JPS62257131A - Driving method for liquid crystal element - Google Patents
Driving method for liquid crystal elementInfo
- Publication number
- JPS62257131A JPS62257131A JP10057486A JP10057486A JPS62257131A JP S62257131 A JPS62257131 A JP S62257131A JP 10057486 A JP10057486 A JP 10057486A JP 10057486 A JP10057486 A JP 10057486A JP S62257131 A JPS62257131 A JP S62257131A
- Authority
- JP
- Japan
- Prior art keywords
- liquid crystal
- voltage
- ferroelectric liquid
- crystal element
- pulse voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000004973 liquid crystal related substance Substances 0.000 title claims abstract description 49
- 238000000034 method Methods 0.000 title claims description 24
- 239000005262 ferroelectric liquid crystals (FLCs) Substances 0.000 claims abstract description 41
- 239000011159 matrix material Substances 0.000 claims description 10
- 230000005540 biological transmission Effects 0.000 claims description 7
- 239000000758 substrate Substances 0.000 claims description 7
- 239000004990 Smectic liquid crystal Substances 0.000 claims description 4
- 238000003487 electrochemical reaction Methods 0.000 abstract description 3
- 230000002542 deteriorative effect Effects 0.000 abstract 1
- 230000005684 electric field Effects 0.000 description 15
- 238000002834 transmittance Methods 0.000 description 10
- 230000010287 polarization Effects 0.000 description 9
- 238000010586 diagram Methods 0.000 description 7
- 230000006866 deterioration Effects 0.000 description 5
- 230000004044 response Effects 0.000 description 5
- 229920006395 saturated elastomer Polymers 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000012935 Averaging Methods 0.000 description 1
- 101000746134 Homo sapiens DNA endonuclease RBBP8 Proteins 0.000 description 1
- 101000969031 Homo sapiens Nuclear protein 1 Proteins 0.000 description 1
- 239000004988 Nematic liquid crystal Substances 0.000 description 1
- 102100021133 Nuclear protein 1 Human genes 0.000 description 1
- 210000000988 bone and bone Anatomy 0.000 description 1
- 210000002858 crystal cell Anatomy 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910003437 indium oxide Inorganic materials 0.000 description 1
- PJXISJQVUVHSOJ-UHFFFAOYSA-N indium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[In+3].[In+3] PJXISJQVUVHSOJ-UHFFFAOYSA-N 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 239000009719 polyimide resin Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000000565 sealant Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 1
- 229910001887 tin oxide Inorganic materials 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、強誘電性液晶を使用したＸＹマトリックス液
晶表示素子や液晶−光シヤツターアレイ等の液晶素子で
諧調表示の出来る駆動方法に関する。DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a driving method that allows gradation display in a liquid crystal element such as an XY matrix liquid crystal display element using a ferroelectric liquid crystal or a liquid crystal-optical shutter array.
（従来の技術）
従来より、走査電極群と信号電極群をマトリックス状に
構成し、その電極間に液晶材料を充填し多数の画素を形
成して、画像あるいは情報の表示を行う液晶表示素子は
、良く知られている。この表示素子の駆動方法としては
、走査電極群に順次周期的にアドレス（３号を選択印加
し、信号電極群には所定の情報信号をアドレス信号と同
期させて並列的に選択印加する時分割駆動が採用されて
いるが、この表示素子及びその駆動方法には以下に述べ
るような致命的欠点がある。(Prior Art) Conventionally, liquid crystal display elements display images or information by configuring a group of scanning electrodes and a group of signal electrodes in a matrix, and filling a liquid crystal material between the electrodes to form a large number of pixels. , is well known. The driving method for this display element is a time-sharing method in which an address (No. 3) is selectively and periodically applied to the scanning electrode group, and a predetermined information signal is selectively applied in parallel to the signal electrode group in synchronization with the address signal. However, this display element and its driving method have fatal drawbacks as described below.
即ち、画素密度を高く、或いは画面を大きくするのが難
しいことである。従来の液晶の中で応答速度が比較的速
く、しかも消費電力が小さいところから、表示素子とし
て実用に供されているのは殆どが、ツィステッドネマチ
ック型の液晶を用いた表示物である。この型の液晶を用
いてマトリックス型電極構造によって表示素子を構成し
た場合、走査電極と信号電極が共に選択される領域（以
下選択点と略）には、液晶分子を電極面に垂直にさせる
に要する闇値以上の電圧が印加され、走査電極と信号電
極が共に選択されない領域（以下非選択点と略）には電
圧が印加されず、したがって液晶分子は電極面に対して
並行な安定配列を保っている。このような液晶セルの上
下に互いにクロスニコル関係にある直線偏光子を配置す
ることにより、選択点では光が透過せず、非選択点では
光が透過するため、画像表示が可能となる。然しこれら
、マトリックス電極構造を構成した場合には、走査電極
が選択され、信号電極が選択されない領域、或いは信号
電極が選択され、走査電極が選択されない領域（以下半
選択点と略）にも有限に電圧が印加されてしまう。選択
点にかかる電圧と、半選択点にかかる電圧の差が充分に
大きく、液晶分子を電極面に垂直にさせるに要する電圧
闇値がこの中間の電圧値に設定されるならば、表示素子
として適切に動作するわけであるが、走査線数（Ｎ）を
増やして行った場合、画面全体（１フレーム）を走査す
る間に１つの選択点に有効な電界がかかつている時間（
デユーティ−比）が１／Ｎの割合で減少してしまう。こ
のために、繰り返し走査を行った場合の選択点と非選択
点にかかる実効値としての電圧差は、走査線数が増えれ
ば増える程小さくなって閣値電圧に近すき、結果的には
画像コントラストの低下やクロストークが避けがたい欠
点となっている。この点を改良するために、電圧平均化
法、２周波駆動法や、多重マトリックス法なども考えら
れてはいるが、いずれの方法でも不十分であった。That is, it is difficult to increase the pixel density or enlarge the screen. Among conventional liquid crystals, most of the displays using twisted nematic liquid crystals are used in practical use as display elements because they have a relatively fast response speed and low power consumption. When a display element is constructed using this type of liquid crystal with a matrix-type electrode structure, the area where both the scanning electrode and the signal electrode are selected (hereinafter referred to as the selection point) is located so that the liquid crystal molecules are perpendicular to the electrode surface. A voltage higher than the required dark value is applied, and no voltage is applied to areas where both the scanning electrode and the signal electrode are not selected (hereinafter referred to as non-selected points), and therefore the liquid crystal molecules are stably aligned parallel to the electrode surface. I keep it. By arranging linear polarizers in a cross-Nicol relationship above and below such a liquid crystal cell, light does not pass through selected points, but light passes through non-selected points, making it possible to display images. However, when such a matrix electrode structure is configured, there is a finite point in the area where the scanning electrode is selected and the signal electrode is not selected, or the area where the signal electrode is selected and the scanning electrode is not selected (hereinafter abbreviated as half-selected point). A voltage is applied to the If the difference between the voltage applied to the selected point and the voltage applied to the half-selected point is sufficiently large, and the voltage value required to make the liquid crystal molecules perpendicular to the electrode surface is set to an intermediate voltage value, it can be used as a display element. It works properly, but if you increase the number of scanning lines (N), the time during which an effective electric field is applied to one selected point while scanning the entire screen (one frame) increases (
(duty ratio) decreases at a rate of 1/N. For this reason, the voltage difference as an effective value between selected points and non-selected points when repeated scanning is performed becomes smaller as the number of scanning lines increases, approaching the value voltage, and as a result, the image Reduced contrast and crosstalk are unavoidable drawbacks. In order to improve this point, voltage averaging methods, two-frequency driving methods, multiple matrix methods, and the like have been considered, but all of these methods have been insufficient.
そのため、これらの欠点を改善するものとして、メモリ
ー性を有する液晶素子についてＣ１ａｒｋとＬａｇｅｒ
ａｌｌにより特開昭５６−１０７２１６号公報に提案さ
れている。これは強誘電性液晶を使用するもので特にカ
イラルスメクチックＣ相、カイラルスメクチックＨ相を
呈する液晶等が知られている。この強誘電性液晶を使用
する液晶素子の印加電圧に対する応答速度は非常に高速
で、十分な大きさの電界を印加すれば１０−６秒オーダ
ーのパルス幅を持つ電圧パルスにも応答する。またメモ
リー性を有しているため、走査線数が増えても画像コン
トラストの低下がない表示が可能である。Therefore, in order to improve these drawbacks, C1ark and Lager are proposed for liquid crystal elements with memory properties.
This method was proposed in Japanese Unexamined Patent Publication No. 107216/1983 by All. This uses a ferroelectric liquid crystal, and particularly liquid crystals exhibiting a chiral smectic C phase and a chiral smectic H phase are known. The response speed of a liquid crystal element using this ferroelectric liquid crystal to an applied voltage is very high, and if a sufficiently large electric field is applied, it will respond to a voltage pulse having a pulse width on the order of 10 -6 seconds. Furthermore, since it has memory properties, it is possible to display images without deterioration in image contrast even when the number of scanning lines increases.
ところが諧調表示を含めたＸＹＹマトリツクス駆動に関
して具体的にどのような電圧を印加して動かせば良いの
か明らかにされていなかった。However, it has not been made clear what voltage should be specifically applied to drive the XYY matrix including gradation display.
（発明の目的）
本発明の目的は印加電圧と強誘電性液晶の光透過状態と
の関係を明らかに刷ることにより任意の光透過状態を高
速で得ようとするものであり、かつ駆動中に印加される
一方通行的な直流成分を相殺するような駆動方式を採る
ことにより、強誘電性液晶の劣化を防ぐことができるＸ
Ｙマトリックス型型読誘電性液晶素子駆動方法を提供す
ることにある。(Object of the Invention) The object of the present invention is to obtain an arbitrary light transmission state at high speed by clearly printing the relationship between applied voltage and light transmission state of a ferroelectric liquid crystal, and to Deterioration of ferroelectric liquid crystal can be prevented by adopting a driving method that cancels out the applied one-way DC component.X
An object of the present invention is to provide a method for driving a Y-matrix type dielectric liquid crystal element.
（発明の構成）
上記目的を達成する本発明の特徴とするところは、液晶
素子の光透過率の状態を定めるパルス電圧を時間軸方向
で分割して短時間のパルス電圧を必要な回数だけ連続し
て所定周期で強誘電性液晶に印加し任意の光透過率の状
態を得るＸＹマトリックス型型読誘電性液晶素子駆動方
法であり、特に短時間のパルス電圧の中でこの直流成分
と等しくかつ逆極性の直流成分をこの短時間のパルス電
圧と連続的に強誘電性液晶に印加することによって、表
示内容による変化もなく強誘電性液晶に印加される電圧
の平均値が零になり、かつ強誘電性液晶の特徴でもある
メモリー性により保持している前走査の表示内容を必要
量だけ消去する短時間のパルス電圧を付加した信号電圧
を周期的に加えることで高速、諧調表示のできることを
特徴とするＸＹマトリックス型型読誘電性液晶素子駆動
方法である。(Structure of the Invention) The present invention that achieves the above object is characterized by dividing the pulse voltage that determines the state of light transmittance of the liquid crystal element in the time axis direction, and continuously applying short-time pulse voltage as many times as necessary. This is an XY matrix-type dielectric liquid crystal device driving method in which a voltage is applied to a ferroelectric liquid crystal at a predetermined period to obtain an arbitrary light transmittance state. By continuously applying a DC component of opposite polarity to this short-time pulse voltage to the ferroelectric liquid crystal, the average value of the voltage applied to the ferroelectric liquid crystal becomes zero without any change depending on the displayed content, and By periodically applying a signal voltage with a short pulse voltage that erases the required amount of the display content of the previous scan, which is retained due to the memory property that is a feature of ferroelectric liquid crystals, high-speed, gradation display is possible. This is a characteristic method of driving a dielectric liquid crystal element of an XY matrix type.
（発明の詳細な 説明を以下の実施例に基いて説明する。(Details of the invention The explanation will be based on the following examples.
第２図に示すように、一対のガラス基板２１１゜２２１
の対向面に厚さ５００〜１０００人の酸化インジュウム
（ＩｎｚＯ３）、酸化スズ（ＳｎＯ。As shown in FIG. 2, a pair of glass substrates 211 and 221
Indium oxide (InzO3) and tin oxide (SnO) with a thickness of 500 to 1000 on opposite sides.
）、またねこれらの混合物等からなる表示電極２１２．
２２２設け、さらに厚さ１００〜１０００人のポリイミ
ド樹脂）（ＬＩｌｏｏ（日立化成■製部品名）配向膜２
１３を必要に応じて設は基板２１１，２２１のギャップ
（約０．５μ）間に、強誘電性液晶であるＣ５−１０１
１（＠チッソ製商品名）２１６を室温で封入、挟持する
。尚、２１５は強誘電性液晶２１６を封止するための封
止剤である。当然ながら、配向膜２１３は、強誘電性液
晶分子の螺旋軸が、基板２１１に略平行になるように配
向処理されている。さらに、基板２１２，２２１の表示
電極２１２．２２２が設けられていない面に偏光板２１
４，２２４を隣接させる。), or a mixture thereof.
222 (polyimide resin with a thickness of 100 to 1000) (LIloo (part name manufactured by Hitachi Chemical) alignment film 2
C5-101, which is a ferroelectric liquid crystal, is installed between the substrates 211 and 221 (approximately 0.5μ) as needed.
1 (trade name manufactured by Chisso) 216 is sealed and clamped at room temperature. Note that 215 is a sealant for sealing the ferroelectric liquid crystal 216. Naturally, the alignment film 213 is aligned so that the helical axes of the ferroelectric liquid crystal molecules are substantially parallel to the substrate 211. Furthermore, a polarizing plate 21 is placed on the surface of the substrates 212 and 221 where the display electrodes 212 and 222 are not provided.
4,224 adjacent.
第３図（ａ）に示す様に偏光板２１４の偏光軸方向３１
１と偏光板２２４の偏光軸方向３２１をクロスニコル関
係を持たせるように略直交させる。さらに一方の偏光板
の偏光軸方向を、強誘電性液晶２１６の飽和電界ＩＥＩ
以上の電界を印加したきの強誘電性液晶分子３１３の螺
旋軸方向３１２と略一致させる。As shown in FIG. 3(a), the polarization axis direction 31 of the polarizing plate 214 is
1 and the polarization axis direction 321 of the polarizing plate 224 are made substantially perpendicular to each other so as to have a crossed Nicol relationship. Furthermore, the direction of the polarization axis of one polarizing plate is set to the saturation electric field IEI of the ferroelectric liquid crystal 216.
The helical axis direction 312 of the ferroelectric liquid crystal molecules 313 is made to substantially coincide with the direction of the helical axis 312 of the ferroelectric liquid crystal molecules 313 when the above electric field is applied.
第３図（ａ）では、偏光板２１４の偏光軸方向３１１を
、紙面の手前から紙面をつらぬく方向３０１に電界Ｅを
印加したときの螺旋軸の方向と一敗させクロスニコル関
係を持たせている。尚、以後、この方向の電界を負の符
号をつけて−Ｅと表し、さらに、第２図に示す構造の液
晶素子を例にとって説明するが、本発明はこれに限定さ
れるものではない。In FIG. 3(a), the polarization axis direction 311 of the polarizing plate 214 is made to have a cross Nicol relationship with the direction of the helical axis when an electric field E is applied in a direction 301 extending from the front of the page to the page. There is. Hereinafter, the electric field in this direction will be denoted by -E with a negative sign, and the liquid crystal element having the structure shown in FIG. 2 will be explained as an example, but the present invention is not limited thereto.
第３図（ａ）は−Ｅの電界を印加した場合を示しており
、このとき紙面手前から入射した光は、上側偏光板２１
４により偏光軸方向３１１に偏光され、強誘電性液晶分
子３１２の長軸方向にのみ振動成分をもつ直線偏光とな
り、長軸方向の屈折率ｎ Ｉｆに従って直線偏光のまま
液晶層を通過する。その後、下側偏光板２２４に入射す
るが、この偏光板２２４の偏光軸方向３２１と偏光り１
３１４の偏光軸方向３１１は垂直であるから、光は遮断
され、表示素子では暗く見える。また、第３図（ｂ）は
十Ｅの電界を印加した場合を示しており、このとき強誘
電性液晶分子３２３の長軸は、上下偏光板２１４．２２
４の偏光軸３１１．３２１のどちらとも一致しない方向
３２２を向いている。この場合、上側偏光板２１４によ
り直線偏光となった光のうち強誘電性液晶分子３２３の
長軸方向の成分は、長軸方向の屈折率ｎ１１、短軸方向
の成分は、短軸方向の屈折率ｎ上にしたがって液晶層２
１６を通過するので液晶層２１６を通過した光はだ円偏
光となる。よって下側偏光板を透過する光成分を有する
ため、表示素子では明るく見える。FIG. 3(a) shows the case where an electric field of -E is applied, and at this time, the light incident from the front of the paper is transmitted to the upper polarizing plate 21.
4, the light is polarized in the polarization axis direction 311, becomes linearly polarized light having a vibration component only in the long axis direction of the ferroelectric liquid crystal molecules 312, and passes through the liquid crystal layer as linearly polarized light according to the refractive index n If in the long axis direction. After that, it enters the lower polarizing plate 224, but the polarization axis direction 321 of this polarizing plate 224 and the polarization 1
Since the polarization axis direction 311 of 314 is perpendicular, light is blocked and appears dark on the display element. Further, FIG. 3(b) shows the case where an electric field of 10 E is applied, and in this case, the long axis of the ferroelectric liquid crystal molecules 323 is
It faces in a direction 322 that does not coincide with either of the polarization axes 311 and 321 of No. 4. In this case, of the light linearly polarized by the upper polarizing plate 214, the component in the long axis direction of the ferroelectric liquid crystal molecules 323 has a refractive index n11 in the long axis direction, and the component in the short axis direction has a refraction index in the short axis direction. Liquid crystal layer 2 according to the rate n
16, the light that has passed through the liquid crystal layer 216 becomes elliptical polarized light. Therefore, since it has a light component that passes through the lower polarizing plate, it appears bright on the display element.
このようにして、電界十Ｅ、−Ｅの印加により明暗の切
り換えができ、表示素子、光シヤツター、偏光素子とし
て機能し得る。なお液晶、配向膜、両電極基板間のギャ
ップを調整することにより光の透過、非透過状態を一度
十Ｅ、−Ｅの印加により既定したならば、電界が印加さ
れ続けなくても、その状態を保持する、メモリー性を発
現する。In this way, brightness and darkness can be switched by applying electric fields 1E and -E, and the display element can function as a display element, a light shutter, and a polarizing element. By adjusting the gap between the liquid crystal, the alignment film, and both electrode substrates, once the light transmission state and non-transmission state are established by applying 10E and -E, that state will be maintained even if the electric field is not continuously applied. Maintains memory and exhibits memory properties.
また本現象をここでは、強誘電性液晶の電気光学効果と
呼ぶこととする。Further, this phenomenon will be referred to herein as the electro-optic effect of ferroelectric liquid crystal.
この電気光学効果をくわしく調べた結果、第４図に示す
ような特性を持つことが明らかになった。As a result of detailed investigation of this electro-optic effect, it was revealed that it has the characteristics shown in Figure 4.
まず、強誘電性液晶に加わる印加電圧ＶＬＣを横軸とし
、該表示素子を透過する光の明るさＩを縦軸とする。First, the horizontal axis represents the applied voltage VLC applied to the ferroelectric liquid crystal, and the vertical axis represents the brightness I of light transmitted through the display element.
そこで、印加電圧ＶＬＣによる電界を−Ｅから上げて行
くと＋Ｅｃ（闇値電界）から徐々に光が透過するように
なり・１−Ｅ（飽和電界）で飽和する。Therefore, when the electric field due to the applied voltage VLC is increased from -E, light gradually begins to pass from +Ec (dark value electric field) and becomes saturated at 1-E (saturated electric field).
今度は、そこから印加電圧ＶＬＣを下げて行くと−Ｅｃ
まで光は透過状態を続け、その後徐々に光が透過しすら
（なり−Ｅで飽和する。Next time, if we lower the applied voltage VLC from there, -Ec
The light continues to be transmitted until it reaches -E, after which the light gradually becomes transmitted.
次に、パルス電圧に対する応答特性を調べた。Next, we investigated the response characteristics to pulse voltage.
印加するパルス電圧の電圧ｖｐを紙面の手前から紙面の
奥へ貫く方向の軸とし、パルス電圧の印加時間ＴＰを２
．５ Ｘ １０−’秒として、該表示素子を遇遇する光
の明るさ■の時間Ｔに対する変化を測定して第５［ＩＪ
（ａ）に示すような三次元グラフで現わされる結果を得
た。 次に、パルス電圧の印加時間ＴＰを紙面の手前か
ら紙面の奥へ貫く方向の軸とし、該表示素子を透過する
光の明るさ■の時間Ｔに対する変化を測定して第５図（
ｂ）に示すような三次元グラフで現わせれる結果を得た
。The voltage vp of the pulse voltage to be applied is set as the axis extending from the front of the page to the back of the page, and the application time TP of the pulse voltage is set as 2.
．． 5 x 10-' seconds, measure the change in the brightness of the light that surrounds the display element over time T, and calculate the fifth [IJ
The results shown in a three-dimensional graph as shown in (a) were obtained. Next, with the application time TP of the pulse voltage set as the axis extending from the front of the page to the back of the page, the change in the brightness of the light transmitted through the display element (■) with respect to the time T was measured, as shown in FIG.
We obtained results that can be expressed in a three-dimensional graph as shown in b).
また、連続するパルス電圧に対する応答特性を調べた。We also investigated the response characteristics to continuous pulse voltage.
印加するパルス電圧のパルスとパルスの間の時間をＴＳ
として、該表示素子を透過する光の明るさＩの時間Ｔに
対する変化を測定して第６図のような結果を得た。The time between the pulses of the applied pulse voltage is TS
The change in the brightness I of light transmitted through the display element with respect to time T was measured, and the results shown in FIG. 6 were obtained.
以上の結果から、
（ｉ）強誘電性液晶素子のメモリー性と闇値が確認でき
た。本実施例に使用した素子においては、１Ｅｌ＝５〜
ＩＯＶで ＥＣ−１〜３ｖであった。From the above results, (i) the memory property and dark value of the ferroelectric liquid crystal element were confirmed. In the element used in this example, 1El=5~
IOV was EC-1-3v.
（１１）強誘電性液晶素子では、パルス電圧の電圧ＶＰ
と、パルス電圧の印加時間ＴＰの何れか、または両方を
調整することにより任意の光透過率を得、かつ該素子に
メモリーさせる事ができる。本実施例に使用した素子に
おいては、印加電圧ＶＬＣをＶＬＣ＝１５Ｖ印加したと
きの最小応答時間ＴＳは、第５図（ｂ）で８１と示した
よう！、０．１ｍ５ｅｔ：程で透過光の強さが飽和する
時間ＴＰは、Ｓ２と示したように２．５ｍＳｅ［’程度
であった。(11) In a ferroelectric liquid crystal element, the voltage VP of the pulse voltage
By adjusting either or both of the pulse voltage application time TP and the pulse voltage application time TP, an arbitrary light transmittance can be obtained and stored in the element. In the element used in this example, the minimum response time TS when the applied voltage VLC=15V is 81 as shown in FIG. 5(b)! , 0.1 m5 et: The time TP at which the intensity of the transmitted light is saturated is about 2.5 mSe[', as indicated by S2.
（ｉｉｉ ）強誘電性液晶素子では、低い電圧または、
短い時間のパルス電圧で、何回にも分けて電界を変化さ
せることにより任意の光透過率を得、かつ該素子にメモ
リーさせる事ができる。しかし液晶、配向膜、両電極基
板間のギヤツブなどの組合せによっては、印加するパル
ス電圧のパルスとパルスの間の時間ＴＳが長くなるとメ
モリーされている状態に応じた、ある程度以上の電界が
印加されないと異なる光透過率の状態には移行しない強
誘電性液晶素子もある。(iii) In ferroelectric liquid crystal elements, low voltage or
By changing the electric field several times using a pulsed voltage for a short time, it is possible to obtain an arbitrary light transmittance and store it in memory in the element. However, depending on the combination of the liquid crystal, the alignment film, the gear between both electrode substrates, etc., if the time TS between the pulses of the applied pulse voltage becomes long, an electric field exceeding a certain level depending on the memorized state will not be applied. There are also ferroelectric liquid crystal elements that do not transition to a state with a light transmittance different from that of the ferroelectric liquid crystal element.
以上のような性質と液晶素子では、駆動中に一方通行的
な直流成分が印加されると電気化学反応によって液晶素
子の劣化が促進され寿命低下をきたすのであり、この対
策とＸＹＹマトリツクス線順次走査駆動であることへの
工夫および前走査時の表示メモリーの消去について考え
た。そして以下の駆動方法によりＸＹマトリックス型型
読誘電性液晶素子の諧調表示が可能となった。With the above properties and liquid crystal elements, if a one-way DC component is applied during driving, the deterioration of the liquid crystal element will be accelerated due to electrochemical reactions and the life span will be shortened. We considered ways to improve the drive and erase the display memory during pre-scanning. The following driving method has made it possible to display gradations using an XY matrix type dielectric liquid crystal element.
まず第７図のように印加するパルス電圧の直流分に等し
い逆極性の電荷を闇値電圧 ＥＣより低い電圧であるパ
ルスを、実際に強誘電性液晶を動かすパルス電圧の前後
に割り振ることにより、一方通行的な直流成分を相殺す
るような駆動電圧信号とするものであり、この電圧信号
の充分に短時間のものを単位ユニットとした。 この単
位ユニットには逆極性のＯＮとＯＦＦの二つがある。First, as shown in Figure 7, by allocating opposite polarity charges equal to the DC component of the applied pulse voltage to pulses with a voltage lower than the dark value voltage EC, before and after the pulse voltage that actually moves the ferroelectric liquid crystal, The driving voltage signal is such that it cancels out the one-way DC component, and a sufficiently short period of this voltage signal is used as a unit. This unit has two types, ON and OFF, with opposite polarity.
このようにすれば所定周期内に強誘電性液晶に印加され
る電荷量の平均値を零にする駆動電圧信号となり、直流
成分による電気化学反応により液晶素子を劣化させない
のである。In this way, the driving voltage signal is such that the average value of the amount of charge applied to the ferroelectric liquid crystal within a predetermined period becomes zero, and the liquid crystal element is not deteriorated by an electrochemical reaction caused by a DC component.
次に第８図のように前走査時にメモリーされた内容を次
の表示に影響及ぼさない程度まで消去するのに必要な回
数骨のＯＦＦユニットを印加するための消去時間Ｔｃ１
ｓＯ中にＯＦＦユニットをならべて、以前の表示を消去
し、次に光透過率が飽和されるまで強誘電性液晶を動か
すのに必要なＯＮユニットを並べられる時間Ｔｆｕｌｌ
の中に、望む光透過率（諧調表示）に強誘電性液晶を動
かしメモリーさせるのに必要なＯＮユニットを並べ残り
のＴｆｕｌｌをうめるためのＯＦＦユニットをＯＮユニ
ットの前に並べる。このようにすれば液晶表示素子に所
望の、８！ａ調濃度をもった新しい表示内容をメモリー
させることができる。またその画素が選択されていない
ときには、闇値電圧 ＥＣ以下の電圧で単位ユニット時
間内の実効値が零の信号しか印加されないように電圧を
Ｘ、Ｙに分割してみると第１図のように考えられた。こ
れはＯＮユニットまたはＯＦＦユニットの波形を８個並
べることにより明状態から暗状態または暗状態から明状
態へ完全反転できるようにした例であり８諧調まで表示
できるものについて例示した。また液晶素子の特性によ
っては消去時間Ｔｃ１ｓを短くしてもよい。Next, as shown in FIG. 8, an erasing time Tc1 is required for applying the bone OFF unit the number of times necessary to erase the contents stored in memory during the previous scan to the extent that they do not affect the next display.
Tfull time to line up the OFF units during sO, erase the previous display, and then line up the ON units necessary to move the ferroelectric liquid crystal until the light transmittance is saturated.
Inside, the ON unit necessary to move and memorize the ferroelectric liquid crystal to the desired light transmittance (gradation display) is arranged, and the OFF unit for filling the remaining Tfull is arranged in front of the ON unit. In this way, the desired 8! New display contents with a tone density can be stored in memory. Also, when that pixel is not selected, if we divide the voltage into was considered. This is an example in which it is possible to completely invert from a bright state to a dark state or from a dark state to a bright state by arranging eight waveforms of ON units or OFF units, and an example is shown in which up to eight gradations can be displayed. Furthermore, depending on the characteristics of the liquid crystal element, the erasing time Tc1s may be shortened.
Ａは画素選択電極ＣＯＭ １と表示信号電極５ＥＧｌの
電気信号によって液晶に印加された電圧でこの信号によ
り１００％暗状態となる。ＢはＣ０Ｍ２と５ＥＧＩの電
気信号によって液晶に印加された電圧でこの信号により
１００％明状態となる。A is a voltage applied to the liquid crystal by electric signals from the pixel selection electrode COM1 and the display signal electrode 5EGl, and this signal causes a 100% dark state. B is a voltage applied to the liquid crystal by the electric signals C0M2 and 5EGI, and this signal brings the liquid crystal into a 100% bright state.
ＣはＣＯＭＩと５ＥＧ２の電気信号によって液晶に印加
された電圧でこの信号により１００％明状態となる。Ｄ
はＣ０Ｍ２と５ＥＧ２の電気信号によって液晶に印加さ
れた電圧でこの信号により５０％暗状態となる。C is a voltage applied to the liquid crystal by the electric signals of COMI and 5EG2, and this signal brings the liquid crystal into a 100% bright state. D
is the voltage applied to the liquid crystal by the electric signals C0M2 and 5EG2, and this signal causes a 50% dark state.
（発明の効果）
このようにして任意の光透過状態を高速で得ることがで
き、また印加パルス信号を分割したことにより非選択時
の画素にかかる電圧による画質の低下を抑え、かつ強誘
電性液晶の劣化を防ぐＸＹマトリックス型型読誘電性液
晶素子駆動方法を提供することができる。(Effects of the invention) In this way, an arbitrary light transmission state can be obtained at high speed, and by dividing the applied pulse signal, deterioration in image quality due to the voltage applied to the pixel when not selected is suppressed, and the ferroelectric It is possible to provide an XY matrix type readable dielectric liquid crystal element driving method that prevents deterioration of liquid crystal.
第１図は本発明の駆動方法による分割パルスをＸＹマト
リックス型型読誘電性液晶素子印加した際の諧調駆動と
、それに対応する印加した信号電圧の実施例を示す電圧
波形図であり、第２図は本発明の駆動方法に用いたＸＹ
マトリックス型型読誘電性液晶素子一例を示す断面図で
あり、第３図（ａ）（ｂ）は本発明で使用した強誘電性
液晶素子の動作原理を説明する図であり、第４図は本発
明で使用した強誘電性液晶素子への印加電圧と素子の光
透過率の関係を示す説明図であり、第５図（ａ）（ｂ）
は本発明で使用した強誘電性液晶素子への印加電圧、印
加時間と素子の光透過率の関係を説明する三次元図グラ
フ図であり、第６図は本発明の使用した強誘電性液晶素
子への印加パルス電圧と素子の光透過率の関係を示すグ
ラフ図である。
第７図（ａ）（ｂ）は本発明の駆動方法で使用する基本
駆動印加パルス電圧の２例を示す電圧波形図であり、第
８図は本発明の駆動方法で使用する単位選択時間内で画
素に印加される基本駆動パルスを組み合わせた印加パル
ス電圧波形を示す説明図である。
第６図
Ｔ（制ｅｃ）
第５図（ａ）
Ｔ（情５ｅｃ）
第５図（ｂ）
丁（、＊ｇｃｃ）
第７因（ａ） 第７図（ｂ）
第８図FIG. 1 is a voltage waveform diagram showing an example of gradation driving when divided pulses are applied to an XY matrix-type dielectric liquid crystal element according to the driving method of the present invention, and the corresponding applied signal voltages; The figure shows the XY used in the driving method of the present invention.
FIG. 4 is a cross-sectional view showing an example of a matrix-type dielectric liquid crystal device; FIGS. 3(a) and 3(b) are diagrams explaining the operating principle of the ferroelectric liquid crystal device used in the present invention; FIGS. 5(a) and 5(b) are explanatory diagrams showing the relationship between the applied voltage to the ferroelectric liquid crystal element used in the present invention and the light transmittance of the element;
6 is a three-dimensional diagram illustrating the relationship between the applied voltage to the ferroelectric liquid crystal element used in the present invention, the application time, and the light transmittance of the element. FIG. FIG. 2 is a graph diagram showing a relationship between a pulse voltage applied to an element and a light transmittance of the element. FIGS. 7(a) and 7(b) are voltage waveform diagrams showing two examples of basic drive applied pulse voltages used in the driving method of the present invention, and FIG. FIG. 3 is an explanatory diagram showing an applied pulse voltage waveform that is a combination of basic drive pulses applied to a pixel in FIG. Figure 6 T (control ec) Figure 5 (a) T (information 5ec) Figure 5 (b) Ding (, *gcc) 7th factor (a) Figure 7 (b) Figure 8
Claims (4)
状に構成した一対の電極基板間に強誘電性液晶を挟持し
てなる液晶素子を駆動する方法に於いて、該液晶素子の
光透過状態を変化させるパルス電圧を所定周期に分割し
てかつ所望の回数上記強誘電性液晶に印加して諧調表示
を行うとともに、上記所定周期内に上記強誘電性液晶に
印加される電流量の平均値を零にする電圧信号を上記強
誘電性液晶に印加することを特徴とする液晶素子の駆動
方法。(1) In a method for driving a liquid crystal element in which a ferroelectric liquid crystal is sandwiched between a pair of electrode substrates having a scanning electrode group and a signal electrode group arranged in a matrix on opposing surfaces, light transmission of the liquid crystal element is performed. A pulse voltage for changing the state is divided into predetermined periods and applied to the ferroelectric liquid crystal a desired number of times to display a gradation, and an average amount of current applied to the ferroelectric liquid crystal within the predetermined period. A method for driving a liquid crystal element, characterized in that a voltage signal that makes the value zero is applied to the ferroelectric liquid crystal.
号は、上記パルス電圧とは、逆極性でかつ実効値が等し
い電圧信号であることを特徴とする液晶素子の駆動方法
。(2) A method for driving a liquid crystal element according to claim (1), wherein the voltage signal is a voltage signal having a polarity opposite to that of the pulse voltage and an equal effective value.
いて、上記強誘電性液晶はカイラルスメクチックＣ層液
晶あるいはカイラルスメクチックＨ層液晶であることを
特徴とする液晶素子の駆動方法。(3) Driving a liquid crystal element according to claim (1) or (2), wherein the ferroelectric liquid crystal is a chiral smectic C-layer liquid crystal or a chiral smectic H-layer liquid crystal. Method.
は第（３）項に於いて、上記液晶素子の特性に応じて、
光透過状態を定めるパルス電圧を印加するまえに前周期
時の表示内容を消去する為のパルス電圧を印加すること
を特徴とする液晶素子の駆動方法。(4) In claim (1), (2), or (3), depending on the characteristics of the liquid crystal element,
A method for driving a liquid crystal element, comprising applying a pulse voltage for erasing display contents in a previous cycle before applying a pulse voltage for determining a light transmission state.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10057486A JPS62257131A (en) | 1986-04-30 | 1986-04-30 | Driving method for liquid crystal element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10057486A JPS62257131A (en) | 1986-04-30 | 1986-04-30 | Driving method for liquid crystal element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS62257131A true JPS62257131A (en) | 1987-11-09 |
Family
ID=14277670
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10057486A Pending JPS62257131A (en) | 1986-04-30 | 1986-04-30 | Driving method for liquid crystal element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62257131A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5285214A (en) * | 1987-08-12 | 1994-02-08 | The General Electric Company, P.L.C. | Apparatus and method for driving a ferroelectric liquid crystal device |
-
1986
- 1986-04-30 JP JP10057486A patent/JPS62257131A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5285214A (en) * | 1987-08-12 | 1994-02-08 | The General Electric Company, P.L.C. | Apparatus and method for driving a ferroelectric liquid crystal device |
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