FERROELECTRIC LIQUID CRYSTAL • (i)
COMPOSITION AND LIQUID CRYSTAL DEVICE /—\ /—\ I TR
INCORPORATING SAME ^ ... J=0
This is a continuation of copending application(s) Ser.
No. 07/502,570 filed on Mar. 30,1990, now abandoned. . . „, . . „t • ,t
wherein R1 and R2 are, the same or different, a straight
BACKGROUND OF THE INVENTION chain or branched-chain alkyl group having 1 to 15
i c;.u „/■ *i. T 10 carbon atoms, and each asterisk represents an asymmet
LField of the Invention ric carbon atom, and at least one compound represented
The present invention relates to ferroelectric liquid . tj)e formula crystal compositions and liquid crystal devices incorporating the composition.
2. Description of the Prior Art 15 r~~\ I \ I VK*
Presently liquid crystal display devices predomi- I Wa\ _ I J_
nantly utilize the nematic phase of liquid crystals, while R —\ ° CH2~"S Q
active research has also been conducted in recent years \ / \ /
on various display modes utilizing a smectic phase.
Especially promising is ferroelectric liquid crystal dis- 20 wherein R3 R4are, the same or different, a straightplay utilizing a chiral smectic C phase because this chain or branched-chain alkyl group having 1 to 15 mode is adapted to large-capacity display with a wide carbon atoms, and each asterisk represents an asymmetviewing angle. ric carbon atom;
The liquid crystal material for use in the ferroelectric b) a ferroelectric liquid crystal composition of a)
liquid crystal display device wherein the smectic C 25 which further contains at least one chiral or non-chiral
phase is utilized must of course exhibit the smectic C ^ «y«al or non-liquid crystal compound;
phase over a wide temperature range around room . c) • ferroelectric liquid crystal composition compns
temperature and needs to fulfill various other require- m* at 6351 one «»»P°TMd represented by the formate
ments First the device for laree-canacitv disnlavmust ®» at least one comPound represented by the formula ments^rirst, tne device tor large-capacity display must one ^ represcnted by the for
have high-speed responsiveness, and from this view- 3U mJja r r
point, the liquid crystal material needs to be highly amenable to spontaneous polarization and low in viscosity. Further to obtain satisfactory orientation and bista- fZ-^* /HA ^ bility when used for the liquid crystal cell, the liquid 3J crystal material needs to exhibit the phase series of IAC (Isotropic-Smectic-A-Smectic C) or INAC (IsotropicNematic-Smectic A-Smectic C), and the helical pitch of
nematic phase and smectic C phase needs to be suffi- wherein and R« are a straight-chain or branchedciently larger than the cell thickness. It is also desired 40 chain alkyl or alkoxyl group having 1 to 15 carbon that the material be great in tilt angle which is relevant atoms;
to the contrast and brightness of liquid crystal display. . d> 8 ferroelectric liquid crystal composition compnsThe material must also be optimized in dielectric anisot- m« * ^ one <***PTM°* represented by he formu a . ^ . , . . . . (I), at least one compound represented by the formula
ropy, refractive mdex anisotropy, specific resistance, \.t\ .., „ _, * J u *i. r 1
yj *^ '(II), at least one compound represented by the formula
... .., , . , (III) and at least one compound represented by the
At present, however, it is impossible for a single com- formula (TV)
pound to fulfill all the desired requirements, so that a plurality of compounds are usually mixed together for
use as a liquid crystal composition. To prepare a liquid /_\ /_\
crystal composition fulfilling the requirements for ac- 50 R7_/( j\_coo—/(
tual use, it is necessary to use numerous single liquid y-—'/ crystal compounds having a wide variety of properties.
It is even likely that compounds which per se exhibit no R7 ^ R8 m a strai htK:hain or branched.
liquid crystal properties will be useful as components of J5 ^ ^ Qt ^, haym { tQ „
the liquid crystal composition. atoms> ^ A ^ a i)4-phenylene group or 1,4
SUMMARY OF THE INVENTION cyclohexylene group or a single bond; and hquid crystal
, device incorporating one of these ferroelectric liquid
An object of the invention is to provide a ferroelec- crystal compositions a)-d).
trie hquid crystal composition having a wide range of ^ ^ compound of the formula (I) permits the ferro
operating temperatures, satisfactory in orientation and electric hquid crystal composition to exhibit enhanced
exhibiting high-speed responsiveness at room tempera- spontaneous polarization and high-speed responsive
ture, and a liquid crystal device comprising the compo- ness
sition. The combination of the compounds of the formulae
The present invention provides: 65 (I) and (II) acts synergistically ensuring enhanced spon
a) a ferroelectric hquid crystal composition compris- taneous polarization while preventing the crystalliza
ing at least one compound represented by the formula tion of the ferroelectric hquid crystal composition com
(I) prising these compounds.
