DE19825484A1 - Monostable ferroelectric active matrix display useful in television, multimedia or data processing - Google Patents

Abstract

In a monostable ferroelectric active matrix display having a monodomain liquid crystal (LC) layer with a well-defined direction of the normal z of the smectic C asterisk (smC asterisk ) phase, the angle between z and the preferred orientation n of the nematic or cholesteric phase (N asterisk phase) is over 5 deg . The LC layer consists of >= 5 compounds, comprising an achiral base mixture of fluorobenzene or fluoronaphthalene compound(s) (IA) and/or fluorophenanthrene compound(s) (IB) and optionally other compound(s) (II) and/or (III) and chiral component(s) (IV). In a monostable ferroelectric active matrix display having a monodomain liquid crystal (LC) layer with a well-defined direction of the normal z of the smectic C asterisk (smC asterisk ) phase, the angle between z and the preferred orientation n of the nematic or cholesteric phase (N asterisk phase) is over 5 deg . The LC layer consists of >= 5 compounds, comprising an achiral base mixture of fluorobenzene or fluoronaphthalene compound(s) (IA) and/or fluorophenanthrene compound(s) (IB) and optionally other compound(s) (II) and/or (III) and chiral component(s) (IV) of the formulae; A<3> = 2-fluoro-, 2,3-difluoro-, 2,6-difluoro-, 2,5-difluoro-, 2,3,6-trifluoro- or 2,3,5,6-tetrafluoro-1,4-phenylene, 5-fluoro-, 3,4-difluoro or 1,3-difluoro-naphthalen-2,6-diyl; A'<3> = 1-fluoro- or 1,8-difluoro-phenanthren-2,7-diyl or 1-fluoro- or 1,8-difluoro-9,10-dihydro-phenanthren-2,7-diyl; R<7> = a group with asymmetric carbon (C) atom(s) as a constituent of a substituted 3-12 C alkyl group or 3-7-membered carbo- or hetero-cycle . The full definitions are given in the DEFINITIONS (Full Definitions) Field. An Independent claim is also included for a method of producing a display.

Description

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, and it is also inexpensive to manufacture. So far, there is no technology that fully fulfills all of these features at the same time.

Many manufacturers have screens based on nematic liquid crystals developed, for example in the area of notebook PC, Personal digital assistants and desktop monitors are in use. In doing so the technologies STN (Supertwisted Nematics), AM-TN (Active Matrix-Twisted Nematics), AM-IPS (Active Matrix-In Plane Switching), AM-MVA (Active Matrix- Multidomain Vertically Aligned) used extensively in the literature be described, see e.g. B. 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; 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 literature cited therein. In addition, the technologies PDP (Plasma Display Panel), PALC (Plasma Addressed Liquid Crystal), ELD (Electro Luminescent Display) and FED (Field Emission Display) applied, which are also cited in the SID Report are explained.  

Clark and Lagerwall (US 4,367,924) were able to show that the use ferroelectric liquid crystals (FLC) in very thin cells to optoelectric Switching or display elements leads, compared to the conventional TN ("twisted nematic") cells up to a factor of 1000 faster switching times have, see also EP-A 0 032 362. Because of this and others cheaper Properties, e.g. B. the bistable switching option and almost angle-independent contrast, FLCs are basically for Areas of application such as computer displays and televisions suitable as a monitor marketed by Canon in Japan since May 1995.

For the use of FLCs in electro-optical or completely optical Components require either connections, the smectic phases train and are optically active themselves, or you can by doping Connections that form such smectic phases, but not themselves are optically active, with optically active compounds ferroelectric smectic Induce phases. The desired phase should be as large as possible Temperature range to be stable.

The individual picture elements (pixels) of an LC display are usually in an x, y Matrix arranged by the arrangement of a series of electrodes (Conductor tracks) along the rows and the columns at the bottom or top of the display is formed. The crossing points of the horizontal (row) and vertical (column) electrodes form addressable pixels.

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 the associated low manufacturing costs, but the disadvantage that passive addressing can only be carried out line by line, which means that the addressing time of the entire screen for N lines is N times the line addressing time is. With usual line addressing times of approx. 50 microseconds, this means a screen addressing time of approx. 60 milliseconds at z. B. HDTV standard (High Definition TV, 1152 lines), ie a maximum frame rate of approx. 16 Hz. This frequency is too low for the display of moving pictures. The display of grayscale is also difficult. Mizutani et. al. who on the occasion of the FLC Conference in Brest, France (July 20 to 24 1997 see Abstract Book 6 ^th International Conference on Ferroelectric Liquid Crystals, Brest / France) a passive FLC display with digital gray scale presented in which each of the RGB pixels (RGB = red, green, blue) was subdivided into sub-items, which enables the display of gray values in digital form using partial switching. With N gray values using three primary colors (red, green, blue), there are 3 ^N colors. The disadvantage of this method is a large increase in the number of display drivers required and thus in the cost. In the case of the screen shown in Brest, three times as many drivers were required as with a normal FLC display without digital grayscale.

With the so-called active matrix technology (AMLCD), a non- structured substrate combined with an active matrix substrate. At every pixel of the active matrix substrate is an electrically non-linear element, for example a Thin film transistor, integrated. The nonlinear element can also around diodes, metal insulator metal u. Act elements that are advantageous with Thin film processes are produced and in the relevant literature are described, see e.g. B. 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 built with nematic liquid crystals in the TN (twisted nematics), ECB- (electrically controlled birefringence), VA- (vertically  aligned) or IPS (in plane switching) mode. In any case, the active matrix generates an electric field of individual strength at each pixel, this is a change in orientation and thus a change in birefringence generated, which in turn is visible in polarized light. A serious one The disadvantage of this method is the lack of video capability due to the long switching times of nematic liquid crystals.

For this reason, among other things, liquid crystal displays based on a Combination of ferroelectric liquid crystal materials and active matrix Elements are based, proposed, see e.g. B. WO 97/12355 or Ferroelectrics 1996, 179, 141-152, W.J.A. 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. However, the QBG is not stable over a wide temperature range because the field-induced layer structure breaks up or rotates due to the temperature dependence of the smectic layer thickness. In addition, Hartmann uses an FLC material with a spontaneous polarization of more than 20 nC / cm ² , which is the case with pixels with realistic dimensions of e.g. B. 0.01 mm ² area leads to large electrical charges (with saturation Q = 2 AP, A = pixel area, P = spontaneous polarization), the z. B. with inexpensive to manufacture amorphous silicon TFT during the opening time of the TFT can not get to the pixel. For these reasons, this technology has not been pursued until now.

While Hartmann used charge-controlled bistability to represent an almost continuous gray scale, Nito et. al. a monostable FLC Geometry suggested, see Journal of the SID, 1/2, 1993, pages 163-169, in which the FLC material with the aid of relatively high voltages  is oriented that only a stable position arises, from which then by applying of an electric field via a thin film transistor Intermediate states are generated, which, with adapted cell geometry, between crossed polarizers of a number of different degrees of brightness (Gray values) correspond.

However, 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, such a field treatment is not suitable for the mass production of screens and generally does not lead to temperature-stable textures. In addition, 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.

The object of the present invention is to provide a ferroelectric Active matrix liquid crystal display, which is a ferroelectric liquid crystal mixture contains, wherein the liquid crystal mixture assumes a monostable position, thereby but does not form a stripe texture, is light and temperature stable and has a very high Maximum transmission and a very high contrast enables.

The object is achieved according to the invention by a monostable ferroelectric active matrix display comprising a liquid crystal layer in the form of a monodomain with a clearly defined direction of the layer normals z of the smC * phase, the layer normals z and the preferred direction n of the nematic or cholesteric phase (N * -Phase form an angle of more than 5 °, wherein the liquid crystal layer from a liquid crystal mixture of at least 5 compounds, which is composed of
an achiral base mixture containing at least one compound from the group (I) formed by (Ia-Ik), optionally additionally at least one compound from the group formed by (IIa-IIg) and / or optionally at least one compound from group (III),
and
at least one chiral component of group (IV)

R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ia)

in the A ³

means and the remaining substituents have the following meanings

R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ib)

in the A ³

means and the remaining substituents have the following meanings

R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ic)

in the A ³

means and the remaining substituents have the following meanings

R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Id)

in the A ³

means and the remaining substituents have the following meanings

R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ie)

in the A ³

means and the remaining substituents have the following meanings

R ¹ (- (A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (If)

in the A ³

means and the remaining substituents have the following meanings

R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ig)

in the A ³

means and the remaining substituents have the following meanings

R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ih)

in the A ³

means and the remaining substituents have the following meanings

R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ii)

in the A ³

means and the remaining substituents have the following meanings
R ¹ , R ² independently of one another, identically or differently, are hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two -CH ₂ groups can be replaced by -CH = CH- or -OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl and in which one or more H atoms can also be replaced by F with the proviso that R ¹ , R ² cannot both be hydrogen
A ¹ , A ² , A ⁴ , A ^5, independently of one another, the same or different 1,4-phenylene, optionally mono- or disubstituted by F or Cl, cyclohexane-1,4-diyl, optionally monosubstituted by F, cyclohex-1- en-1,4-diyl, cyclohex-2-ene-1,4-diyl, 1-alkyl-1-sila-cyclohexane-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl, Indane-2,6-diyl, naphthalene-2,6-diyl
M ¹ , M ² , M ⁴ , M ^5, independently of one another, the same or different, a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or CH ₂ -O- CH ₂ CH ₂ - CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero

R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ik)

in the A ³

means and the remaining substituents have the following meanings:
R ¹ , R ² independently of one another, identically or differently, are hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two -CH ₂ groups can be replaced by -CH = CH- or -OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl and in which one or more H atoms can also be replaced by F with the proviso that R ¹ , R ² cannot both be hydrogen
G1-G2 -CH = CH- or -CH ₂ -CH ₂ - means
n means zero or one
A ¹ , A ² , A ⁴ , A ^5, independently of one another, the same or different 1,4-phenylene, optionally mono- or disubstituted by F or Cl, cyclohexane-1,4-diyl, optionally monosubstituted by F
M ¹ , M ² , M ⁴ , M ⁵ independently of one another, the same or different, are a single bond, -OC (= O) - or- (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH _2-, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 0 <{a + b + c + d} ≦ 2 and the understanding that M ^{x is} a single bond if the corresponding index is zero.

R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIa)

where A ⁶

means.
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and wherein one or more H atoms can also be replaced by F, with the proviso that R ¹ , R ² cannot both be hydrogen
A ¹ , A ⁸ , A ⁹ , A ^10, independently of one another, the same or different 1,4-phenylene, cyclohexane-1,4-diyl, cyclohex-1-en-1,4-diyl, cyclohex-2-en-1, 4-diyl, bicyclo [2.2.2] octane-1,4-diyl,
M ⁷ , M ⁸ , M ⁹ , M ^10, independently of one another, the same or different, are a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH ₂ -, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,

R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ ) _d -R ⁴ (IIb)

where A ⁶

means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and wherein one or more H atoms can also be replaced by F, with the proviso that R ¹ , R ² cannot both be hydrogen
A ¹ , A ⁸ , A ⁹ , A ^10, independently of one another, the same or different 1,4-phenylene, optionally mono- or disubstituted by F or Cl, cyclohexane-1,4-diyl, optionally monosubstituted by F, cyclohex-1- en-1,4-diyl, cyclohex-2-ene-1,4-diyl, 1-alkyl-1-sila-cyclohexane-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl, Indane-2,6-diyl, naphthalene-2,6-diyl
M ⁷ , M ⁸ , M ⁹ , M ¹⁰ independently of one another, identically or differently, are a single bond, -OC (= O) - or- (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH ₂ -, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,

R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIc)

where A ⁶

means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
M ⁷ , M ⁸ , M ⁹ , M ^10, independently of one another, the same or different, are a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH _2-, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,

R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IId)

where A ⁶

means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and wherein one or more H atoms can also be replaced by F, with the proviso that R ¹ , R ² cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of one another, the same or different 1,4-phenylene, cyclohexane-1,4-diyl, optionally optionally substituted by F, cyclohex-1-ene-1,4-diyl, cyclohexyl 2-ene-1,4-diyl, 1-alkyl-1-sila-cyclohexane-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl, naphthalene-2,6-diyl
M ⁷ , M ⁸ , M ⁹ , M ¹⁰ independently of one another, identically or differently, are a single bond, -OC (= O) - or- (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,

R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIe)

where A ⁶

means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and wherein one or more H atoms can also be replaced by F, with the proviso that R ¹ , R ² cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of one another, identically or differently, cyclohexane-1,4-diyl, optionally simply substituted by F, cyclohex-1-ene-1,4-diyl, cyclohex-2-ene-1, 4-diyl
M ⁷ , M ⁸ , M ⁹ , M ^10, independently of one another, the same or different, are a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH _2-, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,

R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIf)

where A ⁶

means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and wherein one or more H atoms can also be replaced by F, with the proviso that R ¹ , R ² cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of the same or different 1,4-phenylene, cyclohexane-1,4-diyl, optionally simply substituted by F, cyclohex-1-ene-1,4-diyl, cyclohex-2 -en-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl
M ⁷ , M ⁸ , M ⁹ , M ^10, independently of one another, the same or different, are a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH _2-, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,

R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIg)

where A ⁶

means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CC- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and wherein one or more H atoms can also be replaced by F, with the proviso that R ¹ , R ² cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of one another, identically or differently, cyclohexane-1,4-diyl, optionally simply substituted by F, cyclohex-1-ene-1,4-diyl, cyclohex-2-ene-1, 4-diyl
M ⁷ , M ⁸ , M ⁹ , M ^10, independently of one another, the same or different, are a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH ₂ -, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,

R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIh)

where A ⁶

means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and in which one or more H atoms can also be replaced by F.
with the proviso that R ¹ , R ² cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of one another, identically or differently, cyclohexane-1,4-diyl, optionally simply substituted by F, cyclohex-1-ene-1,4-diyl, cyclohex-2-ene-1, 4-diyl
M ⁷ , M ⁸ , M ⁹ , M ¹⁰ independently of one another, identically or differently, are a single bond, -OC (= O) - or- (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH ₂ -, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: is zero, zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,

R ⁵ (-A ¹¹ -M ¹¹ ) _a (-A ¹² -M ¹² ) _b -A ¹³ (III)

where A ¹³

means
and
X ¹ , X ² , X ³ independently, X ³ independently of one another, identically or differently, H, Cl, F, OCF ₂ H, CF ₃ mean with the proviso that at least one of X ¹ , X ² , X ^{3 is} not H,
R ^{5 is} hydrogen, alkyl or alkyloxy with 2-12 C atoms, in which one or two -CH ₂ groups can be replaced by -CH = CH- or -OC (= O) - or - (O =) CO - or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and in which one or more H atoms can also be replaced by F.
A ¹¹ , A ^12, independently of one another, the same or different 1,4-phenylene, cyclohexane-1,4-diyl, cyclohex-1-en-1,4-diyl, cyclohex-2-en-1,4-diyl, 1- Alkyl-1-sila-cyclohexane-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl, indane-2,6-diyl, naphthalene-2,6-diyl
M ⁷ , M ⁸ , M ⁹ , M ^10, independently of one another, the same or different, are a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH ₂ -, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,

R ⁶ (-A ¹⁴ -M ¹⁴ ) _a (-A ¹⁵ -M ¹⁵ ) _b - (M ¹⁶ -A ¹⁶ ) _c - (M ¹⁷ -A ¹⁷ ) _d -M ¹⁸ -R ⁷ (IV)

wherein
R ⁶ hydrogen, alkyl or alkyloxy with 2-12 C atoms, in which one or two -CH ₂ groups can be replaced, can be replaced by -CH = CH- or -OC (= O) - or - (O = ) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and in which one or more H atoms can also be replaced by F,
R ^{7 is} a grouping with at least one asymmetric carbon atom, which is either part of an alkyl group of 3-12 carbon atoms, in which one or two -CH ₂ groups can also be replaced by -O- or -OC (= O) or - (O =) CO- and in which -CH ₃ , -CF ₃ , -OCH ₃ -CH ₃ Cl, F must be one of the substituents of the asymmetric C atom,
or is part of a 3-7-membered carbocycle (in which one or two non-adjacent -CH ₂ groups by -O- or a -CH ₂ group by -OC (= O) - or - (O =) CO- can be replaced.
A ¹⁴ , A ¹⁵ , A ¹⁶ , A ^17, independently of one another, the same or different 1,4-phenylene, optionally mono- or disubstituted by F or Cl, cyclohexane-1,4-diyl, optionally monosubstituted by F, cyclohex-1- en-1,4-diyl, cyclohex-2-ene-1,4-diyl, 1-alkyl-1-sila-cyclohexane-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl, Indane-2,6-diyl, naphthalene-2,6-diyl
M ¹⁴ , M ¹⁵ , M ¹⁶ , M ^17, independently of one another, identical or different, are a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ -, -CH ₂ -O- -CH ₂ CH _2-, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
M ^{18 is} a single bond if the asymmetric carbon atom is part of an alkyl chain,
and a single bond, -OCH ₂ -, -CH ₂ O-, -OC (= O) - or -C (= O) O- in the event that the asymmetric carbon atom is part of a carbocycle
a, b, c, d: zero or 1, with the proviso 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero.

Preferred mixtures have one or more of the following features:

• - R ¹ and R ^{2 represent} straight-chain alkyl or alkyloxy having 2 to 12 carbon atoms.
• - The mixture contains at least one compound in which a non-terminal -CH ₂ group in R ¹ or R ^{2 is} replaced by -OC (= O).
• - In at least one compound of the formula (I) or (II) in R ¹ and / or R ^2, at least one or more, but not the —CH ₂ group adjacent to the nucleus, is replaced by —CF ₂ -.
• - In at least one compound of the formulas (I) or (II), R ¹ or R ^{2 is} hydrogen
• - R ⁷ is sec-alkyl or sec-alkyloxy with 4 to 12 carbon atoms
• - R ⁷ is 2-methyl-alkyl or 2-methyl-alkyloxy or 2-methyl-alkylcarbonyloxy or 2-methyl-alkyloxycarbonyl with 4 to 12 carbon atoms
• - R ⁷ is 2-fluoro-alkyl or 2 fluoro-alkyloxy or 2-fluoro-alkylcarbonyloxy or 2-fluoro-alkyloxycarbonyl with 3 to 12 carbon atoms
• - R ⁷ is 2-trifluoromethyl-alkyl or 2-trifluoromethyl-alkyloxy or 2-trifluoromethyl-alkylcarbonyloxy or 2-trifluoromethyl-alkyloxycarbonyl with 3 to 12 carbon atoms
• - R ⁷ contains the grouping [-O-CH (CH ₃ ) -C (= O) O-] as part of an alkyl chain
• - R ⁷ contains the grouping -C (= O) O- as part of a 5- or 6-membered cycle.

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
Isotropic-nematic or cholesteric (N *) - smectic C *
or a phase sequence isotropic-nematic or cholesteric (N *) - smectic A * - smectic C *, the smectic A * phase having a range of existence (phase range) of at most 2 ° C, preferably at most 1 ° C, particularly preferably at most 0.5 ° C owns. The asterisk (*) on the phase label indicates that it is a chiral phase.

The FLC mixtures have high values for resistance and tension (voltage-retaining-ability).  

The displays are produced, preferably by a process in which the liquid crystal layer in the space between a rubbed Top substrate plate and a rubbed bottom substrate plate of the active matrix Introduces displays, the rubbing directions on the top and bottom substrate plate are substantially parallel, and the liquid crystal phase from the isotropic phase cools down, at least during the phase transition N * → smC * or N * → smA * → smC * there is an electrical DC voltage on the display.

The FLC mixture is filled into an active matrix display. The manufacture and the Components of such an AM display is detailed in the above literature from Tsukuda. The thickness of the FLC layer is however, unlike nematic displays, only 0.7 to 2.5, preferably 1-2 µm. In addition, the rubbing directions on the upper and lower substrate plates in the essentially parallel. The term "essentially parallel" includes anti-parallel or weak, d. H. friction directions crossed by up to 10 °.

It is important for the functioning of this display that in the manufacture of the Displays controlled DC voltage when cooling down, preferably below 5 V, applied and at the phase transition N * → smC * or N → smA * → smC * is maintained, which leads to the fact that the entire display is a monostable monodomain that occupies between crossed polarizers appears completely dark.

After receiving this domain, the DC voltage is switched off. The so obtained Texture is contrary to Hartmann's approach or in contrast to conventional bistable FLCD monostable. This means that 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 (who the Preferred direction of the smectic position normal indicates) around the The amount of the tilt angle is at an angle to the rubbing direction. This constellation is  just opposite to the usual Clark and bistable cell Lagerwall, with the z director in the rubbing direction.

In contrast to Nito's approach, there are no two in this orientation Position normals and therefore no two orientation domains that ultimately lead to the lead above disturbing stripe texture, but only a clear Direction of the z director and therefore a monodomain. In addition, the double tilt angle, 100% transmission based on parallel polarizers leads, accessible, d. H. double brightness is achieved.

The display thus obtained appears at a suitable angle of rotation between crossed Polarizers completely dark. When applying a control voltage of only A few volts it appears bright, the brightness continuously across the voltage can be varied and, when saturated, almost the brightness of two parallel ones Owns polarizing foils. An important feature of this display is that the Angle between the preferred direction of the nematic (or cholesteric) Phase and the layer normal (z director) ideally equal to the tilt angle of the is smectic C phase, or is at least substantially equal to the tilt angle. "Essentially" in the sense of this invention preferably means one Range of values from half to full, particularly preferably 0.8 to 1 times Tilt angle, but at least 5 °.

The ferroelectric active matrix liquid crystal display according to the invention is in highly practical, especially for TV and HDTV or multimedia, since it high transmission, short switching time, gray scale and therefore full color capability, cost-effective production and a wide temperature range with each other agreed. In addition, the display can be operated at voltages of ≦ 10 volts, preferably operate ≦ 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 in the liquid crystal layer is preferably nematic or cholesteric pitch in one Temperature range of at least 2 ° C above the transition to smectic Phase more than 50 µm.

The displays can, for example, in the TV, HDTV or multimedia area or used in the field of information processing, e.g. B. in notebook PCs, personal digital assistants or desktop monitors.

The production processes of those suitable for the mixtures according to the invention In principle, materials are known, as is the production of Liquid crystal mixtures from the individual components.

So z. B. Compounds of the respective formulas below described in:
(Ia) EP-B-0 210215 and GB-B 2198743
(Ib) EP-B-0 210 215 and from JP-B 2732765
(Ic) Gray et. al., Mol. Cryst. Liq. Cryst. 1991, vol. 204, pp. 43-64
(Id) Gray et. al., Mol. Cryst. Liq. Cryst. 1991, vol. 204, pp. 43-64
(Ie) EP-B 602596
(If) Xu et. al., Liq. Cryst. 1995, 18 (I), 105-8
(Ig) JP-A 09052859
(Ih) DE-A 195 22 167
(II) DE-A-196 52 252
(Ik) US 5,648,021
(IIa) Liquid crystals in Tables II, pp. 269-304
(IIb) US 5,447,656
(IIc) Liquid crystals in Tables II, pp. 313-322
(IId) EP-A-0 546 338
(IIe) Liquid crystals in Tables II, pp. 32-72
(IIf) EP-A-0 761 674, 742 222, 732 335, 727 428 etc.
(IIg) Liquid crystals in Tables II, pp. 85-95
(III) EP-A-0 832 954
(IV) chiral dopants with
oxirane as a unit with an asymmetric carbon atom EP-B-0 292 954/263 437
dioxolane as a unit with an asymmetric carbon atom EP-B-0 351 746/361 272
2,3-difluoroalkyloxy as a unit with an asymmetric carbon atom US 5,051,506
2-fluoroalkyloxy as a unit with an asymmetric carbon atom US 4,798,680
α-chlorocarboxylate as a unit with an asymmetric carbon atom US 4,855,429
α-fluorocarboxylate as a unit with an asymmetric carbon atom Arakawa et. al., Liquid Crystals 1997, vol. 23, no. 5, pp. 659-666
Methyl-branched alkyl chains as a unit with an asymmetric carbon atom EP-B-0 201 578, 211 030
Lactones as a unit with an asymmetric carbon atom z. B. US 5,061,398, 5,256,330, 5,026,506
as well as connections with the structural elements
silylalkyl- from EP-B-0 366 561
cyclopropylalkyl- from EP-B-0 318 423/398 155
perfluroalkyl from Ferroelectrics 1988, 85, 375-384 or US 4,886,619, 5,082,587, 5,254,747, 5,262,082, 5,437,812 or 5,482,650
perflurocyclohexyl from DE-A-197 48 818.

Examples example 1

The particular suitability of the compounds according to the invention as Components of ferroelectric liquid crystal mixtures for active matrix Displays are supported by the measurements below, in which the Compounds according to the invention compared to others, also as Components of ferroelectric liquid crystal mixtures proposed Components are examined.

The resistance is measured using a relevant measuring arrangement following components measured.

• a) 2- (4-Octyloxyphenyl) -5-octyl-pyrimidine (Synthesis according to DD-WP 95892, cleaning according to Nagashima et. al., Liq. Crystals 1997, vol. 4, pp. 537-546)
• b) 2- (4-ethylphenyl) -5- (4-octylphenyl) - (1,3,4) thiadiazole (Synthesis / purification according to EP-B 309514)
• c) 5- (4-Nonanoyloxy-phenyl) -2- (4-hexylphenyl) -1,3-thiazole (Synthesis / cleaning according to EP-B 439170)

Connection example (Ia)

• a) 2'-fluoro-4-octyloxy-4 "-pentylterphenyl (Synthesis / cleaning according to GB-B 2198743)

Connection example (Ib)

• a) 2,3-difluoro-4-heptyl-4 "-pentylterphenyl (Synthesis / purification according to EP-B 329752)

Connection example (Ib)

• a) 4-decyl-2,3-difluoro-4 "-pentylterphenyl (Synthesis / purification according to EP-B 329752)

Connection example (Ib)

• a) 2 ', 3'-difluoro-4-hexyloxy-4 "-pentylterphenyl (Synthesis / purification according to EP-B 329752)

Example of compound (IIa)

• a) 4- (Cyclohexyl) cyclohexane-carboxylic acid (4-octyloxy) phenyl ester.

Table 1

Table 1 shows the particular suitability of the compounds according to the invention for the creation of ferroelectric liquid crystal mixtures for Active matrix displays, as for the materials according to the invention Standard operations can achieve higher resistance values.

Claims (9)

1. Monostable ferroelectric active matrix display, comprising a liquid crystal layer in the form of a mono-domain with a clearly defined direction of the layer normal z of the smC * phase, characterized in that the layer normal z and the preferred direction n of the nematic or cholesteric phase (N * phase ) form an angle of more than 5 °, the liquid crystal layer being composed of a liquid crystal mixture composed of at least 5 compounds
an achiral base mixture containing at least one compound from the group (I) formed by (Ia-Ik), optionally additionally at least one compound from the group formed by (IIa-IIg) and / or at least one compound from group (III),
and
at least one chiral component of group (IV)
R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ia)
in the A ³
means and the remaining substituents have the following meanings
R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b (-A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ib)
in the A ³
means and the remaining substituents have the following meanings
R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ic)
in the A ³
means and the remaining substituents have the following meanings
R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c (M ⁵ -A ⁵ ) _d -R ² (Id)
in the A ³
means and the remaining substituents have the following meanings
R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ie)
in the A ³
means and the remaining substituents have the following meanings
R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (If)
in the A ³
means and the remaining substituents have the following meanings
R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ig)
in the A ³
means and the remaining substituents have the following meanings
R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ih)
in the A ³
means and the remaining substituents have the following meanings
R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ii)
in the A ³
means and the remaining substituents have the following meanings
R ¹ , R ² independently of one another, identically or differently, are hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two -CH ₂ groups can be replaced by -CH = CH- or -OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl and in which one or more H atoms can also be replaced by F with the proviso that R ¹ , R ² cannot both be hydrogen
A ¹ , A ² , A ⁴ , A ^5, independently of one another, the same or different 1,4-phenylene, optionally mono- or disubstituted by F or Cl, cyclohexane-1,4-diyl, optionally monosubstituted by F, cyclohex-1- en-1,4-diyl, cyclohex-2-en-1,4-diyl, 1-alkyl-1-silacyclohexane-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl, Indane-2,6-diyl, naphthalene-2,6-diyl
M ¹ , M ² , M ⁴ , M ⁵ independently of one another, the same or different, are a single bond, -OC (= O) - or (O =) CO-, -OCH ₂ - or CH ₂ -O-CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero
R ¹ (-A ¹ -M ¹ ) _a (-A ² -M ² ) _b -A ³ - (M ⁴ -A ⁴ ) _c - (M ⁵ -A ⁵ ) _d -R ² (Ik)
in the A ³
means and the remaining substituents have the following meanings:
R ¹ , R ² independently of one another, identically or differently, are hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two -CH ₂ groups can be replaced by -CH = CH- or -OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl and in which one or more H atoms can also be replaced by F with the proviso that R ¹ , R ² cannot both be hydrogen
G1-G2 is -CH = CH- or-CH ₂ -CH ₂ -bedeutet
n means zero or one
A ¹ , A ² , A ⁴ , A ^5, independently of one another, the same or different 1,4-phenylene, optionally mono- or disubstituted by F or Cl, cyclohexane-1,4-diyl, optionally monosubstituted by F
M ¹ , M ² , M ⁴ , M ^5, independently of one another, the same or different, a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or -CH ₂ -O, -CH ₂ CH ₂ -, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 0 <{a + b + c + d} ≦ 2 and the understanding that M ^{x is} a single bond if the corresponding index is zero.
R ³ (-A ⁷ -M ⁷ ) _a (A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIa)
where A ⁶
means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl and in which one or more H atoms can also be replaced by F.
with the proviso that R ¹ , R ² cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of one another, the same or different 1,4-phenylene, cyclohexane-1,4-diyl, cyclohex-1-ene-1,4-diyl, cyclohex-2-ene-1, 4-diyl, bicyclo [2.2.2] octane-1,4-diyl,
M ⁷ , M ⁸ , M ⁹ , M ¹⁰ independently of one another, the same or different, are a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or -CH ₂ -O - CH ₂ CH _2-, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,
R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIb)
where A ⁶
means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and wherein one or more H atoms can also be replaced by F, with the proviso that R ¹ , R ² cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of one another, the same or different 1,4-phenylene, optionally mono- or disubstituted by F or Cl, cyclohexane-1,4-diyl, optionally monosubstituted by F, cyclohex-1- en-1,4-diyl, cyclohex-2-ene-1,4-diyl, 1-alkyl-1-sila-cyclohexane-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl, Indane-2,6-diyl, naphthalene-2,6-diyl
M ⁷ , M ⁸ , M ⁹ , M ¹⁰ independently of one another, the same or different, are a single bond, -OC (= O) - or - (O =) CO- -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH _2-, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,
R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIc)
where A ⁶
means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl and in which one or more H atoms can also be replaced by F.
with the proviso that R ¹ , R ² cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of one another, the same or different 1,4-phenylene, cyclohexane-1,4-diyl, optionally simply substituted by F, cyclohex-1-ene-1,4-diyl, cyclohexyl 2-en-1,4-diyl, 1-alkyl-1-sila-cyclohexane-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl, indane-2,6-diyl,
M ⁷ , M ⁸ , M ⁹ , M ^10, independently of one another, the same or different, are a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH ₂ -, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,
R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IId)
where A ⁶
means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl and in which one or more H atoms can also be replaced by F.
with the proviso that R ¹ , R ² cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of one another, the same or different 1,4-phenylene, cyclohexane-1,4-diyl, optionally optionally substituted by F, cyclohex-1-ene-1,4-diyl, cyclohexyl 2-ene-1,4-diyl, 1-alkyl-1-sila-cyclohexane-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl, naphthalene-2,6-diyl
M ⁷ , M ⁸ , M ⁹ , M ^10, independently of one another, the same or different, are a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH _2-, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,
R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIe)
where A ⁶
means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and wherein one or more H atoms can also be replaced by F, with the proviso that R ¹ , R ² cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of one another, identically or differently, cyclohexane-1,4-diyl, optionally simply substituted by F, cyclohex-1-ene-1,4-diyl, cyclohex-2-ene-1, 4-diyl
M ⁷ , M ⁸ , M ⁹ , M ^10, independently of one another, the same or different, are a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH _2-, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,
R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIf)
where A ⁶
means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and wherein one or more H atoms can also be replaced by F, with the proviso that R, R2 cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of the same or different 1,4-phenylene, cyclohexane-1,4-diyl, optionally simply substituted by F, cyclohex-1-ene-1,4-diyl, cyclohex-2 -en-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl
M ⁷ , M ⁸ , M ⁹ , M ^10, independently of one another, the same or different, are a single bond, -OC (= O) - or - (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH ₂ -, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,
R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIg)
where A ⁶
means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl and in which one or more H atoms can also be replaced by F.
with the proviso that R ¹ , R ² cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of one another, identically or differently, cyclohexane-1,4-diyl, optionally simply substituted by F, cyclohex-1-ene-1,4-diyl, cyclohex-2-ene-1, 4-diyl
M ⁷ , M ⁸ , M ⁹ , M ¹⁰ independently of one another, identically or differently, are a single bond, -OC (= O) - or- (O =) CO-, -OCH ₂ - or -CH ₂ -O-, -CH ₂ CH ₂ -, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
a, b, c, d: zero or 1, with the reservation. 1 ≦ {a + b + c + d} ≦ 3 and understanding that M ^{x is} a single bond if the corresponding index is zero,
R ³ (-A ⁷ -M ⁷ ) _a (-A ⁸ -M ⁸ ) _b -A ⁶ - (M ⁹ -A ⁹ ) _c - (M ¹⁰ -A ¹⁰ ) _d -R ⁴ (IIh)
where A ⁶
means
R ³ , R ^{4 are,} independently of one another, identical or different, hydrogen, alkyl or alkyloxy having 2-12 C atoms, in which one or two —CH ₂ groups can be replaced by —CH = CH— or —OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl and in which one or more H atoms can also be replaced by F.
with the proviso that R ¹ , R ² cannot both be hydrogen
A ⁷ , A ⁸ , A ⁹ , A ^10, independently of one another, identically or differently, cyclohexane-1,4-diyl, optionally simply substituted by F, cyclohex-1-ene-1,4-diyl, cyclohex-2-ene-1, 4-diyl
M ⁷ , M ⁸ , M ⁹ , M ¹⁰ independently of one another, identically or differently, are hydrogen, alkyl or alkyloxy with 2-12 C atoms, in which one or two -CH ₂ groups can be replaced by -CH = CH- or -OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and wherein one or more H atoms can also be replaced by F, with the proviso that R ¹ , R ² cannot both be hydrogen
a, b, c, d: is zero, zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,
R ⁵ (-A ¹¹ -M ¹¹ ) _a (-A ¹² -M ¹² ) _b -A ¹³ (III)
where A ¹³
means
and
X ¹ , X ² , X ^3, independently of one another, are the same or different H, Cl, F, OCF ₂ H, CF _3, with the proviso that at least one of X ¹ , X ² , X ^{3 is} not H,
R ^{5 is} hydrogen, alkyl or alkyloxy with 2-12 C atoms, in which one or two -CH ₂ groups can be replaced by -CH = CH- or -OC (= O) - or - (O =) CO - or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and in which one or more H atoms can also be replaced by F.
A ¹¹ , A ^12, independently of one another, the same or different 1,4-phenylene, cyclohexane-1,4-diyl, cyclohex-1-en-1,4-diyl, cyclohex-2-en-1,4-diyl, 1- Alkyl-1-sila-cyclohexane-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl, indane-2,6-diyl, naphthalene-2,6-diyl
M ⁷ , M ⁸ , M ⁹ , M ¹⁰ independently of one another, identically or differently, are hydrogen, alkyl or alkyloxy with 2-12 C atoms, in which one or two -CH ₂ groups can be replaced by -CH = CH- or -OC (= O) - or - (O =) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and wherein one or more H atoms can also be replaced by F, with the proviso that R ¹ , R ² cannot both be hydrogen
a, b, c, d: is zero, zero or 1, with the reservation 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero,
R ⁶ (-A ¹⁴ -M ¹⁴ ) _a (-A ¹⁵ -M ¹⁵ ) _b - (M ¹⁶ -A ¹⁶ ) _c - (M ¹⁷ -A ¹⁷ ) _d -M ¹⁸ -R ⁷ (IV)
wherein
R ⁶ hydrogen, alkyl or alkyloxy with 2-12 C atoms, in which one or two -CH ₂ groups can be replaced, can be replaced by -CH = CH- or -OC (= O) - or - (O = ) CO- or -Si (CH ₃ ) ₂ - or cyclopropane-1,2-diyl
and in which one or more H atoms can also be replaced by F.
R ^{7 is} a grouping with at least one asymmetric carbon atom,
either component is an alkyl group of 3-12 carbon atoms, in which one or two -CH ₂ groups can also be replaced by -O- or -OC (= O) or (O =) CO- and in which -CH ₃ , -CF ₃ , -OCH ₃ , -CH ₃ , Cl, F must be one of the substituents of the asymmetric C atom,
or is a component of a 3-7-membered carbocycle in which one or two non-adjacent -CH ₂ groups are replaced by -O- or a -CH ₂ group by -OC (= O) - or - (O =) CO- could be.
A ¹⁴ , A ¹⁵ , A ¹⁶ , A ^17, independently of one another, the same or different 1,4-phenylene, optionally mono- or disubstituted by F or Cl, cyclohexane-1,4-diyl, optionally monosubstituted by F, cyclohex-1- en-1,4-diyl, cyclohex-2-ene-1,4-diyl, 1-alkyl-1-sila-cyclohexane-1,4-diyl, bicyclo [2.2.2] octane-1,4-diyl, Indane-2,6-diyl, naphthalene-2,6-diyl
M ¹⁴ , M ¹⁵ , M ¹⁶ , M ^17, independently of one another, the same or different, a single bond, -O (= O) -, -OC (= O) - or - (O =) CO-, or -CH ₂ -O- CH ₂ CH _2-, -CH ₂ CH ₂ -CH ₂ CH ₂ - or -C∼C-
M ^{18 is} a single bond if the asymmetric carbon atom is part of an alkyl chain,
and a single bond, -OCH ₂ -, -CH ₂ O-, -OC (= O) - or -C (= O) O- in the event that the asymmetric carbon atom is part of a carbocycle
a, b, c, d: zero or 1, with the proviso 1 ≦ {a + b + c + d} ≦ 3 and the understanding that M ^{x is} a single bond if the corresponding index is zero. 2. Active matrix display according to claim 1, characterized in that R ¹ and R ^{2 are} straight-chain alkyl or alkyloxy having 2 to 12 carbon atoms. 3. Active matrix display according to claim 1 or 2, characterized in that the mixture contains at least one compound in which a non-terminal -CH ₂ group is replaced by -OC (= O) - in R ¹ and R ² . 4. Active matrix display according to one of claims 1 to 3, characterized in that in at least one compound of the formulas (I) or (II) in R ¹ and / or R ² at least one or more, but not the one adjacent to the nucleus - CH ₂ group is replaced by -CF ₂ -. 5. Active matrix display according to one of claims 1 to 4, characterized characterized in that the length of the chiral in the liquid crystal layer nematic or cholesteric pitch in one Temperature range of at least 2 ° C above the transition to smectic phase is more than 50 µm. 6. Process for the production of active matrix displays according to one of the Claims 1 to 5, in which the liquid crystal layer in the Space between a grated top substrate plate and one  brings grated sub-substrate plate of the active matrix display, whereby the rubbing directions on the upper and lower substrate plate essentially are parallel and the liquid crystal phase cools from the isotropic phase, where at least in the phase transition N * → smC * or N * → smA * → smC * there is an electrical DC voltage on the display. 7. active matrix display, producible by the method according to claim 6. 8. Use of active matrix displays according to one of claims 1 to 5 and 7 in the TV, HDTV, or multimedia area or in the area of Information processing. 9. Use according to claim 8 in notebook PCs, personal digital assistants and desktop monitors.