 1995-05-31 | Antiferroelectric liquid crystal display |
| US08/657,017 US5847799A (en) | 1995-05-31 | 1996-05-28 | Antiferroelectric liquid crystal display device |
| CN96105391A CN1164665A (en) | 1995-05-31 | 1996-05-31 | Antiferroelectric liquid crystal display device |
| KR1019960019199A KR100246700B1 (en) | 1995-05-31 | 1996-05-31 | Antiferoelectric lcd device |
| TW085106496A TW325528B (en) | 1995-05-31 | 1996-05-31 | An antiferroelectric liquid crystal display element |
| US09/141,495 US6122034A (en) | 1995-05-31 | 1998-08-27 | Antiferroelectric liquid crystal display device |
| US09/556,655 US6208403B1 (en) | 1995-05-31 | 2000-04-24 | Antiferroelectric liquid crystal display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15711395A JP3259600B2 (en) | 1995-05-31 | 1995-05-31 | Antiferroelectric liquid crystal display |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08328046A true JPH08328046A (en) | 1996-12-13 |
| JP3259600B2 JP3259600B2 (en) | 2002-02-25 |
Family
ID=15642514
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15711395A Expired - Fee Related JP3259600B2 (en) | 1995-05-31 | 1995-05-31 | Antiferroelectric liquid crystal display |
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| Country | Link |
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| JP (1) | JP3259600B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998044383A1 (en) * | 1997-03-31 | 1998-10-08 | Citizen Watch Co., Ltd. | Antiferroelectric liquid crystal device and method for manufacturing the same |
| US6040889A (en) * | 1996-12-25 | 2000-03-21 | Nec Corporation | Liquid crystal display with continuous grayscale, wide viewing angle, and exceptional shock resistance |
| US6177968B1 (en) | 1997-09-01 | 2001-01-23 | Canon Kabushiki Kaisha | Optical modulation device with pixels each having series connected electrode structure |
| JP2010509606A (en) * | 2006-11-15 | 2010-03-25 | ビオスルフィット ソシエダッド アノニマ | Dynamic detection device based on surface plasmon resonance effect |
-
1995
- 1995-05-31 JP JP15711395A patent/JP3259600B2/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6040889A (en) * | 1996-12-25 | 2000-03-21 | Nec Corporation | Liquid crystal display with continuous grayscale, wide viewing angle, and exceptional shock resistance |
| WO1998044383A1 (en) * | 1997-03-31 | 1998-10-08 | Citizen Watch Co., Ltd. | Antiferroelectric liquid crystal device and method for manufacturing the same |
| US5995181A (en) * | 1997-03-31 | 1999-11-30 | Citizen Watch Co., Ltd. | Antiferroelectric liquid crystal with polarizing axes oriented between a molecular axis direction in rightward-tilted antiferroelectric state and a molecular axis direction in leftward-tilted antiferroelectric state |
| US6177968B1 (en) | 1997-09-01 | 2001-01-23 | Canon Kabushiki Kaisha | Optical modulation device with pixels each having series connected electrode structure |
| JP2010509606A (en) * | 2006-11-15 | 2010-03-25 | ビオスルフィット ソシエダッド アノニマ | Dynamic detection device based on surface plasmon resonance effect |
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