Liquid Crystal Displays
1. “In liquid crystal display devices used in mobile phones and liquid crystal televisions, optical films including a retardation film are used to compensate for optical distortion due to optical anisotropy of a liquid crystal and dependency of chromatic display upon the viewing direction.
As the materials for these optical films, for example, a synthetic resin such as a polycarbonate resin and a cyclic olefin polymer is used; however, these synthetic resins are expensive. As an optical film formed of an inexpensive resin, a retardation film formed of a propylene-ethylene copolymer film is known.” [Hino, Takahata and Yada, US Patent 8,217,117 (7/10/2012)]
2. “Liquid-crystal displays (LCDs) are used in many areas for the display of information. LCDs are used both for direct-view displays and for projection-type displays. The electro-optical modes used are, for example, the twisted nematic (TN), super twisted nematic (STN), optically compensated bend (OCB) and electrically controlled birefringence (ECB) modes together with their various modifications, as well as others. All these modes utilise an electric field which is substantially perpendicular to the substrates or the liquid-crystal layer. Besides these modes, there are also electro-optical modes that utilise an electric field which is substantially parallel to the substrates or the liquid-crystal layer, such as, for example, the in-plane switching (IPS) mode (as disclosed, for example, in DE 40 00 451 and EP 0 588 568) and the fringe field switching (FFS) mode, in which a strong "fringe field" is present, i.e. a strong electric field close to the edge of the electrodes and, throughout the cell, an electric field which has both a strong vertical component and a strong horizontal component. These latter two electro-optical modes in particular are used for LCDs in modern desk-top monitors and are intended for use in displays for TV sets and multi-media applications. The liquid crystals according to the present invention are preferably used in displays of this type. In general, dielectrically positive liquid-crystalline media having rather lower values of the dielectric anisotropy are used in FFS displays, but in some cases liquid-crystalline media having a dielectric anisotropy of only about 3 or even less are also used in IPS displays.
For these displays, novel liquid-crystalline media having improved properties are required. The addressing times in particular have to be improved for many types of application. Thus, liquid-crystalline media having lower viscosities (.eta.), especially having lower rotational viscosities (.gamma..sub.1), are required. In particular for monitor applications, the rotational viscosity should be 80 mPas or less, preferably 60 mPas or less and especially 55 mPas or less. Besides this parameter, the media must have a nematic phase range of suitable width and position and an appropriate birefringence (.DELTA.n), and the dielectric anisotropy (.DELTA..di-elect cons.) should be sufficiently high to allow a leasonably low operating voltage. .DELTA..di-elect cons. should preferably be greater than 2 and very preferably greater than 3, but preferably not greater than 15 and in particular not greater than 12, as this would prevent an at least fairly high resistivity.”
[Czanto et al, US Patent 8,231,806 (7/31/2012)]
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Roger D. Corneliussen
Maro Polymer Links
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Copyright 2012 by Roger D. Corneliussen.
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* Date of latest addition; date of first entry is 7/30/2012.