JPH07333580A - Ferroelectric liquid crystal display device and method for driving ferroelectric liquid crystal display element - Google Patents
Ferroelectric liquid crystal display device and method for driving ferroelectric liquid crystal display elementInfo
- Publication number
- JPH07333580A JPH07333580A JP6151817A JP15181794A JPH07333580A JP H07333580 A JPH07333580 A JP H07333580A JP 6151817 A JP6151817 A JP 6151817A JP 15181794 A JP15181794 A JP 15181794A JP H07333580 A JPH07333580 A JP H07333580A
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- ferroelectric liquid
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- 239000005262 ferroelectric liquid crystals (FLCs) Substances 0.000 title claims abstract description 70
- 238000000034 method Methods 0.000 title claims description 38
- 239000004973 liquid crystal related substance Substances 0.000 claims abstract description 203
- 230000003287 optical effect Effects 0.000 claims abstract description 54
- 239000000758 substrate Substances 0.000 claims description 56
- 230000004044 response Effects 0.000 claims description 25
- 239000010409 thin film Substances 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 6
- 239000011159 matrix material Substances 0.000 claims description 6
- 230000001747 exhibiting effect Effects 0.000 claims description 5
- 230000005621 ferroelectricity Effects 0.000 claims 2
- 239000000126 substance Substances 0.000 claims 1
- 238000002834 transmittance Methods 0.000 description 34
- 230000005540 biological transmission Effects 0.000 description 27
- 239000004990 Smectic liquid crystal Substances 0.000 description 13
- 230000010287 polarization Effects 0.000 description 11
- 238000000926 separation method Methods 0.000 description 8
- 230000007704 transition Effects 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 238000010521 absorption reaction Methods 0.000 description 6
- 239000010408 film Substances 0.000 description 6
- 239000003566 sealing material Substances 0.000 description 6
- 239000002131 composite material Substances 0.000 description 5
- 230000002269 spontaneous effect Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000002243 precursor Substances 0.000 description 3
- 241001270131 Agaricus moelleri Species 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 238000000819 phase cycle Methods 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 239000004988 Nematic liquid crystal Substances 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- -1 polyimide Chemical class 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
- G09G3/3611—Control of matrices with row and column drivers
- G09G3/3648—Control of matrices with row and column drivers using an active matrix
- G09G3/3651—Control of matrices with row and column drivers using an active matrix using multistable liquid crystals, e.g. ferroelectric liquid crystals
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
- G09G3/3611—Control of matrices with row and column drivers
- G09G3/3648—Control of matrices with row and column drivers using an active matrix
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/2007—Display of intermediate tones
- G09G3/2011—Display of intermediate tones by amplitude modulation
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
- G09G3/3611—Control of matrices with row and column drivers
- G09G3/3614—Control of polarity reversal in general
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Liquid Crystal (AREA)
- Liquid Crystal Display Device Control (AREA)
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】この発明は強誘電性液晶（反強誘
電性液晶を含む）を用いた液晶表示素子及びその駆動方
法に関し、特に、階調表示が可能な強誘電性液晶表示装
置及び強誘電性液晶表示素子の駆動方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device using a ferroelectric liquid crystal (including an antiferroelectric liquid crystal) and a driving method thereof, and more particularly to a ferroelectric liquid crystal display device capable of gradation display and The present invention relates to a driving method of a ferroelectric liquid crystal display element.
【０００２】[0002]
【従来の技術】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
速応答や、広い視野角が得られる等の点で注目されてい
る。強誘電性液晶表示素子としては、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。2. Description of the Related Art Ferroelectric liquid crystal display elements have been attracting attention because of their high-speed response and wide viewing angle as compared with TN mode liquid crystal display elements using nematic liquid crystals. 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.
【０００３】強誘電性液晶表示素子の実用化に関する研
究は、従来、ＳＳ−Ｆ液晶と呼ばれる強誘電性液晶を対
象として行なわれていた。しかし、ＳＳ−Ｆ液晶を用い
る強誘電性液晶表示素子は透過率を段階的に変化させる
ことができず、階調表示を行うことができない。Studies on the practical use of a ferroelectric liquid crystal display device have hitherto been made on a ferroelectric liquid crystal called SS-F liquid crystal. However, the ferroelectric liquid crystal display element using the SS-F liquid crystal cannot change the transmittance stepwise and cannot perform gradation display.
【０００４】そこで、階調表示の可能な強誘電性液晶表
示素子が研究されており、カイラルスメクティック相の
螺旋ピッチが表示素子の基板間隔より小さい強誘電性液
晶を用いることが提案されている。この種の強誘電性液
晶は、メモリ性を有するものがＳＢＦ液晶と呼ばれ、非
メモリ性のものがＤＨＦ液晶と呼ばれている（「LIQUID
CRYSTALS」, 1989, Vol.5, NO.4, の第1171頁ないし第
1177頁参照）。Therefore, a ferroelectric liquid crystal display device capable of displaying gray scales has been studied, and it has been proposed to use a ferroelectric liquid crystal in which the spiral pitch of the chiral smectic phase is smaller than the substrate interval of the display device. Of this type of ferroelectric liquid crystal, one having a memory property is called an SBF liquid crystal, and one having a non-memory property is called a DHF liquid crystal (“LIQUID
CRYSTALS '', 1989, Vol.5, NO.4, pages 1171 to
See page 1177).
【０００５】また、ＤＨＦ液晶を用いる強誘電性液晶表
示素子では、ＤＨＦ液晶が螺旋構造をもった状態で基板
間に封入されている。ＤＨＦ液晶は、液晶層を挟んで対
向する電極間に絶対値が十分大きい値の電圧を印加した
時、印加電圧の極性に応じて、液晶分子のダイレクタが
第１の方向にほぼ配向した第１の配向状態と液晶分子の
ダイレクタが第２の方向にほぼ配向した第２の配向状態
とのいずれかになり、印加電圧の絶対値が前記第１の配
向状態又は第２の配向状態となる電圧より小さい場合、
分子配列の螺旋の歪みにより、液晶分子のダイレクタの
平均的な方向が前記第１と第２の方向の間となる中間の
配向状態になる。Further, in the ferroelectric liquid crystal display element using the DHF liquid crystal, the DHF liquid crystal is enclosed between the substrates in a state having a spiral structure. In the DHF liquid crystal, when a voltage having a sufficiently large absolute value is applied between the electrodes facing each other with the liquid crystal layer interposed therebetween, the director of the liquid crystal molecule is substantially aligned in the first direction according to the polarity of the applied voltage. And the second alignment state in which the director of the liquid crystal molecules is substantially aligned in the second direction, and the absolute value of the applied voltage becomes the first alignment state or the second alignment state. If less than
Due to the distortion of the spiral of the molecular alignment, the average orientation of the directors of the liquid crystal molecules is in the intermediate orientation state between the first and second directions.
【０００６】ＳＢＦ液晶を用いる強誘電性液晶表示素子
では、ＳＢＦ液晶が螺旋構造をもった状態で基板間に封
入される。ＳＢＦ液晶は、液晶層を挟んで対向する電極
間に絶対値が所定値以上の電圧を印加した時、印加電圧
の極性に応じて、液晶分子の長軸の方向（ダイレクタ）
が第１の方向にほぼ配向した第１の配向状態と液晶分子
のダイレクタが第２の方向にほぼ配向した第２の配向状
態とのいずれかになり、印加電圧の絶対値が前記第１の
配向状態又は第２の配向状態となる電圧より小さい場
合、ダイレクタが第１の方向に配向した液晶分子とダイ
レクタが第２の方向に配向した液晶分子が混在した中間
の配向状態になる。In the ferroelectric liquid crystal display element using the SBF liquid crystal, the SBF liquid crystal is enclosed between the substrates in a spiral structure. The SBF liquid crystal has a long axis direction (director) of liquid crystal molecules depending on the polarity of the applied voltage when a voltage whose absolute value is equal to or greater than a predetermined value is applied between electrodes facing each other with a liquid crystal layer interposed therebetween.
Is in a first alignment state in which the liquid crystal molecules are substantially aligned in the first direction or in a second alignment state in which the director of the liquid crystal molecules is substantially aligned in the second direction, and the absolute value of the applied voltage is the first When the voltage is smaller than the voltage that causes the alignment state or the second alignment state, the director is in an intermediate alignment state in which liquid crystal molecules aligned in the first direction and liquid crystal molecules aligned in the second direction are mixed.
【０００７】従来、ＤＨＦ液晶或いはＳＢＦ液晶を用い
る液晶表示素子においては、一方の偏光板の光学軸は前
記第１又は第２の方向に平行に設定され、他方の偏光板
の光学軸は一方の偏光板の光学軸に直交するように配置
されている。Conventionally, in a liquid crystal display device using DHF liquid crystal or SBF liquid crystal, the optical axis of one polarizing plate is set parallel to the first or second direction, and the optical axis of the other polarizing plate is one. It is arranged so as to be orthogonal to the optical axis of the polarizing plate.
【０００８】しかし、このような構成の強誘電性液晶表
示素子では、表示したい階調に対応する電圧を液晶に印
加しても、印加電圧と画素の透過率とが対応せず、実用
レベルの階調表示を実現することはできない。これは、
これらの液晶表示素子の光学特性（印加電圧と透過率の
関係）のヒステリシスが大きく、表示階調に対応する電
圧を液晶に印加しても、それ以前に印加された電圧の影
響で表示階調が一義的に定まらないためである。However, in the ferroelectric liquid crystal display device having such a structure, even if a voltage corresponding to the gradation to be displayed is applied to the liquid crystal, the applied voltage and the pixel transmittance do not correspond, and the level is practical. Gradation display cannot be realized. this is,
The optical characteristics (relationship between applied voltage and transmittance) of these liquid crystal display elements have large hysteresis, and even if a voltage corresponding to the display gradation is applied to the liquid crystal, the display gradation is affected by the voltage applied before that. Is not uniquely determined.
【０００９】このヒステリシスの影響を小さくして表示
階調を制御するため、各画素の選択期間に液晶分子を第
１又は第２の方向に一旦配向させる電圧を印加し、その
後、表示階調に対応する電圧を印加して液晶表示素子を
駆動する手法等も提案されている。しかし、このような
駆動方法では、駆動回路が複雑になり、また、各画素の
選択期間が長くなるという問題がある。In order to control the display gradation by reducing the influence of this hysteresis, a voltage for temporarily aligning the liquid crystal molecules in the first or second direction is applied during the selection period of each pixel, and then the display gradation is changed. A method of driving a liquid crystal display element by applying a corresponding voltage has also been proposed. However, such a driving method has a problem that the driving circuit becomes complicated and the selection period of each pixel becomes long.
【００１０】一方、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。すなわち、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の方向に配列する第１の強誘電相ま
たは第２の方向に配列する第２の強誘電相に配向し、絶
対値が前記第１のしきい値及び第２のしきい値より低い
電圧を印加したとき、液晶分子の平均的な配列方向がス
メクテック相の層の法線とほぼ平行な方向の反強誘電相
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、光の透過率を制御して画像を表示す
ることができる。On the other hand, 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 orientation 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 first in accordance with the polarity of the applied voltage. A voltage having an absolute value lower than the first threshold value and the second threshold value and oriented in a first ferroelectric phase arranged in one direction or a second ferroelectric phase arranged in a second direction. When is applied, the average alignment direction of the liquid crystal molecules is oriented in the antiferroelectric phase in a direction substantially parallel to the normal of the smectic phase layer. 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, it is possible to control the light transmittance and display an image.
【００１１】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のしきい値を境とする各範囲で、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。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。このため、従来の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。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では、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。The antiferroelectric liquid crystal has a first or second ferroelectric phase or an antiferroelectric phase in each range with the first and second threshold values as boundaries 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. The memory property of the alignment state of the antiferroelectric liquid crystal is determined by the voltage at which the liquid crystal undergoes a phase transition from the first or second ferroelectric phase to the antiferroelectric phase and the antiferroelectric phase to the first or second ferroelectric phase. It is determined by the voltage difference between the phase transition voltage and the voltage. The larger this voltage difference, the higher the memory property of the alignment state. Therefore, in the conventional antiferroelectric liquid crystal display element,
As the antiferroelectric liquid crystal, the liquid crystal having a large voltage difference is used. However, in the conventional anti-ferroelectric liquid crystal display device using the anti-ferroelectric liquid crystal having a high memory property, it is almost impossible to control the display gradation, and the gradation display cannot be realized.
【００１２】[0012]
【発明が解決しようとする課題】この発明は、上記実状
に鑑みてなされたもので、簡単な構成で且つ階調表示が
可能な強誘電性液晶表示装置及びその駆動方法を提供す
ることを目的とする。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a ferroelectric liquid crystal display device having a simple structure and capable of gradation display, and a driving method thereof. And
【００１３】[0013]
【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の観点にかかる強誘電性液晶表示装
置は、画素電極が形成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
２つの基板間に配置された強誘電性を持つ液晶と、前記
２つの基板を挟む位置に配置された一対の偏光板と、を
有し、前記画素電極と前記対向電極との間に印加される
極性の異なる電圧の絶対値の変化に対応して実質的に等
しい光学的変化を示す強誘電性液晶表示素子と、表示画
像に対応する信号を受け、この信号に対応する絶対値を
持ち且つ極性が異なる電圧を前記画素電極と前記対向電
極間に複数のフレームにわたって交互に印加する駆動手
段と、を備えたことを特徴とする。In order to achieve the above object, in a ferroelectric liquid crystal display device according to a first aspect of the present invention, one substrate on which a pixel electrode is formed is opposed to the pixel electrode. The liquid crystal display device having the other substrate on which the counter electrode is formed, the ferroelectric liquid crystal disposed between the two substrates, and the pair of polarizing plates disposed at a position sandwiching the two substrates, A ferroelectric liquid crystal display element that exhibits substantially the same optical change corresponding to a change in absolute value of voltages having different polarities applied between the pixel electrode and the counter electrode, and a signal corresponding to a display image are displayed. And driving means for alternately applying a voltage having an absolute value corresponding to this signal and having a different polarity between the pixel electrode and the counter electrode over a plurality of frames.
【００１４】この発明の第２の観点にかかる強誘電性液
晶表示素子の駆動方法は、画素電極と画素電極に接続さ
れた薄膜トランジスタ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、これらの基板の間に配置され、層
構造をもち、前記画素電極と対向電極間に印加された電
圧に応じて液晶分子が第１の方向にほぼ配列した第１の
配向状態と、液晶分子が第２の方向にぼぼ配列した第２
の配向状態と、液晶分子の平均的な配列方向が前記第１
の方向と第２の方向の間の任意の方向となる中間の配向
状態にそれぞれ配向する強誘電性液晶と、前記一方の基
板側に配置され、前記強誘電性液晶層の法線と実質的に
平行な方向に光学軸が設定された一方の偏光板と、前記
他方の基板側に配置され、前記一方の偏光板の光学軸に
直交又は平行に光学軸が設定された他方の偏光板と、を
備えた強誘電性液晶表示素子の駆動方法において、絶対
値が表示階調に対応し、極性が異なる電圧をフレーム毎
に前記アクティブ素子を介して前記画素電極に印加す
る、ことを特徴とする。According to a second aspect of the present invention, there is provided a method for driving a ferroelectric liquid crystal display device, wherein a pixel electrode and one substrate on which a plurality of thin film transistors connected to the pixel electrode are arranged in a matrix form and the pixel electrode. It is arranged between the other substrate on which the opposing electrode is formed and between these substrates, has a layered structure, and has liquid crystal molecules in a first direction according to a voltage applied between the pixel electrode and the opposing electrode. A substantially aligned first alignment state and a second alignment state in which liquid crystal molecules are aligned in a second direction.
And the average alignment direction of liquid crystal molecules is the first
Of the ferroelectric liquid crystal that is oriented in an intermediate alignment state that is an arbitrary direction between the first direction and the second direction, and is disposed on the one substrate side, and is substantially the same as the normal line of the ferroelectric liquid crystal layer. One polarizing plate having an optical axis set in a direction parallel to, and the other polarizing plate arranged on the other substrate side and having an optical axis orthogonal or parallel to the optical axis of the one polarizing plate, In the method for driving a ferroelectric liquid crystal display element, the voltage is applied to the pixel electrode via the active element for each frame, the voltage having an absolute value corresponding to a display gradation and different polarities. To do.
【００１５】[0015]
【作用】上記構成によれば、画素電極と対向電極との間
に印加される極性が異なる電圧の絶対値の変化に対応し
て実質的に等しい光学的変化を示す強誘電性液晶表示素
子、即ち、一方の偏光板の光学軸が第１と第２の方向の
中間の方向に設定され、他方の偏光板の光学軸が一方の
偏光板の光学軸に直交又は平行するように配置された強
誘電性液晶表示素子を用いている。従って、絶対値が等
しく極性が異なる電圧に対して、実質的に同一の階調が
表示される。そして、この液晶に極性が異なり且つ絶対
値がほぼ等しい電圧を複数のフレームにわたって交互に
印加しているので、この複数フレームの平均的な明るさ
により１つの階調を表示することができ、極性が異なる
印加電圧に対する光学的特性が異なっていても、良好な
階調表示を行うことができる。また、各選択期間に表示
階調に応じた電圧の１つのパルスを印加することにより
任意の階調表示を行うことができる。さらに、液晶に印
加される電荷の片寄りをなくし、表示の焼き付き現象等
を防止できる。従って、この発明によれば、簡単な構成
で階調表示が可能となる。According to the above structure, a ferroelectric liquid crystal display element exhibiting substantially equal optical changes corresponding to changes in absolute values of voltages having different polarities applied between the pixel electrode and the counter electrode, That is, the optical axis of one of the polarizing plates is set to an intermediate direction between the first and second directions, and the optical axis of the other polarizing plate is arranged so as to be orthogonal or parallel to the optical axis of the one polarizing plate. A ferroelectric liquid crystal display element is used. Therefore, substantially the same gradation is displayed for voltages having the same absolute value but different polarities. Since voltages having different polarities and substantially equal absolute values are alternately applied to the liquid crystal over a plurality of frames, one gradation can be displayed by the average brightness of the plurality of frames, and the polarities can be displayed. Even if the optical characteristics for different applied voltages are different, good gradation display can be performed. Further, by applying one pulse of the voltage corresponding to the display gradation in each selection period, it is possible to perform arbitrary gradation display. Further, it is possible to eliminate the bias of the electric charges applied to the liquid crystal and prevent the image sticking phenomenon of the display. Therefore, according to the present invention, gradation display is possible with a simple configuration.
【００１６】[0016]
【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。 （第１実施例）まず、この実施例にかかる強誘電性液晶
表示素子の構成を説明する。図１は強誘電性液晶表示素
子の断面図、図２は強誘電性液晶表示素子の画素電極と
アクティブ素子を形成した透明基板の平面図である。こ
の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）
１、２を有する。図１において下側の透明基板（以下、
下基板）１には、ＩＴＯ等の透明導電材料から構成され
た画素電極３と画素電極３にソースが接続された薄膜ト
ランジス（以下、ＴＦＴ）４とがマトリクス状に形成さ
れている。Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) First, the structure of a ferroelectric liquid crystal display device according to this embodiment will be described. FIG. 1 is a sectional view of a ferroelectric liquid crystal display element, and FIG. 2 is a plan view of a transparent substrate on which pixel electrodes and active elements of the ferroelectric liquid crystal display element are formed. This ferroelectric liquid crystal display element is of an active matrix type and has a pair of transparent substrates (for example, glass substrates).
Have one and two. In FIG. 1, the lower transparent substrate (hereinafter,
On a lower substrate 1, pixel electrodes 3 made of a transparent conductive material such as ITO and thin film transistors (hereinafter, referred to as TFTs) 4 having sources connected to the pixel electrodes 3 are formed in a matrix.
【００１７】図２に示すように、画素電極３の行間にゲ
ートライン（走査ライン）５が配線され、画素電極３の
列間にデータライン（階調信号ライン）６が配線されて
いる。各ＦＴＦ４のゲート電極は対応するゲートライン
５に接続され、ドレイン電極は対応するデータライン６
に接続されている。ゲートライン５は、端部５ａを介し
て行（走査ドライバ）ドライバ２１に接続され、データ
ライン６は端部６ａを介して列ドライバ（信号ドライ
バ）２２に接続される。行ドライバ２１は、後述するゲ
ート電圧を印加して、ゲートライン５をスキャンする。
一方、列ドライバ２２は、表示信号（階調信号）を受
け、データライン６に表示信号に対応するデータ信号を
印加する。As shown in FIG. 2, gate lines (scanning lines) 5 are arranged between the rows of the pixel electrodes 3, and data lines (gradation signal lines) 6 are arranged between the columns of the pixel electrodes 3. The gate electrode of each FTF 4 is connected to the corresponding gate line 5, and the drain electrode is corresponding to the data line 6
It is connected to the. The gate line 5 is connected to the row (scan driver) driver 21 via the end 5a, and the data line 6 is connected to the column driver (signal driver) 22 via the end 6a. The row driver 21 scans the gate line 5 by applying a gate voltage described later.
On the other hand, the column driver 22 receives the display signal (gradation signal) and applies the data signal corresponding to the display signal to the data line 6.
【００１８】図１において、上側の透明基板（以下、上
基板）２には、下基板１の各画素電極３と対向し、基準
電圧Ｖ０が印加されている対向電極７が形成されてい
る。下基板１と上基板２の電極形成面には、それぞれ配
向膜８、９が設けられている。配向膜８、９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
の対向面にはラビングによる配向処理が施されている。In FIG. 1, an upper transparent substrate (hereinafter, upper substrate) 2 is provided with a counter electrode 7 facing each pixel electrode 3 of the lower substrate 1 and to which a reference voltage V0 is applied. Alignment films 8 and 9 are provided on the electrode formation surfaces of the lower substrate 1 and the upper substrate 2, respectively. The alignment films 8 and 9 are horizontal alignment films made of an organic polymer compound such as polyimide, and their facing surfaces are subjected to an alignment treatment by rubbing.
【００１９】下基板１と上基板２は、その外周縁部にお
いて枠状のシール材１０を介して接着されている。基板
１、２とシール材１０で囲まれた領域には液晶１１が封
入されている。液晶１１は、カイラルスメクティックＣ
相の螺旋ピッチが両基板１、２の間隔より小さく、か
つ、配向状態のメモリ性を有さない強誘電性液晶であ
る。液晶１１は、螺旋ピッチが、可視光帯域の波長であ
る７００nm〜４００nm以下（例えば、４００nm〜３００
nm）であり、自発分極が大きく、コーンアングルが約２
７度ないし４５゜（望ましくは、２７゜ないし３０゜）
の強誘電性液晶組成物からなる。なお、図１において、
符号１２は両基板１、２の間隔を規制する透明なギャッ
プ材を示し、ギャップ材１２は液晶封入領域内に点在状
態で配置されている。The lower substrate 1 and the upper substrate 2 are adhered to each other at their outer peripheral edges via a frame-shaped sealing material 10. A liquid crystal 11 is enclosed in a region surrounded by the substrates 1 and 2 and the sealing material 10. The liquid crystal 11 is a chiral smectic C
It is a ferroelectric liquid crystal in which the spiral pitch of the phase is smaller than the distance between the substrates 1 and 2 and does not have the memory property of the alignment state. The liquid crystal 11 has a spiral pitch of 700 nm to 400 nm or less, which is a wavelength in the visible light band (for example, 400 nm to 300 nm).
nm), the spontaneous polarization is large, and the cone angle is about 2
7 degrees to 45 degrees (desirably 27 degrees to 30 degrees)
Of the ferroelectric liquid crystal composition. In addition, in FIG.
Reference numeral 12 indicates a transparent gap material that regulates the distance between the substrates 1 and 2, and the gap material 12 is arranged in a scattered state in the liquid crystal enclosing region.
【００２０】液晶１１は、カイラルスメクティックＣ相
が有する層構造の層の法線を配向膜８、９の配向処理方
向に向けて均一な層構造を形成する。また、その螺旋ピ
ッチが基板間隔より小さいため、螺旋構造をもった状態
で基板１、２間に封入されている。画素電極３と対向電
極７との間に絶対値が十分大きい電圧を印加したとき、
液晶１１は印加電圧の極性に応じて、液晶分子の平均的
なダイレクタが第１の方向に配向する第１の配向状態と
液晶分子の平均的なダイレクタが第２の方向に配向する
第２の配向状態のいずれかの状態に設定される。また、
絶対値が液晶分子を第１又は第２の配向状態に配向させ
る電圧より低い電圧を画素電極３と対向電極７間に印加
したとき、液晶１１の分子配列の螺旋が歪み、液晶１１
の平均的なダイレクタが第１の方向と第２の方向の間の
方向に配向する中間配向状態となる。The liquid crystal 11 forms a uniform layer structure by directing the normal of the layer structure of the chiral smectic C phase toward the alignment treatment direction of the alignment films 8 and 9. Further, since the spiral pitch is smaller than the substrate interval, the spiral pitch is enclosed between the substrates 1 and 2. When a voltage having a sufficiently large absolute value is applied between the pixel electrode 3 and the counter electrode 7,
The liquid crystal 11 has a first alignment state in which an average director of liquid crystal molecules is aligned in a first direction and a second alignment state in which an average director of liquid crystal molecules is aligned in a second direction, depending on the polarity of an applied voltage. It is set to one of the orientation states. Also,
When a voltage whose absolute value is lower than the voltage for aligning the liquid crystal molecules in the first or second alignment state is applied between the pixel electrode 3 and the counter electrode 7, the spiral of the molecular alignment of the liquid crystal 11 is distorted and the liquid crystal 11
The average director of is in an intermediate alignment state in which it is oriented in a direction between the first direction and the second direction.
【００２１】液晶表示素子の上下には、一対の偏光板１
３、１４が配置されている。偏光板１３、１４の透過軸
と液晶１１の液晶分子の配向方向との関係を図３を参照
して説明する。図３において、符号１１Ａ、１１Ｂは、
液晶１１の第１と第２の配向状態における液晶分子の配
向方向（平均的なダイレクタの方向）を示し、符号１３
Ａ、１４Ａは図１において下側の偏光板１３、上側の偏
光板１４の透過軸の方向を示す。A pair of polarizing plates 1 is provided above and below the liquid crystal display element.
3, 14 are arranged. The relationship between the transmission axes of the polarizing plates 13 and 14 and the alignment direction of the liquid crystal molecules of the liquid crystal 11 will be described with reference to FIG. In FIG. 3, reference numerals 11A and 11B indicate
Reference numeral 13 indicates the alignment direction of liquid crystal molecules (average director direction) in the first and second alignment states of the liquid crystal 11.
A and 14A indicate the directions of the transmission axes of the lower polarizing plate 13 and the upper polarizing plate 14 in FIG.
【００２２】一方の極性でかつ絶対値が十分大きい電圧
を液晶１１に印加した時、液晶１１は、第１の配向状態
となり、液晶分子の平均的なデイレクタは一点鎖線で示
す第１の配向方向１１Ａに配向する。他方の極性でかつ
絶対値が十分大きい電圧を液晶１１に印加したとき、液
晶１１は第２の配向状態となり、液晶分子の平均的なダ
イレクタは２点鎖線で示す第２の配向方向１１Ｂに配向
する。一方、印加電圧が０のとき、液晶分子の平均的な
ダイレクタは液晶のスメクティック相の層の法線方向、
即ち、第１と第２の配向方向１１Ａと１１Ｂの中間の方
向１１Ｃとなる。When a voltage having one polarity and a sufficiently large absolute value is applied to the liquid crystal 11, the liquid crystal 11 is in the first alignment state, and the average director of the liquid crystal molecules is the first alignment direction indicated by the chain line. Oriented to 11A. When a voltage having the other polarity and a sufficiently large absolute value is applied to the liquid crystal 11, the liquid crystal 11 is in the second alignment state, and the average director of the liquid crystal molecules is aligned in the second alignment direction 11B indicated by the chain double-dashed line. To do. On the other hand, when the applied voltage is 0, the average director of the liquid crystal molecules is the normal direction of the smectic phase layer of the liquid crystal,
That is, the direction 11C is intermediate between the first and second alignment directions 11A and 11B.
【００２３】第１の配向方向１１Ａと第２の配向方向１
１Ｂとのずれ角θは、液晶１１の種類によって異なる
が、２５゜〜４５゜に選定され、望ましくは２７゜〜４
５゜である。偏光板１３、１４のうち、一方の偏光板、
例えば、上偏光板１４の透過軸１４Ａは、液晶１１のス
メクティック相の層の法線方向とほぼ平行に設定されて
いる。下偏光板１３の透過軸１３Ａは、上偏光板１４の
透過軸１４Ａとほぼ直交している。First orientation direction 11A and second orientation direction 1
The deviation angle θ from 1B varies depending on the type of the liquid crystal 11, but is selected to be 25 ° to 45 °, preferably 27 ° to 4 °.
It is 5 °. One of the polarizing plates 13 and 14,
For example, the transmission axis 14A of the upper polarizing plate 14 is set substantially parallel to the normal direction of the smectic phase layer of the liquid crystal 11. The transmission axis 13A of the lower polarizing plate 13 is substantially orthogonal to the transmission axis 14A of the upper polarizing plate 14.
【００２４】図３に示すように偏光板１３、１４の透過
軸を設定した強誘電性液晶表示素子は、液晶分子を第１
又は第２の配向方向１１Ａ、１１Ｂに配向させた第１又
は第２の配向状態の時に透過率が最も高く（表示が最も
明るく）なり、液晶分子を前記スメクティック相の層の
法線方向とほぼ平行な中間方向１１Ｃに配向させた時に
透過率が最も低く（表示が最も暗く）なる。より詳細に
説明すると、液晶分子のダイレクタが第１又は第２の配
向方向１１Ａ、１１Ｂを向いた状態では、入射側偏光板
（ポーラライザ）を通過した直線偏光は液晶１１の偏光
作用により非直線偏光となる。そして、液晶層を通過し
た光のうち出射側偏光板（アナライザ）の透過軸と平行
な成分がアナライザを透過して出射し、表示は明るくな
る。一方、液晶分子のダイレクタが中間方向１１Ｃを向
いた状態では、入射側偏光板を通った直線偏光は液晶１
１の偏光作用をほとんど受けず、直線偏光のまま液晶層
を通過する。このため、液晶層を通過した光のほとんど
が出射側偏光板で吸収され、表示が暗くなる。In the ferroelectric liquid crystal display device in which the transmission axes of the polarizing plates 13 and 14 are set as shown in FIG.
Alternatively, the transmittance is highest (display is brightest) in the first or second alignment state in which the liquid crystal molecules are aligned in the second alignment directions 11A and 11B, and the liquid crystal molecules are almost in the normal direction of the smectic phase layer. When oriented in the parallel intermediate direction 11C, the transmittance is the lowest (display is darkest). More specifically, when the director of the liquid crystal molecules is oriented in the first or second alignment direction 11A, 11B, the linearly polarized light that has passed through the incident side polarization plate (polarizer) is non-linearly polarized light by the polarization action of the liquid crystal 11. Becomes Then, of the light that has passed through the liquid crystal layer, a component parallel to the transmission axis of the emission side polarization plate (analyzer) is transmitted through the analyzer and emitted, and the display becomes bright. On the other hand, when the director of the liquid crystal molecules is oriented in the intermediate direction 11C, the linearly polarized light passing through the incident side polarization plate is the liquid crystal 1
It receives almost no polarization effect of 1 and passes through the liquid crystal layer as it is as linearly polarized light. Therefore, most of the light that has passed through the liquid crystal layer is absorbed by the emission side polarization plate, and the display becomes dark.
【００２５】液晶１１のダイレクタの平均的な方向は、
印加電圧の極性と電圧値（絶対値）に応じて、配向方向
１１Ａと１１Ｂの間で連続的に変化する。このため、こ
の強誘電性液晶表示素子の透過率は連続的に変化可能で
ある。The average direction of the director of the liquid crystal 11 is
It continuously changes between the alignment directions 11A and 11B according to the polarity of the applied voltage and the voltage value (absolute value). Therefore, the transmittance of this ferroelectric liquid crystal display element can be continuously changed.
【００２６】次に、液晶１１の特性について説明する。
偏光板１３、１４を図３に示すように配置した場合にお
いては、液晶１１（電極３と７間）に電圧を印加しない
時の透過率が最も低くなり、印加電圧の絶対値が大きく
なるに従って、透過率が上昇する。この実施例において
は、図４（Ａ）に示すように、周期が比較的長い（０．
１Ｈｚ程度）の三角波の電圧を印加した時にその光学応
答特性が図４（Ａ）に示すように、連続的に滑らかに変
化するものを使用する。また、光学応答特性のヒステリ
シスは小さい方が望ましい。Next, the characteristics of the liquid crystal 11 will be described.
When the polarizing plates 13 and 14 are arranged as shown in FIG. 3, the transmittance becomes the lowest when no voltage is applied to the liquid crystal 11 (between the electrodes 3 and 7), and the absolute value of the applied voltage increases as the applied voltage increases. , The transmittance increases. In this embodiment, as shown in FIG. 4A, the cycle is relatively long (0.
When a triangular wave voltage of about 1 Hz) is applied, an optical response characteristic of which continuously and smoothly changes as shown in FIG. 4 (A) is used. Further, it is desirable that the hysteresis of the optical response characteristic is small.
【００２７】また、図４（Ｂ）に示すように、光学応答
特性に明確な閾値、即ち、わずかな電圧の変化で透過率
が急激に変化する特性の強誘電性液晶は望ましくない。Further, as shown in FIG. 4B, a ferroelectric liquid crystal having a clear threshold value in the optical response characteristic, that is, a characteristic in which the transmittance changes abruptly with a slight change in voltage is not desirable.
【００２８】次に、上記構成の強誘電性液晶表示素子の
駆動方法を図５（Ａ）と（Ｂ）を参照して説明する。図
５（Ａ）は、行ドライバ２１が第１行のＴＦＴ４に接続
されたゲートライン５に印加するゲートパルスの波形を
示し、図５（Ｂ）は、列ドライバ２２がデータライン６
に印加するデータ信号の波形を示す。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 method of driving the ferroelectric liquid crystal display device having the above structure will be described with reference to FIGS. 5 (A) and 5 (B). FIG. 5A shows a waveform of a gate pulse applied to the gate line 5 connected to the TFT 4 of the first row by the row driver 21, and FIG.
3 shows a waveform of a data signal applied to. 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.
【００２９】図５（Ａ）、（Ｂ）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４５μ
秒である。この実施例においては、図５（Ｂ）に示すよ
うに、連続する２つのフレームの選択期間に、表示階調
に応じ、極性が反対で絶対値が同一の電圧値ＶＤ、−Ｖ
Ｄを有する駆動パルス（書き込みパルス）をデータライ
ン６に印加する。即ち、１つの表示データ（表示信号）
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にそれぞれ１つずつ印加
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。5A and 5B, TF represents one frame period, TS represents a selection period of pixels in the first row, and TO represents a non-selection period. Each selection period TS is, for example, about 45 μ
Seconds. In this embodiment, as shown in FIG. 5B, voltage values VD and −V having opposite polarities and the same absolute value are selected according to the display gradation during the selection period of two consecutive frames.
A drive pulse (writing pulse) having D is applied to the data line 6. That is, one display data (display signal)
With respect to, the two drive pulses having the voltage values of + VD and -VD are applied one each in each selection period of the 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.
【００３０】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（図４（Ａ）では、Ｖsat）よりも若干低い値とし
て、Ｖ０乃至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, and the maximum value Vmax is set to a value slightly lower than the voltage at which saturation of the transmittance occurs (Vsat in FIG. 4A), and V0 to Vmax are set. The write voltage VD is controlled within the range.
【００３１】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がゲートパルスによりオンしているＴＦＴ４を
介して画素電極３に印加される。ゲートパルスがオフ
し、非選択期間ＴＯになると、ＴＦＴ４がオフ状態にな
り、書き込み電圧ＶＤに応じた電圧が画素電極３と対向
電極７とその間の液晶１１とで形成される容量（画素容
量）に保持される。このため、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、
即ち、書き込み電圧ＶＤに対応した値に維持される。When the ferroelectric liquid crystal display element is driven by using the gate signal and the data signal having the above waveforms,
In the selection period TS of each row, the drive pulse voltage (writing voltage) VD is applied to the pixel electrode 3 via the TFT 4 which is turned on by the gate pulse. When the gate pulse is turned off and the non-selection period TO is entered, the TFT 4 is turned off and a voltage (pixel capacity) corresponding to the write voltage VD is formed by the pixel electrode 3, the counter electrode 7 and the liquid crystal 11 between them. Held in. Therefore, during the non-selection period TO, the transmittance of the pixel has a value corresponding to the holding voltage of the pixel capacitance,
That is, the value is maintained at the value corresponding to the write voltage VD.
【００３２】この実施例では、液晶１１として印加電圧
の変化に対する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
性の電圧を印加しているので、正負の電圧に対する光学
特性が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 liquid crystal 11 whose transmittance changes continuously with respect to the change of the applied voltage 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 is controlled by the absolute value of the writing voltage VD, so that clear gradation display can be realized. Further, since voltages of positive and negative opposite polarities for one pixel data are applied by two consecutive frames, even if the optical characteristics for positive and negative voltages are different, it is observed as an average value of these optical changes. It is possible to perform clear gradation display even if there is a difference in optical characteristics with respect to positive / negative and reverse polarity voltages.
【００３３】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を各画素（画素電極）に印加す
るので、液晶１１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液晶の劣化を
生ずることもない。Further, in two consecutive frames, voltages having opposite polarities and equal absolute values are applied to each pixel (pixel electrode), so that the DC voltage component is not biasedly applied to the liquid crystal 11. Therefore, the display burn-in phenomenon and the deterioration of the liquid crystal do not occur.
【００３４】具体例１ 図６は液晶としてＩ−ＳA転移温度が６２．５℃、ＳA−
ＳC*転移温度が６１．２℃で、且つ、らせんピッチが
０．１５μｍのＤＨＦ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
選択期間を６０μＳとし、図５（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まで
０．５Ｖ単位で上昇させ、その後、低下させた場合の印
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 1 FIG. 6 shows a liquid crystal having an I-SA transition temperature of 62.5 ° C. and an SA-
Using DHF liquid crystal with SC * transition temperature of 61.2 ° C and helical pitch of 0.15 μm, the alignment treatment direction and the transmission axis direction of the polarizing plate are set as shown in FIG. The period is set to 60 μS, the drive pulses having the same absolute value as shown in FIG. 5B have different polarities in the two frames, and the write voltage is increased from 0 V to 10 V in 0.5 V units, and then, , Shows the relationship between the applied voltage and the transmittance when it is lowered. As is clear from this graph, according to this driving method, by changing the writing voltage, the transmittance changes continuously, and further, the display gradation is almost uniquely determined according to the writing voltage, and Key display becomes possible.
【００３５】なお、液晶１１（電極３と７の間）に逆極
性で絶対値が同一の電圧を印加した場合、その透過率は
若干異なり、完全に同一ではない。従って、表示画像の
ちらつき（フリッカ）を防止するため、フレーム期間Ｔ
Ｆは１／３０秒以下に設定することが望ましい。When liquid crystal 11 (between electrodes 3 and 7) is applied with a voltage of opposite polarity and the same absolute value, the transmissivities thereof are slightly different and are not completely the same. Therefore, in order to prevent flicker of the display image, the frame period T
It is desirable to set F to 1/30 seconds or less.
【００３６】（第２実施例）第１実施例では、強誘電性
液晶１１としてＤＨＦ液晶を用いたが、液晶１１として
ＳＢＦ液晶を使用してもよい。ＳＢＦ液晶は、カイラル
スメクティック相の螺旋ピッチが両基板１、２の間隔よ
り小さく、かつ、双安定性を有する強誘電性液晶であ
る。ＳＢＦ液晶は、螺旋ピッチが、可視光帯域の波長で
ある７００nm〜４００nm以下（例えば、４００nm〜３０
０nm）であり、自発分極が大きく、コーンアングルが大
きい（例えば、約２７度ないし４５゜（望ましくは、２
７゜ないし３０゜））の強誘電性液晶組成物からなる。(Second Embodiment) In the first embodiment, the DHF liquid crystal is used as the ferroelectric liquid crystal 11, but the SBF liquid crystal may be used as the liquid crystal 11. The SBF liquid crystal is a ferroelectric liquid crystal in which the spiral pitch of the chiral smectic phase is smaller than the distance between the substrates 1 and 2 and which has bistability. The SBF liquid crystal has a helical pitch of 700 nm to 400 nm or less, which is a wavelength in the visible light band (for example, 400 nm to 30 nm).
0 nm), the spontaneous polarization is large, and the cone angle is large (for example, about 27 degrees to 45 degrees (desirably 2 degrees).
7 ° to 30 °)) ferroelectric liquid crystal composition.
【００３７】ＳＢＦ液晶１１は、その螺旋ピッチが基板
間隔より小さいため、螺旋構造をもった状態で基板１、
２間に封入されている。ＳＢＦ液晶を使用する場合の偏
光板１３、１４の透過軸とＳＢＦ液晶１１の液晶分子の
配向方向との関係は第１実施例のそれと同一である。即
ち、一方の極性でかつ絶対値が十分大きな値の電圧を印
加した時、ＳＢＦ液晶１１は、第１の安定状態となり、
液晶分子のダイレクタは図３（Ｂ）に実線で示す第１の
配向方向１１Ａに配向する。他方の極性でかつ絶対値が
十分大きな値の電圧を印加したとき、ＳＢＦ液晶１１は
第２の安定状態となり、液晶分子は図３（Ｂ）に破線で
示す第２の配向方向に配向する。第１の配向方向１１Ａ
と第２の配向方向１１Ｂとのずれ角θは、ＳＢＦ液晶１
１の種類によって異なるが、２５゜〜４５゜に選定さ
れ、望ましくは２７゜〜４５゜である。Since the SBF liquid crystal 11 has a spiral pitch smaller than the distance between the substrates, the SBF liquid crystal 11 has a spiral structure.
It is enclosed between two. When the SBF liquid crystal is used, the relationship between the transmission axes of the polarizing plates 13 and 14 and the alignment direction of the liquid crystal molecules of the SBF liquid crystal 11 is the same as that of the first embodiment. That is, when a voltage having one polarity and a sufficiently large absolute value is applied, the SBF liquid crystal 11 is in the first stable state,
The director of the liquid crystal molecules is aligned in the first alignment direction 11A shown by the solid line in FIG. When a voltage of the other polarity and a value whose absolute value is sufficiently large is applied, the SBF liquid crystal 11 enters the second stable state, and the liquid crystal molecules are aligned in the second alignment direction shown by the broken line in FIG. 3B. First orientation direction 11A
The deviation angle θ between the second alignment direction 11B and the second alignment direction 11B is
Although it varies depending on the type, it is selected from 25 ° to 45 °, preferably from 27 ° to 45 °.
【００３８】一方の偏光板、例えば、上偏光板１４の透
過軸１４Ａは、図３に示すように配向方向１１Ａ、１１
Ｂの中間方向１１Ｃとほぼ平行になっている。また、下
偏光板１３の透過軸１３Ａは、上偏光板１４の透過軸１
４Ａとほぼ直交している。図３に示すように偏光板１
３、１４の透過軸１３Ａ、１４Ａを設定した液晶表示素
子は、第１実施例と同様に、液晶分子を第１の配向方向
１１Ａ又は第２の配向方向１１Ｂに配向させた時に透過
率が最も高くなり、液晶分子を中間方向方向１１Ｃに配
向させた時に透過率が最も低くなる。The transmission axis 14A of one of the polarizing plates, for example, the upper polarizing plate 14, has alignment directions 11A and 11A as shown in FIG.
It is substantially parallel to the intermediate direction 11C of B. The transmission axis 13 A of the lower polarizing plate 13 is the transmission axis 1 of the upper polarizing plate 14.
It is almost orthogonal to 4A. Polarizing plate 1 as shown in FIG.
The liquid crystal display element in which the transmission axes 13A and 14A of 3 and 14 are set has the highest transmittance when the liquid crystal molecules are aligned in the first alignment direction 11A or the second alignment direction 11B, as in the first embodiment. When the liquid crystal molecules are oriented in the intermediate direction 11C, the transmittance becomes the lowest.
【００３９】なお、この実施例の強誘電性液晶表示素子
のその他の構成は、第１実施例の構成と同一である。The other structure of the ferroelectric liquid crystal display device of this embodiment is the same as that of the first embodiment.
【００４０】第２実施例の構成においても、映像信号に
応答して、連続する２つのフレームに極性が異なり、絶
対値が同一の書き込み電圧を印加して、液晶表示素子を
駆動することにより、駆動パルスの絶対値に対応する階
調の画像を表示できる。Also in the configuration of the second embodiment, in response to a video signal, a write voltage having different polarities and the same absolute value is applied to two consecutive frames to drive the liquid crystal display element. It is possible to display a gradation image corresponding to the absolute value of the drive pulse.
【００４１】（第３実施例）第１、第２実施例では、液
晶１１として強誘電性液晶であるＤＨＦ液晶とＳＢＦ液
晶を使用したが、反強誘電性液晶（以下、ＡＦＬＣ）を
使用してもよい。ＡＦＬＣは、その螺旋ピッチが基板間
隔より大きいため、螺旋構造を消失した状態で基板１、
２間に封入されている。一方の極性でかつあるしきい値
電圧（ＯＮしきい値電圧）以上の電圧が印加されたと
き、液晶分子の平均的なダイレクタは第１の方向１１Ａ
に配向し、極性が逆でかつ絶対値が前記ＯＮしきい値電
圧以上の電圧を印加した時に、平均的なダイレクタは二
点鎖線で示した第２の方向１１Ｂに配向し、前記ＯＮし
きい値電圧より低い他のしきい値電圧（ＯＦＦしきい値
電圧）以下の電圧を印加した時に、平均的なダイレクタ
が第３の方向１１Ｃに向くように配向する。また、ＯＮ
しきい値電圧とＯＦＦしきい値電圧の間の電圧を印加し
た時、平均的なダイレクタが第１の方向１１Ａと第３の
方向１１Ｃの間、又は、第２の方向１１Ｂと第３の方向
１１Ｃの間となるように配向し、光学的中間状態とな
る。(Third Embodiment) In the first and second embodiments, the DHF liquid crystal and the SBF liquid crystal which are the ferroelectric liquid crystal are used as the liquid crystal 11, but the anti-ferroelectric liquid crystal (hereinafter, AFLC) is used. May be. Since the spiral pitch of AFLC is larger than the distance between the substrates, the substrate 1 in the state where the spiral structure disappears,
It is enclosed between two. When a voltage having one polarity and a certain threshold voltage (ON threshold voltage) or more is applied, the average director of the liquid crystal molecules is in the first direction 11A.
When a voltage having a polarity opposite to that of the ON threshold voltage is applied, the average director is oriented in the second direction 11B indicated by the chain double-dashed line, and the ON threshold is When a voltage equal to or lower than another threshold voltage (OFF threshold voltage) lower than the value voltage is applied, the average director is oriented so as to face the third direction 11C. Also ON
When a voltage between the threshold voltage and the OFF threshold voltage is applied, the average director is between the first direction 11A and the third direction 11C or the second direction 11B and the third direction. It is oriented so as to be between 11C, and is in an optical intermediate state.
【００４２】一対の偏光板１３、１４の透過軸は、第１
実施例と同様に、図３に示すように配置される。The transmission axes of the pair of polarizing plates 13 and 14 are the first
Similar to the embodiment, they are arranged as shown in FIG.
【００４３】この実施例では、例えば、次の３つのタイ
プの反強誘電性液晶を使用できる。 （１） 印加電圧が０Ｖ近傍の非常に狭い範囲でのみ反
強誘電相を示し、光学応答の特性カーブが急峻であり、
反強誘電相を示す領域に平坦な領域がほとんど存在しな
い液晶。図７はこの種の反強誘電性液晶の光学応答特性
の一例を示す。この光学応答特性は一対の偏光板を図３
に示すように配置し、０．１Ｈｚ程度の十分低周波の三
角波電圧を印加して得られたものである。この反強誘電
性液晶は、±０．５Ｖ程度の非常に狭い印加電圧領域に
おいてのみ、反強誘電相を示す特性を有し、特性カーブ
が急峻であり、反強誘電相を示す領域に平坦な領域がほ
とんど存在しない。この種の反強誘電性液晶は、反強誘
電−強誘電相転移前駆現象を呈する印加電圧の範囲が広
いため、印加電圧に応じて無数の中間的光学状態を有
し、その光学応答特性に明確な閾値が存在せず、この発
明の駆動方法に適している。In this embodiment, for example, the following three types of antiferroelectric liquid crystals can be used. (1) The antiferroelectric phase is exhibited only in a very narrow range where the applied voltage is near 0 V, and the characteristic curve of the optical response is steep,
A liquid crystal with almost no flat region in the region showing the antiferroelectric phase. FIG. 7 shows an example of optical response characteristics of this type of antiferroelectric liquid crystal. This optical response characteristic is shown in FIG.
It is obtained by applying the triangular wave voltage of sufficiently low frequency of about 0.1 Hz as shown in FIG. This antiferroelectric liquid crystal has a characteristic that it exhibits an antiferroelectric phase only in a very narrow applied voltage region of about ± 0.5 V, has a steep characteristic curve, and is flat in a region that exhibits an antiferroelectric phase. There is almost no real area. Since this type of antiferroelectric liquid crystal has a wide range of applied voltage exhibiting the antiferroelectric-ferroelectric phase transition precursor phenomenon, it has innumerable intermediate optical states depending on the applied voltage, and its optical response characteristics Since there is no clear threshold value, it is suitable for the driving method of the present invention.
【００４４】（２） 印加電圧０Ｖでは、平均的分子長
軸方向が層の法線方向に揃わず、印加電圧０Ｖ以外の２
つの電圧値で平均的分子長軸方向が、層の法線方向に揃
い、透過率が最小となる反強誘電性液晶。図８はこの種
の反強誘電性液晶の光学応答特性の一例を示す。この光
学応答特性も一対の偏光板を図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印加して得
られたものである。この特性を有する辺強誘電性液晶
は、印加電圧０Ｖでは、平均的分子長軸方向が層法線方
向に揃わず、印加電圧０Ｖ以外の２つの電圧値で平均的
分子長軸方向が、層法線方向に揃い、透過率が最小とな
る。即ち、暗状態になる電圧領域が２つに分離してお
り、印加電圧が０Ｖ付近に平坦な部分が存在しない。こ
の種の反強誘電性液晶は、反強誘電−強誘電相転移前駆
現象を呈する印加電圧の範囲が広いため、印加電圧に応
じて無数の中間的光学状態を有し、その光学応答特性に
明確な閾値が存在せず、この発明の駆動方法に適してい
る。(2) When the applied voltage is 0V, the average long axis of the molecules are not aligned with the normal direction of the layer, and when the applied voltage is 0V, 2
An antiferroelectric liquid crystal in which the average long axis direction of molecules is aligned with the normal direction of the layer at two voltage values, and the transmittance is minimized. FIG. 8 shows an example of the optical response characteristics of this type of antiferroelectric liquid crystal. This optical response characteristic also has a pair of polarizing plates arranged as shown in FIG.
It was obtained by applying a triangular wave voltage having a sufficiently low frequency of about 0.1 Hz. In the edge ferroelectric liquid crystal having this characteristic, the average molecular long axis direction is not aligned with the layer normal direction at the applied voltage of 0 V, and the average molecular long axis direction is at the two layers of the voltage value other than the applied voltage of 0 V. It is aligned in the normal direction and has the minimum transmittance. That is, the voltage region in the dark state is separated into two, and there is no flat portion near the applied voltage of 0V. Since this type of antiferroelectric liquid crystal has a wide range of applied voltage exhibiting the antiferroelectric-ferroelectric phase transition precursor phenomenon, it has innumerable intermediate optical states depending on the applied voltage, and its optical response characteristics Since there is no clear threshold value, it is suitable for the driving method of the present invention.
【００４５】第１及び第２の反強誘電性液晶は、コーン
アングルが３０゜から４５゜（望ましくは、３５゜以
上）と大きく、自発分極が約２００以上と大きく、さら
に、相シーケンスがＩ、ＳｍＡ（スメクティックＡ
相）、ＡＳｍＣ*（アンチ（反）スメクティックＣ*相）
と相転移する液晶である。The first and second antiferroelectric liquid crystals have a large cone angle of 30 ° to 45 ° (preferably 35 ° or more), a spontaneous polarization of about 200 or more, and a phase sequence I. , SmA (Smectic A
Phase), ASmC * (anti (anti) smectic C * phase)
It is a liquid crystal that undergoes a phase transition with.
【００４６】（３） 光学応答特性のヒステリシスの幅
が非常に小さい反強誘電性液晶 図９はこの種の反強誘電性液晶の光学応答特性の一例を
示す。この光学応答特性も一対の偏光板を図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
をこの反強誘電性液晶に印加して得られたものである。
この特性を有する反強誘電性液晶は、光学応答特性のヒ
ステリシスの幅が０．５Ｖ以下と、非常に狭い。この種
の反強誘電性液晶も、この発明の駆動方法に適してい
る。(3) Antiferroelectric liquid crystal having a very small hysteresis width of optical response characteristics FIG. 9 shows an example of the optical response characteristics of this type of antiferroelectric liquid crystal. This optical response characteristic is also obtained by arranging a pair of polarizing plates as shown in FIG. 3 and applying a triangular wave voltage having a sufficiently low frequency of about 0.1 Hz to the antiferroelectric liquid crystal.
The antiferroelectric liquid crystal having this characteristic has a very narrow hysteresis width of the optical response characteristic of 0.5 V or less. This type of antiferroelectric liquid crystal is also suitable for the driving method of the present invention.
【００４７】なお、第３実施例における液晶表示素子の
その他の構成は第１及び第２実施例と同一である。The other construction of the liquid crystal display element in the third embodiment is the same as that in the first and second embodiments.
【００４８】このような構成の反強誘電性液晶表示素子
においても、連続する２つのフレームに、極性が異な
り、表示階調に応じた絶対値を有する書き込み電圧を印
加することにより、第１実施例と同様に任意の階調画像
を表示できる。Also in the anti-ferroelectric liquid crystal display element having such a structure, by applying a write voltage having different polarities and an absolute value according to a display gradation to two consecutive frames, the first embodiment is applied. Similar to the example, any gradation image can be displayed.
【００４９】具体例２ 図１０は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、各選択期間を６０μＳとし、図
５（Ｂ）に示すように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まで０．５Ｖ単位で上
昇させ、その後、低下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
て表示階調が一義的に定まり、階調表示が可能になる。Concrete Example 2 FIG. 10 shows the alignment treatment direction and the transmission axis direction of the polarizing plate.
5B, each selection period is set to 60 μS, the two frames are set to have different polarities as shown in FIG. 5B, the write voltage is increased in units of 0.5 V from 0 V to 10 V, and then, The relationship between the applied voltage and the transmittance when the voltage is lowered is shown. As is clear from this graph, according to this driving method, by changing the write voltage,
The transmittance changes continuously, and the display gradation is uniquely determined according to the writing voltage, which enables gradation display.
【００５０】（第４実施例）次に、第１実施例にかかる
駆動方法を用いてテレビ映像等の動画を表示する液晶表
示素子の駆動回路について説明する。図１１はこの実施
例の液晶表示装置の構成を示す。(Fourth Embodiment) Next, a drive circuit of a liquid crystal display element for displaying a moving image such as a television image by using the drive method according to the first embodiment will be described. FIG. 11 shows the structure of the liquid crystal display device of this embodiment.
【００５１】外部より供給される通常のＮＴＳＣコンポ
ジット信号はＡ／Ｄ変換器５１により、デジタル信号に
変換され、分離回路５３に供給される。分離回路５３は
供給されたデジタル信号から同期信号、輝度信号、色相
信号を分離する。分離された同期信号は、クロック回路
６５と書き込み制御回路６７に供給される。また、輝度
信号と色相信号は復調／変換回路５５に供給される。A normal NTSC composite signal supplied from the outside is converted into a digital signal by the A / D converter 51 and supplied to the separation circuit 53. The separation circuit 53 separates the sync signal, the luminance signal, and the hue signal from the supplied digital signal. The separated sync signal is supplied to the clock circuit 65 and the write control circuit 67. Further, the luminance signal and the hue signal are supplied to the demodulation / conversion circuit 55.
【００５２】復調／変換回路５５は輝度信号と色相信号
から、ＲＧＢそれぞれの輝度信号を生成し、フレームメ
モリ５７の第１のポートに供給する。フレームメモリ５
７は、１画面（１フレーム）分の記憶容量を有するデュ
アルポートメモリから構成され、第１のポートに供給さ
れたＲＧＢ輝度信号を順次格納する。Ｄ／Ａ変換器５９
は、フレームメモリ５７の第２ポートから出力されたＲ
ＧＢ輝度信号を対応するアナログ輝度信号＋Ｒ、＋Ｇ、
＋Ｂに変換する。この際、反転輝度信号−Ｒ、−Ｇ、−
Ｂも出力する。セレクタ６１はＤ／Ａ変換器５９から供
給されるＲＧＢアナログ輝度信号＋Ｒ、＋Ｇ、＋Ｂと反
転輝度信号−Ｒ、−Ｇ、−Ｂを交互に選択して液晶表示
モジュールに６３に供給する。The demodulation / conversion circuit 55 generates RGB luminance signals from the luminance signal and the hue signal, and supplies them to the first port of the frame memory 57. Frame memory 5
Reference numeral 7 is composed of a dual port memory having a storage capacity for one screen (one frame), and sequentially stores the RGB luminance signals supplied to the first port. D / A converter 59
Is the R output from the second port of the frame memory 57.
Analog luminance signals corresponding to GB luminance signals + R, + G,
Convert to + B. At this time, the inverted luminance signals -R, -G,-
B is also output. The selector 61 alternately selects the RGB analog luminance signals + R, + G, + B and the inverted luminance signals -R, -G, -B supplied from the D / A converter 59 and supplies them to the liquid crystal display module 63.
【００５３】液晶表示モジュール６３は、図１〜図３に
示す構成を有する。但し、この実施例では、液晶表示素
子は、カラー画像を表示するもので、図１、図２の各画
素電極３の上にはＲ、Ｇ、又はＢのカラーフィルタが配
置されている。The liquid crystal display module 63 has the structure shown in FIGS. However, in this embodiment, the liquid crystal display element displays a color image, and an R, G, or B color filter is arranged on each pixel electrode 3 in FIGS.
【００５４】クロック回路６５は、Ａ／Ｄ変換器５１、
分離回路５３、復調／変換回路５５の動作を制御するた
めのクロック信号を生成し、これらに供給する。書き込
み制御回路６７は、分離回路５３からの同期信号に応答
し、フレームメモリ５７に書き込み制御信号を供給す
る。読み出し制御回路６９は、フレームメモリ５７に読
み出し制御信号を供給してフレームメモリ５７の記憶デ
ータを第２ポートに読み出し、Ｄ／Ａ変換器５９に変換
タイミング信号を供給してフレームメモリ５７から読み
出されたＲＧＢディジタル映像信号をＲＧＢアナログ映
像信号に変換し、セレクタ６１に選択制御信号を供給
し、液晶表示モジュール６３の行ドライバと列ドライバ
２２にタイミング制御信号を供給する。The clock circuit 65 includes the A / D converter 51,
A clock signal for controlling the operations of the separation circuit 53 and the demodulation / conversion circuit 55 is generated and supplied to these. The write control circuit 67 supplies a write control signal to the frame memory 57 in response to the synchronization signal from the separation circuit 53. The read control circuit 69 supplies a read control signal to the frame memory 57 to read the data stored in the frame memory 57 to the second port, and supplies a conversion timing signal to the D / A converter 59 to read from the frame memory 57. The converted RGB digital video signal is converted into an RGB analog video signal, a selection control signal is supplied to the selector 61, and a timing control signal is supplied to the row driver and the column driver 22 of the liquid crystal display module 63.
【００５５】次に、上記構成の表示装置の動作を図１２
のタイミングチャートを参照して説明する。Ａ／Ｄ変換
器５１には、図１２（Ａ）に示すＮＴＳＣコンポジット
信号が順次供給される。Ａ／Ｄ変換器５１は、クロック
回路６５から供給される変換タイミング信号に従って、
このＮＴＳＣコンポジット信号を順次デジタル信号に変
換し、分離回路５３に供給する。分離回路５３は、クロ
ック回路６５から供給されるタイミング信号に従って、
Ａ／Ｄ変換器５１から供給されるデジタル信号から同期
信号、輝度信号、色相信号を分離する。Next, the operation of the display device having the above configuration will be described with reference to FIG.
The timing chart will be described. The NTSC composite signal shown in FIG. 12A is sequentially supplied to the A / D converter 51. The A / D converter 51 follows the conversion timing signal supplied from the clock circuit 65.
The NTSC composite signal is sequentially converted into a digital signal and supplied to the separation circuit 53. The separation circuit 53 follows the timing signal supplied from the clock circuit 65.
The sync signal, the luminance signal, and the hue signal are separated from the digital signal supplied from the A / D converter 51.
【００５６】復調／変換回路５５は輝度信号と色相信号
から、Ｒ輝度信号、Ｇ輝度信号、Ｂ輝度信号を生成し、
フレームメモリ５７に供給する。書き込み制御回路６７
は、分離回路５３から供給される同期信号に従って、図
１２（Ｂ）に示すように、連続する２つのフレームの第
１のフレームで書き込みイネーブル信号をオン（アクテ
ィブ）とし、第２のフレームで書き込みイネーブル信号
をオフ（アンアクティブ）とする。The demodulation / conversion circuit 55 generates an R luminance signal, a G luminance signal, and a B luminance signal from the luminance signal and the hue signal,
It is supplied to the frame memory 57. Write control circuit 67
12B, the write enable signal is turned on (active) in the first frame of two consecutive frames according to the synchronization signal supplied from the separation circuit 53, and the writing is performed in the second frame. The enable signal is turned off (inactive).
【００５７】このため、フレームメモリ５７は、書き込
み制御回路６７からの書き込み制御信号に従って、供給
されたＲ、Ｇ、Ｂ輝度信号を、１フレーム毎に順次格納
する。従って、フレームメモリ５７は、例えば、図１２
の場合には、第Ｎフレーム、Ｎ＋２フレーム・・・のＲＧ
Ｂ輝度信号を順次格納する。Therefore, the frame memory 57 sequentially stores the supplied R, G, B luminance signals for each frame in accordance with the write control signal from the write control circuit 67. Therefore, the frame memory 57 is, for example, as shown in FIG.
, The RG of the Nth frame, the N + 2th frame ...
The B luminance signal is sequentially stored.
【００５８】フレームメモリ５７は、読み出し制御回路
６９からの図１２（Ｃ）に示す読み出しイネーブル信号
を含む制御信号に従って、記憶しているＲＧＢ輝度信号
を読み出し、Ｄ／Ａ変換器５９に供給する。Ｄ／Ａ変換
器５９は、フレームメモリ５７から読み出されたディジ
タルのＲＧＢ輝度信号を対応するＲＧＢアナログ輝度信
号＋Ｒ、＋Ｇ、＋Ｂとその反転輝度信号−Ｒ、−Ｇ、−
Ｂに変換する。セレクタ６１はＤ／Ａ変換器５９から供
給されるＲＧＢアナログ輝度信号＋Ｒ、＋Ｇ、＋Ｂと反
転輝度信号−Ｒ、−Ｇ、−Ｂを、図１２（Ｄ）に示す選
択切換信号に従って、順次選択して液晶表示モジュール
６３に供給する。従って、例えば、セレクタ６１は、第
Ｎフレーム、第Ｎ＋２フレーム・・・では、正極性のＲＧ
Ｂアナログ輝度信号＋Ｒ、＋Ｇ、＋Ｂを選択して出力
し、第Ｎ＋１フレーム、第Ｎ＋３フレーム・・・では、負
極性のＲＧＢ反転輝度信号−Ｒ、−Ｇ、−Ｂを出力す
る。The frame memory 57 reads the stored RGB luminance signal in accordance with a control signal including the read enable signal shown in FIG. 12C from the read control circuit 69 and supplies it to the D / A converter 59. The D / A converter 59 converts the digital RGB luminance signals read from the frame memory 57 into the corresponding RGB analog luminance signals + R, + G, + B and their inverted luminance signals -R, -G,-.
Convert to B. The selector 61 sequentially selects the RGB analog luminance signals + R, + G, + B and the inverted luminance signals -R, -G, -B supplied from the D / A converter 59 in accordance with the selection switching signal shown in FIG. And supplies it to the liquid crystal display module 63. Therefore, for example, in the Nth frame, the (N + 2) th frame, ...
B analog luminance signals + R, + G, + B are selected and output, and negative RGB inversion luminance signals -R, -G, -B are output in the (N + 1) th frame, the (N + 3) th frame, ....
【００５９】列ドライバ２２は、セレクタ６１から供給
されるＲＧＢアナログ輝度信号とその反転信号を順次サ
ンプリングし、対応する駆動パルスを各データライン６
に印加する。一方、行ドライバ２１は、ゲートライン５
にゲートパルスを順次印加してゲートライン５を走査す
る。このため、ゲートパルスが印加されたゲートライン
５に接続されたＴＦＴ４がオンし、対応する画素電極３
に駆動パルスが印加される。その行の選択期間ＴＳが終
了し、非選択期間ＴＯになると、ゲートパルスがオフ
し、ＴＦＴ４もオフし、駆動パルスの電圧が画素容量に
保持され、保持された電圧に対応する階調で各画素が表
示される。The column driver 22 sequentially samples the RGB analog luminance signal and its inverted signal supplied from the selector 61, and outputs a corresponding driving pulse to each data line 6.
Apply to. On the other hand, the row driver 21 uses the gate line 5
A gate pulse is sequentially applied to scan the gate line 5. Therefore, the TFT 4 connected to the gate line 5 to which the gate pulse is applied is turned on, and the corresponding pixel electrode 3
A drive pulse is applied to. When the selection period TS of the row is completed and the non-selection period TO is reached, the gate pulse is turned off, the TFT 4 is also turned off, the voltage of the drive pulse is held in the pixel capacitance, and each of the gradations corresponds to the held voltage. Pixels are displayed.
【００６０】このような構成によれば、フレームメモリ
５７に記憶されたＲＧＢ輝度信号が２回ずつ読み出さ
れ、異なった極性のアナログ輝度信号に変換されて液晶
表示モジュール６３に供給される。従って、第１〜第３
実施例において説明したように、連続する２つのフレー
ムにおいて、表示階調に応じた絶対値を有し、異なった
極性の駆動パルスが順次各画素（画素電極３）に印加さ
れ、任意の階調画像が表示される。なお、ＮＴＳＣ方式
のテレビ画像を表示する構成を例示したが、他の構成を
使用してもよく、また、他の画像を表示してもよい。With such a configuration, the RGB luminance signals stored in the frame memory 57 are read twice, converted into analog luminance signals of different polarities, and supplied to the liquid crystal display module 63. Therefore, the first to third
As described in the embodiment, in two consecutive frames, drive pulses having absolute values according to the display gradation and having different polarities are sequentially applied to each pixel (pixel electrode 3), and an arbitrary gradation is obtained. The image is displayed. Although the configuration for displaying the television image of the NTSC system has been illustrated, other configurations may be used and other images may be displayed.
【００６１】また、第４実施例では、ＮＴＳＣコンポジ
ット信号のフレーム周波数と液晶表示モジュール６３の
フレーム周波数を同一としたが、例えば、ＮＴＳＣコン
ポジット信号のフレーム周波数を６０Ｈｚと、液晶表示
モジュール６３のフレーム周波数を３０Ｈｚ（２フレー
ムで１画像を形成するので、１５フィールド／秒）とす
る等、両者のフレーム周波数を異ならせてもよい。この
場合、例えば、書き込み制御回路６７は独自の書き込み
周期でフレームメモリ５７にＲＧＢ輝度データを書き込
み、読み出し制御回路６９が独自の読み出し周期でフレ
ームメモリ５７からＲＧＢ輝度データを読み出し、後段
の回路に供給するようにすればよい。Further, in the fourth embodiment, the frame frequency of the NTSC composite signal and the frame frequency of the liquid crystal display module 63 are the same. However, for example, the frame frequency of the NTSC composite signal is 60 Hz and the frame frequency of the liquid crystal display module 63. May be 30 Hz (1 image is formed in 2 frames, so 15 fields / sec), and the frame frequencies of the two may be different. In this case, for example, the write control circuit 67 writes the RGB brightness data in the frame memory 57 in the unique write cycle, the read control circuit 69 reads the RGB brightness data from the frame memory 57 in the unique read cycle, and supplies the RGB brightness data to the subsequent circuit. You can do it.
【００６２】図１１の構成では、Ｄ／Ａ変換器５９の後
段にセレクタ６１を配置してＤ／Ａ変換器５９の出力す
る正負２つの極性のアナログ輝度信号の一方を選択した
が、読み出し制御回路６９の制御により、Ｄ／Ａ変換器
５９に、その時点で必要な極性のアナログ輝度信号のみ
を出力させ、その信号を列ドライバ２２に供給するよう
にしてもよい。In the configuration of FIG. 11, the selector 61 is arranged at the subsequent stage of the D / A converter 59 to select one of the positive and negative polarities of the analog luminance signal output from the D / A converter 59. Under the control of the circuit 69, the D / A converter 59 may be caused to output only the analog luminance signal having the necessary polarity at that time, and the signal may be supplied to the column driver 22.
【００６３】図３では、第１の方向１１Ａと第２の方向
１１Ｂの中間の方向１１Ｃに一方の偏光板１４の透過軸
１４Ａを一致させ、他方の偏光板１３の透過軸１３Ａを
透過軸１４Ａに直交させるようにしたが、他方の偏光板
１３の透過軸１３Ａを透過軸１４Ａに平行にしてもよ
い。また、第１の方向１１Ａと第２の方向１１Ｂの中間
の方向１１Ｃに一方の偏光板１４の吸収軸を一致させ、
他方の偏光板１３の吸収軸を一方の偏光板１４の吸収軸
に直交させるようにしてもよい。この場合、印加電圧が
０（又はほぼ０）の時に液晶表示素子の透過率が最大と
なり、印加電圧の絶対値が大きくなるに従って透過率が
低下する。しかし、この場合も、絶対値が等しければ、
その極性によらず透過率が等しくなり、この発明の駆動
方法が適用できる。In FIG. 3, the transmission axis 14A of one polarizing plate 14 is aligned with the intermediate direction 11C between the first direction 11A and the second direction 11B, and the transmission axis 13A of the other polarizing plate 13 is changed to the transmission axis 14A. However, the transmission axis 13A of the other polarizing plate 13 may be parallel to the transmission axis 14A. Further, the absorption axis of one polarizing plate 14 is made to coincide with the intermediate direction 11C between the first direction 11A and the second direction 11B,
The absorption axis of the other polarizing plate 13 may be made orthogonal to the absorption axis of the one polarizing plate 14. In this case, the transmittance of the liquid crystal display element becomes maximum when the applied voltage is 0 (or almost 0), and the transmittance decreases as the absolute value of the applied voltage increases. But again, if the absolute values are equal,
The transmittance becomes equal regardless of the polarity, and the driving method of the present invention can be applied.
【００６４】[0064]
【発明の効果】以上説明したように、この発明によれ
ば、強誘電性液晶を用いた液晶表示素子において、複数
フレームの各選択期間に表示階調に応じた電圧の１つの
パルスを印加するだけで任意の階調表示を行うことがで
きる。また、１つの階調について、複数フレームで極性
の異なるパルスを印加するので、印加電圧と透過率の関
係に歪みがあるような場合にも、表示階調が平均化さ
れ、適切な階調が表示される。また、液晶に印加される
電荷の片寄りをなくし、表示の焼き付き現象等を防止で
きる。さらに、極性が異なる電圧に対し表示特性が若干
異なる場合でも、適切な画像を表示できる。As described above, according to the present invention, in a liquid crystal display element using a ferroelectric liquid crystal, one pulse of a voltage corresponding to a display gradation is applied during each selection period of a plurality of frames. It is possible to perform arbitrary gradation display only. Further, since the pulses having different polarities are applied to one gray scale in a plurality of frames, the display gray scales are averaged even when the relationship between the applied voltage and the transmissivity is distorted, and an appropriate gray scale is obtained. Is displayed. Further, it is possible to eliminate the deviation of the electric charges applied to the liquid crystal and prevent the image sticking phenomenon of the display. Further, even when the display characteristics are slightly different for voltages having different polarities, an appropriate image can be displayed.
【図１】この発明の第１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 the structure of a liquid crystal display element according to a first 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】上下偏光板の透過軸の方向と液晶分子の配方方
向を示す平面図である。FIG. 3 is a plan view showing directions of transmission axes of upper and lower polarizing plates and orientation directions of liquid crystal molecules.
【図４】印加電圧と透過率の関係を示すグラフであり、
（Ａ）は第１実施例で使用されるＤＨＦ液晶を使用した
場合の例、（Ｂ）は第１実施例で使用することが望まし
くないＤＨＦ液晶を使用した場合の例を示す。FIG. 4 is a graph showing the relationship between applied voltage and transmittance,
(A) shows an example when the DHF liquid crystal used in the first embodiment is used, and (B) shows an example when the DHF liquid crystal which is not desirable to be used in the first embodiment is used.
【図５】この発明の第１実施例にかかる強誘電性液晶表
示素子の駆動方法を説明するための波形図であり、
（Ａ）はこの発明の第１実施例にかかかる強誘電性液晶
表示素子の駆動方法によりゲートラインに供給されるゲ
ート信号の波形を示す図である。（Ｂ）は第１実施例に
かかかる強誘電性液晶表示素子の駆動方法によりデータ
ラインに供給されるデータ信号の波形を示す図である。FIG. 5 is a waveform diagram for explaining a driving method of the ferroelectric liquid crystal display element according to the first embodiment of the present invention,
FIG. 3A is a diagram showing a waveform of a gate signal supplied to a gate line by the method for driving a ferroelectric liquid crystal display element according to the first embodiment of the present invention. FIG. 6B is a diagram showing a waveform of a data signal supplied to a data line by the driving method of the ferroelectric liquid crystal display element according to the first example.
【図６】この発明の第１実施例のＤＨＦ液晶表示素子の
具体例における印加電圧と透過率の関係を示すグラフで
ある。FIG. 6 is a graph showing the relationship between the applied voltage and the transmittance in a specific example of the DHF liquid crystal display device according to the first embodiment of the present invention.
【図７】この発明の第３実施例で使用可能な反強誘電性
液晶を説明するための光学応答特性を示すグラフであ
る。FIG. 7 is a graph showing optical response characteristics for explaining an antiferroelectric liquid crystal usable in the third embodiment of the present invention.
【図８】この発明の第３実施例で使用可能な反強誘電性
液晶を説明するための光学応答特性を示すグラフであ
る。FIG. 8 is a graph showing an optical response characteristic for explaining an antiferroelectric liquid crystal usable in a third embodiment of the present invention.
【図９】この発明の第３実施例で使用可能な反強誘電性
液晶を説明するための光学応答特性を示すグラフであ
る。FIG. 9 is a graph showing optical response characteristics for explaining an antiferroelectric liquid crystal usable in the third embodiment of the present invention.
【図１０】この発明の第３実施例の反強誘電性液晶表示
素子の具体例における印加電圧と透過率の関係を示すグ
ラフである。FIG. 10 is a graph showing the relationship between the applied voltage and the transmittance in a specific example of the antiferroelectric liquid crystal display element according to the third embodiment of the present invention.
【図１１】この発明の第４実施例にかかる強誘電性液晶
表示素子の駆動回路のブロック図である。FIG. 11 is a block diagram of a drive circuit for a ferroelectric liquid crystal display element according to a fourth embodiment of the present invention.
【図１２】図１１に示す回路の動作を説明するためのタ
イミングチャートである。FIG. 12 is a timing chart for explaining the operation of the circuit shown in FIG.
１・・・透明基板、２・・・透明基板、３・・・画素電極、４・・・
ＴＦＴ、５・・・ゲートライン、６・・・データライン、７・・
・対向電極、８・・・配向膜、９・・・配向膜、１０・・・シール
材、１１・・・液晶、１２・・・シール材、１３・・・偏光板、
１４・・・偏光板、２１・・・行ドライバ、２２・・・列ドライ
バ、４１・・・第１のサンプル・ホールド回路、４２・・・第
２のサンプル・ホールド回路、４３・・・反転回路、４４・
・・加算器、４５・・・セレクタ、４６・・・タイミング回路、
４７・・・電圧発生回路、５１・・・Ａ／Ｄ変換器、５３・・・
分離回路、５５・・・復調／変換回路、５７・・・フレームメ
モリ、５９・・・Ｄ／Ａ変換器、６１・・・セレクタ、６３・・
・液晶表示モジュール、６５・・・クロック回路、６７・・・
書き込み制御回路、６９・・・読み出し制御回路1 ... Transparent substrate, 2 ... Transparent substrate, 3 ... Pixel electrode, 4 ...
TFT, 5 ... Gate line, 6 ... Data line, 7 ...
-Counter electrode, 8 ... Alignment film, 9 ... Alignment film, 10 ... Sealing material, 11 ... Liquid crystal, 12 ... Sealing material, 13 ... Polarizing plate,
14 ... Polarizing plate, 21 ... Row driver, 22 ... Column driver, 41 ... First sample-hold circuit, 42 ... Second sample-hold circuit, 43 ... Inversion Circuit, 44
..Adders, 45 ... Selectors, 46 ... Timing circuits,
47 ... Voltage generating circuit, 51 ... A / D converter, 53 ...
Separation circuit, 55 ... Demodulation / conversion circuit, 57 ... Frame memory, 59 ... D / A converter, 61 ... Selector, 63 ...
・ Liquid crystal display module, 65 ... Clock circuit, 67 ...
Write control circuit, 69 ... Read control circuit
【手続補正書】[Procedure amendment]
【提出日】平成６年１１月２８日[Submission date] November 28, 1994
【手続補正１】[Procedure Amendment 1]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】００１７[Correction target item name] 0017
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【００１７】図２に示すように、画素電極３の行間にゲ
ートライン（走査ライン）５が配線され、画素電極３の
列間にデータライン（階調信号ライン）６が配線されて
いる。各ＴＦＴ４のゲート電極は対応するゲートライン
５に接続され、ドレイン電極は対応するデータライン６
に接続されている。ゲートライン５は、端部５ａを介し
て行（走査ドライバ）ドライバ２１に接続され、データ
ライン６は端部６ａを介して列ドライバ（信号ドライ
バ）２２に接続される。行ドライバ２１は、後述するゲ
ート電圧を印加して、ゲートライン５をスキャンする。
一方、列ドライバ２２は、表示信号（階調信号）を受
け、データライン６に表示信号に対応するデータ信号を
印加する。As shown in FIG. 2, gate lines (scanning lines) 5 are arranged between the rows of the pixel electrodes 3, and data lines (gradation signal lines) 6 are arranged between the columns of the pixel electrodes 3. The gate electrode of each TFT 4 is connected to the corresponding gate line 5, and the drain electrode is corresponding to the data line 6
It is connected to the. The gate line 5 is connected to the row (scan driver) driver 21 via the end 5a, and the data line 6 is connected to the column driver (signal driver) 22 via the end 6a. The row driver 21 scans the gate line 5 by applying a gate voltage described later.
On the other hand, the column driver 22 receives the display signal (gradation signal) and applies the data signal corresponding to the display signal to the data line 6.
【手続補正２】[Procedure Amendment 2]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】００１９[Correction target item name] 0019
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【００１９】下基板１と上基板２は、その外周縁部にお
いて枠状のシール材１０を介して接着されている。基板
１、２とシール材１０で囲まれた領域には液晶１１が封
入されている。液晶１１は、カイラルスメクティックＣ
相の螺旋ピッチが両基板１、２の間隔より小さく、か
つ、配向状態のメモリ性を有さない強誘電性液晶であ
る。液晶１１は、螺旋ピッチが、可視光帯域の波長であ
る７００ｎｍ〜４００ｎｍ以下（例えば、４００ｎｍ〜
３００ｎｍ）であり、自発分極が大きく、コーンアング
ルが約２７度ないし４５°（望ましくは、２７°ないし
３０°）の強誘電性液晶組成物からなる。なお、図１に
おいて、符号１２は両基板１、２の間隔を規制するギャ
ップ材を示し、ギャップ材１２は液晶封入領域内に点在
状態で配置されている。The lower substrate 1 and the upper substrate 2 are adhered to each other at their outer peripheral edges via a frame-shaped sealing material 10. A liquid crystal 11 is enclosed in a region surrounded by the substrates 1 and 2 and the sealing material 10. The liquid crystal 11 is a chiral smectic C
It is a ferroelectric liquid crystal in which the spiral pitch of the phase is smaller than the distance between the substrates 1 and 2 and does not have the memory property of the alignment state. The liquid crystal 11 has a helical pitch of 700 nm to 400 nm or less, which is a wavelength in the visible light band (for example, 400 nm to
300 nm), large spontaneous polarization and a cone angle of about 27 ° to 45 ° (desirably 27 ° to 30 °). 1, reference numeral 12 denotes the conservation catcher <br/>-up material to regulate the spacing between the substrates 1 and 2, a gap material 12 are arranged in a dotted state liquid crystal sealing area.
【手続補正３】[Procedure 3]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】００４４[Correction target item name] 0044
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【００４４】（２） 印加電圧０Ｖでは、平均的分子長
軸方向が層の法線方向に揃わず、印加電圧０Ｖ以外の２
つの電圧値で平均的分子長軸方向が、層の法線方向に揃
い、透過率が最小となる反強誘電性液晶。図８はこの種
の反強誘電性液晶の光学応答特性の一例を示す。この光
学応答特性も一対の偏光板を図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印加して得
られたものである。この特性を有する反強誘電性液晶
は、印加電圧０Ｖでは、平均的分子長軸方向が層法線方
向に揃わず、印加電圧０Ｖ以外の２つの電圧値で平均的
分子長軸方向が、層法線方向に揃い、透過率が最小とな
る。即ち、暗状態になる電圧領域が２つに分離してお
り、印加電圧が０Ｖ付近に平坦な部分が存在しない。こ
の種の反強誘電性液晶は、反強誘電−強誘電相転移前駆
現象を呈する印加電圧の範囲が広いため、印加電圧に応
じて無数の中間的光学状態を有し、その光学応答特性に
明確な閾値が存在せず、この発明の駆動方法に適してい
る。(2) When the applied voltage is 0V, the average long axis of the molecules are not aligned with the normal direction of the layer, and when the applied voltage is 0V, 2
An antiferroelectric liquid crystal in which the average long axis direction of molecules is aligned with the normal direction of the layer at two voltage values, and the transmittance is minimized. FIG. 8 shows an example of the optical response characteristics of this type of antiferroelectric liquid crystal. This optical response characteristic also has a pair of polarizing plates arranged as shown in FIG.
It was obtained by applying a triangular wave voltage having a sufficiently low frequency of about 0.1 Hz. An antiferroelectric liquid crystal having this characteristic has an average molecular major axis direction which is not aligned with the layer normal direction at an applied voltage of 0 V, and the average molecular major axis direction is at a voltage of two layers other than the applied voltage of 0 V. It is aligned in the normal direction and has the minimum transmittance. That is, the voltage region in the dark state is separated into two, and there is no flat portion near the applied voltage of 0V. Since this type of antiferroelectric liquid crystal has a wide range of applied voltage exhibiting the antiferroelectric-ferroelectric phase transition precursor phenomenon, it has innumerable intermediate optical states depending on the applied voltage, and its optical response characteristics Since there is no clear threshold value, it is suitable for the driving method of the present invention.
【手続補正４】[Procedure amendment 4]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】００４５[Name of item to be corrected] 0045
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【００４５】第１及び第２の反強誘電性液晶は、コーン
アングルが３０°から４５°（望ましくは、３５°以
上）と大きく、自発分極が約２００以上と大きく、さら
に、相シーケンスがＩ、ＳｍＡ（スメクティックＡ
相）、ＳｍＣＡ＊（カイラルスメクティックＣＡ＊）と
相転移する液晶である。The first and second antiferroelectric liquid crystals have a large cone angle of 30 ° to 45 ° (preferably 35 ° or more), a large spontaneous polarization of about 200 or more, and a phase sequence of I. , SmA (Smectic A
Phase) and SmCA * (chiral smectic CA * ) .
【手続補正５】[Procedure Amendment 5]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】００６３[Correction target item name] 0063
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【００６３】図３では、第１の方向１１Ａと第２の方向
１１Ｂの中間の方向１１Ｃに一方の偏光板１４の透過軸
１４Ａを一致させ、他方の偏光板１３の透過軸１３Ａを
透過軸１４Ａに直交させるようにしたが、他方の偏光板
１３の透過軸１３Ａを透過軸１４Ａに平行にしてもよ
い。この場合、印加電圧が０（又はほぼ０）の時に液晶
表示素子の透過率が最大となり、印加電圧の絶対値が大
きくなるに従って透過率が低下する。しかし、この場合
も、絶対値が等しければ、その極性によらず透過率が等
しくなり、この発明の駆動方法が適用できる。また、第
１の方向１１Ａと第２の方向１１Ｂの中間の方向１１Ｃ
に一方の偏光板１４の吸収軸を一致させ、他方の偏光板
１３の吸収軸を一方の偏光板１４の吸収軸に直交させる
ようにしてもよい。In FIG. 3, the transmission axis 14A of one polarizing plate 14 is aligned with the intermediate direction 11C between the first direction 11A and the second direction 11B, and the transmission axis 13A of the other polarizing plate 13 is changed to the transmission axis 14A. However, the transmission axis 13A of the other polarizing plate 13 may be parallel to the transmission axis 14A. In this case, when the applied voltage is 0 (or almost 0), the liquid crystal
The transmittance of the display element is maximum, and the absolute value of the applied voltage is large.
The transmittance decreases as the intensity increases. But in this case
However, if the absolute values are the same, the transmittance is the same regardless of the polarity.
The driving method of the present invention can be applied. Also, a direction 11C intermediate between the first direction 11A and the second direction 11B.
The absorption axis of one of the polarizing plates 14 may be aligned with each other, and the absorption axis of the other polarizing plate 13 may be orthogonal to the absorption axis of the one polarizing plate 14.
Claims (10)
板と、 前記２つの基板間に配置された強誘電性を持つ液晶と、 前記２つの基板を挟む位置に配置された一対の偏光板
と、を有し、 前記画素電極と前記対向電極との間に印加される極性の
異なる電圧の絶対値の変化に対応して実質的に等しい光
学的変化を示す強誘電性液晶表示素子と、 表示画像に対応する信号を受け、この信号に対応する絶
対値を持ち且つ極性が異なる電圧を前記画素電極と前記
対向電極間に複数のフレームにわたって交互に印加する
駆動手段と、を備えることを特徴とする強誘電性液晶表
示装置。1. A substrate on which a pixel electrode is formed, another substrate on which a counter electrode facing the pixel electrode is formed, and a liquid crystal having ferroelectricity disposed between the two substrates, A pair of polarizing plates arranged at positions sandwiching the two substrates, and substantially corresponding to a change in absolute value of voltages having different polarities applied between the pixel electrode and the counter electrode. And a ferroelectric liquid crystal display element exhibiting an optical change equal to, and receiving a signal corresponding to a display image and applying a voltage having an absolute value corresponding to the signal and having a different polarity between the pixel electrode and the counter electrode. A ferroelectric liquid crystal display device, comprising: a driving unit that alternately applies the voltage over a frame.
ィブ素子がマトリクス状に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、前記基板間に配置され、層構造をもち、前記画素電
極と前記対向電極間に印加された電圧に応じて液晶分子
が第１の方向にほぼ配列した第１の配向状態と、液晶分
子が第２の方向にぼぼ配列した第２の配向状態と、液晶
分子がその平均的な配列方向を前記第１と第２の配向状
態の間の任意の方向に向けて配列した中間の配向状態と
に配向する強誘電性液晶と、前記一方の基板側に配置さ
れ、前記強誘電性液晶の層の法線方向と実質的に平行な
方向に光学軸が設定された一方の偏光板と、前記他方の
基板側に配置され、前記一方の偏光板の光学軸に直交又
は平行に光学軸が設定された他方の偏光板と、を備えた
強誘電性液晶表示素子と、 前記アクティブ素子に接続され、表示画像を定義する信
号を受け、各画素の選択期間に、絶対値が表示階調に対
応し且つ複数フレームにわたって共通で、極性がフレー
ム毎に反転する複数の電圧パルスを前記アクティブ素子
を介して前記画素電極に印加する駆動手段と、 を備えることを特徴とする強誘電性液晶表示装置。2. A substrate between one substrate on which a pixel electrode and active elements connected to the pixel electrode are arranged in a matrix, another substrate on which a counter electrode facing the pixel electrode is formed, and between the substrates. A first alignment state in which liquid crystal molecules are arranged in a layered structure and liquid crystal molecules are substantially aligned in a first direction according to a voltage applied between the pixel electrode and the counter electrode; and liquid crystal molecules are in a second direction. Ferroelectricity in which the liquid crystal molecules are aligned in a second alignment state in which they are roughly aligned, and an intermediate alignment state in which liquid crystal molecules are arranged so that their average alignment direction is an arbitrary direction between the first and second alignment states. Liquid crystal, one polarizing plate disposed on the one substrate side and having an optical axis set in a direction substantially parallel to the normal direction of the layer of the ferroelectric liquid crystal, and one polarizing plate on the other substrate side. And the optical axis of the one polarizing plate is orthogonal or parallel to the optical axis of the one polarizing plate. A ferroelectric liquid crystal display device including the other polarizing plate that is set, and a signal that is connected to the active device and that defines a display image, and receives a signal that defines a display image, and an absolute value becomes a display gradation. A ferroelectric liquid crystal display device, comprising: a driving unit that applies a plurality of voltage pulses corresponding to each other and common to a plurality of frames, the polarity of which is inverted every frame to the pixel electrode via the active element. .
表す１つの信号に対応し、絶対値が実質的に等しく、且
つ、極性が異なる電圧を各フレーム毎に前記画素電極に
印加することを特徴とする請求項１又は２に記載の強誘
電性液晶表示装置。3. The driving means applies a voltage corresponding to one signal representing a display gradation of each pixel, the absolute value of which is substantially the same and the polarity of which is different, to the pixel electrode for each frame. The ferroelectric liquid crystal display device according to claim 1 or 2, wherein
表す１つの信号に対応し、絶対値が実質的に等しく、且
つ、極性が異なる電圧を偶数個のフレームにわたって前
記画素電極に交互に順次印加することを特徴とする請求
項１又は２に記載の強誘電性液晶表示装置。4. The driving means corresponds to one signal representing a display gradation of each pixel, and applies a voltage having substantially the same absolute value and different polarities to the pixel electrode over an even number of frames. The ferroelectric liquid crystal display device according to claim 1 or 2, wherein the voltages are applied alternately and sequentially.
する画素電極に接続された薄膜トランジスタから構成さ
れ、 前記駆動手段は、 対応する行の複数の前記薄膜トランジスタのゲートに接
続されたゲートラインと、 対応する列の複数の前記薄膜トランジスタの電流路の他
端に接続されたデータラインと、 各選択期間に、対応する行の前記ゲートラインに前記薄
膜トランジスタをオンさせるゲート電圧を供給する行駆
動手段と、 各選択期間に、絶対値が前記表示階調に対応し、極性が
異なる電圧をフレーム毎に前記データラインに印加する
列駆動手段と、 を備えることを特徴とする請求項２に記載の強誘電性液
晶表示装置。5. The active element comprises a thin film transistor whose one end of a current path is connected to a corresponding pixel electrode, and the driving means includes a gate line connected to the gates of the plurality of thin film transistors in a corresponding row, A data line connected to the other end of the current path of the plurality of thin film transistors in the corresponding column; and row driving means for supplying a gate voltage for turning on the thin film transistor to the gate line of the corresponding row in each selection period, The column driving means for applying a voltage having an absolute value corresponding to the display gradation and different polarities to the data line for each frame in each selection period, the ferroelectric device according to claim 2. Liquid crystal display device.
間に低周波三角の電圧を印加した際に、明確なしきい値
を持たない光学応答特性を示す液晶物質から構成される
ことを特徴とする請求項１乃至５のいずれか１つに記載
の強誘電性液晶表示装置。6. The liquid crystal is composed of a liquid crystal material that exhibits optical response characteristics without a clear threshold value when a low frequency triangular voltage is applied between the pixel electrode and the counter electrode. The ferroelectric liquid crystal display device according to any one of claims 1 to 5.
強誘電性液晶のいずれか１つから構成されることを特徴
とする請求項１乃至６のいずれか１つに記載の強誘電性
液晶表示装置。7. The ferroelectric substance according to claim 1, wherein the liquid crystal is composed of any one of DHF liquid crystal, SBF liquid crystal and antiferroelectric liquid crystal. Liquid crystal display device.
ンジスタ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、これらの基板の間に配置され、層構造をも
ち、前記画素電極と対向電極間に印加された電圧に応じ
て液晶分子が第１の方向にほぼ配列した第１の配向状態
と、液晶分子が第２の方向にぼぼ配列した第２の配向状
態と、液晶分子の平均的な配列方向が前記第１の方向と
第２の方向の間の任意の方向となる中間の配向状態にそ
れぞれ配向する強誘電性液晶と、前記一方の基板側に配
置され、前記強誘電性液晶層の法線と実質的に平行な方
向に光学軸が設定された一方の偏光板と、前記他方の基
板側に配置され、前記一方の偏光板の光学軸に直交又は
平行に光学軸が設定された他方の偏光板と、を備えた強
誘電性液晶表示素子の駆動方法において、 絶対値が表示階調に対応し、１つの表示階調に対してフ
レーム毎に極性が異なる電圧パルスを前記アクティブ素
子を介して前記画素電極に印加する、ことを特徴とする
強誘電性液晶表示素子の駆動方法。8. A substrate on which a plurality of pixel electrodes and thin film transistors 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 these substrates. And has a layered structure and has a first alignment state in which liquid crystal molecules are substantially aligned in a first direction in accordance with a voltage applied between the pixel electrode and a counter electrode, and liquid crystal molecules in a second direction. A second alignment state that is roughly aligned, and a ferroelectric liquid crystal that is aligned in an intermediate alignment state in which the average alignment direction of liquid crystal molecules is an arbitrary direction between the first direction and the second direction. , One of the polarizing plates disposed on the one substrate side and having an optical axis set in a direction substantially parallel to the normal line of the ferroelectric liquid crystal layer, and the one polarizing plate disposed on the other substrate side. The optical axis is set to be orthogonal or parallel to the optical axis of the polarizing plate of In the method for driving a ferroelectric liquid crystal display device including the other polarizing plate, a voltage pulse whose absolute value corresponds to a display gradation and whose polarity is different for each frame for one display gradation is activated. A method for driving a ferroelectric liquid crystal display element, characterized in that the voltage is applied to the pixel electrode via an element.
間に低周波三角波電圧を印加した際に、明確なしきい値
を持たない光学応答特性を示す液晶物質から構成される
ことを特徴とする請求項８に記載の強誘電性液晶表示素
子の駆動方法。9. The liquid crystal is composed of a liquid crystal material that exhibits optical response characteristics without a clear threshold value when a low frequency triangular wave voltage is applied between the pixel electrode and the counter electrode. The method for driving a ferroelectric liquid crystal display element according to claim 8.
反強誘電性液晶のいずれか１つから構成されることを特
徴とする請求項８又は９に記載の強誘電性液晶表示素子
の駆動方法。10. The liquid crystal is a DHF liquid crystal, an SBF liquid crystal,
10. The method for driving a ferroelectric liquid crystal display element according to claim 8 or 9, wherein the method is constituted by any one of antiferroelectric liquid crystals.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6151817A JPH07333580A (en) | 1994-06-10 | 1994-06-10 | Ferroelectric liquid crystal display device and method for driving ferroelectric liquid crystal display element |
| EP95108911A EP0686956A3 (en) | 1994-06-10 | 1995-06-09 | Liquid crystal display apparatus using liquid crystal having ferroelectric phase and method of driving liquid crystal display device using liquid crystal having ferroelectric phase |
| US08/622,090 US5920301A (en) | 1994-06-10 | 1996-03-26 | Liquid crystal display apparatus using liquid crystal having ferroelectric phase and method of driving liquid crystal display device using liquid crystal having ferroelectric phase |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6151817A JPH07333580A (en) | 1994-06-10 | 1994-06-10 | Ferroelectric liquid crystal display device and method for driving ferroelectric liquid crystal display element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07333580A true JPH07333580A (en) | 1995-12-22 |
Family
ID=15526968
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6151817A Pending JPH07333580A (en) | 1994-06-10 | 1994-06-10 | Ferroelectric liquid crystal display device and method for driving ferroelectric liquid crystal display element |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0686956A3 (en) |
| JP (1) | JPH07333580A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001042290A (en) * | 1999-05-14 | 2001-02-16 | Semiconductor Energy Lab Co Ltd | Liquid crystal display device |
| US6921600B2 (en) | 2001-09-28 | 2005-07-26 | Nissan Motor Co., Ltd. | Separator for fuel cell and method of manufacture therefor |
| US7768488B2 (en) | 1999-05-14 | 2010-08-03 | Semiconductor Energy Laboratory Co., Ltd. | Liquid crystal display device |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6163360A (en) | 1996-06-24 | 2000-12-19 | Casio Computer Co., Ltd. | Liquid crystal display apparatus |
| GB2324899A (en) * | 1997-04-30 | 1998-11-04 | Sharp Kk | Active matrix display |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5381253A (en) * | 1991-11-14 | 1995-01-10 | Board Of Regents Of University Of Colorado | Chiral smectic liquid crystal optical modulators having variable retardation |
| JP2866518B2 (en) * | 1992-01-17 | 1999-03-08 | シャープ株式会社 | Driving method of antiferroelectric liquid crystal device |
-
1994
- 1994-06-10 JP JP6151817A patent/JPH07333580A/en active Pending
-
1995
- 1995-06-09 EP EP95108911A patent/EP0686956A3/en not_active Ceased
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001042290A (en) * | 1999-05-14 | 2001-02-16 | Semiconductor Energy Lab Co Ltd | Liquid crystal display device |
| US7768488B2 (en) | 1999-05-14 | 2010-08-03 | Semiconductor Energy Laboratory Co., Ltd. | Liquid crystal display device |
| US6921600B2 (en) | 2001-09-28 | 2005-07-26 | Nissan Motor Co., Ltd. | Separator for fuel cell and method of manufacture therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0686956A3 (en) | 1996-08-21 |
| EP0686956A2 (en) | 1995-12-13 |
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