JPH0146874B2 - - Google Patents

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Publication number
JPH0146874B2
JPH0146874B2 JP54173321A JP17332179A JPH0146874B2 JP H0146874 B2 JPH0146874 B2 JP H0146874B2 JP 54173321 A JP54173321 A JP 54173321A JP 17332179 A JP17332179 A JP 17332179A JP H0146874 B2 JPH0146874 B2 JP H0146874B2
Authority
JP
Japan
Prior art keywords
liquid crystal
voltage
hysteresis
state
electric field
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
JP54173321A
Other languages
Japanese (ja)
Other versions
JPS5692591A (en
Inventor
Tomio Sonehara
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Seiko Epson Corp
Original Assignee
Seiko Epson Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Seiko Epson Corp filed Critical Seiko Epson Corp
Priority to JP17332179A priority Critical patent/JPS5692591A/en
Publication of JPS5692591A publication Critical patent/JPS5692591A/en
Publication of JPH0146874B2 publication Critical patent/JPH0146874B2/ja
Granted legal-status Critical Current

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  • Liquid Crystal (AREA)
  • Liquid Crystal Display Device Control (AREA)

Description

【発明の詳細な説明】[Detailed description of the invention]

本発明は、電界による液晶の相転移現象を応用
した、液晶表示装置に関する。 電界による液晶の相転移現象で、現在表示装置
に応用されているのは、コレステリツク―ネマチ
ツク相転移現象がある。このコレステリツク―ネ
マチツク相転移現象を生じる液晶を透明電極を有
する2枚の基板間に挾持したセルに於いては、分
子の配列が印加電界に対し、1対1に対応しない
つまり、増加電界に対する構造と減少電界に対す
る構造が一致しない電界範囲が存在する。横軸に
印加電界強度、縦軸に配列を表わすパラメータを
とつてみれば、ヒステリシスを描く。このこと
は、印加電圧に対する誘電率、又は、色素分子に
平行、垂直な偏光に対し吸収の異なる二色性色素
を添加した、いわゆるゲスト―ホスト型液晶表示
装置の印加電圧に対する透過率を描いてみれば、
明白である。 このヒステリシスを描く中間状態は、電界を上
昇させて印加した場合、非常に不安定である。ヒ
ステリシスをとる電圧と電圧零を切換えて表示の
オン・オフをすると、電界の印加されたオン状態
は再現性のある構造をとらないため、表示にむら
を生じ、かつ不安定であり、表示品位が低下して
しまう。この中間状態を避けるためには、ヒステ
リシスが生じない、さらに高い電界を加え駆動を
行なう必要がある。しかしこの方法は、不必要に
高い電圧を印加し続けることから、電力を余分に
消費する。 本発明は、このような欠点を解消したものであ
る。 本発明は、情報表示のための電圧印加と、次の
情報表示のための電圧印加の間の1周期内に、す
くなくとも1回、ヒステリシスをとり得ない高電
圧を該液晶セルに印加することにより、直接印加
ではヒステリシスを生じる電圧でも、安定な表示
を得る方法を提供するものである。 以下、実施例に基づき本発明を詳しく説明す
る。第1図は、二色性色素を添加したコレステリ
ツク―ネマチツク相転移を生じる液晶を、対向す
る2枚の透明電極間に挾持したセルの印加電圧と
透過率の関係図である。第1図で、V1は透過率
変化の10%での電圧、V2は電界減少時にネマチ
ツク相をとりうる臨界電圧、V3はヒステリシス
を生じない臨界電圧を示している。 使用した2枚の透明電極は、ラビング等の通の
平行配向処理を施され、液晶は第2図に示すよう
に、無電界時にはコレステリツク相をとり、電界
印加時には透明電極に対し液晶分子が垂直に配向
したネマチツク相をとる。なお、第1図に示した
電圧―透過率特性を得た液晶及び色素は、第1表
に示す通りである。
The present invention relates to a liquid crystal display device that applies a phase transition phenomenon of liquid crystal caused by an electric field. Among the phase transition phenomena of liquid crystals caused by electric fields, the cholesteric-nematic phase transition phenomenon is currently applied to display devices. In a cell in which a liquid crystal that exhibits this cholesteric-nematic phase transition phenomenon is sandwiched between two substrates having transparent electrodes, the arrangement of molecules does not correspond one-to-one to the applied electric field. There exists an electric field range in which the structures for decreasing electric fields do not match. If we take the applied electric field strength on the horizontal axis and the parameter representing the arrangement on the vertical axis, hysteresis is depicted. This describes the dielectric constant with respect to applied voltage, or the transmittance with respect to applied voltage of a so-called guest-host type liquid crystal display device in which a dichroic dye is added that has different absorption for light polarized parallel to and perpendicular to the dye molecules. If you look,
It's obvious. This intermediate state depicting hysteresis is highly unstable when an increasing electric field is applied. When the display is turned on and off by switching between a voltage with hysteresis and a zero voltage, the on-state with an electric field applied does not have a reproducible structure, resulting in uneven and unstable display, resulting in poor display quality. will decrease. In order to avoid this intermediate state, it is necessary to drive by applying a higher electric field that does not cause hysteresis. However, this method continues to apply an unnecessarily high voltage, consuming excess power. The present invention eliminates these drawbacks. The present invention is characterized by applying a high voltage that does not cause hysteresis to the liquid crystal cell at least once within one cycle between applying a voltage for displaying information and applying a voltage for displaying the next information. , provides a method for obtaining stable display even at voltages that would cause hysteresis when directly applied. Hereinafter, the present invention will be explained in detail based on Examples. FIG. 1 is a diagram showing the relationship between the applied voltage and the transmittance of a cell in which a dichroic dye-added liquid crystal exhibiting a cholesteric-nematic phase transition is sandwiched between two opposing transparent electrodes. In FIG. 1, V 1 is the voltage at 10% of the transmittance change, V 2 is the critical voltage at which a nematic phase can be taken when the electric field decreases, and V 3 is the critical voltage at which hysteresis does not occur. The two transparent electrodes used were subjected to parallel alignment treatment such as rubbing, and as shown in Figure 2, the liquid crystal takes a cholesteric phase when no electric field is applied, and when an electric field is applied, the liquid crystal molecules are perpendicular to the transparent electrodes. It takes on a nematic phase oriented to . The liquid crystals and dyes from which the voltage-transmittance characteristics shown in FIG. 1 were obtained are shown in Table 1.

【表】 第2図に示した液晶セルに印加する電圧は、第
3図に示すように、2段階の電圧VON1とVON2
よつて与えられる。ここでVON1,VON2はVON1
V3>VON2>V2の関係を満足している。 情報表示にあたつて、まずVON1の電圧が該液
晶セルに印加され、第1図に於ける領域3をと
る。領域3は、透明電極に対し液晶分子が垂直に
配向したネマチツク状態である。液晶の応答性に
応じた時間t1(この場合は0℃で100m sec)VON1
を印加した後、次にVON2に印加電圧を減ずる。
以後、表示状態を消去するまでVON1の電圧印加
でも該液晶セル内の液晶は、透明電極に対し垂直
に配向したネマチツク相を安定にとることができ
る。この状態は、第1図中領域2に対応してい
る。 情報表示状態を消去する場合は、VON2より電
圧を減じ、V1以下とすればよい。V1以下の電圧
では、該液晶セル内の液晶は、第1図の領域1に
対応した第2図aに示すコレステリツク相をと
る。 さらに本発明は、コレステリツク―ネマチツク
相転移現象に限定されることなく、例えば、スメ
クチツクA―スメクチツクC相転移現象のような
電界による構造の変化に、ヒステリシスを有する
液晶にも適用される。 以上の例にみられるように、電界による構造の
変化にヒステリシスを有する液晶を用いた液晶表
示体を駆動する際に、ヒステリシスをとらない高
電圧を情報表示と次の情報表示の間に加えること
により、電力消費の少ない、表示の安定した液晶
表示装置を得ることができる。 上述の如く本発明は、一対の基板間に液晶が封
入され、該基板の液晶が接する側に透明電極が形
成され、該液晶は電圧に対しヒステリシスを有す
る相転移現象を生ずる液晶である液晶表示装置に
おいて、該液晶には二色性色素が添加されてな
り、情報表示状態にあつては、該液晶がヒステリ
シスを生じない臨界電圧以上であつて、かつ点燈
電圧を越えた第1の電圧を初期の期間該液晶に印
加し、続いて該液晶がネマチツク相をとりうる臨
界電圧まで下げた第2電圧を印加し、情報表示の
消去状態にあつては、該液晶がヒステリシスを生
じない電圧以下の第3の電圧を非点燈電圧として
該液晶に印加してなるようにしたから、従来の相
転移現象を有する液晶にみられたフオーカルコニ
ツク状態を回避することができるので、液晶の混
濁状態が発生することがない。従つて、情報表示
状態における液晶の完全な透明状態と、非表示状
態における二色性色素の完全な発色状態とのみが
得られ、明瞭な表示を得ることができるものであ
る。
[Table] The voltage applied to the liquid crystal cell shown in FIG. 2 is given by two levels of voltages V ON1 and V ON2 , as shown in FIG. Here, V ON1 and V ON2 are V ON1
The relationship V 3 > V ON2 > V 2 is satisfied. When displaying information, first a voltage of V ON1 is applied to the liquid crystal cell, which takes area 3 in FIG. Region 3 is in a nematic state in which liquid crystal molecules are aligned perpendicularly to the transparent electrode. Time t 1 depending on the responsiveness of the liquid crystal (in this case, 100 m sec at 0°C) V ON1
After applying , then reduce the applied voltage to V ON2 .
Thereafter, even when the voltage V ON1 is applied until the display state is erased, the liquid crystal in the liquid crystal cell can stably assume a nematic phase aligned perpendicular to the transparent electrode. This state corresponds to region 2 in FIG. When erasing the information display state, the voltage may be reduced from V ON2 to V 1 or less. At voltages below V1 , the liquid crystal in the liquid crystal cell assumes the cholesteric phase shown in FIG. 2a, which corresponds to region 1 in FIG. Further, the present invention is not limited to the cholesteric-nematic phase transition phenomenon, but is also applicable to liquid crystals having hysteresis due to structural changes caused by electric fields, such as the smectic A-smectic C phase transition phenomenon. As seen in the above example, when driving a liquid crystal display using a liquid crystal that has hysteresis when changing its structure due to an electric field, a high voltage without hysteresis is applied between one information display and the next information display. Accordingly, a liquid crystal display device with low power consumption and stable display can be obtained. As described above, the present invention provides a liquid crystal display in which a liquid crystal is sealed between a pair of substrates, a transparent electrode is formed on the side of the substrate in contact with the liquid crystal, and the liquid crystal is a liquid crystal that causes a phase transition phenomenon having hysteresis with respect to voltage. In the device, a dichroic dye is added to the liquid crystal, and when the liquid crystal is in an information display state, a first voltage that is equal to or higher than a critical voltage at which hysteresis does not occur and exceeds a lighting voltage is applied. is applied to the liquid crystal for an initial period, and then a second voltage lowered to a critical voltage at which the liquid crystal can assume a nematic phase is applied, and in the erased state of information display, a voltage at which the liquid crystal does not cause hysteresis is applied. Since the following third voltage is applied to the liquid crystal as a non-lighting voltage, it is possible to avoid the focal conic state observed in conventional liquid crystals having a phase transition phenomenon. No turbidity occurs. Therefore, only a completely transparent state of the liquid crystal in the information display state and a completely colored state of the dichroic dye in the non-display state can be obtained, and a clear display can be obtained.

【図面の簡単な説明】[Brief explanation of drawings]

第1図は、二色性色素を添加したコレステリツ
ク―ネマチツク相転移を生じる液晶を、ラビング
による平行配向処理を施した2枚の相対する透明
電極間に挾持した液晶セルの印加実効電圧と透過
率の関係を示すものである。 1は領域1、2は領域2、3は領域3を示す。
第2図は、コレステリツク―ネマチツク相転移に
於ける液晶分子の配向状態を示すものである。a
は無電界状態、bは電界印加状態である。4は透
明電極基板、5は液晶分子、66は電源を示す。
第3図は、液晶セルに印加される電圧波形の1つ
の例を示している。図中、ONと記したところ
が、電界を印加した表示状態である。7は、30Hz
以上誘電緩和周波数以下の矩形波を示す。
Figure 1 shows the applied effective voltage and transmittance of a liquid crystal cell in which a dichroic dye-added liquid crystal that exhibits a cholesteric-nematic phase transition is sandwiched between two opposing transparent electrodes that have been subjected to parallel alignment treatment by rubbing. This shows the relationship between 1 indicates area 1, 2 indicates area 2, and 3 indicates area 3.
FIG. 2 shows the alignment state of liquid crystal molecules during cholesteric-nematic phase transition. a
b is a state in which no electric field is applied, and b is a state in which an electric field is applied. 4 is a transparent electrode substrate, 5 is a liquid crystal molecule, and 66 is a power source.
FIG. 3 shows one example of a voltage waveform applied to a liquid crystal cell. In the figure, the area marked ON is the display state in which an electric field is applied. 7 is 30Hz
The above shows a rectangular wave below the dielectric relaxation frequency.

Claims (1)

【特許請求の範囲】[Claims] 1 一対の基板間に液晶が封入され、該基板の液
晶が接する側に透明電極が形成され、該液晶は電
圧に対しヒステレシスを有するコレステリツクー
ネマチツク相転移現象を生ずる液晶である液晶表
示装置において、該液晶には二色性色素が添加さ
れてなり、情報表示状態にあつては、液晶がヒス
テレシスを生じない臨界電圧以上であつて、かつ
点燈電圧を越えた第1の電圧を初期の期間該液晶
に印加し、続いて該液晶がネマチツク相をとりう
る臨界電圧まで下げた第2電圧を印加し、情報表
示の消去状態にあつては、該液晶がヒステリシス
を生じない電圧以下の第3の電圧を非点燈電圧と
して該液晶に印加してなることを特徴とする液晶
表示装置。
1. A liquid crystal display device in which a liquid crystal is sealed between a pair of substrates, a transparent electrode is formed on the side of the substrate in contact with the liquid crystal, and the liquid crystal is a liquid crystal that exhibits a cholesteritschnematic phase transition phenomenon having hysteresis with respect to voltage. A dichroic dye is added to the liquid crystal, and when the liquid crystal is in an information display state, a first voltage which is equal to or higher than a critical voltage at which the liquid crystal does not cause hysteresis and exceeds the lighting voltage is applied as an initial voltage. A second voltage lowered to a critical voltage at which the liquid crystal can assume a nematic phase is applied for a period of A liquid crystal display device characterized in that a third voltage is applied to the liquid crystal as a non-lighting voltage.
JP17332179A 1979-12-26 1979-12-26 Liquiddcrystal display unit Granted JPS5692591A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP17332179A JPS5692591A (en) 1979-12-26 1979-12-26 Liquiddcrystal display unit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP17332179A JPS5692591A (en) 1979-12-26 1979-12-26 Liquiddcrystal display unit

Publications (2)

Publication Number Publication Date
JPS5692591A JPS5692591A (en) 1981-07-27
JPH0146874B2 true JPH0146874B2 (en) 1989-10-11

Family

ID=15958260

Family Applications (1)

Application Number Title Priority Date Filing Date
JP17332179A Granted JPS5692591A (en) 1979-12-26 1979-12-26 Liquiddcrystal display unit

Country Status (1)

Country Link
JP (1) JPS5692591A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4861657B2 (en) * 2005-08-18 2012-01-25 東芝モバイルディスプレイ株式会社 Liquid crystal display

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54155796A (en) * 1978-05-30 1979-12-08 Seiko Instr & Electronics Ltd Driving method for phase-transition type liquid-crystal display unit

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54155796A (en) * 1978-05-30 1979-12-08 Seiko Instr & Electronics Ltd Driving method for phase-transition type liquid-crystal display unit

Also Published As

Publication number Publication date
JPS5692591A (en) 1981-07-27

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