JPH0933957A - Liquid-crystal display device - Google Patents
Liquid-crystal display deviceInfo
- Publication number
- JPH0933957A JPH0933957A JP8192230A JP19223096A JPH0933957A JP H0933957 A JPH0933957 A JP H0933957A JP 8192230 A JP8192230 A JP 8192230A JP 19223096 A JP19223096 A JP 19223096A JP H0933957 A JPH0933957 A JP H0933957A
- Authority
- JP
- Japan
- Prior art keywords
- liquid crystal
- display device
- crystal display
- substrates
- crystal layer
- 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
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Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
- G02F1/139—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
- G02F1/1396—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent the liquid crystal being selectively controlled between a twisted state and a non-twisted state, e.g. TN-LC cell
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
- G02F1/139—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
- G02F1/141—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent using ferroelectric liquid crystals
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133553—Reflecting elements
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Mathematical Physics (AREA)
- Liquid Crystal (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は液晶表示装置に関
し、詳しくは、強誘電性ネマチック液晶物質を用いた、
液晶表示装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more specifically, it uses a ferroelectric nematic liquid crystal material.
The present invention relates to a liquid crystal display device.
【0002】[0002]
【従来の技術】一般に固体は、分子の位置と方向が拘束
されていて位置秩序(positional order)と方向秩序
(orientational order)をもっているが、固体が溶け
て液体になると、この2つの秩序はなくなる。液晶は、
固体で見られる方向秩序と位置秩序の一部を持っている
ので、液体および固体とは区別される相(pase)或は状
態(state)と言える。液晶状の物質は、一般的に方向
秩序を持っているため、方向によって物理的な性質が違
って現れる異方性物質である。液晶分子は細くて長い棒
状の形をしているのが一般的であり、この長い分子は巨
視的に見てある方向に優先的に互いに平行配列しようと
する性質を持っている。その配列方向はディレクタ(方
向子:director)で表され、液晶に存在する方向秩序の
程度は、このディレクタとの関係で示される。即ち、個
々の液晶分子がディレクタとなす角度をθとすれば、
(3cos2θ−1)/2の平均した値を秩序パラメー
タ(order parameter)として、液晶の方向秩序の程度
を表す尺度として使う。液晶の秩序パラメータは、一般
に温度が上昇するに共に減少し、約0.3〜0.9の間
の値を示す。このような液晶を、その秩序の態様によっ
て大きく3つに分類することができる。つまり、ネマチ
ック(nematic)、コレステリック(cholesteric)又は
キラール・ネマチック(chiral nematic)、スメクチッ
ク(smectic)等である。2. Description of the Related Art Generally, solids have a positional order and a molecular orientation, and have a positional order and a directional order. . The liquid crystal is
Since it has a part of the directional order and the positional order found in solids, it can be said to be a phase or state that is distinguished from liquids and solids. Since a liquid crystal substance generally has a directional order, it is an anisotropic substance whose physical properties differ depending on the direction. The liquid crystal molecules are generally in the shape of thin and long rods, and these long molecules have a property of macroscopically preferentially aligning with each other in a certain direction. The arrangement direction is represented by a director (director), and the degree of directional order existing in the liquid crystal is indicated by the relationship with this director. That is, if the angle that each liquid crystal molecule makes with the director is θ,
An average value of (3 cos 2 θ−1) / 2 is used as an order parameter to measure the degree of directional order of the liquid crystal. The liquid crystal order parameter generally decreases with increasing temperature and exhibits values between about 0.3 and 0.9. Such liquid crystals can be roughly classified into three types according to their order. That is, it is nematic, cholesteric, chiral nematic, smectic, or the like.
【0003】ネマチック液晶は、分子の位置に規則性が
なく、分子相互間の力が存在して分子が互いに平行を維
持しようとする方向秩序だけを持っている。この液晶物
質は、主に表示装置で使われている。キラール・ネマチ
ック液晶またはコレステリック液晶は、分子の方向が互
いに小さい角度を維持しようとする分子力を持っている
ので、ネマチック液晶と同様にディレクタが空間の1つ
の方向に固定されず、液晶層全体を通じて回転する。液
晶のこのような性質をカイラリティーであると称し、デ
ィレクタが液晶層を通じて完全に一回りを回転した場
合、この距離をピッチ(pitch)という。キラール・ネ
マチックでないネマチック液晶の場合も、配向(alignm
ent)によって液晶層の全体を通じてディレクタが回転
できるようにすることは可能で、このときもピッチとい
う用語を使う。キラール・ネマチック液晶上の物質は、
表示装置の他にも、圧力、温度、磁場、超音波または電
磁場を測定する時にだけ使うのではなく、偏光板を制作
する時にも使われている。スメクチック液晶は、前記2
つの種類の液晶に比べて配列がより規則的であり、層状
構造を成している。スメクチック液晶相は、方向秩序だ
けでなく位置秩序も持っている。即ち、この液晶分子
は、自ら層を作ろうとする傾向を持っていて、液晶層面
の上から観るときは分子の位置に規則性はないが、液晶
層面の直角の方向に対しては規則性を持つ。それ故、一
方向に対して分子位置の規則性を維持すると共に、方向
秩序がある。The nematic liquid crystal has no regularity in the position of the molecules, and has only the directional order in which the forces between the molecules exist to keep the molecules parallel to each other. This liquid crystal material is mainly used in display devices. Since the chiral nematic liquid crystal or cholesteric liquid crystal has a molecular force to keep the directions of the molecules at a small angle with each other, the director is not fixed in one direction of the space like the nematic liquid crystal, and the whole liquid crystal layer is not fixed. Rotate. This property of the liquid crystal is called chirality, and when the director rotates a full turn through the liquid crystal layer, this distance is called a pitch. For nematic liquid crystals that are not chiral nematic, the alignment (alignm
It is possible to allow the director to rotate through the entire liquid crystal layer by ent), again using the term pitch. The substance on the chiral nematic liquid crystal is
Besides display devices, it is used not only when measuring pressure, temperature, magnetic field, ultrasonic waves or electromagnetic fields, but also when making polarizing plates. The smectic liquid crystal is the same as the above 2
The alignment is more regular than that of the two types of liquid crystals, forming a layered structure. The smectic liquid crystal phase has not only directional order but also positional order. That is, the liquid crystal molecules have a tendency to form a layer by themselves, and there is no regularity in the position of the molecules when viewed from above the liquid crystal layer surface, but there is regularity in the direction perpendicular to the liquid crystal layer surface. To have. Therefore, there is directional order while maintaining the regularity of the molecular position in one direction.
【0004】一方、スメクチック液晶の中では、強誘電
性を持つ液晶が存在するが、スメクチックC*液晶がこ
のような性質を有している。最近、このスメクチックC
*液晶相の物質を用いた液晶表示装置に対する研究が活
発に進んでいる。スメクチックC*液晶は、液晶層に垂
直の面に対して斜めになっている相であり、光学的に不
活性の分子からなる場合にはスメクチックCとし、光学
的な活性分子がある場合には、層に従って螺旋運動をし
スメクチックC*液晶相と称される。この相は、特に分
子永久双極子が存在するために強誘電性液晶相といわれ
る。このとき、双極子の方向は液晶ディレクタに対して
垂直である。通常のスメクチックC相の場合には、ディ
レクタに対して垂直な軸に対する回転対称性(rotation
ary symmetry)と、その軸に垂直なスメクチック層に平
行な面に対する反転対称性(inversion symmetry)が存
在するが、分子がキラールした部分を持つと、反転対称
が崩れて分子に垂直な方向に双極子モーメント(dipole
moment)が存在するので、巨視的には自発分極(spont
aneous polarization)又は永久分極(permanent polar
ization)を持つ強誘電性を表す。On the other hand, among smectic liquid crystals, liquid crystals having ferroelectricity exist, but smectic C * liquid crystals have such properties. Recently, this smectic C
* Research on liquid crystal display devices using liquid crystal phase materials is actively underway. Smectic C * liquid crystal is a phase that is inclined with respect to a plane perpendicular to the liquid crystal layer. Smectic C is used when it is composed of optically inactive molecules, and smectic C is used when it is composed of optically active molecules. , Has a spiral motion according to the layer, and is called a smectic C * liquid crystal phase. This phase is called a ferroelectric liquid crystal phase because of the presence of molecular permanent dipoles. At this time, the dipole direction is perpendicular to the liquid crystal director. In the case of the ordinary smectic C phase, rotation symmetry (rotation symmetry about an axis perpendicular to the director)
ary symmetry) and inversion symmetry with respect to a plane parallel to the smectic layer perpendicular to the axis, but if the molecule has a chiral part, the inversion symmetry collapses and the dipole becomes perpendicular to the molecule. Child moment (dipole
moment, there is macroscopic spontaneous polarization (spont
aneous polarization or permanent polar
represents the ferroelectricity.
【0005】しかしながら、一般的なスメクチックC*
相で分子がスメクチック層に従って螺旋運動をするの
で、一周期または一ピッチに対する巨視的な自発分極は
0になる。従って、強誘電性液晶を不適合(improper)
強誘電性液晶とも呼んでいる。このような螺旋構造は、
外部で電界を印加することによって解けるが、臨界値以
上の電界では、螺旋構造が完全に解けて巨視的な自発分
極が存在する。このようなスメクチックC*液晶を用い
た液晶表示装置は、現在種々な所で開発されているとこ
ろで、配向が難しくて層状構造が外部に弱いことなどの
様々な問題点を有している。However, the general smectic C *
Since the molecules make a spiral motion according to the smectic layer in the phase, the macroscopic spontaneous polarization for one period or one pitch becomes zero. Therefore, the ferroelectric liquid crystal is improper
It is also called ferroelectric liquid crystal. Such a spiral structure is
It can be solved by applying an electric field externally, but in an electric field above the critical value, the spiral structure is completely solved and macroscopic spontaneous polarization exists. A liquid crystal display device using such a smectic C * liquid crystal has various problems such as a difficulty in alignment and a weak layered structure, which are currently being developed in various places.
【0006】液晶は、電気感受率(electric susceptib
ility)、磁気感受率(magnetic susceptbility)等の物
理的な性質がディレクタの方向とそれに垂直の方向では
それぞれ違うという点から、異方性を持っていると言え
る。これは前述した通り、空間対称でない棒の形の分子
が一定の方向に配列しようとする方向秩序を持っている
からである。例えば、電気感受率がディレクタの方向
と、それと垂直な方向とでそれぞれ違ってくるので、誘
電率(permittivity)もまた方向によって異なる。液晶
ディレクタ方向の誘電率をεh、それに対して直角方向
での誘電率をεtとすると、下記の2つがある。The liquid crystal has an electric susceptib
It can be said to have anisotropy because the physical properties such as ility) and magnetic susceptibility differ in the direction of the director and the direction perpendicular to it. This is because, as described above, rod-shaped molecules that are not spatially symmetrical have a directional order in which they are arranged in a certain direction. For example, since the electric susceptibility differs between the direction of the director and the direction perpendicular thereto, the permittivity also differs depending on the direction. If the permittivity in the direction of the liquid crystal director is εh and the permittivity in the direction perpendicular thereto is εt, there are the following two.
【0007】[0007]
【数1】 [Equation 1]
【0008】前者をp型(positive)の誘電率異方性
(dielectric anisotropy)、後者をn型(negative)
の誘電率異方性と呼ぶ。n∧をディレクタとすると、直
流電界Evectorを印加したとき、電気変位(electric d
isplacement)Dvectorは、以下のようになる。The former is a p-type (positive) dielectric anisotropy, and the latter is an n-type (negative).
Is called the dielectric anisotropy of. When n∧ is the director, when the DC electric field E vector is applied, the electric displacement (electric d
isplacement) D vector is as follows.
【0009】[0009]
【数2】 [Equation 2]
【0010】静電気的なエネルギーは、下記のようにな
る。The electrostatic energy is as follows.
【0011】[0011]
【数3】 (Equation 3)
【0012】安定状態になる為には、その値を最小にす
る必要があるので、p型の誘電率異方性を持つ液晶の場
合、即ち△ε>0である場合には、ディレクタが電界と
平行であるとき安定になり、n型の誘電率異方性を持つ
場合には、ディレクタが電界と垂直のとき安定になる。
従って、p型の誘電率異方性液晶の場合、印加された電
界に対してディレクタが平行に配列しようとする傾向が
あり、反対にn型の誘電率異方性液晶の場合には、印加
された電界に対して垂直に配列する傾向がある。In order to reach a stable state, it is necessary to minimize its value. Therefore, in the case of a liquid crystal having a p-type dielectric anisotropy, that is, when Δε> 0, the director changes the electric field. When the director is perpendicular to the electric field, it becomes stable when the director is perpendicular to the electric field.
Therefore, in the case of the p-type dielectric anisotropy liquid crystal, the director tends to be arranged in parallel to the applied electric field, and conversely, in the case of the n-type dielectric anisotropy liquid crystal, the application is performed. It tends to align perpendicular to the applied electric field.
【0013】このような液晶の性質を用いて液晶表示装
置を製造するが、その中でもネマチック液晶物質を用い
た代表的な場合である捻れたネマチック方式について、
図面を参考として詳細に説明する。図1(イ)及び
(ロ)は、誘電率異方性がp型である液晶物質を使う一
般的な捻れたネマチック方式の液晶表示装置を示し、図
1(イ)は電圧が印加されていない状態を示したもの
で、図1(ロ)は電圧が印加されている状態を示したも
のである。この方式では、p型の誘電率異方性を持つ液
晶物質を、透明電極がそれぞれ形成されている2つの透
明基板11,12の間に充填した後(これを「液晶セ
ル」という)、各基板11,12の外側にそれぞれ偏光
板13,14を設置し、液晶セル内部の透明電極15,
16上にある配向膜17,18を処理して、2つの透明
電極面の液晶分子のディレクタが90°捻じれるように
する。液晶セルの厚さと液晶物質をうまく選択すると、
偏光方向の回転がディレクタの捻じれに従うように作成
することができる。このような状態で両側の透明電極に
電圧を加えると、基板11,12表面のすぐ上の分子を
除いた液晶分子が、基板11,12に対して垂直に配列
する。図1(イ)及び(ロ)の矢印は、ディレクタを表
す。A liquid crystal display device is manufactured by using such properties of liquid crystal. Among them, a twisted nematic system, which is a typical case using a nematic liquid crystal substance, is described.
A detailed description will be given with reference to the drawings. 1A and 1B show a general twisted nematic liquid crystal display device using a liquid crystal material having a p-type dielectric anisotropy, and FIG. 1A shows that a voltage is applied. FIG. 1B shows a state in which a voltage is applied. In this method, a liquid crystal substance having p-type dielectric anisotropy is filled between two transparent substrates 11 and 12 on which transparent electrodes are respectively formed (this is called a "liquid crystal cell"), and then each Polarizing plates 13 and 14 are provided outside the substrates 11 and 12, respectively, and transparent electrodes 15 and
The alignment films 17 and 18 on 16 are processed so that the directors of the liquid crystal molecules on the two transparent electrode surfaces are twisted by 90 °. If you choose the thickness of the liquid crystal cell and the liquid crystal material well,
The rotation of the polarization direction can be made to follow the twist of the director. When a voltage is applied to the transparent electrodes on both sides in such a state, liquid crystal molecules excluding the molecules immediately above the surfaces of the substrates 11 and 12 are aligned vertically to the substrates 11 and 12. The arrows in FIGS. 1A and 1B represent directors.
【0014】ここで、このような捻じれたネマチック方
式の液晶表示装置の作用を詳く説明する。「OFF」状態
では、液晶セルが光導波管(Waveguide)のように作用す
る。1つの偏光板13を通過して線偏光された光は、捻
じれた液晶層を通過する時に偏光方向が回転する。光が
液晶層を通過して、他方の基板11に到達したとき、光
の偏光方向は90°回転する。若し、2つの偏光板1
3,14を垂直に配列したとすれば、この光は2番目の
偏光板を通過するはずである。しかし、2つの偏光板1
3,14の偏光軸を互いに平行であるようにとすると、
光の偏光方向がこれと垂直であるので、通過できない。
「ON」の状態では、2つの基板11,12の間に電圧が
印加される。液晶は、p型の誘電率異方性を持っている
ので、液晶ディレクタが基板11,12の付近を除いた
残りの部分で電界の方向に配列しようとする。このと
き、傾斜角(tilted angle)を電気的に調節可能であり、
このようなディレクタの傾斜によって液晶層の導波管効
果がなくなる。即ち、初めの偏光板13を通過して変更
された光は、その偏光方向を殆ど変えずに2番目の偏光
板14に到達する。若し、2つの偏光板13,14の偏
光軸が互いに垂直であれば、この光は2番目の偏光板1
4を殆ど通過できないが、2つの偏光板13,14が互
いに平行であれば、この光は殆ど2番目の偏光板を通過
する。以上に説明したように、光が通過しない「OFF」
状態と光が通過する「ON」状態が得られ、印加される電
圧を適切に調節して階調表示が可能となる。図1(イ)
の「OFF」状態での液晶ディレクタの捻じれ角度(twiste
d angle)は90°であるが、所謂超捻じれたネマチック
方式(supertwisted nematic mode)では、捻じれ角度が
220°或は270°等であって、もっと大きい。The operation of such a twisted nematic liquid crystal display device will be described in detail. In the "OFF" state, the liquid crystal cell acts like a light guide. The linearly polarized light passing through one polarizing plate 13 rotates in the polarization direction when passing through the twisted liquid crystal layer. When the light passes through the liquid crystal layer and reaches the other substrate 11, the polarization direction of the light is rotated by 90 °. Two polarizing plates 1
If 3 and 14 are arranged vertically, this light should pass through the second polarizing plate. However, the two polarizing plates 1
Assuming that the polarization axes of 3 and 14 are parallel to each other,
Since the polarization direction of light is perpendicular to this, it cannot pass through.
In the “ON” state, a voltage is applied between the two substrates 11 and 12. Since the liquid crystal has p-type dielectric anisotropy, the liquid crystal director tries to align it in the direction of the electric field in the remaining portion except the vicinity of the substrates 11 and 12. At this time, the tilt angle can be adjusted electrically,
Such director tilt eliminates the waveguide effect of the liquid crystal layer. That is, the light that has passed through the first polarizing plate 13 and has been changed reaches the second polarizing plate 14 with almost no change in its polarization direction. If the polarization axes of the two polarizing plates 13 and 14 are perpendicular to each other, this light is emitted from the second polarizing plate 1.
However, if the two polarizing plates 13 and 14 are parallel to each other, this light almost passes through the second polarizing plate. As explained above, "OFF" where light does not pass
The state and the "ON" state in which light passes are obtained, and gradation display is possible by appropriately adjusting the applied voltage. Fig. 1 (a)
The twisting angle of the liquid crystal director (twiste
The d angle) is 90 °, but in the so-called super twisted nematic mode, the twist angle is 220 ° or 270 °, which is larger.
【0015】[0015]
【発明が解決しようとする課題】しかし、このような従
来の捻じれたネマチック方式または超捻じれたネマチッ
ク方式の場合は、液晶の誘電率異方性だけを用いるの
で、液晶表示装置を駆動するときにかかる駆動電圧が高
いという問題点を有している。However, in the case of the conventional twisted nematic system or super twisted nematic system, only the dielectric anisotropy of the liquid crystal is used, so that the liquid crystal display device is driven. There is a problem that the driving voltage applied sometimes is high.
【0016】本発明は、上記従来技術の有する問題点を
解決するになされたもので、その目的は、駆動電圧が低
いにもかかわらず、速い動作速度で配向することが容易
な液晶表示装置を提供することにある。The present invention has been made to solve the above-mentioned problems of the prior art. An object of the present invention is to provide a liquid crystal display device which can be easily aligned at a high operating speed despite a low driving voltage. To provide.
【0017】[0017]
【課題を解決するための手段】上記目的は請求項記載の
発明により達成される。即ち、本発明の液晶表示装置の
特徴構成は、電圧を印加可能な一対の透明基板間に、強
誘電性ネマチック液晶物質からなる液晶層を有する点に
ある。強誘電性ネマチック液晶が存在する可能性は、早
くから予測されてきた("Novel Ferroelectric Fluids",
Rolfe G. Petschek and Kimbrly M. Wiefling, Physic
al Review Letters 1987 vol. 59, No.3, pp. 343-346;
" Ferroelectric Nematic Liquid Crystals: Realizab
ility and Molecular Constraints", P.Palffy-Muhora
y, M.A. Lee and Rolfe G. Petschek, Physical Review
Letters 1988 vol. 60, No. 22, pp. 2303-2306; "Fer
roelectric nematic liquid-crystal Phases of dipola
r hard ellipsiods", Marc Baus and Jean-Lois Colot,
PhsicalReview A 1989 col. 40, No. 9, pp. 5444-544
6)。特に、出願人はMol. Cryst.Liq. Cryst. 1994, Vo
l. 254, pp. 395-403に掲載されている"FERROELECTRIC
LIQUID CRYSTALLINE ORDERING OF RIGID RODS WITH DIP
OLAR INTERACTIONS"という題目の論文中で、通常の等方
性−ネマチック相(conventional isotropic-nematic: I
-N)、ネマチックー強誘電性ネマチック相(nematic-ferr
oelectric nematic:N-FN) 及び直接等方性−強誘電性ネ
マチック相(direct isotropic-ferroelectric nematic:
I-FN)電位を表す状態図を提示した。The above object is achieved by the invention described in the claims. That is, the characteristic configuration of the liquid crystal display device of the present invention is that a liquid crystal layer made of a ferroelectric nematic liquid crystal substance is provided between a pair of transparent substrates to which a voltage can be applied. The possibility of the presence of ferroelectric nematic liquid crystals has long been predicted ("Novel Ferroelectric Fluids",
Rolfe G. Petschek and Kimbrly M. Wiefling, Physic
al Review Letters 1987 vol. 59, No. 3, pp. 343-346;
"Ferroelectric Nematic Liquid Crystals: Realizab
ility and Molecular Constraints ", P. Palffy-Muhora
y, MA Lee and Rolfe G. Petschek, Physical Review
Letters 1988 vol. 60, No. 22, pp. 2303-2306; "Fer
roelectric nematic liquid-crystal Phases of dipola
r hard ellipsiods ", Marc Baus and Jean-Lois Colot,
PhsicalReview A 1989 col. 40, No. 9, pp. 5444-544
6). In particular, the applicant is Mol. Cryst. Liq. Cryst. 1994, Vo
l. 254, pp. 395-403 "FERRO ELECTRIC"
LIQUID CRYSTALLINE ORDERING OF RIGID RODS WITH DIP
In a paper entitled "OLAR INTERACTIONS", the conventional isotropic-nematic: I
-N), nematic-ferroelectric nematic phase
o-electric nematic: N-FN) and direct isotropic-ferroelectric nematic:
A state diagram representing the I-FN) potential was presented.
【0018】最近、このような強誘電性ネマチック物質
の存在を立証する論文が発表されている。特に、自発分
極の方向が液晶ディレクタの方向と平行した強誘電性ネ
マチック物質の存在が報告されている。一般に、自発分
極または永久分極が存在する強誘電性物質の場合、印加
された電界に対して分極は平行になろうとする性質を有
する。従って、電界が印加された強誘電性ネマチック液
晶物質の場合、電界と平行または垂直になろうとする液
晶自体の性質と、電界に平行になろうとする分極の性質
を合わせ持った効果が現われるので、小さい電位差を加
えても液晶ディレクタの方向を容易に変えることができ
る。このような強誘電性液晶の性質を用いた本発明にか
かる液晶表示装置は、電圧を印加可能な一対の透明な基
板が互い向き合っており、その間に、強誘電性ネマチッ
ク液晶物質が充填された液晶層がある。Recently, a paper proving the existence of such a ferroelectric nematic substance has been published. In particular, the existence of a ferroelectric nematic substance in which the direction of spontaneous polarization is parallel to the direction of the liquid crystal director has been reported. Generally, in the case of a ferroelectric substance having spontaneous polarization or permanent polarization, it has a property that the polarization tends to be parallel to an applied electric field. Therefore, in the case of a ferroelectric nematic liquid crystal substance to which an electric field is applied, an effect having both the property of the liquid crystal itself that tends to be parallel or perpendicular to the electric field and the property of polarization that tends to be parallel to the electric field appears. Even if a small potential difference is applied, the direction of the liquid crystal director can be easily changed. In the liquid crystal display device according to the present invention using such a property of the ferroelectric liquid crystal, a pair of transparent substrates to which a voltage can be applied face each other, and a ferroelectric nematic liquid crystal substance is filled between them. There is a liquid crystal layer.
【0019】液晶物質は、液晶ディレクタと平行した自
発分極を持っているのが望ましい。この場合、液晶はp
型の誘電率異方性を持っているのが良い。2つの基板
は、水平配向に処理されることが有り得るし、水平配向
の方向は0°乃至360°ずれていて、その角度だけ液
晶ディレクタが回転していることも有り得る。液晶層に
キラール添加剤を追加して液晶層のピッチを調節するこ
とができ、液晶ディレクタは前記液晶層全体を通じて0
°乃至360°回転していることも有り得る。このと
き、2つの基板間の間隙を前記液晶層のピッチで割る値
が、0.0から1.0の間であってもよい。更に、2つ
の基板間の間隙と前記液晶層のピッチとの比は1:4で
あることが好ましい。そして、液晶物質の光学的異方性
と基板間の間隙との積は、0.1μmから2.0μmで
あってもよい。2つの基板に、偏光子がそれぞれ付着さ
れていてもよいし、2つの偏光子の偏光軸は液晶分子の
回転角度、又は液晶分子の回転角度に±90°を加えた
角度だけずらすようにしてもよい。又、2つの偏光子の
偏光軸は、互い平行するか直交するようにすることがで
きる。2つの基板の中、基板の一方または双方に位相差
板を付着されて視野角の特性を向上させるようにしても
よい。The liquid crystal material preferably has a spontaneous polarization parallel to the liquid crystal director. In this case, the liquid crystal is p
It should have a dielectric anisotropy of the mold. The two substrates may be processed for horizontal alignment, and the directions of horizontal alignment may be offset by 0 ° to 360 °, and the liquid crystal director may be rotated by that angle. A chiral additive may be added to the liquid crystal layer to control the pitch of the liquid crystal layer, and the liquid crystal director may have a thickness of 0.
It is possible that the rotation is between 0 ° and 360 °. At this time, a value obtained by dividing the gap between the two substrates by the pitch of the liquid crystal layer may be between 0.0 and 1.0. Further, the ratio of the gap between the two substrates and the pitch of the liquid crystal layer is preferably 1: 4. The product of the optical anisotropy of the liquid crystal substance and the gap between the substrates may be 0.1 μm to 2.0 μm. Polarizers may be attached to the two substrates, and the polarization axes of the two polarizers may be shifted by the rotation angle of the liquid crystal molecules or the rotation angle of the liquid crystal molecules plus ± 90 °. Good. Also, the polarization axes of the two polarizers can be parallel or orthogonal to each other. A phase difference plate may be attached to one or both of the two substrates to improve the viewing angle characteristics.
【0020】2つの基板の中、1つの基板に光を発する
発光手段を付着してもよいし、その代わりに反射板を付
着して自然光を用いてもよい。このような構成を持つ液
晶表示装置は、従来の捻じれたネマチック方式または超
捻じれたネマチック方式と類似な作用をする。下記に、
その作用を詳しく説明する。電圧が印加されていない
「OFF」状態では、液晶分子が捻じれた水平配列状態を
維持する。勿論、ここで初期傾斜角(Pretilt angle)は
存在する。このような状態で偏光された光が1つの基板
を通って入射されると、その光は捻じれた液晶層を通過
しながら偏光方向が回転する。光が液晶層を通過して他
の側の基板に到達したとき、光の偏光方向は液晶ディレ
クタが回転した分だけ回転する。もし、2つの偏光子の
偏光軸を、液晶ディレクタが捻じれた角度だけずらすよ
うに配置したとすれば、この光は2番目の偏光板を通過
するのである。しかし、2つの偏光板の偏光軸が、液晶
ディレクタが捻じれた角度より±90°ずらすように配
列したとすれば、光の偏光方向が2番目の偏光子の偏光
軸と垂直なので通過することができない。Of the two substrates, the light emitting means for emitting light may be attached to one of the substrates, or alternatively, a reflecting plate may be attached to use natural light. The liquid crystal display device having such a structure operates similarly to the conventional twisted nematic type or super twisted nematic type. Below,
The operation will be described in detail. In the “OFF” state where no voltage is applied, the liquid crystal molecules are maintained in a twisted horizontal alignment state. Of course, there is an initial tilt angle here. When light polarized in such a state enters through one substrate, the light rotates in the polarization direction while passing through the twisted liquid crystal layer. When the light passes through the liquid crystal layer and reaches the substrate on the other side, the polarization direction of the light is rotated by the amount of rotation of the liquid crystal director. If the polarization axes of the two polarizers are arranged so that they are offset by the twisted angle of the liquid crystal director, this light will pass through the second polarizer. However, if the polarization axes of the two polarizers are arranged so as to be offset by ± 90 ° from the twisted angle of the liquid crystal director, the light polarization direction is perpendicular to the polarization axis of the second polarizer, so the light will pass. I can't.
【0021】電界が印加された「ON」状態では、水平に
配列された液晶物質は液晶ディレクタに平行した永久分
極を持っているので、電界の方向に平行になるよう方向
を変えようとする。特に、液晶がp型の誘電率異方性を
持つ場合には、液晶自体の性質上、分子が電界と平行し
た方向に向かおうとする傾向があるので、永久分極によ
る効果と共に通常のネマチック液晶物質より低い電界で
も液晶分子の方向を変えられる。しかも、電界強度を調
節すると、液晶ディレクタが基板となす角度を適切に調
節できるので、階調表示が可能である。従って、片側の
基板に入射されて偏光された光は、液晶分子が傾いた角
度に従ってその偏光方向が回転するか、そうでなければ
回転しないままの状態で他の基板に到達するのである。
電界が十分大きく、液晶分子がほとんどの基板に対して
垂直に配列した場合を考えてみる。もし、2つの偏光子
の偏光軸が平行であれば、この光は2番目の偏光板を通
過する。しかし、2つの偏光板の偏光軸が±90°だけ
ずらすよう配列したとすると、光の偏光方向が2番目の
偏光子の偏光軸と垂直なので通過できないのである。In the “ON” state in which an electric field is applied, the horizontally aligned liquid crystal substance has a permanent polarization parallel to the liquid crystal director, so that the liquid crystal substance tries to change its direction to be parallel to the direction of the electric field. In particular, when the liquid crystal has a p-type dielectric anisotropy, the nature of the liquid crystal itself tends to cause the molecules to go in the direction parallel to the electric field. The direction of liquid crystal molecules can be changed even in an electric field lower than that of a substance. Moreover, since the angle formed by the liquid crystal director and the substrate can be adjusted appropriately by adjusting the electric field strength, gradation display is possible. Therefore, the light that is incident on one of the substrates and is polarized has its polarization direction rotated according to the angle at which the liquid crystal molecules are tilted, or otherwise reaches the other substrate without rotating.
Consider the case where the electric field is large enough that the liquid crystal molecules are aligned perpendicular to most substrates. If the polarization axes of the two polarizers are parallel, this light will pass through the second polarizer. However, if the polarization axes of the two polarizing plates are arranged so as to be offset by ± 90 °, the light cannot pass through because the polarization direction of light is perpendicular to the polarization axis of the second polarizer.
【0022】[0022]
【発明の実施の形態】本発明の実施形態にかかる液晶表
示装置を、前述の図1(イ)及び(ロ)を参照して詳し
く説明する。図1(イ)は電圧が印加されていない「OF
F」の状態を表し、図1(ロ)は電圧が印加されている
「ON」の状態を表す。図1(イ)及び(ロ)に示す通
り、この液晶表示装置は、水平配向処理をした1又は2
個の電極15,16と配向膜17,18を被覆した透明
な絶縁基板11,12が互いに向き合っている。その間
には、強誘電性ネマチック液晶物質が充填されている液
晶層10がある。そして、基板11,12の外側には、
偏光軸が一定角度をなす偏光子13,14がそれぞれ付
着されている。液晶層10に充填された強誘電性ネマチ
ック液晶物質は、自発分極が液晶ディレクタと平行する
p型誘電率異方性液晶を選ぶことが好ましい。このよう
な液晶物質に、S811,CB15等のキラール添加剤
を混ぜると、ネマチック物質であってもカイラリティー
を持つようになり、その混合されるキラール添加剤の量
を調節することにより、液晶物質のピッチを調節するこ
とができる。BEST MODE FOR CARRYING OUT THE INVENTION A liquid crystal display device according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 (a) and 1 (b) described above. Fig. 1 (a) shows "OF when no voltage is applied.
1B shows the state of "F", and FIG. 1B shows the state of "ON" in which a voltage is applied. As shown in FIGS. 1A and 1B, this liquid crystal display device has a horizontal alignment treatment 1 or 2.
The transparent insulating substrates 11 and 12 covering the individual electrodes 15 and 16 and the alignment films 17 and 18 face each other. In between is a liquid crystal layer 10 filled with a ferroelectric nematic liquid crystal material. Then, on the outside of the substrates 11 and 12,
Polarizers 13 and 14 whose polarization axes form a constant angle are attached. As the ferroelectric nematic liquid crystal material filled in the liquid crystal layer 10, it is preferable to select a p-type dielectric anisotropy liquid crystal whose spontaneous polarization is parallel to the liquid crystal director. When a chiral additive such as S811 and CB15 is mixed with such a liquid crystal substance, even a nematic substance has chirality, and by adjusting the amount of the mixed chiral additive, the liquid crystal substance is adjusted. You can adjust the pitch of.
【0023】液晶層10に接する配向膜17,18の両
表面は、水平配向をなす。一般に、アルキルフェノール
(alkylphenol)誘導体、ヘキサデカトリメチルアンモニ
ウム・ブロマイド(hexadecyltrimethylammonium bromid
e)等の界面活性剤、ポリイミド樹脂(polyimide)等に塗
布するか、SiOx 四方蒸着するか、ラングミュア・ブ
ロジェット・フィルム積層方法(Langmuir-Blodgett dep
osition method)で配向吸着剤を塗布した後、望む方向
にラビング(rubbing)して両基板の間に存在する液晶物
質らが基板11,12に水平に配向されるようにする。
このような水平配向処理は片側の基板にだけ行うことも
できるし、両基板に行うこともできる。両基板に水平配
向処理をする場合には、両基板の水平配向の方向をずら
すようにするのが望ましいが、両基板の水平配向方向の
相互になす角度は、0°から360°の範囲で任意に選
択できる。Both surfaces of the alignment films 17 and 18 in contact with the liquid crystal layer 10 are horizontally aligned. Generally, an alkylphenol
(alkylphenol) derivative, hexadecyltrimethylammonium bromid
e) or other surface active agent, polyimide resin (polyimide) coating, SiOx tetragonal vapor deposition, Langmuir-Blodgett dep method (Langmuir-Blodgett dep
After the alignment adsorbent is applied by an osition method), the liquid crystal substances existing between the substrates are horizontally aligned on the substrates 11 and 12 by rubbing in a desired direction.
Such horizontal alignment treatment can be performed on one substrate or both substrates. When performing horizontal alignment processing on both substrates, it is desirable to shift the horizontal alignment directions of both substrates, but the angle between the horizontal alignment directions of both substrates is in the range of 0 ° to 360 °. It can be arbitrarily selected.
【0024】両基板間の距離をdとし、液晶のピッチを
pとすると、d/pは任意として液晶のディレクタが、
電圧の印加された状態で液晶層10全体を通じて任意の
角度に回転するようにもできるが、およそ0.0から
1.0の間のものが望ましい。そして、この値が1/4
である場合は「off」状態で、液晶ディレクタが液晶層
10全体を通じて90°回転するようにできる。又、水
平配向をするとしても初期傾斜角を0°から180°程
度の範囲内で与えることもできる。If the distance between both substrates is d and the pitch of the liquid crystal is p, d / p is arbitrary and the director of the liquid crystal is
It is possible to rotate the liquid crystal layer 10 at any angle under the applied voltage, but it is preferable to rotate the liquid crystal layer 10 between about 0.0 and 1.0. And this value is 1/4
In the “off” state, the liquid crystal director can be rotated through 90 ° throughout the liquid crystal layer 10. Further, even if the orientation is horizontal, the initial tilt angle can be given within the range of about 0 ° to 180 °.
【0025】このような構成をもつ本実施形態による液
晶表示装置の作用を、詳しく説明する。電圧が印加され
ていない状態を表す図1(イ)のように、印加されてい
ない「off」状態では、液晶層10の液晶分子が水平配
列状態を維持する。このような状態で初めの偏光子13
を通過して変更された光が、基板11に対して垂直に入
射されると、この光は液晶ディレクタの回転に従ってそ
の偏光方向が回転しながら外の基板12及び偏光子14
に到達する。2番目の偏光子14の偏光軸が初めの偏光
子13の偏光軸となす角度は、液晶層10全体を通じる
液晶ディレクタの回転角度と同一であれば、2番目の偏
光子14に到達する光は、その偏光方向が2番目の偏光
子14と平行になり、従って2番目の偏光子14を通過
する。しかし、2番目の偏光子14の偏光軸が初めの偏
光子13の偏光軸となす角度が、液晶層10全体を通じ
た液晶ディレクタの回転角度に±90°をたした値と同
一であれば、2番目の偏光子14に到達した光は、その
偏光方向が2番目の偏光子14と平行となり、従って、
2番目の偏光子を通過する。ところが、2番目の偏光子
14の偏光軸が初めの偏光子13の偏光軸となす角度
が、液晶層10全体を通じる液晶ディレクタの回転角度
に±90°を加えた値と同じであれば、2番目の偏光子
14に到達した光は、その偏光方向が2番目の偏光向1
4と垂直となり、従って、2番目の偏光子14を通過す
ることができない。The operation of the liquid crystal display device according to the present embodiment having the above structure will be described in detail. As shown in FIG. 1A, which represents a state in which no voltage is applied, the liquid crystal molecules of the liquid crystal layer 10 maintain the horizontal alignment state in the “off” state in which no voltage is applied. In this state, the first polarizer 13
When the changed light passes through the substrate 11 and is vertically incident on the substrate 11, the light has its polarization direction rotated according to the rotation of the liquid crystal director, and the outer substrate 12 and the polarizer 14 are rotated.
To reach. If the angle formed by the polarization axis of the second polarizer 14 and the polarization axis of the first polarizer 13 is the same as the rotation angle of the liquid crystal director throughout the liquid crystal layer 10, the light that reaches the second polarizer 14 Has its polarization direction parallel to the second polarizer 14 and therefore passes through the second polarizer 14. However, if the angle formed by the polarization axis of the second polarizer 14 and the polarization axis of the first polarizer 13 is equal to the value obtained by adding ± 90 ° to the rotation angle of the liquid crystal director throughout the liquid crystal layer 10, The light that reaches the second polarizer 14 has its polarization direction parallel to the second polarizer 14, and thus,
It passes through the second polarizer. However, if the angle formed by the polarization axis of the second polarizer 14 and the polarization axis of the first polarizer 13 is equal to the value obtained by adding ± 90 ° to the rotation angle of the liquid crystal director throughout the liquid crystal layer 10, The light that reaches the second polarizer 14 has the second polarization direction 1
4 and thus cannot pass through the second polariser 14.
【0026】図1(ロ)は、電圧が印加されて液晶ディ
レクタが変化した形を示すものである。電界が印加され
ると、水平に配列された液晶物質はディレクタの平行し
た永久分極を持っている強誘電性物質なので、ディレク
タが電界に対して平行配列しようとする。更に、液晶物
質がp型の誘電率異方性を持っている場合は、ディレク
タが、一層容易に電界に対して平行に配列しようとす
る。電界が十分に強いと、全ての液晶分子が電界に対し
て平行配列することもできるが、そうでない場合は、電
界と平行でない一定な角度を維持する。そして、基板1
1,12の表面に近くなればなるほど水平配向力が強く
作用するので、基板表面に近づくば近づくほど水平に近
く配列される。それでは十分強い電界が印加されて、液
晶ディレクタが基板11,12に対してほぼ垂直に配列
しており、光が初めの基板に対して垂直に入射したとす
る。線型偏光子13を通過した光は、基板11の面に平
行に偏光されるであろう。初めの基板11を通過して、
線偏光された光は何の影響を受けないで液晶層を通過
し、2番目の基板12に到達する。もし、2つの偏光子
13,14の偏光軸が互い直交しているとすれば、光の
偏光方向は、2番目の偏光子14の偏光軸と垂直である
ので、2番目の偏光子14を通過することはできない。
しかし、2つの偏光子13,14の偏光軸が互い平行で
あれば、光の偏光方向は2番目の偏光子14の偏光軸と
平行であるので、2番目の偏光子14を通過する。この
とき、光が液晶セルを透過する程度は、2つの基板1
1,12の間の距離d、屈折率異方性Δn、入射光の波
長λ等に依存するが、偏光子が互いに平行である場合、
これを数式で表すと次の通りである。FIG. 1B shows a shape in which the liquid crystal director is changed by applying a voltage. When an electric field is applied, the horizontally aligned liquid crystal substance is a ferroelectric substance having a director's parallel permanent polarization, and therefore the director tries to align it in parallel to the electric field. Further, if the liquid crystal material has a p-type dielectric anisotropy, the director tends to more easily align parallel to the electric field. If the electric field is strong enough, all liquid crystal molecules can be aligned parallel to the electric field, but otherwise maintain a constant angle that is not parallel to the electric field. And the substrate 1
Since the horizontal aligning force is stronger as it gets closer to the surface of Nos. 1 and 12, it becomes closer to horizontal as it gets closer to the surface of the substrate. Then, it is assumed that a sufficiently strong electric field is applied, the liquid crystal directors are arranged substantially perpendicularly to the substrates 11 and 12, and light is incident perpendicularly to the first substrate. Light that has passed through the linear polarizer 13 will be polarized parallel to the plane of the substrate 11. Passing through the first substrate 11,
The linearly polarized light passes through the liquid crystal layer without any influence and reaches the second substrate 12. If the polarization axes of the two polarizers 13 and 14 are orthogonal to each other, the polarization direction of light is perpendicular to the polarization axis of the second polarizer 14, so that the second polarizer 14 is You cannot pass.
However, if the polarization axes of the two polarizers 13 and 14 are parallel to each other, the polarization direction of light is parallel to the polarization axis of the second polarizer 14, and therefore passes through the second polarizer 14. At this time, the degree to which light passes through the liquid crystal cell is such that the two substrates 1
Depending on the distance d between 1 and 12, the refractive index anisotropy Δn, the wavelength λ of the incident light, etc., when the polarizers are parallel to each other,
This can be expressed by a mathematical formula as follows.
【0027】[0027]
【数4】T=1−(sin2(π/2)Sqrt[1+
u2])/(1+u2)## EQU4 ## T = 1− (sin 2 (π / 2) Sqrt [1+
u 2 ]) / (1 + u 2 )
【0028】ここで、Sqrt[1+u2]は(1+
u2)の平方根を示し、Tは偏光されていない単色光の
透過率であり、u=2d(△n/λ)である。この式で
わかるように、Tは、μ=0、Sqrt[3]、Sqr
t[15]、Sqrt[35]で極大値になり、Sqr
t[3]から次第に第1極大、第2極大などと呼ぶ。可
視光線の波長は、ほぼ0.4μm〜0.7μmまでなの
で、第3極大までを用いるとすれば、dΔnを2μm以
下にすることが望ましい。特に、0.08μm〜2μm
迄にすることが望ましい。Here, Sqrt [1 + u 2 ] is (1+
u 2 ), where T is the transmittance of unpolarized monochromatic light, u = 2d (Δn / λ). As can be seen from this equation, T is μ = 0, Sqrt [3], Sqr
At t [15] and Sqrt [35], the maximum value is reached, and Sqr
From t [3], they are called the first maximum, the second maximum, and so on. Since the wavelength of visible light is approximately 0.4 μm to 0.7 μm, it is desirable that dΔn be 2 μm or less if the third maximum is used. Particularly, 0.08 μm to 2 μm
It is desirable to do so.
【0029】図2は、液晶層全体を通じて液晶ディレク
タが90°回転した場合、即ち、通常の捻じれたネマチ
ック方式で作成した強誘電性ネマチック液晶表示装置に
印加された電圧に対する透過率の変化を、従来の捻じれ
たネマチック方式の液晶表示装置と比較して示したもの
である。誘電率異方性Δε=+5である液晶層の厚さを
5μmとして、2つの偏光子の偏光軸が直交するように
配置して実現した結果、図2のグラフと同じく、強誘電
性のないネマチック液晶物質を使った時より低電圧でも
透過率が変化して、自発分極pの値が大きくなればなる
ほど印加された電圧に対する透過率は、急激に変化する
ことがわかる。以上の通りであるから本実施形態の液晶
表示装置は、種々の液晶を用いた表示装置に適用可能で
ある。例えば、マトリックス方式の液晶表示装置などに
も使用可能である。FIG. 2 shows a change in transmittance with respect to a voltage applied to a ferroelectric nematic liquid crystal display device manufactured by a conventional twisted nematic method when the liquid crystal director is rotated by 90 ° throughout the liquid crystal layer. This is shown in comparison with a conventional twisted nematic liquid crystal display device. When the thickness of the liquid crystal layer having a dielectric anisotropy Δε = + 5 is set to 5 μm and the polarizers are arranged so that the polarization axes of the two polarizers are orthogonal to each other, the result is the same as in the graph of FIG. It can be seen that the transmissivity changes even at a lower voltage than when a nematic liquid crystal material is used, and the transmissivity with respect to the applied voltage changes abruptly as the value of the spontaneous polarization p increases. As described above, the liquid crystal display device of this embodiment is applicable to display devices using various liquid crystals. For example, it can be used for a matrix type liquid crystal display device and the like.
【0030】[0030]
【発明の効果】このように、本発明は、強誘電性ネマチ
ック液晶物質を2つの基板間に、好ましくは水平配向す
ることによって、従来のネマチック液晶を用いた液晶表
示装置の長所を生かしながら、従来のネマチック液晶を
用いた表示装置より小さい駆動電圧で駆動でき、従来の
強誘電性スメクチックC*液晶表示装置で現われる配向
の問題も容易に解決でき、しかも動作速度の速い液晶表
示装置を提供できた。As described above, according to the present invention, the ferroelectric nematic liquid crystal material is aligned horizontally between the two substrates, preferably in the horizontal direction, thereby utilizing the advantages of the conventional liquid crystal display device using the nematic liquid crystal. A liquid crystal display device that can be driven with a driving voltage smaller than that of a display device using a conventional nematic liquid crystal, can easily solve the alignment problem that appears in the conventional ferroelectric smectic C * liquid crystal display device, and can provide a liquid crystal display device with a high operating speed. It was
【図1】従来技術および本発明の実施形態を説明するた
めの液晶表示装置の断面図で、 (イ)は「off」状態 (ロ)は「on」状態FIG. 1 is a cross-sectional view of a liquid crystal display device for explaining a conventional technique and an embodiment of the present invention, in which (a) is an “off” state and (b) is an “on” state.
【図2】本発明の実施形態の液晶表示装置から印加電圧
と透過率の変化を表したグラフFIG. 2 is a graph showing changes in applied voltage and transmittance of the liquid crystal display device according to the embodiment of the present invention.
10 液晶層 11,12 基板 13,14 偏光板 10 Liquid crystal layer 11, 12 Substrate 13, 14 Polarizing plate
Claims (18)
強誘電性ネマチック液晶物質からなる液晶層を有する液
晶表示装置。1. A pair of transparent substrates to which a voltage can be applied,
A liquid crystal display device having a liquid crystal layer made of a ferroelectric nematic liquid crystal substance.
タと平行な自発分極をもっている強誘電性ネマチック物
質である請求項1記載の液晶表示装置。2. The liquid crystal display device according to claim 1, wherein the liquid crystal material of the liquid crystal layer is a ferroelectric nematic material having spontaneous polarization parallel to the liquid crystal director.
性をもっている請求項2記載の液晶表示装置。3. The liquid crystal display device according to claim 2, wherein the material of the liquid crystal layer has p-type dielectric anisotropy.
ている請求項1〜3のいずれか1項記載の液晶表示装
置。4. The liquid crystal display device according to claim 1, wherein the two substrates are horizontally aligned.
乃至360°ずれていて、その角度だけ液晶ディレクタ
が回転している請求項4記載の液晶表示装置。5. The horizontal alignment direction of the two substrates is 0 °.
5. The liquid crystal display device according to claim 4, wherein the liquid crystal director is shifted by 360 ° to 360 °, and the liquid crystal director is rotated by that angle.
晶層にキラール添加剤が含まれている請求項1又は3記
載の液晶表示装置。6. The liquid crystal display device according to claim 1, wherein a chiral additive is contained in the liquid crystal layer for adjusting the pitch of the liquid crystal layer.
は、前記液晶層の全体を通じて0°乃至360°回転し
ている請求項6記載の液晶表示装置。7. The liquid crystal display device according to claim 6, wherein the liquid crystal director of the liquid crystal material of the liquid crystal layer is rotated by 0 ° to 360 ° through the entire liquid crystal layer.
のピッチで割った値が0.0〜1.0である請求項5又
は7記載の液晶表示装置。8. The liquid crystal display device according to claim 5, wherein a value obtained by dividing the gap between the two substrates by the pitch of the liquid crystal layer is 0.0 to 1.0.
ピッチとの比が、1:4である請求項8記載の液晶表示
装置。9. The liquid crystal display device according to claim 8, wherein a ratio of a gap between the two substrates and a pitch of the liquid crystal layer is 1: 4.
と前記基板間の間隙の積が、0.1μmから2.0μm
である請求項9記載の液晶表示装置。10. The product of the refractive index anisotropy of the liquid crystal material of the liquid crystal layer and the gap between the substrates is 0.1 μm to 2.0 μm.
10. The liquid crystal display device according to claim 9.
着されている請求項5、7又は9記載の液晶表示装置。11. The liquid crystal display device according to claim 5, wherein a polarizer is attached to each of the two substrates.
晶層の液晶分子の回転角度だけずれている請求項11記
載の液晶表示装置。12. The liquid crystal display device according to claim 11, wherein the polarization axes of the two polarizers are displaced from each other by a rotation angle of liquid crystal molecules of the liquid crystal layer.
晶層の液晶分子の回転角度に±90°を加えた角度だけ
ずれている請求項11記載の液晶表示装置。13. The liquid crystal display device according to claim 11, wherein the polarization axes of the two polarizers are displaced from each other by an angle obtained by adding ± 90 ° to a rotation angle of liquid crystal molecules of the liquid crystal layer.
平行である請求項11記載の液晶表示装置。14. The liquid crystal display device according to claim 11, wherein the polarization axes of the two polarizers are parallel to each other.
直交する請求項11記載の液晶表示装置。15. The liquid crystal display device according to claim 11, wherein the polarization axes of the two polarizers are orthogonal to each other.
2つの基板前部に位相差板が付着されている請求項1、
3、5又は7記載の液晶表示装置。16. The retardation plate is attached to one of the two substrates or to the front of the two substrates.
The liquid crystal display device according to 3, 5, or 7.
光を発する発光手段が付着されている請求項1、3、5
又は7記載の液晶表示装置。17. On one of the two substrates,
6. A light emitting means for emitting light is attached.
Alternatively, the liquid crystal display device according to item 7.
反射板が付着されている請求項1、3、5又は7記載の
液晶表示装置。18. On one of the two substrates,
The liquid crystal display device according to claim 1, wherein a reflective plate is attached.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1019950021314A KR970007426A (en) | 1995-07-20 | 1995-07-20 | Ferroelectric Nematic Liquid Crystal Display |
KR1995-21314 | 1995-07-20 |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH0933957A true JPH0933957A (en) | 1997-02-07 |
Family
ID=19420977
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP8192230A Pending JPH0933957A (en) | 1995-07-20 | 1996-07-22 | Liquid-crystal display device |
Country Status (5)
Country | Link |
---|---|
JP (1) | JPH0933957A (en) |
KR (1) | KR970007426A (en) |
CN (1) | CN1165311A (en) |
DE (1) | DE19629551A1 (en) |
GB (1) | GB2303464A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2014003399A1 (en) * | 2012-06-25 | 2014-01-03 | 한양대학교 산학협력단 | Liquid crystal composition |
US9664957B2 (en) | 2012-06-25 | 2017-05-30 | Industry-University Cooperation Foundation Hanyang University | Liquid crystal display device and method of driving the same |
US9670410B2 (en) | 2012-06-25 | 2017-06-06 | Industry-University Cooperation Foundation Hanyang University | Liquid crystal composition |
Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR19990027489A (en) * | 1997-09-30 | 1999-04-15 | 윤종용 | Vertically oriented twisted nematic liquid crystal display with ferroelectric liquid crystal |
KR19980033499A (en) * | 1998-04-18 | 1998-07-25 | 이신두 | Reflective liquid crystal display with twisted nematic hybrid orientation |
KR100320102B1 (en) * | 1998-11-21 | 2002-04-22 | 김원대 | Vertically Aligned Helix-Deformed Liquid Crystal Display |
KR100683646B1 (en) * | 2000-04-06 | 2007-02-20 | 삼성에스디아이 주식회사 | A smart card having a display using FLCP |
KR101333614B1 (en) * | 2010-06-25 | 2013-11-27 | 엘지디스플레이 주식회사 | Liquid crystal display device |
CN106773154A (en) * | 2016-11-22 | 2017-05-31 | 福州大学 | A kind of liquid crystal director rapid measurement device and its implementation |
JP2023551552A (en) | 2020-12-02 | 2023-12-08 | メルク パテント ゲゼルシャフト ミット ベシュレンクテル ハフツング | liquid crystal compound |
WO2022117552A1 (en) | 2020-12-02 | 2022-06-09 | Merck Patent Gmbh | Ferroelectric nematic liquid crystalline medium |
WO2023086522A1 (en) * | 2021-11-10 | 2023-05-19 | The Regents Of The University Of Colorado, A Body Corporate | Charge-controlled devices and methods of forming and using same |
WO2023133356A2 (en) * | 2022-01-10 | 2023-07-13 | The Regents Of The University Of Colorado, A Body Corporate | Composite materials based on ferroelectric nematic liquid crystals and devices including same |
WO2023232754A1 (en) | 2022-05-31 | 2023-12-07 | Merck Patent Gmbh | Ferroelectric nematic liquid crystalline medium |
CN117331260B (en) * | 2023-11-20 | 2024-06-14 | 南京邮电大学 | Method for realizing microsecond electro-optic response of low driving electric field in ferroelectric nematic liquid crystal |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS61137127A (en) * | 1984-12-07 | 1986-06-24 | Hitachi Ltd | Liquid crystal display element |
JPS62194224A (en) * | 1986-02-20 | 1987-08-26 | Sharp Corp | Twisted nematic type liquid crystal display element |
JP2551848B2 (en) * | 1989-07-25 | 1996-11-06 | セイコープレシジョン株式会社 | Ferroelectric liquid crystal panel |
US5539555A (en) * | 1990-07-20 | 1996-07-23 | Displaytech, Inc. | High contrast distorted helex effect electro-optic devices and tight ferroelectric pitch ferroelectric liquid crystal compositions useful therein |
-
1995
- 1995-07-20 KR KR1019950021314A patent/KR970007426A/en not_active Application Discontinuation
-
1996
- 1996-07-19 GB GB9615197A patent/GB2303464A/en not_active Withdrawn
- 1996-07-20 CN CN96112274A patent/CN1165311A/en active Pending
- 1996-07-22 JP JP8192230A patent/JPH0933957A/en active Pending
- 1996-07-22 DE DE19629551A patent/DE19629551A1/en not_active Withdrawn
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2014003399A1 (en) * | 2012-06-25 | 2014-01-03 | 한양대학교 산학협력단 | Liquid crystal composition |
US9664957B2 (en) | 2012-06-25 | 2017-05-30 | Industry-University Cooperation Foundation Hanyang University | Liquid crystal display device and method of driving the same |
US9670410B2 (en) | 2012-06-25 | 2017-06-06 | Industry-University Cooperation Foundation Hanyang University | Liquid crystal composition |
US9977294B2 (en) | 2012-06-25 | 2018-05-22 | Industry-University Cooperation Foundation Hanyang University | Liquid crystal display device |
Also Published As
Publication number | Publication date |
---|---|
GB2303464A (en) | 1997-02-19 |
CN1165311A (en) | 1997-11-19 |
GB9615197D0 (en) | 1996-09-04 |
DE19629551A1 (en) | 1997-01-23 |
KR970007426A (en) | 1997-02-21 |
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