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
  • G02F1/1393—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 birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-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 
  • G02F1/07—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 electro-optical liquids exhibiting Kerr effect
• • 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
  • G02F1/1343—Electrodes
  • G02F1/134309—Electrodes characterised by their geometrical arrangement
  • G02F1/134363—Electrodes characterised by their geometrical arrangement for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• • 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
  • G02F1/133382—Heating or cooling of liquid crystal cells other than for activation, e.g. circuits or arrangements for temperature control, stabilisation or uniform distribution over the 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
  • G02F1/13793—Blue phases

Definitions

• the present invention relates to light control elements and displays containing them.
• the light control elements preferably use control media which have anisotropic properties at certain temperatures, such as. B. liquid crystals.
• the light control elements are operated at a temperature at which the control media are in an optically isotropic phase, preferably in the blue phase or in the isotropic phase, particularly preferably in the blue phase. Displays in which the control media are in the isotropic phase are described in DE 102 172 73.0.
• the present invention relates to an electro-optical light control element and to electro-optical displays and display systems containing such elements, such as, for example, television screens and computer monitors.
• the light control elements according to the invention contain a mesogenic control medium which is in an optically isotropic phase when the light control elements are operated. In addition to a good contrast and a low viewing angle dependence of the contrast, they are particularly distinguished by very short switching times.
• the present invention further relates to media and their use as control media in such light control elements.
• the first-mentioned displays are used in combination with a TFT (English: thin film transistor) control for displays with a large amount of information and high resolution.
• TFT thin film transistor
• Liquid crystal displays of the IPS (English: in-pjane sw ⁇ tching, e.g. DE 40 00 451 and EP 0 588 568) or alternatively of the VAN (English: ertically aligned nematic) type used.
• VAN displays are a variant of the ECB (electrically controlled birefringence) displays.
• MVA displays International: rnulti domain ertically aligned
• several domains are stabilized for each controlled electrode and a special optical compensation layer is also used.
• these displays use an electric field which is vertical to the liquid crystal layer.
• IPS displays generally use electrodes on only one substrate, that is to say on one side of the liquid crystal layer, and are therefore characterized by an essential component of the electric field parallel to the liquid crystal layer.
• control voltages can be influenced by appropriate variation of the control media and possibly reduced.
• lowering the control voltages in this way requires the introduction of new polar substances and thus a certain amount of effort and, moreover, the magnitude of the lowering of the control voltages is limited.
• use of highly polar connections leads to reliability problems and the lifespan of the light control elements in many applications.
• the present invention was based on the object of realizing particularly quickly switching light control elements with good viewing angle dependency and in particular with low control voltages.
• These light control elements should have the smallest possible layer thickness of the control media in order to be able to be used as elements of FPDs (English: flat panel displays), such as flat screens for computers.
• FPDs American: flat panel displays
• they should be controllable using the simplest possible electrode configuration and have a low operating voltage.
• they should have a good contrast with a low viewing angle dependence for use in electro-optical displays.
• the electro-optic light control elements according to the present invention comprise - one or more substrates
• control medium are characterized in that the light control element is operated at a temperature at which the control medium is in an optically isotropic phase in the non-activated state and that the electrode arrangement has an electric field with a significant component parallel to the surface of the mesogenic
• the electrode arrangement is designed so that at least one of the four following conditions is met, the electrically conductive layers adjacent to each other in the plane of the control layer have a distance of
• a mesogenic medium is preferably used as the control medium of the light control element.
• mesogenic media or compounds are media or compounds which have a mesophase, are soluble in a mesophase or induce a mesophase.
• the mesophase is a smectic or a nematic phase, both of which can also be chiral or a blue
• Phase preferably a chiral nematic phase or a blue phase, particularly preferably a blue phase.
• the nematic mixture ZLI-4792 from Merck KGaA, Darmstadt, Germany is used as the preferred medium for investigating the mesogenic properties of the media which have no mesophase.
• the mesogenic media preferably have a clearing point of -100 ° C. or more extrapolated from 10% solution in this mixture, particularly preferably from -50 ° C. or more and very particularly preferably from -20 ° C. or more.
• optically isotropic phase means the blue phase, the isotropic phase or another optical phase isotropic phase, preferably the blue phase and blue phase one of the known blue phases.
• Gray and Goodby “Smectic Liquid Crystals, Textures and Structures", Leonhard Hill, USA, Canada (1984) describes three blue phases: Blue Pase I to III, which can be observed in the field-free state. If an electric field is applied, others can Blue phases or other phases occur or are induced.
• the mesophase is a smectic, a nematic or a blue phase.
• the smectic phase or the nematic phase are preferably chiral.
• the terms “chiral nematic phase” and “cholesteric phase” are used synonymously, unless expressly stated otherwise.
• the term “blue phase” stands for each of the known blue phases and also includes several of these phases at the same time, unless expressly stated otherwise.
• Field strength is also a phase transition into a phase that occurs without an electric field at a lower temperature.
• the control media preferably have a blue phase, particularly preferably a blue phase and a further mesophase, preferably a cholesteric phase.
• the control medium is expediently located on or under a substrate or between two substrates.
• the control medium is usually located between two substrates. This embodiment is preferred. If the control medium is between two substrates, at least one of these substrates is translucent.
• the translucent substrate, or the translucent substrates can, for. B. consist of glass, quartz or plastic. If a substrate is used that is not translucent, this can consist, among other things, of a metal or a semiconductor. These media can be used as such or on a support e.g. a ceramic.
• the control medium is a polymeric medium, the use of a second substrate can optionally be dispensed with. Polymer control medium can even be designed to be self-supporting. In this case, no substrate is required.
• the optically isotropic phase in which the control medium is present at the operating temperature or at least one of the operating temperatures of the light control element according to the present invention is the isotropic phase or preferably an optically isotropic mesophase, such as a blue phase (ie the blue phase I, blue phase II or Blue Phase III).
• a blue phase ie the blue phase I, blue phase II or Blue Phase III.
• the embodiment in which the control medium is in the blue phase at at least one operating temperature of the light control element is preferred.
• the term “optically isotropic phase” means a phase which is crossed between in an electro-optical cell with a layer thickness of approximately 10 ⁇ m or less, which is usual for LC displays Polarizers show essentially no light transmission in the visible wavelength range.
• the operating temperature of the light control element is preferably above the characteristic temperature of the control medium, usually that
• Transition temperature of the control medium into the blue phase generally in the range from 0.1 ° to 50 ° above this temperature, preferably in the range from 0.1 ° to 10 ° above this temperature and particularly preferably in the range from 0.1 ° to 5 ° above this temperature.
• the operating temperature is preferably in the range of
• Transition temperature of the control medium in the blue phase up to the transition temperature of the control medium in the isotropic phase the clearing point.
• the light control elements can also be operated at temperatures at which the control medium is in the isotropic phase.
• the operating temperature range of the light control elements according to the invention preferably extends at least over a temperature range of 20 ° or more, preferably 30 ° or more preferably 40 ° or more particularly preferably 60 ° or more and very particularly preferably 80 ° or more.
• the operating temperature range of the light control elements according to the invention preferably extends at least from 10 ° C. or less to 50 ° C. or more, preferably at least from 0 ° C. or less to 60 ° C. or more, particularly preferably at least from -20 ° C. or less to 80 ° C or more, most preferably at least from -30 ° C or less to 100 ° C or more, and most preferably at least from -40 ° C or less to 120 ° C or more.
• the operating temperature range of the light control elements according to the invention extends relative to the characteristic temperature of the control medium at least up to 50 ° C. or more above the characteristic temperature, particularly preferably at least -5 ° C. or less below that characteristic temperature up to 60 ° C or more above the characteristic temperature and very particularly preferably at least from -10 ° C below the characteristic temperature or less to 80 ° C or more above the characteristic temperature.
• an orientation is induced in the mesogenic medium in an optically isotropic phase, which leads to an optical delay which can be visualized in a known manner.
• An inhomogeneous electric field is preferably used.
• the light control elements according to the invention contain at least one element for polarizing the light. In addition, they preferably contain a further optical element. This further optical element is either a second element for polarizing the light, a reflector or a transflector.
• the optical elements are arranged so that the light passes through a polarizing element at least once when it passes through the mesogenic medium of the light control element both before it enters the mesogenic medium and after it exits the mesogenic medium.
• the mesogenic medium is located between two polarizers, that is to say a polarizer and an analyzer.
• Two linear polarizers are preferably used.
• the absorption axes of the polarizers are preferably crossed and preferably form an angle of 90 °.
• the light control element according to the invention optionally contains one or more birefringent layers. It preferably contains one ⁇ / 4 layer or several ⁇ / 4 layers, preferably one ⁇ / 4 layer.
• the optical delay of the ⁇ / 4 layer is preferably approximately 140 nm.
• the layer thickness (d) of the mesogenic control medium is preferably 0.1 ⁇ m to 5,000 ⁇ m (ie 5 mm), particularly preferably 0.5 ⁇ m to 1,000 ⁇ m (ie 1 mm), particularly preferably 1.0 ⁇ m to 100 ⁇ m and very particularly preferably 3.0 ⁇ m to 30 ⁇ m and in particular 3.5 ⁇ m to 20 ⁇ m.
• the layer thickness of the mesogenic control medium is preferably 0.5 ⁇ m to 50 ⁇ m, particularly preferably 1.0 ⁇ m to 20 ⁇ m and very particularly preferably 1.0 ⁇ m to 8.0 ⁇ m.
• the present invention also relates to electro-optical displays which contain one or more light control elements according to the invention. These electro-optical displays are preferably controlled by means of an active matrix.
• the present invention further relates to electro-optical display systems containing one or more electro-optical displays according to the invention.
• These electro-optical display systems are preferably used to display information, among other things, preferably as a television screen or as a computer monitor.
• the information to be displayed is preferably digital signals or video signals.
• the light control element according to the invention can additionally contain one or more other conventional optical elements such as birefringent layers (e.g. compensation layers), diffuser layers, and elements for increasing the brightness and / or the luminous efficiency and / or the viewing angle dependency, this list not being exhaustive.
• birefringent layers e.g. compensation layers
• diffuser layers e.g., diffuser layers
• the light control elements according to the invention are characterized by a good contrast, which depends strongly and almost predominantly on the properties of the polarizers used.
• TN cells with an optical delay of 0.50 ⁇ m, positive contrast and the absorption axis of the polarizers perpendicular to the preferred orientation of the nematic liquid crystals on the adjacent substrate, which do not contain chiral liquid crystals, are used here.
• the contrast of the invention is characterized by a good contrast, which depends strongly and almost predominantly on the properties of the polarizers used.
• Light control elements depends, among other things, especially on the shape, Type and structure of the electrodes used. If the same polarizers are used in the light control elements according to the invention and in these conventional TN lines, the contrast of the light control elements according to the invention is generally around 20% or more, in part, in particular at observation angles that differ from the normal of the
• Display surface deviate significantly, 40% or more larger than the contrast of the TN cells.
• the viewing angle dependence of the contrast of the light control elements according to the invention is very good. It is significantly better than that of the known ECB cells. It is more comparable to the viewing angle dependency observed with the commercially available IPS displays (e.g. from Hitachi and NEC, both Japan) and MVA displays (e.g. from Fujitsu, Japan). It is much lower than that of conventional TN displays. So an isocontrast curve closes a given
• Contrast ratio in the light control elements according to the invention usually an angular range that is more than twice as large, often even more than three times as large as the corresponding isocontrast curve for the same contrast ratio in the TN display.
• the switching times of the light control elements according to the invention are very short. They are generally values of 1 ms or less, preferably 0.5 ms or less, particularly preferably 0.1 ms or less.
• the light control elements according to the invention were each switched to different control voltages.
• Characteristic voltages of the electro-optical characteristic were used as
• Endpoints selected e.g. V 1 0, V 2 o, V 30 , ... to V go .
• one of them given characteristic voltage to the other voltages and switched back for example from V 10 to each of the voltages V 90 , V 8 o, V o to V 2 o-
• a different one of the characteristic voltages was selected and from this to each of the higher characteristic ones Voltages and switched back, for example from V 2 o to each of the voltages V 90 , V 8 o, V 0 to V 30 and so on up to the output voltage Vso from which to Vg 0 and back.
• the switch-on time in all of these cases is from the time the new voltage is switched on until 90% of the respective maximum is reached
• Electro-optical displays according to the present invention contain one or more light control elements according to the invention. In a preferred embodiment, these are controlled by means of an active matrix.
• the light control elements according to the invention are actuated in the so-called “field sequential mode”.
• the switching elements are successively illuminated with differently colored light in synchronism with the actuation.
• a color wheel (“color wheel "), Strobe lamps or flash lamps are used.
• Electro-optical displays according to the present invention can contain a color filter for displaying colored images.
• This color filter expediently consists of a mosaic of filter elements of different colors.
• An element of the color filter mosaic of a color is typically associated with each electro-optical switching element.
• the light control elements according to the invention contain an electrode structure which contains an electrical field with a significant component generated parallel to the layer of the mesogenic medium.
• This electrode structure can be designed in the form of interdigital electrodes. It can be designed in the form of combs or ladders. Designs in the form of superimposed "H” s and double “T” s or s are also advantageous.
• the electrode structure is advantageously located on only one
• the electrode structure is preferably present in at least two different planes, both of which are located on one side of the mesogenic control medium, this applies in particular if the electrode structure contains overlapping partial structures.
• These substructures are advantageously separated from one another by a dielectric layer. If the substructures are on the opposite sides of an insulation layer, a "lay-out" can be selected that allows the implementation of capacitors. This is particularly advantageous when controlling displays using an active matrix.
• Such active matrix displays use a matrix of control elements assigned to the individual light control elements with a non-linear current-voltage characteristic, such as, for. B. TFTs or MIM (English: rnetal insulator metal) diodes.
• An essential aspect of the present invention is the configuration of the electrode structure of the electro-optical switching elements according to the invention.
• Various embodiments are possible here.
• the preferred embodiments of the electrodes of the light control elements according to the invention are described with the help of the corresponding illustrations, if necessary.
• the figure shows a cross-section of the structure of a
• the control medium (2) is located between the inner surfaces of the substrates (1) and (1 '). On the inner surface One of the substrates (1) contains the two electrodes (3) and (4) of the electrode structure, which can be supplied with different potentials.
• “Vop” denotes the voltage, charge or current source. The lines starting from V op symbolize the electrical leads to the electrodes.
• the electrodes can be made of transparent material, such as. B. Indium Tin Oxide (ITO). In this case, it may be advantageous and possibly necessary to cover a part or parts of the light control element using a black mask. This allows areas where the electric field is not effective to shield and thus improve the contrast.
• the electrodes can also be made of opaque material, usually metal, e.g. made of chrome, aluminum, tantalum, copper, silver or gold, preferably made of chrome. In this case, the use of a separate black mask may not be necessary.
• the electric field used is preferably an inhomogeneous field.
• the electrodes are preferably at a distance from one another in the range from 0.5 ⁇ m to 100 ⁇ m, preferably in the range from 1 ⁇ m to 20 ⁇ m, particularly preferably in the range from 1 ⁇ m to 15 ⁇ m, very particularly preferably in the range from 2 ⁇ m to 12 ⁇ m and most preferably in the range of 3 ⁇ m to 11 ⁇ m.
• the distance between the electrodes is preferably 19 ⁇ m or less, particularly preferably 15 ⁇ m or less, very particularly preferably 10 ⁇ m or less and particularly preferably 9 ⁇ m or less.
• the width of the electrodes in the direction of the neighboring electrodes which can be applied with different potential, is less critical than the distance of the electrodes in this direction. It has almost no influence on the characteristic voltages of the light control elements. With increasing width of the electrodes, however, the opening ratio of the light control element becomes smaller and the brightness decreases, especially if the electrodes are made of opaque
• the electrodes preferably have a width in the range from 0.5 ⁇ m to 30 ⁇ m, preferably in the range from 0.5 ⁇ m to 20 ⁇ m, particularly preferably in the range from 0.7 ⁇ m to 19 ⁇ m, very particularly preferably in the range from 1 ⁇ m to 9 ⁇ m and most preferably in the range of 1.5 ⁇ m to 6 ⁇ m.
• the electrodes are raised.
• raised means that the electrodes have a layer thickness that should not be neglected compared to the layer thickness of the control layer.
• the layer thickness of the electrodes is preferably 5% or more, preferably 10% or more, particularly preferably 20% or more of the distance between the substrates, that is to say the layer thickness of the
• the electrode structure can have different topographies.
• the electrode structure can extend over a significant proportion of the total thickness of the layer of the mesogenic control medium.
• the maximum height of the electrode layer or the electrode layer is preferably significantly smaller than the thickness of the mesogenic medium.
• the ratio is preferably 1: 3 or less, particularly preferably 1:10 or less and very particularly 1:50 or less. In some cases the thickness of the electrode layer can be neglected compared to the thickness of the mesogenic medium, then the ratio is preferably 1: 100 or less.
• the electrode arrangement of the light control element is designed such that it over a predominant portion of the layer thickness of the mesogenic control medium, preferably over more than 60%, preferably essentially over the entire layer thickness of the mesogenic control medium, particularly preferably over 80% or more, and very particularly preferably over 90% or more.
• the lower limit is
• Layer thickness of the electrodes 0.5 ⁇ m, particularly preferably 1 ⁇ m and very particularly preferably 2 ⁇ m and the upper limit preferably 10 ⁇ m, preferably 5 ⁇ m and very particularly preferably 3 ⁇ m.
• FIGS 2 to 6 show schematically in cross section the structure for five different embodiments of switching elements according to the invention with raised electrodes according to the preferred embodiment (A).
• the electrodes are designed similarly to the embodiment shown in Figure 1.
• the electrodes (3) and (4) have a rectangular or almost rectangular cross section.
• the electrodes have a thickness which is not to be neglected in relation to the layer thickness [d (2)] of the control layer (2) or in relation to the characteristic layer thickness, e.g. typically in the range from 0.5 ⁇ m to 3 ⁇ m, preferably in the range from 1 ⁇ m to 2 ⁇ m.
• the electrodes (3) and (4) are designed similarly to that shown in Figure 2
• the layer thickness of the electrodes (3) and (4) not constant, but depending on the location.
• the electrodes have a triangular cross section.
• the electrodes (3) and (4) are designed similarly to the one shown in Figure 4
• Electrodes each consist of two superimposed layers (3) and (3 ') and (4) and (4 "), each of which the upper (3') or (4 ') covers a smaller area of the switching element than the corresponding lower layer (3) or (4).
• the electrodes (3) and (4) are again designed similarly to the embodiment shown in Figure 2.
• the electrodes (3) and (4) here have a circular cross section and are shown designed as waveguides.
• they can also have other rounded cross sections and e.g. be designed in the form of a solid wire or as a conductively coated cylinder of a non-conductive or non-conductive material.
• Electrodes with a common potential flank an electrode with a different potential or alternate with at least one pair of electrodes to which the other potential can or can be applied.
• the electrodes can be present in one plane or in different planes.
• the electrodes which have the same potential or are or can be subjected to the same potential are preferably in the same plane.
• the electrodes of the electrode structure which are adjacent to one another are, at least in part, preferably essentially, particularly preferably largely insulated from one another horizontally by a fixed dielectric layer.
• the substructures of the electrode structure are located on the two opposite sides of the mesogenic medium. In this case, the corresponding parts of the electrodes are not perpendicular to one another, but are laterally offset from one another in such a way that a component of the electric field is created parallel to the layer of the mesogenic medium.
• the electrode structure is designed such that the electrodes are at a distance above their respective substrate and preferably over a substantial part of their area, preferably over the predominant part of their area and particularly preferably almost are insulated against it over their entire area or over their entire area.
• the electrodes are preferably formed on a solid dielectric. This is shown by way of example in Figures 7, 9 and 11 to 13.
• a solid insulator such as e.g. Glass is used as described below.
• the solid dielectric is particularly preferably designed as a layer or as a platform.
• the pedestals of the dielectric can be obtained by etching out the spaces between the pedestals from a layer of a dielectric, in the simplest case of the substrate.
• the essential part preferably 20% or more, particularly preferably 30% or more and very particularly preferably 40% or more, the predominant part: preferably 55% or more, particularly preferably 60% or more and very particularly preferably 70% or more,
• FIG. 7 shows a schematic cross section of the structure for a preferred embodiment of embodiment (B) of switching elements according to the invention.
• the electrodes are designed similar to the embodiment shown in Figure 1. However, they are
• the electrode arrangement is configured such that the electrode pairs of a picture element are separated from the associated substrate by a dielectric.
• This embodiment is preferred because it enables the light control elements and the electro-optical displays to be easily manufactured since the electrodes are only on one substrate. With a corresponding choice of the thickness of the solid insulating layer among the conductive layers of the electrodes, a great effect on the control voltages can be achieved and this can be significantly reduced.
• the conductive layers of the electrode structures are raised above the surface of the adjacent substrate.
• This solid, insulating layer can consist of glass, quartz, one or more inorganic layers, such as SiO 2 or SiN, organic polymers or the like.
• the insulating layer is realized as a raised part of the substrate, for example in the form of a pedestal. This embodiment can be obtained simply and preferably by etching the substrate correspondingly deep away at the points where no pedestal is desired. If necessary, the respective conductive layer of the electrode structure can serve as a mask during the etching, or both layers can be etched through the same mask in one step.
• the solid, insulating layer is applied or deposited on the substrate in a known manner in a structured or unstructured manner over the surface, and then structured if necessary.
• the layer thickness of the solid, insulating layer is preferably in the range from 0.1 ⁇ m to 10 ⁇ m, particularly preferably in the range from 0.2 ⁇ m to 7 ⁇ m, very particularly preferably in the range from 0.4 ⁇ m to 5 ⁇ m and particularly preferably in Range from 0.5 ⁇ m to 4 ⁇ m.
• the electrodes of the electrode structure to which the same potential is applied consist of two or more electrically conductive layers. These layers are arranged one above the other in the cell of the switching element and preferably separated and electrically insulated from one another by a dielectric over a substantial part of their area, preferably over most of their area and particularly preferably almost over their entire area or over their entire area. If the conductive layers in the light control element are insulated over 100% of their area, they are electrically conductively connected to one another or to a voltage, charge or current source outside the light control element.
• At least one conductive layer of the electrode structure is located on one of the substrates.
• the layer of the control medium forms the dielectric between the electrode layers.
• the two or more electrically conductive layers of the electrode structure are each separated from one another by a solid dielectric.
• FIG 8 shows a schematic cross section of the structure for a preferred embodiment of embodiment (C) of switching elements according to the invention with an electrode structure in which the electrodes consist of two layers, which are each on one of the substrates.
• the electrodes are designed in such a way that there is a second electrode (3 ') on the second substrate (1') for the electrode (3) on the first substrate (1), to which a first potential can be applied can be applied with the same potential.
• the electrode pairs (3) and (3 ') as well as (4) and (4') face each other. This embodiment is preferred because it allows a very large reduction in the characteristic voltages and the effect achieved does not depend on other parameters, such as the material and the layer thickness of the solid dielectric used.
• the electrode structure preferably has two pairs of electrodes that are assigned to one another, of which at least one pair of electrodes that are assigned to one another can or can be subjected to the same electrical potential.
• the conductive layers of the electrodes assigned to one another in pairs are on the opposite substrates (compare Figures 8 and 9) or on the same substrate (compare e.g. Figures 10 and 11).
• the electrodes of the electrode arrangement preferably consist in the latter
• the individual layers of the electrodes are essentially each - over their entire area separated by a dielectric from one another with the same area and congruent with one another.
• the described embodiments can also be combined with one another. So z. B. in the last described, very particularly preferred embodiment of embodiment (C), the first conductive layer facing the substrate of the separated by a solid dielectric, two or more electrically conductive layers of the electrode structure, as in the second described, preferred embodiment, be separated from the respective substrate by a solid dielectric layer.
• Figures 9 to 13 show schematically in cross section the structure of various embodiments of switching elements according to the invention according to a further preferred embodiment of the present invention.
• Figure 9 shows an embodiment that is a combination of the embodiments shown in Figures 7 and 8. in the
• electrodes ((3) and (4) raised not only on the substrate with the surface (1) are formed on solid insulating layers (5) and (6), but rather, as in the one in Figure 8 and 8 are also formed on the surface of the opposite substrate (1 ') electrodes (3') and (4 '). Like the corresponding electrodes on the first substrate, these electrodes are formed by solid insulating layers (5') and (6 ') lifted off the surface (1').
• the electrodes are designed similarly to that in
• the electrodes each consist of two layers (3) and (3 '), or (4) and (4 "), which can each be acted upon in pairs with the same potential
• the two pairs of conductive layers of the electrode structure (3) and (3 '), or (4) and (4') are not separated from each other here by the dielectric control layer (2), but each with a solid insulating layer (5) or (6).
• the electrodes are designed similarly to the embodiment shown in Figure 10. However, as in the embodiment shown in FIG. 7, the first layers of the electrode structures (3) and (4) are separated from the substrate by a solid insulating layer (5) and (6).
• the two layers of the electrode structure that can be applied with the same potential (3) and (3 '), or (4) and (4') are as in the one in Figure 10
• the electrodes of the electrode structure each consist of four conductive layers (3) to (3 “') or (4) to (4'"). Two of these four layers are located on the same substrate. Layers (3) and (3 ') and (4) and (4') are on the substrate with the surface (1) and (3 ") and (3 '") as well as (4 ") and (4 1 " ) are on the substrate with the surface (1 '). Of these layers, the respective layer (3) and (4) or (3 ") and (4") adjacent to the respective substrate (1) or (1 ') is provided by a solid insulating layer (5) and (6) or (5 ') and (6') separately.
• the two conductive layers that are on the same substrate [(3) and (3 1 )] and [(4) and (4 ') j as well as [(3 ") and (3'")] and [( 4 ") and (4 '")] are also separated from one another by solid insulating layers (5') and (6 ') and (5'") and (6 '").
• the electrodes of the electrode structure each consist of four conductive layers (2) to (2 '") or (3) to (3'").
• the alternating sequence of conductive layers and insulating layers extends over the entire layer thickness of the control layer.
• the inner pairs of the conductive layers (2 ') and (2' ") and (3 ') and (3'") are also separated from one another by solid insulating layers (5 "") and (6 "").
• the layer or parts of the layer of the mesogenic control medium can be located as a dielectric.
• each electrode contains at least four conductive layers (compare FIGS. 12 and 13), it being preferred that at least two of the conductive layers are each on a substrate and can or can be acted upon with different potential.
• each of these two electrodes is assigned at least one further electrode which is or can be acted upon with the same potential.
• Each of these at least one further electrode, which is assigned to each of the electrodes of the electrode pairs, is separated from the latter by a dielectric.
• the respective number of conductive layers on the two substrates can be different.
• the conductive layers of the electrodes can be raised both in the preferred embodiment (B) and in the particularly preferred embodiment (C), as described in the embodiment (A).
• two of the superimposed conductive electrode layers to which the same potential is applied can also be particularly preferably separated from one another both by the dielectric control layer and, at the same time, by a solid dielectric layer from the respective underlying substrate or, if appropriate, one below it other electrically conductive layer must be separated (see Figure 9).
• This embodiment is preferred because it allows the drive voltage to be further reduced compared to the embodiments shown in FIGS. 7 and 8.
• the superimposed conductive layers of the electrode structure are electrically conductively connected to one another or to a control electronics. If the corresponding layers are connected to one another in an electrically conductive manner and the electrical resistance is low, the corresponding layers can be at the same potential, or have the same voltage. In special embodiments, however, these layers can also be at different potentials or can be driven at different times, as a result of which they can be at different potentials at different times.
• the independent or electrically coupled control of the corresponding, superimposed, electrically conductive layers of the electrode structure can be achieved by using appropriate driver electronics which are connected to the corresponding layers. This makes it possible, for example, to apply different potentials to the corresponding layers simultaneously or at different times. This enables an improved control which, for example, can improve the switching times and / or the contrast of the light control elements.
• the strength of the electro-optical effect observed depends on the layer thickness of the isotropic control medium. With small layer thicknesses in the range of less than one micrometer, the necessary control voltage decreases with increasing layer thickness. This effect lasts up to a characteristic layer thickness (de) at which saturation occurs. A further increase in the layer thickness to values above this characteristic layer thickness does not lead to any further significant improvement, that is to say a decrease in the characteristic tensions.
• the characteristic layer thickness is typically in the range from 0.5 ⁇ m to 10 ⁇ m, mostly in the range from 1.0 ⁇ m to 5.0 ⁇ m. For most practically relevant cases, values from approx. 2 ⁇ m to 3 ⁇ m are to be assumed, in particular a value of approx. 3 ⁇ m.
• the layer thickness of the isotropic control layer in the light control elements of embodiment (A) is preferably at least as large as the characteristic layer thickness.
• the layer thickness of the isotropic control layer is preferably twice the characteristic layer thickness or more. This preferred lower limit of the layer thickness of the control medium applies in the event that in embodiment (B) Electrode structure comprises two layers each, which can or can be acted upon by the same potential and in the event that in the embodiment (C) the electrode structure contains exactly one electrically conductive layer which is or can be acted on by the given potential.
• the embodiment (C) with exactly one conductive layer in the electrode structure leads to similar results as the embodiment (B).
• the thickness of the solid insulating layer between the substrate and the conductive layer increases, the characteristic voltages decrease to a saturation that occurs when the layer thickness of the solid insulating layer reaches the value of the characteristic layer thickness as long as the total layer thickness of the control layer is large is enough.
• the height of the insulating layer under the first conductive layer facing the substrate is preferably equal to or greater than the characteristic layer thickness.
• the thickness of the remaining part of the control layer above the conductive layer of the electrode structure is also equal to or larger than the characteristic layer thickness, so preferred lower limit of the total layer thickness of the control layer in this embodiment, as in embodiment (B), is twice as large the characteristic layer thickness.
• the greatest reduction in operating voltage is achieved when the conductive layer is in the center, or nearly in the center, of the thickness of the control layer and extends toward each of the substrates by the characteristic layer thickness or more.
• the mesogenic media according to the present invention preferably have a nematic phase, a chiral phase and / or a blue phase, preferably a blue phase.
• media can also be used in which the temperature range of the nematic phase is so narrow that there is practically a transition from the crystalline phase or from the smectic phase to the isotropic phase.
• the control media according to the invention preferably have a characteristic voltage V 100 in the range from 5 V to 150 V, preferably from 15 V to 110 V, particularly preferably from 20 V to 90 V and in the light control elements according to the invention at a temperature of 2 degrees above the characteristic temperature very particularly preferably from 30 V to 80 V.
• the characteristic voltages are specified in this application for cells with a width of the electrodes of 10 ⁇ m and an electrode spacing of 10 ⁇ m, unless expressly stated otherwise.
• Modulation media according to the invention in the inventive light modulation elements, at a temperature of 2 ° above the characteristic temperature particularly preferably have a characteristic voltage V ⁇ 0 of 105 V or less, preferably 95 V or less, more preferably 75 V or less, and most preferably from 50 V or less.
• control media according to the invention have a characteristic voltage V-io in the range from 5 V to 110 V, particularly preferably from 10 V to 90 V and entirely, in the light control elements according to the invention at a temperature of 2 degrees above the characteristic temperature particularly preferably from 10 V to 80 V.
• control media according to the invention have a characteristic voltage V 0 in the range from 2 V to 100 V, preferably from 3 V to 50 V, in the light control elements according to the invention at a temperature of 2 degrees above the characteristic temperature. particularly preferably from 4 V to 30 V, very particularly preferably from 5 V to 20 V and most preferably from 5 V or 7 V to 15 V.
• T C har. a characteristic temperature
• the characteristic temperature if the characteristic voltage as a function of temperature passes through a minimum, the temperature of this minimum is called the characteristic temperature
• the control medium has one or more blue phases, the temperature of the transition to the blue phase becomes, if several blue phases occur, the temperature of the transition to that with increasing
• characteristic temperature Temperature first occurring blue phase, called characteristic temperature
• the temperature of the transition to the isotropic phase is referred to as the characteristic temperature.
• the clearing point of the mesogenic media having a nematic phase is preferably in the range from -20 ° C. to 80 ° C., particularly preferably in the range from 0 ° C. to 60 ° C. and very particularly preferably in
• the clearing point is preferably in the range of 10 ° C to 70 ° C and particularly preferably in the range of 30 ° C to 50 ° C.
• the nematic phase is preferably stable to -10 ° C, particularly preferably to -30 ° C and very particularly preferably to -40 ° C.
• the mesogenic media according to the present invention preferably have a birefringence ( ⁇ n) of 0.090 or more, preferably of, in the nematic phase at a temperature of 4 degrees below the clearing point 0.100 or more, particularly preferably 0.150 or more, very particularly preferably 0.200 or more.
• ⁇ n birefringence
• the value of the birefringence is virtually unlimited for the application according to the invention. In practice, however, it is usually 0.500 or smaller and usually 0.450 or smaller.
• the value of the birefringence of the media according to the invention is measured here in the nematic phase at a temperature of 4 ° below the clearing point.
• the birefringence of a mixture of 15% of the medium and 85% of the nematic mixture ZLI-4792 from Merck KGaA is determined at 20 ° C and off the change compared to the mixture ZLI-4792 extrapolated to the value of the pure medium.
• the mesogenic media according to the present invention preferably have a dipole moment of 4 debye or more, particularly preferably 6 debye or more and particularly preferably 8 debye or more.
• Both the mesogenic control media which have a positive dielectric anisotropy ( ⁇ ) in the mesophase and those which have a negative dielectric anisotropy can be used for the light control elements according to the present invention.
• Mesogenic control media are preferably used which have a positive dielectric anisotropy ( ⁇ ) in the mesophase.
• the mesogenic control media have a positive dielectric anisotropy, this has a value of preferably 15 or more, particularly preferably 30 or more at 1 kHz and a temperature of 4 ° below the characteristic temperature or the clearing point, preferably in the nematic phase and most preferably 45 or more. If the medium does not have a nematic phase or if it is not in the nematic phase at a temperature of 4 ° below the characteristic temperature or clearing point, its dielectric anisotropy, like birefringence, is extrapolated from the values of a mixture of 15% in the mixture ZLI-4792 determined. If the mesogenic control media have a negative dielectric anisotropy, this has a value of preferably -5 or less, particularly preferably -7 or less and very particularly preferably -10 or less.
• Control media with a positive dielectric anisotropy are particularly preferred.
• the mesogenic media according to the present invention preferably consist of two to 40 compounds, particularly preferably five to 30 compounds and very particularly preferably seven to 25 compounds.
• the mesogenic media according to the invention with positive dielectric anisotropy according to the present invention preferably contain
• component A consisting of one or more compounds with a very strongly positive dielectric anisotropy of 30 or more
• component B consisting of one or more compounds with a highly positive dielectric anisotropy from 10 to ⁇ 30,
• component C consisting of one or more compounds with a moderately positive dielectric anisotropy of> 1.5 to ⁇ 10,
• a component D consisting of one or more dielectrically neutral compounds with a dielectric anisotropy in the range from -1.5 to +1.5 and
• a component E consisting of one or more compounds with a negative dielectric anisotropy of less than -1.5.
• Component A of these media preferably contains one or more compounds of the formula I and particularly preferably consists predominantly and very particularly preferably almost completely of one or more compounds of the formula I,
• Z 11 and Z 12 are each independent of one another, a single bond
• the media according to the invention preferably contain one or more compounds selected from the group of compounds of the formulas 1-1 to I-7 and / or one or more compounds selected from the group of compounds of the formulas 11-1 to II-5, which are also sub-formulas of formula I.
• the media according to the invention particularly preferably comprise one or more compounds selected from the group of the compounds of the formulas 1-1 a to 1-1 e, l-2a to l-2c, l-3a to l-3c, l-4a to l- 4c, l-5a to l-5c, l-6a to l-6c and l-7a to l-7c and / or one or more compounds selected from the group of the compounds of the formulas ll-1a to ll-1c, ll- 2a to ll-2c, ll-3a, Il3b, ll-3a, ll-4b, ll-5a and il-5b.
• the compounds of the formulas 1-1 a to 1-1 e are preferably selected from the group of the compounds of the formulas 1-1 a-1 to 1-1 a-6, 1-1 b-1 to
• n is an integer from 0 to 7, preferably 1 to 7
• m is an integer from 0 to 5
• n + m is an integer from 0 to 7, preferably from 1 to 5.
• the compounds of the formulas I-2a to I-2c are preferably selected from the group of the compounds of the formulas I-2a-1 to I-2a-5, I-2b-1 to I-2b-9 and I-2c-1 to l-2c-17.
• n is an integer from 0 to 7, preferably from 0 to 5 and particularly preferably from 1 to 5
• m is an integer from 0 to 5
• n + m is an integer from 0 to 7, preferably from 1 to 5.
• the compounds of the formulas I-3a to I-3c are preferably selected from the group of the compounds of the formulas I-3a-1 to I-3a-4, I-3b-1 to I-3b-4 and I-3c-1 to l-3c-4.
• n is an integer from 0 to 7, preferably from 0 to 5 and particularly preferably from 1 to 5.
• the compounds of the formulas I-4a to I-4c are preferably selected from the group of the compounds of the formulas I-4a-1 to I-4a-3, I-4b-1 to I-4b-3 and I-4c-1 to l-4c-3.
• n is an integer from 0 to 7, preferably from 0 to 5 and particularly preferably from 1 to 5.
• the compounds of the formulas I-5a to I-5c are preferably selected from the group of the compounds of the formulas I-5a-1b to I-5a-3, I-5b-1 to I-5b-3 and I-5c- 1 to l-5a-1 l-5ca-3.
• n is an integer from 0 to 7, preferably from 0 to 5 and particularly preferably from 1 to 5.
• the compounds of the formulas I-6a to I-6c are preferably selected from the group of the compounds of the formulas I-6a-1 to I-6a-3, I-6b-1 to I-6a-3 and I-6c-1 to l-6a-3.
• n is an integer from 0 to 7, preferably from 0 to 5 and particularly preferably from 1 to 5.
• the compounds of the formulas I-7a to I-7c are preferably selected from the group of the compounds of the formulas I-7a-1 and I-7a-2, I-7b-1 and I-7b-2 and I-7c-1 and l-7c-2.
• n is an integer from 0 to 7, preferably from 0 to 5 and particularly preferably from 1 to 5.
• the media according to the invention particularly preferably comprise one or more compounds selected from the group of the compounds of the formulas 11-1c-1, ll-2c-1, ll-3b-1, ll-4b-1 and ll-5b-1.
• n is an integer from 0 to 7, preferably from 0 to 5 and particularly preferably from 1 to 5.
• the media according to the invention preferably contain one or more compounds selected from the group of compounds of the formulas 1-1 to I-7 and one or more compounds selected from the group of compounds of the formulas 11-1 to II-5.
• the mesogenic media according to the present invention with positive dielectric anisotropy particularly preferably consist predominantly and very particularly preferably almost entirely of component A.
• the mesogenic media according to the present invention with positive dielectric anisotropy contain one or more components selected from the group of components B to D, preferably selected from the group of components B and D.
• Component D of these media preferably contains one or more compounds.
• the mesogenic media with negative dielectric anisotropy according to the present invention preferably contain
• component B optionally a component B 'consisting of one or more compounds with a moderately negative dielectric anisotropy from -1.5 to ⁇ -5,
• a component C consisting of one or more dielectric neutral compounds with a dielectric anisotropy of -1, 5 to +1, 5 and
• the mesogenic medium according to the present invention preferably contains chiral compounds which induce a chiral mesophase, preferably a blue phase.
• the pitch induced in the mesogenic media is less than about 400 nm.
• the chiral compounds used are preferably compounds which have a mesogenic structure and particularly preferably one or more Mesophases show, especially at least one cholesteric phase.
• Preferred chiral compounds include known chiral dopants such as cholesteryl nonanoate, R / S-811, R / S-1001, R / S-2001, R / S-3001, R / S-4001, B (OC) 2C * HC- 3 or CB-15 (Merck KGaA, Darmstadt, Germany).
• chiral compounds with chiral units or mesogenic chiral compounds which are disclosed in DE 34 25 503, DE 35 34 777, DE 35 34778, DE 3534 779, DE 35 34 780, DE 4342 280, EP 01 038 941 and DE 19541 820 and the disclosure of which is hereby incorporated by reference.
• Chiral binaphthyl derivatives as disclosed in EP 01 111 954.2, chiral binaphthalene derivatives as disclosed in WO 02/34739, chiral TADDOL derivatives as disclosed in WO 02/06265 and chiral dopants with at least one are particularly preferred fluorinated linkers and a chiral end group or a central chiral group, as disclosed in WO 02/06196 and WO 02/06195.
• the amount of chiral compound required for inducing the chiral mesophase, in particular the blue phase depends on the fact that a pitch of less than about 400 nm is induced in the phase.
• a higher concentration of the chiral compounds is required than for chiral compounds that induce a relatively large HTP.
• the HTP measured in the host MLC-6620, Merck KGaA, Darmstadt, Germany
• the chiral compounds are preferably in concentrations of about 20 to 70%, particularly preferably of about Contain 30 to about 60% in the medium.
• the proportion of the chiral compounds is preferably about 1 to about 20%, particularly preferably about 5 to 15%, in particular about 10%.
• the mesogenic medium according to the present invention can contain further additives, such as stabilizers and / or dichroic dyes in conventional concentrations.
• the total concentration of these further constituents is in the range from 0% to 10%, preferably in the Range from 0.1% to 6%, based on the total mixture.
• the concentrations of the individual of these compounds are in the range from 0.1 to 3%.
• the concentration of these compounds and similar components of the mixture are not taken into account when specifying the concentration ranges of the other components of the mixture, unlike the chiral dopants.
• the media are obtained from the compounds in the usual way.
• the compounds which are used in a smaller amount are expediently dissolved in the compounds used in a larger amount. If the temperature is raised above the clearing point of the predominant component during the mixing process, the completeness of the dissolution can easily be observed.
• the media according to the invention can also be produced in other ways. So through the use of premixes.
• Premixes can be used, inter alia, homologue mixtures and / or eutectic mixtures. However, the premixes can also themselves be usable media. This is the case with so-called two-bottle or multi-bottle systems.
• Dielectrically positive connections have a ⁇ > 1, 5, dielectrically neutral connections have a ⁇ in the range -1, 5 ⁇ ⁇ 1.5 and dielectrically negative connections have a ⁇ ⁇ -1, 5.
• dielectrically positive connections have a ⁇ > 1, 5 dielectrically neutral connections have a ⁇ in the range -1, 5 ⁇ ⁇ 1.5 and dielectrically negative connections have a ⁇ ⁇ -1, 5.
• dielectrically negative connections have a ⁇ ⁇ -1, 5.
• the same definitions also apply to components of mixtures and for mixtures.
• the dielectric anisotropy ⁇ of the compounds is determined at 1 kHz and 20 ° C. by extrapolation of the values of a 10% solution of the respective compound in a host mixture to a proportion of the respective compound of 100%.
• the capacities of the test mixtures are determined both in a cell with a homeotropic and in a cell with a homogeneous edge orientation.
• the layer thickness of both Cell types are approximately 20 ⁇ m.
• a square wave with a frequency of 1 kHz and an effective voltage (rms, English: root mean square) of typically 0.03 V or 0.2 V to 1.0 V is used for the measurement. In any case, the voltage used is lower than the capacitive threshold of the mixture under investigation.
• the mixture ZLI-4792 is used for dielectrically positive connections and the mixture ZLI-3086, both from Merck KGaA, Germany, is used as the host mixture for dielectrically neutral and for dielectrically negative connections.
• threshold voltage means the optical threshold and is indicated for a relative contrast of 10% (V 10 ).
• the mid-gray voltage and the saturation voltage are also determined optically and specified for a relative contrast of 50% and 90%, respectively.
• the capacitive threshold voltage (V 0 ), also called the Freedericksz threshold, is given, so this is stated explicitly.
• the optical anisotropy ( ⁇ n), also called birefringence, is determined at a wavelength of 589.3 nm
• the dielectric anisotropy ( ⁇ ) is determined at a frequency of 1 kHz.
• composition of the media means - "Contain” that the concentration of the respective material mentioned, ie the component or the compound, in the reference unit, ie the medium or the component, preferably 10% or more, particularly preferably 20% or more and very particularly preferably
• concentration of the material mentioned in the reference unit is preferably 50% or more, particularly preferably 60% or more and very particularly preferably 70% or more and
• the concentration of the material mentioned in the reference unit is preferably 80% or more, particularly preferably 90% or more and very particularly preferably
• the dielectric properties, electro-optical properties (eg the threshold voltages) and the switching times were determined in test cells manufactured by Merck KGaA, Darmstadt, Germany.
• the test cells for determining ⁇ had a layer thickness of 22 ⁇ m and a circular electrode made of indium tin oxide (ITO) with an area of 1.13 cm 2 and a protective ring.
• ITO indium tin oxide
• lecithin (Merck KGaA) can be used as an orientation aid.
• the cells for determining s ⁇ had orientation layers made of the polyimide AL-1054 from Japan Synthetic Rubber, Japan.
• Table B Alkyl groups with n or m carbon atoms.
• Table B is self-explanatory, since it gives the full abbreviation for a formula of homologous compounds.
• Table A shows only the abbreviations for the core structures of the connection types.
• the abbreviations for the respective individual compounds are composed of the respectively applicable abbreviations for the core of the compound and the abbreviation for the groups R 1 , R 2 , L 1 and L 2 attached by means of a hyphen according to the following table.
• the mesogenic media according to the previous application preferably contain
• the mesogenic with the following composition was prepared.
• This mixture has the following properties.
• This liquid crystal mixture was filled into a test cell and its electro-optical properties were examined at a temperature of 24 ° C.
• the test cell used. had electrodes on only one of the two substrates, as shown in Figure 1.
• An electro-optical test cell with a light switching element containing the liquid crystal mixture was produced.
• the substrates were made of glass. Substrates without an orientation layer were used. The
• Electrode structure consisted of interdigitated comb-shaped electrodes. The distance between the electrodes was 20 ⁇ m and the width of the electrodes was 10 ⁇ m. The layer thickness of the electrodes was 60 nm. The electrodes were all in a common plane. The layer thickness of the control medium was 6.8 ⁇ m.
• a first polarizer was used in front and a second polarizer behind the cell as the analyzer.
• the absorption axes of the two poiarizers formed an angle of 90 ° to one another.
• the angle between the axis of maximum absorption of the polarizers and the component of the electric field in the plane of the display was 45 ° in each case.
• the voltage transmission characteristic was determined with an electro-optical measuring station DMS 703 from Autronic-Melchers, Düsseldorf, Germany.
• the operating temperature was 24.0 ° C. When observed vertically, a curve was obtained which is typical for a cell with electrically controlled birefringence (e.g. ECB).
• the value of the threshold voltage (V 10 ) was 40.5 V
• the value of the medium gray voltage (V 50 ) was 56 V
• the value of the saturation voltage (V 90 ) was 65 V.
• the maximum contrast was reached at 73 V. At voltages of 80 V or 90 V, the relative contrast dropped again
• the measuring accuracy was only +/- 3 V here.
• the mixture of the comparative example was filled into a test cell according to the teaching of the present application and its electro-optical properties were also determined at a temperature of 24 ° C.
• the test cell had the same structure as that used in the comparative example, but here the distance between the electrodes was 10 ⁇ m and the width of the electrodes was 5 ⁇ m.
• the cell thus obtained reached 10% relative contrast at a voltage of 26.5 V, 50% relative contrast at 38 V and 90% relative contrast at 46 V.
• the maximum contrast was reached at 51 V. at Voltages of 60 V, the relative contrast dropped back to 90%.
• the mixture used in the comparative example and in example 1 was filled into a test cell according to another embodiment of the teaching of the present application and its electro-optical properties were also determined at a temperature of 24 ° C.
• the test cell had a structure as shown in Figure 7. As with the cell used in Example 1, the distance between the electrodes was 10 ⁇ m and the width of the electrodes was 5 ⁇ m. Here, however, the electrodes were on pedestals. These had a layer thickness of 1.5 ⁇ m and consisted of the material of the substrate.
• the cell thus obtained reached 10% relative contrast at a voltage of 25 V, 50% relative contrast at 33.5 V and 90% relative contrast at 41 V. The maximum contrast was reached at 45 V.
• Example 3 As can be seen here, all the characteristic voltages of the liquid crystal switching element of Example 2 are once again significantly lower than those of Example 1. The reduction in the corresponding values compared to that of Comparative Example 1 is on average around 40% (38%).
• the mixture used in the comparative example and in previous examples 1 and 2 was filled into a test cell according to yet another embodiment according to the teaching of the present application and its electro-optical properties were also determined at a temperature of 24 ° C.
• the test cell had pairs of electrodes on the inside of both substrates as shown in Figure 8.
• the electrodes directly opposite each other on the two substrates were electrically conductively connected to one another, or the same potential was applied to these electrodes.
• the distance between the electrodes was 10 ⁇ m and the width of the electrodes was 5 ⁇ m.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• an electro-optical display is implemented and its characteristic is measured.
• the temperature is 24.0 ° C.
• the value of the threshold voltage (V 10 ) is 22 V
• the value of the medium gray voltage (V 5 o) is 35.5 V
• the value of the saturation voltage (V 90 ) is 44.5 V.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• an electro-optical display is implemented and its characteristic is measured.
• the temperature is 26.5 ° C.
• the characteristic curve begins at a low voltage with a relative intensity of 0% and increases with increasing voltage.
• the value of the threshold voltage (V 10 ) is 18 V
• the value of the medium gray voltage (V 50 ) is 28 V
• the value of the saturation voltage (Vgo) is 34 V.
• V 10 threshold voltage
• V 50 medium gray voltage
• Vgo saturation voltage
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• an electro-optical display is implemented and its characteristic is measured.
• the temperature at which the measurements were carried out is 23.1 ° C.
• the value of the threshold voltage (V 10) is 16.5 V, the value of the mid-gray voltage (V 5u) at 28 V and the value of the saturation voltage (V 90) at 31, 5 V.
• the liquid crystal mixture with the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• the medium has a clearing point of 21 ° C.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties. ⁇ (20 ° C, 1 kHz)> 0
• the liquid crystal mixture having the following composition was prepared.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture having the following composition was prepared.
• This mixture has the following properties.
• the liquid crystal mixture of comparative example 25a is filled into test cells according to the teaching of the present application, as in FIGS.
• Examples 1 to 3 are described.
• the resulting light control elements have similarly good properties, which are correspondingly improved over those of comparative example 25a, as described in the three examples 1 to 3. 10
• Tchar was the temperature at which the mixture in the described cell between crossed polarizers appears to be isotropic for the first time with increasing temperature.
• This mixture is tested in test cells according to the teaching of the present invention, as described in Examples 1 to 3 and for comparison in standard test cells for their properties, in particular for their phase behavior and their electro-optical properties.
• Figure 1 The figure shows schematically in cross section the structure of a switching element or part of a switching element according to the
• the control medium (2) is located between the inner surfaces of the substrates (1) and (1 ').
• the two electrodes (3) and (4) of the electrode structure are located on the inner surface of the one substrate (1) and can be acted upon with different potentials.
• Vop denotes the voltage, charge or current source.
• the lines emanating from Vop symbolize the electrical leads to the electrodes.
• FIGS. 2 to 6 The figures show a schematic cross section of the structure for five different embodiments of switching elements according to the invention with raised electrodes.
• the electrodes are designed similarly to the embodiment shown in Figure 1.
• the electrodes (3) and (4) have a rectangular or almost rectangular cross section.
• the electrodes have a thickness which is not to be neglected in relation to the layer thickness [d (2)] of the control layer (2) or in relation to the characteristic layer thickness, e.g. typically in the range from 0.3 ⁇ m to 5 ⁇ m.
• the electrodes (3) and (4) are designed similarly to the embodiment shown in Figure 2. However, these electrodes extend over the entire thickness [d (2)] of the control layer (2).
• the electrodes (3) and (4) are again designed similarly to the embodiment shown in Figure 2.
• the layer thickness of the electrodes (3) and (4) is not constant, but depends on the location.
• the electrodes have a triangular cross section.
• the electrodes (3) and (4) are designed similarly to the embodiment shown in Figure 4 with a layer thickness that is dependent on the location.
• these electrodes each consist of two superimposed layers (3) and (3 ') and (4) and (4'), each of which the upper (3 ') or (4') has a smaller area of the
• the electrodes (3) and (4) are again designed similarly to the embodiment shown in Figure 2.
• the electrodes (3) and (4) here have a circular cross section and are designed as a waveguide.
• Figure 7 The figure shows schematically in cross section the structure for a further preferred embodiment of the invention
• the electrodes are designed similar to the embodiment shown in Figure 1. However, the electrodes are not located directly on the surface of the substrate, but rather on a solid insulating layer (5) or (6) of a certain thickness, e.g. typically in the range of 1 ⁇ m to 2 ⁇ m.
• FIG 8 The figure shows a schematic cross section of the structure for a further preferred embodiment of switching elements according to the invention with an electrode structure in which the electrodes consist of two layers, which are each on one of the substrates.
• the electrodes are designed in such a way that there is a second electrode (3 ') on the second substrate (1 ") for the electrode (3) on the first substrate (1), to which a first potential can be applied The same potential can also be applied to the electrode (4) on the first substrate, which can be acted upon by the second potential, and a second electrode (4 ') on the second substrate, which can also be acted upon by the second potential
• the pairs of electrodes (3) and (3 ') and (4) and (4') face each other.
• Figures 9 to 13 The figures show schematically in cross section the structure of various embodiments of switching elements according to the invention according to a further preferred embodiment of the present invention.
• Figure 9 shows an embodiment which is a combination of the embodiments shown in Figures 7 and 8.
• electrodes ((3) and (4) are not only formed on solid insulating layers (5) and (6) on the substrate with the surface (1)
• the embodiment shown in Figure 8 is also formed on the surface of the opposite substrate (1 ') electrodes (3') and (4 '). Like the corresponding electrodes on the first substrate, these electrodes are formed by solid insulating layers (5') and ( 6 ') from the surface (1').
• the electrodes are designed similarly to the embodiment shown in Figure 7. However, as in the embodiment shown in Figure 8, the electrodes each consist of two layers (3) and (3 '), or (4) and (4'), each of which can be acted upon in pairs with the same potential. In contrast to the embodiment shown in Figure 8, the two pairs of conductive layers of the electrode structure (3) and (3 '), or (4) and (4') are not replaced by the dielectric control layer (2). separated from each other, but each by a solid insulating layer (5) or (6).
• the electrodes are designed similarly to the embodiment shown in Figure 10. However, as in the embodiment shown in FIG. 7, the first layers of the electrode structures (3) and (4) are separated from the substrate by a solid insulating layer (5) and (6).
• the two layers of the electrode structure that can be applied with the same potential (3) and (3 '), or (4) and (4') are as in the one in Figure 10 Embodiment described, each separated by a solid insulating layer, here (5 ') or (6') called.
• the electrodes of the electrode structure each consist of four conductive layers (3) to (3 '") or (4) to (4'"). Two of these four layers are located on the same substrate. Layers (3) and (3 ') and (4) and (4') are on the substrate with the surface (1) and (3 ") and (3 '") as well as (4 ") and (4'" ) are on the substrate with the surface (1 '). Of these layers, the respective layer (3) and (4) or (3 ") and (4") adjacent to the respective substrate (1) or (1 ') is provided by a solid insulating layer (5) and (6) or (5 ') and (6') separately.
• the electrodes of the electrode structure each consist of four conductive layers (2) to (2 '") or (3) to (3'").
• the alternating sequence of conductive layers and insulating layers extends over the entire layer thickness of the control layer.
• the inner pairs of the conductive layers (2 ') and (2'") and (3 ') and (3'") are also separated from one another by solid insulating layers (5 "") and (6 "").
• Vop voltage, charge or current source
• the lines emanating from Vop illustrate which conductive layers of the electrode structure are subjected to the same potential.

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• 2002
  • 2002-09-04 DE DE10241301A patent/DE10241301A1/de not_active Withdrawn
• 2003
  • 2003-08-25 WO PCT/EP2003/009402 patent/WO2004029697A1/de not_active Ceased
  • 2003-08-25 JP JP2004538836A patent/JP5106753B2/ja not_active Expired - Fee Related
  • 2003-08-25 DE DE10392930.4T patent/DE10392930B4/de not_active Expired - Fee Related
  • 2003-08-25 AU AU2003264099A patent/AU2003264099A1/en not_active Abandoned
  • 2003-08-27 TW TW092123574A patent/TW200408865A/zh unknown

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