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
  • G02F1/141—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent using ferroelectric liquid crystals
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
  • G02F1/139—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
  • G02F1/141—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent using ferroelectric liquid crystals
  • G02F1/1416—Details of the smectic layer structure, e.g. bookshelf, chevron, C1 and C2
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
  • G01N35/0098—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor involving analyte bound to insoluble magnetic carrier, e.g. using magnetic separation
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
  • G01N21/03—Cuvette constructions
  • G01N21/05—Flow-through cuvettes
  • G01N2021/054—Bubble trap; Debubbling

Definitions

• the replacement of the cathode ray tube (picture tube) with a flat screen requires a display technology that simultaneously has high image resolution, ie more than 1000 lines, high image brightness (> 200 Cd / m 2 ), high contrast (> 100: 1), a high image frequency (> 60 Hz), sufficient color display (> 16 million colors), a large image format (> 40 cm screen diagonal), low power consumption and a wide viewing angle enable and also inexpensive to produce. So far, there is no technology that fully fulfills all of these features at the same time.
• Tsukuda, TFT / LCD Liquid Crystal Displays Addressed by Thin-Film Transistors, Gordon and Breach 1996, ISBN 2-919875-01-9 and the literature cited therein; SID Symposium 1997, ISSN-0097-966X, pages 7 to 10, 15 to 18, 47 to 51, 213 to 216, 383 to 386, 397 to 404 and the literature cited therein.
• PDP Plasma Display Panel
• PALC Phase Change RAM
• ELD Electro Luminescent Display
• FED Field Emission Display
• the individual picture elements (pixels) of an LC display are usually arranged in an x, y matrix, which is arranged by a series of electrodes
• This arrangement of the pixels is usually referred to as a passive matrix.
• Various multiplexing schemes have been developed for addressing, as described, for example, in Displays 1993, Vol. 14, No. 2, pp. 86-93 and contacts 1993 (2), pp. 3-14.
• Passive matrix addressing has the advantage of simpler manufacture of the display and associated lower manufacturing costs the disadvantage that the passive addressing can only be done line by line, which means that the addressing time of the entire screen is N times the line addressing time for N lines. With the usual line addressing times of approx. 50 microseconds, this means a screen addressing time of approx. 60 milliseconds with, for example, HDTV standard (High Definition TV, 1152 lines), ie a maximum frame rate of approx. 16 Hz.
• HDTV standard High Definition TV, 1152 lines
• AMLCD active matrix technology
• An electrically non-linear element for example a thin-film transistor, is integrated on each pixel of the active matrix substrate.
• the nonlinear element can also be diodes, metal insulator metal and other elements which are advantageously produced using thin-film processes and are described in the relevant literature, see, for example, T. Tsukuda, TFT / LCD: Liquid Crystal Displays Addressed by Thin -Film Transistors, Gordon and Breach 1996, ISBN 2-919875-01-9 and literature cited therein.
• Active matrix LCDs are usually operated with nematic liquid crystals in TN (twisted nematics), ECB (electrically controlled birefringence), VA (vertically aligned) or IPS (in plane switching) mode.
• TN twisted nematics
• ECB electrically controlled birefringence
• VA vertical aligned
• IPS in plane switching
• the active matrix generates an electric field of individual strength at each pixel, which produces a change in orientation and thus a change in birefringence, which in turn is visible in polarized light.
• a serious disadvantage of this method is the lack of video capability due to the long switching times of nematic liquid crystals.
• liquid crystal displays based on a combination of ferroelectric liquid crystal materials and active matrix elements have been proposed, see e.g. WO 97/12355 or Ferroelectrics 1996, 179, 141-152, W.J.A.M. Hartmann, IEEE Trans. Electron. Devices 1989, 36, (9; Pt. 1), 1895-9, and dissertation Eindhoven, The Netherlands 1990.
• Hartmann used a combination of the so-called 'quasi-bookshelf geometry' (QBG) from FLC and a TFT (thin-film transistor) active matrix and at the same time received a high switching speed, grayscale and high transmission.
• QBG 'quasi-bookshelf geometry'
• TFT thin-film transistor
• a disadvantage of this approach is the appearance of a stripe texture on the display that limits the contrast and brightness of this cell (see Fig. 8 in the above quotation).
• the disadvantageous stripe texture can be corrected by treatment with a high electrical voltage (20-50 V) in the nematic or cholesteric phase (see p. 168 of the above quotation); however is one
• Field treatment is not suitable for the mass production of screens and generally does not lead to temperature-stable textures.
• this method only results in switching in an angular range of up to a maximum of the simple tilt angle, which in the case of Nito et. al.
• the material used is approx. 22 ° (see p. 165 Fig. 6) and thus only results in a transmission of a maximum of 50% of the transmission of two parallel polarizers.
• a monostable ferroelectric active matrix display containing a liquid crystal layer in the form of a Monodomain with a clearly defined direction of the layer normal z of the smC * phase, the layer normal z and the preferred direction n of the nematic or cholesteric phase (N * phase forming an angle of more than 5 °.
• the active matrix FLCD according to the invention contains, as an optically active layer, a ferroelectrically liquid-crystalline medium (liquid-crystal phase) with a phase sequence of
• the asterisk (*) on the phase label indicates that it is a chiral phase.
• the displays are produced, preferably by a process in which the liquid crystal layer is introduced into the space between a rubbed upper substrate plate and a rubbed lower substrate plate of the active matrix display, the rubbing directions on the upper and lower substrate plates being essentially parallel, and the liquid crystal phase cools from the isotropic phase, with at least at the phase transition N * ⁇ smC * or N * ⁇ smA * ⁇ smC * an electrical direct voltage is present on the display.
• the FLC mixture is filled into an active matrix display.
• the manufacture and components of such an AM display is described in detail in the Tsukuda literature listed above.
• the thickness of the FLC layer is however, unlike nematic displays, only 0.7 to 2.5, preferably 1-2 ⁇ m.
• the rubbing directions on the upper and lower substrate plates are essentially parallel.
• the term "substantially parallel” includes antiparallel or weak, ie up to 10 ° crossed rubbing directions.
• an electrical direct voltage preferably below 5 V, is applied during the production of the display during controlled cooling and is maintained during the phase transition N * -> smC * or N-> smA * -> smC * , which leads to the fact that the entire display occupies a monostable mono-domain that appears completely dark between crossed polarizers.
• the DC voltage is switched off.
• the texture thus obtained is monostable in contrast to Hartmann's approach mentioned above or in contrast to conventional bistable FLCD.
• the preferred n-director (which indicates the preferred direction of the molecular longitudinal axes) is located in the rubbing direction of the cell, whereas the z-director (which indicates the preferred direction of the smectic layer normal) is inclined approximately by the amount of the tilt angle Rubbing direction is located.
• This constellation is exactly the opposite of the usual bistable cell according to Clark and Lagerwall, where the z-director lies in the rubbing direction.
• the double tilt angle which leads to 100% transmission in relation to parallel polarizers, is now accessible, ie double brightness is achieved.
• the display thus obtained appears completely dark with a suitable angle of rotation between crossed polarizers.
• a control voltage of only a few volts is applied, it appears bright, whereby the brightness can be varied continuously over the voltage and, when saturated, has almost the brightness of two parallel polarizing foils.
• the angle between the preferred direction of the nematic (or cholesteric) phase and the layer normal (z director) is ideally equal to the tilt angle of the smectic C phase, or at least substantially the same as the tilt angle .
• "In essence" in the sense of this invention preferably means a range of values from half to the full, particularly preferably 0.8 to 1 times the tilt angle, but at least 5 °.
• the ferroelectric active matrix liquid crystal display according to the invention is highly practical, in particular for TV and HDTV or multimedia, since it agrees high transmission, short switching times, gray scale and therefore full color capability, cost-effective production and a wide temperature range.
• the display can be operated at voltages of ⁇ 10 volts, preferably ⁇ 8 V, particularly preferably ⁇ 5 V.
• the spontaneous polarization of the active matrix FLCD according to the invention is preferably below 15 nC / cm 2 , preferably in the range from 0.01 to 10 nC / cm 2 at the operating temperature of the display.
• the length of the chiral-nematic or cholesteric pitch in a temperature range of at least 2 ° C. above the transition to the smectic phase is more than 50 ⁇ m.
• IC integrated circuit
• the displays can be used for example in the TV, HDTV or multimedia area or in the field of information processing, e.g. in notebook PCs, personal digital assistants or desktop monitors.
• phase sequence is:
• the tilt angle is 25 ° at 30 ° C.
• the spontaneous polarization is 2 nC / cm 2 Example 2
• a glass substrate coated with transparent-conductive indium-tin oxide is patterned in a photolithographic process so that an electrode pattern is obtained.
• the transparent conductor tracks of this electrode structure are used for the electrical control of the display by means of a function generator, thus simulating the switching behavior of a thin-film transistor.
• Two glass panes structured in this way, which form the top and bottom of the display - that is to say the carrier plates - are joined together with the aid of an adhesive frame.
• the layer thickness is 1.3 ⁇ m.
• the adhesive is hardened by careful heating, the liquid crystal mixture from Example 1 is filled in at 100 ° C. and the cell is brought to a temperature of 60 ° by slow cooling. A DC voltage of 4 V is applied at this temperature and the cooling process is then continued up to 22 ° C. The DC voltage is switched off.
• a monostable monodomain is obtained which appears completely dark between crossed polarizers.
• the cell is now connected with rectangular pulses of variable amplitude and the transmission is measured using a photodiode and an oscilloscope.
• the following transmission values are obtained:
• phase sequence is:
• a glass substrate coated with transparent - conductive indium tin oxide is structured in a photolithographic process, so that an electrode pattern is obtained.
• the transparent conductor tracks of this electrode structure are used for the electrical control of the display by means of a function generator, thus simulating the switching behavior of a thin-film transistor.
• Two glass panes structured in this way, which form the top and bottom of the display - that is to say the carrier plates - are joined together with the aid of an adhesive frame.
• the layer thickness is 1.3 ⁇ m.
• the adhesive is hardened by careful heating, the liquid crystal mixture from Example 3 is filled in at 100 ° C. and the cell is brought to a temperature of 63 ° C. by slow cooling. A DC voltage of 4 V is applied at this temperature and the cooling process is then continued up to 22 ° C. The DC voltage is switched off.
• a monostable monodomain is obtained which appears completely dark between crossed polarizers.
• the cell is now connected with rectangular pulses of variable amplitude and the transmission is measured using a photodiode and an oscilloscope.
• the following transmission values are obtained:

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• 1998
  • 1998-05-20 DE DE19822830A patent/DE19822830A1/de not_active Withdrawn
• 1999
  • 1999-05-19 US US09/700,517 patent/US6704086B1/en not_active Expired - Lifetime
  • 1999-05-19 WO PCT/EP1999/003437 patent/WO1999060441A1/de active IP Right Grant
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