WO1990006534A1 - Electro-optical arrangement - Google Patents

Electro-optical arrangement Download PDF

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Publication number
WO1990006534A1
WO1990006534A1 PCT/EP1989/001446 EP8901446W WO9006534A1 WO 1990006534 A1 WO1990006534 A1 WO 1990006534A1 EP 8901446 W EP8901446 W EP 8901446W WO 9006534 A1 WO9006534 A1 WO 9006534A1
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WO
WIPO (PCT)
Prior art keywords
electro
nematic
optical arrangement
optical
cell
Prior art date
Application number
PCT/EP1989/001446
Other languages
German (de)
French (fr)
Inventor
Bernd Brauer
Harri Brauer
Original Assignee
MERCK Patent Gesellschaft mit beschränkter Haftung
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.)
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Publication of WO1990006534A1 publication Critical patent/WO1990006534A1/en

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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
    • G02F1/133—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
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • 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
    • G02F1/133528—Polarisers
    • G02F1/133531—Polarisers characterised by the arrangement of polariser or analyser axes
    • 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
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G02F1/133638—Waveplates, i.e. plates with a retardation value of lambda/n
    • 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
    • G02F1/1347—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
    • G02F1/13471—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells
    • 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
    • G02F2413/00—Indexing scheme related to G02F1/13363, i.e. to birefringent elements, e.g. for optical compensation, characterised by the number, position, orientation or value of the compensation plates
    • G02F2413/01—Number of plates being 1

Definitions

  • the invention relates to an electro-optical arrangement for modulating circularly polarized light.
  • electro-optical arrangements can generally be used in optical displays and as modulation devices.
  • Liquid crystal devices are known in which the twisted nematic phase effect is used (Appl. Phys. Lett. Vol. 18, No. 4, 127-128 / 1971). It is controlled according to the effective value method and a uniform achromatic contrast is achieved (Alt P.M. and Pleshko P. IEEE Trans. Electron. Dev. ED 21, 146/1974).
  • the time dependence of the optical effect can only be influenced via the material parameters, such as viscosity and elastic constants. The time constant is too long for many applications.
  • the object of the invention is to provide an electro-optical arrangement with which the inexpensive technology of the twisted nematic phase can be used and an improved switching regime can be implemented using the polar properties of nematic substances.
  • the polarity of the voltages can be switched from a right-handed to a left-handed optical structure.
  • the structures have different interference conditions in the 45 "position.
  • a light source 1 which emits white light that is transmitted through a polarizer 2 e.g. is polarized in the direction of the arrow.
  • the direction-polarized light is converted into circular-polarized light by means of a downstream double-spreading film 3 and passes through a nematic rotary cell 4 which contains a nematic mixture with a very high positive DK anisotropy (eg ZLI 1289) and is arranged in the 45 "position
  • the nematic rotary cell 4 is connected to a voltage source 5, via whose positive and negative impulses the transmission of the light passing through can be changed quickly, and finally the light arrives at a photodiode 7 via an analyzer 6 and can be evaluated.
  • interference occurs.
  • the analyzer 6 which effects a polarization of the light oriented perpendicular to the polarizer 1
  • interference occurs.
  • the right-handed circularly polarized wave of light is preferred to the left-handed one and when switching to a negative pulse of 5 V, for example, the left-handed wave is preferred.
  • a color-neutral interference order can be implemented, the two switching times being less than 1 ms.
  • the relaxation time can be influenced by the voltage and thus improved properties can be achieved.

Landscapes

  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
  • Liquid Crystal (AREA)

Abstract

In an electro-optical arrangement for modulating circularly polarized light, the nematic phase is transported by a cost-effective technology and the polar properties of the nematic substances are exploited in order to obtain an improved switching regime. To this end, the arrangement comprises a polarizer (2), a birefringent layer (3), a rotary nematic cell (4) and a polarizing analyser (6). The rotary nematic cell (4) is set at 45 to the polarizers (2, 6) and the transmission conditions can be varied by applying positive and negative voltages.

Description

Elektrooptische Anordnung Electro-optical arrangement
Die Erfindung betrifft eine elektrooptische Anordnung zur Modulation zirkulär polarisierten Lichtes. Solche elektrooptischen Anordnungen sind in optischen Anzeigen und als Modulationsvorrichtungen generell verwendbar.The invention relates to an electro-optical arrangement for modulating circularly polarized light. Such electro-optical arrangements can generally be used in optical displays and as modulation devices.
Es sind Flüssigkristallvorrichtungen bekannt, bei denen der Effekt der verdrillten nematischen Phase genutzt wird (Appl. Phys. Lett. Bd. 18, No. 4, 127-128/1971). Es wird nach dem Effektivwertverfahren angesteuert und man erreicht einen gleichmäßigen achromatischen Kontrast (Alt P.M. and Pleshko P. IEEE Trans. Electron. Dev. ED 21, 146/1974). Die Zeitabhängigkeit des optischen Effektes kann nur über die Materialparameter, wie Viskosität und elastische Konstanten beeinflußt werden. Die Zeitkonstante ist für viele Anwendungen zu lang.Liquid crystal devices are known in which the twisted nematic phase effect is used (Appl. Phys. Lett. Vol. 18, No. 4, 127-128 / 1971). It is controlled according to the effective value method and a uniform achromatic contrast is achieved (Alt P.M. and Pleshko P. IEEE Trans. Electron. Dev. ED 21, 146/1974). The time dependence of the optical effect can only be influenced via the material parameters, such as viscosity and elastic constants. The time constant is too long for many applications.
Eine entscheidende Verbesserung bezüglich der Zeitab¬ hängigkeit kristallinflüssiger optischer Schaltelemente ist aus der US-PS 4 367 924 bekannt. Es werden dort die ferroelektrischen Eigenschaften smektischer C*-Phasen ausgenutzt, um sowohl die Anklingzeit als auch die Rela¬ xationszeit durch einen Spannungsimpuls entsprechender Polarität zu beeinflussen. Die Nutzbarkeit dieser vor¬ teilhaften Eigenschaften ist aber an extreme technolo¬ gische Forderungen geknüpft (S.T. Lagerwall, I. Dahl Mol. Cryst. Li. Cryst. vol. 114, pp. 151-187/1984). So sind sehr kleine Schichtdicken von etwa 1-3 μm erfor¬ derlich, um die Ausbildung einer kompletten Helix der S*-Phase zu verhindern. Weiterhin ist die Realisierung eines eindo änigen Zustands des Flüssigkristalls εchwie- rig. Die sehr aufwendige Technologie bildet in Verbindung mit dem erheblichen Kostenfaktor für eine Ausnützung dieses Effektes ein großes Hindernis.A decisive improvement with regard to the time dependency of crystalline-liquid optical switching elements is known from US Pat. No. 4,367,924. The ferroelectric properties of smectic C * phases are used there in order to influence both the response time and the relaxation time by means of a voltage pulse of corresponding polarity. However, the usability of these advantageous properties is linked to extreme technological requirements (ST Lagerwall, I. Dahl Mol. Cryst. Li. Cryst. Vol. 114, pp. 151-187 / 1984). Very small layer thicknesses of about 1-3 μm are necessary in order to prevent the formation of a complete helix of the S * phase. Furthermore, the realization of a one-state state of the liquid crystal is difficult. The very complex technology combined with the considerable cost factor for exploiting this effect is a major obstacle.
Neuere Untersuchungen zeigen, daß es eine feldinduzierte Biaxilität in Nematen mit negativer DK-Anisotropie gibt (T.F. Waterworth in Mol. Cryst. Liq. Cryst. 1985, vol. 124, pp. 73-88 und 1987, vol. 149, pp. 385-392); dabei werden jedoch nur die 2. optische und höhere gerade optische Harmonische betrachtet, die für eine elektro¬ optische Anzeige praktisch nicht nutzbar sind.Recent studies show that there is field-induced biaxility in nemates with negative DK anisotropy (TF Waterworth in Mol. Cryst. Liq. Cryst. 1985, vol. 124, pp. 73-88 and 1987, vol. 149, pp. 385 -392); however, only the 2nd optical and higher straight optical harmonics are considered, which are practically unusable for an electro-optical display.
Aufgabe der Erfindung ist es, eine elektrooptische Anord¬ nung anzugeben, mit der die kostengünstige Technologie der verdrillten nematischen Phase genutzt und ein ver¬ bessertes Schaltregime unter Nutzung der polaren Eigen¬ schaften nematischer Substanzen realisiert werden kann.The object of the invention is to provide an electro-optical arrangement with which the inexpensive technology of the twisted nematic phase can be used and an improved switching regime can be implemented using the polar properties of nematic substances.
Es wurde gefunden, daß die Transmission einer verdrillten nematischen Zelle mit einer Substanz mit positiver DK- Anisotropie beim Durchstrahlen mit zirkulär polarisiertem Licht in der 45"-Stellung - nach Passieren eines Analysa- tors - durch elektrische Spannungen unterschiedlicher Polarität beeinflußt werden kann. Durch Änderung derIt was found that the transmission of a twisted nematic cell with a substance with positive DK anisotropy when irradiated with circularly polarized light in the 45 "position - after passing through an analyzer - can be influenced by electrical voltages of different polarity the
Polarität der Spannungen kann von einer rechtsdrehenden zu einer linksdrehenden optischen Struktur umgeschaltet werden. Die Strukturen haben in der 45"-Stellung unter¬ schiedliche Interferenzbedingungen.The polarity of the voltages can be switched from a right-handed to a left-handed optical structure. The structures have different interference conditions in the 45 "position.
ERSATZ Die gestellte Aufgabe wird nach der Erfindung gemäß den kennzeichnenden Merkmalen des Anspruches 1 gelöst. Vor¬ teilhafte Ausgestaltungen sind den Unteransprüchen ent¬ nehmbar.REPLACEMENT The object is achieved according to the invention according to the characterizing features of claim 1. Advantageous refinements can be found in the subclaims.
Anhand eines schematischen Ausführungsbeispieles für eine optische Modulationsvorrichtung wird die Erfindung im nachstehenden näher erläutert.The invention is explained in more detail below on the basis of a schematic exemplary embodiment for an optical modulation device.
In der Figur ist eine Lichtquelle 1 dargestellt, die weißes Licht abgibt, das durch einen Polarisator 2 beim Durchtritt z.B. in Pfeilrichtung polarisiert wird. Durch eine nachgeschaltete doppelbreσhende Folie 3 wird das richtungspolarisierte Licht in zirkularpolarisiertes Licht umgewandelt und gelangt durch eine nematische Drehzelle 4, die eine nematische Mischung mit sehr hoher positiver DK-Anisotropie (z.B. ZLI 1289) enthält und in der 45"-Stellung angeordnet ist. An die nematische Drehzelle 4 ist eine Spannungsquelle 5 angeschlossen, über deren positive und negative Impulse die Transmission des hindurchtretenden Lichtes schnell verändert werden kann. Das Licht gelangt schließlich über einen Analy¬ sator 6 auf eine Photodiode 7 und kann ausgewertet werden.In the figure, a light source 1 is shown, which emits white light that is transmitted through a polarizer 2 e.g. is polarized in the direction of the arrow. The direction-polarized light is converted into circular-polarized light by means of a downstream double-spreading film 3 and passes through a nematic rotary cell 4 which contains a nematic mixture with a very high positive DK anisotropy (eg ZLI 1289) and is arranged in the 45 "position The nematic rotary cell 4 is connected to a voltage source 5, via whose positive and negative impulses the transmission of the light passing through can be changed quickly, and finally the light arrives at a photodiode 7 via an analyzer 6 and can be evaluated.
Nach Passieren des Analysators 6, der eine senkrecht zum Polarisator 1 ausgerichtete Polarisierung des Lichtes bewirkt, kommt es zur Interferenz. So wird beim Anlegen eines positiven Impulses von 5 V z.B. die rechtsdrehende zirkulär polarisierte Welle des Lichtes gegenüber der linksdrehenden bevorzugt durchgelassen und beim Umschalten auf einen negativen Impuls von 5 V umgekehrt z.B. die linksdrehende Welle bevorzugt. Damit ergibt sich ein polaritätsabhängiger Transmissionsunterschied. Mit höhe- rer Spannung kann eine farbneutrale Interferenzordnung realisiert werden, wobei die beiden Schaltzeiten unter¬ halb 1 ms liegen.After passing through the analyzer 6, which effects a polarization of the light oriented perpendicular to the polarizer 1, interference occurs. For example, when a positive pulse of 5 V is applied, the right-handed circularly polarized wave of light is preferred to the left-handed one and when switching to a negative pulse of 5 V, for example, the left-handed wave is preferred. This results in a polarity-dependent transmission difference. With high With the voltage, a color-neutral interference order can be implemented, the two switching times being less than 1 ms.
Durch das εpannungsinduzierte Umschalten von einer Struktur in die entgegengesetzte ist die Relaxationεzeit durch die Spannung beeinflußbar und es können so verbes¬ serte Eigenschaften realisiert werden. As a result of the voltage-induced switching from one structure to the opposite, the relaxation time can be influenced by the voltage and thus improved properties can be achieved.

Claims

Patentansprüche Claims
1. Elektrooptische Anordnung zur Modulation zirkulär polarisierten Lichtes, dadurch gekennzeichnet, daß eine Anordnung aus einem Polarisator (2) , einer doppelbrechenden Schicht (3) , einer nematischen1. Electro-optical arrangement for modulating circularly polarized light, characterized in that an arrangement of a polarizer (2), a birefringent layer (3), a nematic
Drehzelle (4) und einem polarisierenden Analysator (6) Verwendung findet, wobei die nematische Dreh¬ zelle (4) in der 45°-Stellung zu den Polarisatoren (2, 6) angeordnet ist und mittels anlegbarer posi- tiver und negativer Spannungen die Transmissions- bedingungen veränderbar sind.Rotary cell (4) and a polarizing analyzer (6) are used, the nematic rotary cell (4) being arranged in the 45 ° position to the polarizers (2, 6) and the transmissions by means of positive and negative voltages that can be applied - conditions are changeable.
2. Elektrooptische Anordnung nach Anspruch 1, dadurch gekennzeichnet, daß eine nematische Drehzelle (4) mit einem Verdrillungswinkel von 0 bis 270° Verwen- düng findet.2. Electro-optical arrangement according to claim 1, characterized in that a nematic rotary cell (4) with a twist angle of 0 to 270 ° is used.
3. Elektrooptische Anordnung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die doppelbrechende Schicht (3) aus einer Folie besteht.3. Electro-optical arrangement according to claim 1 or 2, characterized in that the birefringent layer (3) consists of a film.
4. Elektrooptische Anordnung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die doppelbrechende4. Electro-optical arrangement according to claim 1 or 2, characterized in that the birefringent
Schicht (3) aus einer elektrisch schaltbaren Flüεεiσkristallzelle besteht. Layer (3) consists of an electrically switchable liquid crystal cell.
PCT/EP1989/001446 1988-12-01 1989-11-28 Electro-optical arrangement WO1990006534A1 (en)

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DE3840797A DE3840797A1 (en) 1988-12-01 1988-12-01 ELECTROOPTIC ARRANGEMENT
DEP3840797.3 1988-12-01

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WO1990006534A1 true WO1990006534A1 (en) 1990-06-14

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DE102009057033A1 (en) * 2009-12-04 2011-06-09 Bayerische Motoren Werke Aktiengesellschaft Projection unit for a head-up display and method for operating a projection unit for a head-up display

Citations (3)

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Publication number Priority date Publication date Assignee Title
FR2331110A1 (en) * 1974-09-16 1977-06-03 Beckman Instruments Inc Liquid crystal display cell - has front depolariser plate enabling viewing through polarising sunglasses or car windscreen
EP0162775A2 (en) * 1984-05-18 1985-11-27 Commissariat A L'energie Atomique Liquid-crystal cell presenting a homeotropic structure, with birefringence compensation for this structure
EP0239433A1 (en) * 1986-02-28 1987-09-30 Commissariat A L'energie Atomique Liquid-crystal cell with electrically controlled birefringence and method for making the same

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Publication number Priority date Publication date Assignee Title
FR2358676A1 (en) * 1976-07-13 1978-02-10 Labo Electronique Physique INFORMATION DISPLAY DEVICE CONTAINING A LIQUID CRYSTAL CELL
US4367924A (en) * 1980-01-08 1983-01-11 Clark Noel A Chiral smectic C or H liquid crystal electro-optical device
DD292601A7 (en) * 1987-04-15 1991-08-08 Zentralinstitut Fuer Elektronenphysik,De METHOD FOR CONTROLLING A LIQUID CRYSTAL CELL

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2331110A1 (en) * 1974-09-16 1977-06-03 Beckman Instruments Inc Liquid crystal display cell - has front depolariser plate enabling viewing through polarising sunglasses or car windscreen
EP0162775A2 (en) * 1984-05-18 1985-11-27 Commissariat A L'energie Atomique Liquid-crystal cell presenting a homeotropic structure, with birefringence compensation for this structure
EP0239433A1 (en) * 1986-02-28 1987-09-30 Commissariat A L'energie Atomique Liquid-crystal cell with electrically controlled birefringence and method for making the same

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Applied Physics Letters, Band 44, Nr. 9, 1 May 1984 American Institute of Physics (New York, US) S.T. WU et al.: "Optical Rotatory Power of 90} Twisted Nematic liquid Crystals", seiten 842-844 *

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