Compositions – Liquid crystal compositions – Containing nonsteryl liquid crystalline compound of...
Patent
1987-10-23
1989-10-31
Gron, Teddy S.
Compositions
Liquid crystal compositions
Containing nonsteryl liquid crystalline compound of...
25229901, 2522995, 25229963, 25229964, 25229965, 25229966, 25229967, 350350R, G02F 113, G09F 935, C09K 1942, C09K 1908, C09K 1930/19/20, C09K 1934
Patent
active
048775479
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a liquid crystal display element (LC display element) with a low multiplex ratio and low operating voltage.
For LC display elements, the properties of nematic or nematic-cholesteric liquid crystal materials are utilized to modify their optical properties, such as absorption of light, light scattering, birefringence, reflectance or color, under the influence of electrical fields. Functioning of such display elements is based here, for example, on the phenomenon of dynamic scattering, the deformation of aligned phases, the guest-host effect, the Schadt-Helfrich effect in the twisted cell or the cholesteric-nematic phase transfer.
LC phases which must meet a number of requirements are required for technical use of these effects in electronic components. mechanical stability towards moisture, air and physical influences, such as heat, radiation in the infrared, visible and ultraviolet range and constant and alternating electrical fields, are particularly important here. Technically usable LC phases are also required to have a liquid crystal mesophase in a suitable temperature range, a low viscosity, a low optical anisotropy, a high gradient of the electrooptical characteristic line and an adequate dissolving power for pleochroic dyestuffs.
In none of the series of compounds so far known with a liquid crystal mesophase is there a single compound which meets all these requirements. Mixtures of two to 25, preferably three to 18, compounds are therefore prepared in order to obtain substances which can be used as LC phases. However, optimum phases cannot easily be prepared in this manner, since components with high melting and clear points frequently also impart to the mixtures a high viscosity. The switching times of the electrooptical display elements produced with these components are thereby modified in an undesirable manner.
There is therefore still a great need for LC phases with a wider operating temperature range, a low viscosity (and therefore short switching times) and a low threshold voltage.
Most LC display elements produced today are controlled in multiplex operation with multiplex ratios of about 1:2 to 1:4 and with operating voltages of about 3 volts. The operating temperature range of such display elements is in general between about -10.degree.and +50.degree..
However, a wider operating temperature range is desirable for applications in the open air, for example also in cars.
The invention is based on the object of providing LC display elements which have a wide operating temperature range and display the abovementioned disadvantages to only a small extent, if at all.
It has been found that this object can be achieved if liquid crystal dielectrics which have operating temperature ranges of between -30.degree. and +80.degree. C. and viscosities of less than 40 mPa.s at 20.degree. are used in these display elements.
The invention thus relates to an LC display element with static or multiplex control with a low multiplex ratio and an operating voltage below 3.3 volts, containing a liquid crystal dielectric, wherein the operating temperature range extends from -30.degree. C. to +80.degree. C. and the viscosity of the dielectric at 20.degree. C. is less than 40 mPa.s.
The invention particularly relates to LC display elements of the type mentioned, in which the threshold voltage of the dielectric is not more than 1.7, preferably not more than 1.5 volts.
The invention furthermore relates to LC display elements, wherein the dielectric contains at least one component of one of the formulae I to VII: ##STR1## wherein
R.sup.1 is alkyl with 1 to 12 C atoms, wherein one or two non-adjacent CH.sub.2 groups can also be replaced by O atoms, --CO--, --O--CO--, --CO--O-- and/or --CH.dbd.CH-- groups,
A.sup.o and A.sup.1 each independently of one another are Cy, Dio or Phe, Z is --CO--O--, --O--CO--, --CH.sub.2 --O--, --O--CH.sub.2 -- or a single bond,
X.sub.1 is F, Cl, --CN or --NCS,
X.sup.2 is F, Cl or, in the case where X.sup.1 =NCS, also H,
m is 0 or 1,
Cy is trans-1,4-cyclohexylene,
Dio i
REFERENCES:
patent: 4464283 (1984-08-01), Hasegawa et al.
patent: 4469618 (1984-09-01), Hasegawa et al.
patent: 4483595 (1984-11-01), Irving et al.
patent: 4490276 (1984-12-01), Hsu
patent: 4528115 (1985-07-01), Ishii et al.
patent: 4528116 (1985-07-01), Dabronski et al.
patent: 4536321 (1985-08-01), Sugimori et al.
patent: 4551280 (1985-11-01), Sasaki et al.
patent: 4621901 (1986-11-01), Petrzilea et al.
patent: 4622162 (1986-11-01), Kimura et al.
patent: 4670182 (1987-06-01), Fujita et al.
patent: 4676924 (1987-06-01), Dabrowski et al.
patent: 4707296 (1987-11-01), Sugimori et al.
patent: 4726911 (1988-02-01), Krause et al.
patent: 4737311 (1988-04-01), Scheuble et al.
patent: 4770503 (1988-09-01), Buchecker et al.
patent: 4776973 (1988-10-01), Bofinger et al.
patent: 4797228 (1989-01-01), Goto et al.
patent: 4814523 (1989-03-01), Tanaka et al.
patent: 4815825 (1989-03-01), Nakagomi et al.
patent: 4818428 (1989-04-01), Scheuble et al.
patent: 4820443 (1989-04-01), Goto et al.
patent: 4822519 (1989-04-01), Saito et al
Krause Joachim
Scheuble Bernhard
Weber Georg
Gron Teddy S.
Merck Patent Gesellschaft mit beschrankter Haftung
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