Liquid crystal display element and liquid crystal composition

Abstract: An active OCB (Optically Compensated Bend or Birefringence) element for switching respective pixels of a sealed cell formed by two substrates having transparent electrodes, wherein a nematic liquid crystal composition contained in the cell comprises one or more than one terminal group structure(s) of the following general formula (I): as the first component (wherein, X denotes F, Cl, CF 3 , OCF 3 , CF 2 H, OCF 2 H, OCF 2 CF 2 H, OCF 2 Cl or OCF 2 CFHCF 3 , Q 1 and Q 2 denote independently each other H or F.) as the first component.

Description: The present invention relates to a liquid crystal display element based on an OCB mode using a nematic liquid crystal composition. Background Art A liquid crystal cell presently used for an active matrix LCD (AM-LCD) such as a thin film transistor (TFT) which is widely realized as a display method of a liquid crystal display element (LCD) is a twist nematic (TN) cell. An active matrix (AM-LCD) method using the said twist nematic (TN) cell is improved in its display quality compared to the conventional display methods but is still inferior to CRT about a viewing angle and a response time. Recently, an OCB (Optically Compensated Bend or Birefringence) mode has been proposed and noticed [by Y.Yamaguchi, T.Miyashita, T.Uchida, SID 93 DIGEST, 1993: Late-News Paper; Wide-Viewing-Angle Di splay Mode for the Active-Matrix Lcd Using Bend-Alignment Liquid-Crystal Cell, page 277 et seq.; by T.Miyashita, C.-L.Kuo, M.Suzuki, T.Uchida, SID 95 DIGEST, 1995: Properties of the OCB Mode for Active-Matrix LCDs with Wide Viewing Angle, page 797 et seq.]. A liquid crystal composition used for a liquid crystal display element of AM-LCD method based on the said OCB mode is required commonly to have the following characteristics: (1) K 3 /K 1 should be low in order to attain a driving property in a lower voltage range, a high contrast and a wide viewing angle, (2) a dielectric anisotropy (Δε) should be high in order to drive in a lower voltage range, (3) a refractive anisotropy (Δn) should be high in order to attain a wide viewing angle, (4) a voltage holding ratio (V. H. R.) should be high in order to maintain a high contrast, and (5) it should be chemically stable. The OCB mode is quite different from the conventional TN (twist nematic) and STN (supertwist nematic) modes and it uses a cell having a twist angle of 0° between upper and lower substrates, a biaxial phase different plate, and a nematic liquid crystal composition without any chiral agent added. A characteristic of the said OCB mode on driving is to drive liquid crystal molecules in the cell at a bend-aligned state. That is, by combining bend-aligned liquid crystals and a phase different plate, it can be realized to obtain a very wide viewing angle and a very high contrast compared to those of the conventional TN (twist nematic) and STN (supertwist nematic) modes. Furthermore, by driving liquid crystals in their bend-aligned states, it can be also realized to obtain a very fast response time such as about 1/20 to 1/500 compared to that of the conventional TN (twist nematic) and STN (supertwist nematic) modes. By driving an OCB mode with the above-mentioned characteristics and advantages as an active matrix LCD (AM-LCD) element, a liquid crystal display element can be proposed which has a distinctly wide viewing angle and a high-speed response compared to those of the active matrix LCD (AM-LCD) method using the conventional twist nematic (TN) cells. As described above, a characteristic of the OCB mode on driving is to drive liquid crystal molecules in cells at their bend-aligned states. However, since they are splay-aligned without any voltage applied, they should be driven in a voltage range higher than a transition voltage (V CR ) at which a splay-aligned state being transited to a bend-aligned state. If dielectric anisotropies (Δε) of liquid crystal compositions are the same, magnitudes of transition voltage (V CR ) depend on respective absolute values of a bend elastic constant K 3 and a splay elastic constant K 1 as well as an elastic constant ratio K 3 /K 1 of these two constants, wherein the smaller the absolute values of these two elastic constants K 3 and K 1 as well as the smaller the ratio K 3 /K 1 , the smaller the transition voltage (V CR ). Therefore, for driving in a lower voltage range by the OCB mode, it is necessary to decrease absolute values of these two elastic constants K 3 and K 1 as well as K 3 /K 1 as possible, in order to decrease the said transition voltage (V CR ). Furthermore, if refractive anisotropies (Δn) and dielectric anisotropies (Δε) are the same and a cell thickness is constant, the smaller the elastic constant ratio K 3 /K 1 , the higher the retardation of liquid crystals which are bend-aligned near the transition voltage. As the result, a contrast can be thus increased. Furthermore, a wider viewing angle can be obtained since a driving voltage range can be shifted to a lower voltage range due to the obtained high contrast. From the above-mentioned matters, in order to obtain a driving property in a lower voltage range, a high contrast and a wide viewing angle, K 3 /K 1 of a liquid crystal composition is required to be low. And, for driving in a lower voltage range, a dielectric anisotropy (Δε) is required to be high in addition to the above-mentioned requirements for absolute values of elastic constants K 3 and K 1 as well as their ratio K 3 /K 1 of a liquid crystal composition. Furthermore, in the OCB mode, the thinner the thickness of cells, the wider the viewing angle. Thus, in order to make the thickness of cells thin without changing retardation, a refractive anisotropy (Δn) of a liquid crystal composition is required to be high. Furthermore, as one advantage of the OCB mode, there is mentioned a response speed of ten times faster than that of TN cell. However, since a change in a transmittance due to a change of a voltage with the lapse of time becomes more dependent on the said faster response speed, a voltage holding ratio (V. H. R.) is required to be high in order to maintain a high contrast. Of the physical properties required for the liquid crystal composition in the OCB mode described above, a liquid crystal composision to satisfy such characteristics that K 3 /K 1 being low, a dielectric anisotropy (Δε) being high and a refractive anisotropy (Δn) being high generally tends to contain impure ions in liquid crystals. As the result, it becomes difficult to raise a voltage holding ratio (V. H. R.). However, as described above, it is required in the OCB mode that the voltage holding ratio (V. H. R.) is high to maintain a high contrast. That is, it is presently difficult to coexist such characteristics that a K 3 /K 1 being low, a dielectric anisotropy (Δε) being high and a refractive anisotropy (Δn) being high as well as that a voltage holding ratio being raised. Disclosure of the Invention We inventors found that a liquid crystal composition satisfying these characteristics can be prepared by means of the below-mentioned first component, second component and third component and invented a liquid crystal display element based on an OCB mode. As clear from the above-mentioned description, an object of the present invention is to propose a liquid crystal display element using a liquid crystal composition satisfying various characteristics required for an AM-LCD display based on the below-mentioned OCB mode. Best Mode for carrying out the Invention The first inventive matter of the present invention relates to an active driving OCB (Optically Compensated Bend) liquid crystal display element, wherein a) a sealed cell formed of two substrates having transparent electrodes is used, b) a nematic liquid crystal mixture having a positive dielectric anisotropy and a high resistance is contained in the cell, c) rubbing directions of aligned membranes coated on the two upper and lower substrates are made in the same direction (a twist angle of 0° ), d) an arrangement is made such that one angle constituted by a pre-tilt direction of liquid crystals on the aligned membranes and the substrates being + and the other being -, e) a biaxial phase different film is arranged on the top of the upper substrate of the upper and lower substrates in the cell, and polarized plates are arranged above and below the cell containing the arranged biaxial phase different film, and f) respective pixels in the sealed cell are switched, characterized in that the said nematic liquid crystal composition contains at least one compound having (a) terminal group structure(s) of the following general formula (I) (wherein, X denotes F, Cl, CF 3 , OCF 3 , CF 2 H, OCF 2 H, OCF 2 CF 2 H, OCF 2 Cl or OCF 2 CFHCF 3 , Q 1 and Q 2 denote independently each other H or F.) as the first component. By using the compound having the polar terminal group structure(s) of the general formula (I), a dielectric anisotropy. (Δε) of a liquid crystal composition can be increased. Thus, a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment can be decreased, so that an active driving OCB element with a lower voltage driving property can be realized as the result. Furthermore, since the terminal group of the general formula (I) is a polar group such as fluorine or chlorine type one, a high specific resistant value can be realized irrelevant to having a high dielectric anisotropy (Δε), and also thermal stability and chemical stability are superior. Therefore, a voltage holding ratio (V. H. R.) of the liquid crystal composition using the said compound is high. That is, an active driving OCB element maintaining a high contrast can be realized. Furthermore, in the case that the polar groups X are the same a compound with lateral F's (in Q 1 and Q 2 ) has low absolute values of elastic constants K 3 and K 1 as well as a high dielectric anisotropy (Δε) compared to the case without F. Thus, by using a compound with lateral F's in the general formula (I), it is possible to prepare a liquid crystal composition having low absolute values of elastic constants K 3 and K 1 as well as a high dielectric anisotropy (Δε). As the result, it is possible to realize an active driving OCB element for driving in a lower voltage. Furthermore, it is possible to realize a high voltage holding ratio (V. H. R.) for the compound of the formula (I) having F's laterally, since it has a high specific resistant value in spite of having a high dielectric anisotropy (Δε) as mentioned above. The second inventive matter of the present invention relates to a liquid crystal display element described in the explanation of the above-mentioned first inventive matter, characterized in that the compound of the general formula (I) is one expressed by the general formulae (I-a), (I-b) and (I-c) (wherein, R 1 denotes an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, of which optional one or non-adjacent two or more than two methylene (-CH 2 ) group(s) may be optionally substituted by (an) oxygen atom(s) or -CH=CH-; X denotes F, Cl, CF 3 , OCF 3 , CF 2 H, OCF 2 H, OCF 2 CF 2 H, OCF 2 Cl or OCF 2 CFHCF 3 ; Q 1 and Q 2 denote independently each other H or F; Z 1 , Z 2 , Z 3 , Z 4 , Z 5 and Z 6 denote independently each other -CH 2 CH 2 -, -(CH 2 ) 4 -, -COO-, -CF 2 O-, -CH=CH- or a single bond; A, B, C, D and E denote independently each other trans-1,4-cyclohexylene, pyrimidine-2,5-diyl, 1,4-cyclohexenylene or 1,4-phenylene optionally substituted with F at a branching H.). By combining these compounds of the general formulae (I-a), (I-b) and (I-c), a dielectric anisotropy (Δε) and a transparent point (NI point) of the liquid crystal composition may be optionally adjusted. Particularly, the compounds in which bondings of Z 1 , Z 2 , Z 3 , Z 4 , Z 5 and Z 6 are -COO- or -CF 2 O- have higher dielectric anisotropies (Δε) than the compounds with -CH 2 CH 2 -, -CH=CH- or a single bond, and additionally, in the case of those having -COO-bonding, absolute values of elastic constants K 3 and K 1 are low. As the result, it is thus possible to realize an active driving OCB element wigh a driving property at a very low voltage. Furthermore, of the compounds having -COO or -CF 2 O- as Z 1 , Z 2 , Z 3 , Z 4 , Z 5 and Z 6 , those having F's laterally have high dielectric anisotropies (Δε) and even smaller absolute values of elastic constants K 3 and K 1 , so that an active driving OCB element with a driving property at a lower voltage can be realized. Furthermore, since the compounds shown by the general formulae (I-a), (I-b) and (I-c) have polar groups such as fluorine type or chlorine type ones, liquid crystal compositions using the compounds show high specific resistant values and also they are superior in thermal stability and chemical stability. Thus, it is possible to raise a voltage holding ratio (V. H. R.) of the liquid crystal composition. That is, an active driving OCB element maintaining a high contrast can be realized. Furthermore, of the general formulae (I-a), (I-b) and (I-c), compounds with pyrimidine-2,5-diyl have a very low elastic constant ratio K 3 /K 1 such as less than 1.3 and a high refractive anisotropy (Δn) such asΔn ≦ 0.2. Thus, it is possible to adjust an elastic constant ratio K 3 /K 1 of the liquid crystal composition low and a refractive anisotropy (Δn) thereof particularly high, an active driving OCB element having a lower voltage driving property, a high contrast and a wide viewing angle can be realized by using these compounds with pyrimidine-2,5-diyl. The third inventive matter of the present invention relates to a liquid crystal display element according to the above-mentioned first or second inventive matter, characterized in that an amount of the first component used is from 50 to 100% by weight based on the total weight of the liquid crystal composition. The fourth inventive matter of the present invention relates to a liquid crystal display element according to any of the above-mentioned first to third inventive matters, characterized in that at least one compound selected from the group of compound shown by the general formulae (II), (III) and (IV) is contained as the second component: R 2 -(G)-Z 7 -(J)-R 3 (wherein, R 2 and R 3 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene (-CH 2 -) group(s) may be substituted by (an) oxygen (-O-) atom(s) or -CH=CH-; G and J denote independently each other trans-1,4-cyclohexylene, 1,4-phenylene or pyrimidine-2,5-diyl; and Z 7 denotes -CH 2 CH 2 -, -COO-, -CH=CH-, -C≡C- or a single bond.), R 4 -(K)-Z 8 -(L)-Z 9 -(M)-R 5 (wherein, R 4 and R 5 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene (-CH 2 -) group(s) may be substituted by (an) oxygen (-O-) atom(s) or -CH=CH-; K denotes trans-1,4-cyclohexylene, 1,4-phenylene or pyrimidine-2,5-diyl; L and M denote independently each other trans-1,4-cyclohexylene or 1,4-phenylene optionally substituted by F at one branching H; Z 8 and Z 9 denote independently each other -CH 2 CH 2 -, -CH=CH-, -C≡C-, -COO- or a single bond.), and (wherein, R 6 and R 7 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene (-CH 2 -) group(s) may be substituted by (an) oxygen (-O-) atom(s) or -CH=CH-, and Q 3 denotes H or F.). Since these compounds for the second component shown by the general formulae (II), (III) and (IV) have not any high polar substituent, any impure ion cannot be present stably in these compounds. Thus, these compounds for the second component have very high specific resistant values and also they are very superior in thermal stability and chemical stability. Therefore, by combining the second component with the first component, it is possible to prepare a liquid crystal composition which has a high dielectric anisotropy (≦ ε), low absolute values of elastic constants K 3 and K 1 , a low elastic constant ratio K 3 /K 1 as well as a very high voltage holding ratio (V. H. R.) and which are superior in thermal stability and chemical stability. Thus, an active driving OCB element having a low voltage driving property, a high contrast and a wide viewing angle and also maintaining a high reliability can be realized. Furthermore, of the general formulae (II), (III) and (IV), compounds containing 4-4' -biphenylene as a backbone, compounds containing a 1,4-phenylene backbone bonded with pyrimidine-2,5-diyl, compounds containing a backbone with -CH=CH-between two benzene rings in 4-4' -biphenylene, and compounds containing two or more than two above-mentioned backbones (wherein, optional H in 1,4-phenylene contained in backbones of these compounds may be substituted by F) have a high refractive anisotropy (Δn) such as Δn ≦0.2. Thus, since the refractive anisotropy (Δn) of the liquid crystal composition can be raised by using these compounds containing the said backbones, an active driving OCB element having a high contrast and a wide viewing angle can be realized. Furthermore, of the general formulae (II), (III) and (IV), compounds containing pyrimidine-2,5-diyl in their backbones have low absolute values of elastic constants K 3 and K 1 as well as a very low elastic constant ratio K 3 /K 1 such as <1.3. Thus, since absolute values of K 3 and K 1 as well as an elastic constant ratio K 3 /K 1 of a liquid crystal composition can be decreased by using compounds containing pyrimidine-2,5-diyl in backbones, an active driving OCB element having a lower voltage driving property, a high contrast and a wide viewing angle can be realized. Furthermore, since compounds shown by the general formulae (III) and (IV) have a high transparent point (NI point) such as NI≧100 and a high refractive anisotropy (Δn) such asΔn ≧0.1, it is possible to prepare a liquid crystal composition which has a low dielectric anisotropy (Δε), a low absolute value of elastic constant ratio K3/K1, a high refractive anisotropy (Δn), a high transparent point (NI point) and a very high voltage holding ratio (V. H. R.) and also which is superior in thermal stability and chemical stability, by combining the said compounds with the first component. Thus, an active driving OCB element can be realized which has a lower voltage driving property, a high contrast, a wide viewing angle, a high reliability and a wide driving temperature range. The fifth inventive matter of the present invention relates to a liquid crystal display element according to the above-mentioned fourth inventive matter, characterized in that the amount of the second component used is 40% or less than 40% by weight based on the total weight of the liquid crystal composition. The sixth inventive matter of the present invention relates to a liquid crystal display element according to the above-mentioned fourth or fifth inventive matter, characterized in that one or more than one compound(s) selected from the group of compounds shown by the general formulae (VI-a), (VI-b), (VI-c), (VI-d) and (VI-e) is(are) contained as the third component: (wherein, R 8 denotes an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene (-CH 2 -) group(s) may be substituted by (an) oxygen (-O-) atom(s) or -CH=CH-, R 9 denotes an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene (-CH 2 -) group(s) may be substituted by (an) oxygen (-O-) atom or -CH=CH-, CF 3 or CF 2 H; Z 10 and Z 11 denote independently each other -CH 2 CH 2 -, -COO- or a single bond.). The seventh inventive matter of the present invention relates to a liquid crystal display element according to the above-mentioned sixth inventive matter, characterized in that an amount of the third component used is 20% or less than 20% based on the total weight of the liquid crystal composition. The eighth inventive matter of the present invention relates to a liquid crystal display element according to any of the above-mentioned first to seventh inventive matters, characterized in that a nematic phase range in the liquid crystal composition is 60°C or above 60°C, an optical anisotropy Δn is 0.1 or more than 0.1, an elastic constant ratio K 3 /K 1 of a splay mode and a bend mode is 1.7 or less than 1.7, and a dielectric anisotropy Δε is 5.0 or more than 5.0. The ninth, tenth and eleventh inventive matters of the present invention relate to liquid crysal compositions in which the liquid crystal compositions have the compositions defined in any of the above-mentioned first to fourth or sixth inventive matters. An amount of the first component of the liquid crystal composition used for an active driving OCB element according to the invention is preferably from 50 to 100% by weight based on the total weight of the liquid crystal composition. If it is 50% or less than 50% by weight, a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment becomes higher, which is not preferable in practice. An amount of the second component used is preferably 40% or less than 40% by weight based on the total weight of the liquid crystal composition. If it is above 40% by weight, a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment becomes higher, which is not preferable in practice. It is more preferably 30% or less than 30% by weight. The liquid crystal composition used in the invention can contain other compounds in such a propriate amount not to effect the purpose of the invention, for the aims to adjust a threshold voltage, a nematic range, Δn, a dielectric anisotropy and a viscosity etc., according to the purpose of the active driving OCB elements used. The liquid crystal composition used according to the invention is prepared by the conventional methods known by themselves. In general, there is used a method to dissolve various components mutually at a raised temperature. Examples The present invention will be illustrated by the following Examples, which don't limit the invention. Composition ratios in Comparative Examples and Examples are all shown by weight %. There are described determined values of voltage holding ratios, determination of which being carried out based on an area method. Furthermore, expression ways of respective compounds are according to those in Table 1. Example 1 Concerning a liquid crystal composition consisted of 3-HB-CL 7.0% 2-HHB-CL 5.0% 4-HHB-CL 10.0% 5-HHB-CL 4.0% 2-HHB(F)-F 4.0% 3-HHB(F)-F 4.0% 5-HHB(F)-F 4.0% 2-HBB(F)-F 10.0% 3-HBB(F)-F 10.0% 5-HBB(F)-F 10.0% 3-HBB(F,F)-F 16.0% 5-HBB(F,F)-F 16.0%, a transparent point was T NI =90.4 (°C), a viscosity at 20°C was η 20 =24.2 (mPa . s), a refractive anisotropy at 25°C was Δn=0.119, a dielectric anisotropy at 20°C was Δε=6.8, an elastic constant K 3 at 25 °C was 14.8(PN), K 1 was 8.98(PN) and an elastic constant ratio K 3 /K 1 was 1.65. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.21(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25 °C of 99.3%. Example 2 Concerning a liquid crystal composition consisted of 3-PyB(F)-F 12.0% 7-HB(F)-F 11.0% 2-HHB(F)-F 9.0% 3-HHB(F)-F 8.0% 5-HHB(F)-F 8.0% 2-HBB(F)-F 8.0% 3-HBB(F)-F 8.0% 5-HBB(F)-F 7.0% 3-HHEB-F 5.0% 5-HHEB-F 5.0% 3-HBEB-F 6.0% 3-PyBB-F 7.0% 4-PyBB-F 6.0%, a transparent point was T NI =80.7 (°C), a viscosity at 20°C was η 20 =26.9(mPa·s), a refractive anisotropy at 25°C was Δn=0.122, a dielectric anisotropy at 20°C was Δε =8.6, an elastic constant K 3 at 25 °C was 11.8(PN), K 1 was 9.84(PN) and an elastic constant ratio K 3 /K 1 was 1.20. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =1.82(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25 °C of 98.5%. Example 3 Concerning a liquid crystal composition consisted of 3-H2BB(F,F)-F 10.0% 5-H2BB(F,F)-F 10.0% 3-HH2B(F,F)-F 6.0% 3-HBB(F,F)-F 29.0% 5-HBB(F,F)-F 29.0% 3-HBEB(F,F)-F 3.0% 5-HBEB(F,F)-F 3.0% 3-HHEB(F,F)-F 10.0%, a transparent point was T NI =61.5 (°C), a viscosity at 20°C was η 20 =34.0(mPa·s), a refractive anisotropy at 25°C was Δn=0.114, a dielectric anisotropy at 20°C was Δε=10.3, an elastic constant ratio K 3 /K 1 at 25°C was 1.62. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =1.55(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25 °C of 98.9%. Example 4 Concerning a liquid crystal composition consisted of 3-H2HB(F,F)-F 5.0% 5-H2HB(F,F)-F 5.0% 3-HH2B(F,F)-F 6.0% 4-H2BB(F,F)-F 10.0% 3-HBB(F,F)-F 29.0% 5-HBB(F,F)-F 29.0% 3-HBEB(F,F)-F 3.0% 5-HBEB(F,F)-F 3.0% 3-HHEB(F,F)-F 10.0%, a transparent point was T NI =63.2 (°C), a viscosity at 20°C was η 20 =34.3(mPa·s), a refractive anisotropy at 25 °C was Δn=0.108, a dielectric anisotropy at 20°C was Δε=10.0, an elastic constant ratio K 3 /K 1 at 25°C was 1.65. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =1.63(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25 °C of 98.6%. Example 5 Concerning a liquid crystal composition consisted of 3-H2HB(F,F)-F 5.0% 5-H2HB(F,F)-F 5.0% 3-HH2B(F,F)-F 9.0% 5-HH2B(F,F)-F 9.0% 3-HBB(F,F)-F 26.0% 5-HBB(F,F)-F 26.0% 3-HHEB(F,F)-F 10.0% 3-HBEB(F,F)-F 2.0% 5-HBEB(F,F)-F 2.0% 3-HHBB(F,F)-F 4.0% 3-HH2BB(F,F)-F 2.0%, a transparent point was T NI =83.8 (°C), a viscosity at 20°C was η 20 =31.9(mPa·s), a refractive anisotropy at 25°C was Δn=0.110, a dielectric anisotropy at 20°C was Δε=10.5, an elastic constant ratio K 3 /K 1 at 25°C was 1.69. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =1.70(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25 °C of 99.0%. Example 6 Concerning a liquid crystal composition consisted of 3-HHB(F,F)-F 8.0% 3-HH2B(F,F)-F 10.0% 5-HH2B(F,F)-F 10.0% 3-HBB(F,F)-F 26.0% 5-HBB(F,F)-F 26.0% 3-HHEB(F,F)-F 10.0% 3-HBEB(F,F)-F 2.0% 5-HBEB(F,F)-F 2.0% 3-HHBB(F,F)-F 6.0%, a transparent point was T NI =82.2 (°C), a viscosity at 20°C was η 20 =32.3 (mPa . s), a refractive anisotropy at 25°C was Δn=0.110, a dielectric anisotropy at 20°C was Δε=10.6. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =1.69(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25 °C of 99.2%. Example 7 Concerning a liquid crystal composition consisted of 2-HHEBB(F,F)-F 7.0% 5-HHEBB(F,F)-F 3.0% 5-HB-F 3.0% 7-HB-F 4.0% 2-HHB-OCF 3 12.0% 3-HHB-OCF 3 12.0% 5-HHB-OCF 3 10.0% 2-H2HB-OCF 3 6.0% 3-H2HB-OCF 3 6.0% 4-H2BB(F)-F 15.0% 5-H2BB(F)-F 14.0% 3-HBB(F,F)-OCF 2 CFHCF 3 4.0% 3-H2BB(F,F)-OCF 2 CFHCF 3 2.0% 3-HBB-OCF 2 CFHCF 3 2.0%, a transparent point was T NI =110.5(°C), a viscosity at 20°C was η 20 =22.5 (mPa . s), a refractive anisotropy at 25°C was Δn=0.106, a dielectric anisotropy at 20°C was Δε=5.4. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.65(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25 °C of 98.5%. Example 8 Concerning a liquid crystal composition consisted of 5-H4HB-OCF 3 7.0% 4-H2BB(F)-F 8.0% 5-H2BB(F)-F 7.0% 3-HBB-OCF 2 CFHCF 3 7.0% 3-HBB(F,F)-OCF 2 CFHCF 3 7.0% 5-BB-OCF 2 H 4.0% 3-HEB-OCF 3 3.0% 5-HHEB-OCF 3 7.0% 2-HHB(F)-F 5.0% 3-HHB(F)-F 5.0% 5-HHB(F)-F 4.0% 3-HHEB(F,F)-F 7.0% 5-H2B(F)-F 10.0% 7-HB(F,F)-F 9.0% 3-HBEB-F 10.0%, a transparent point was T NI =72.7 (°C), a viscosity at 20°C was η 20 =22.3(mPa·s), a refractive anisotropy at 25°C was Δn=0.101, a dielectric anisotropy at 20°C was Δε=5.5. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.12(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25 °C of 98.2%. Example 9 Concerning a liquid crystal composition consisted of 5-H4HB-OCF 3 8.0% 4-H2BB(F)-F 9.0% 5-H2BB(F)-F 8.0% 3-HBB(F,F)-OCF 2 CFHCF 3 8.0% 3-HBB(F)-OCF 2 CF 2 H 8.0% 3-HHB-OCF 3 8.0% 3-HHB(F,F)-F 8.0% 3-HBB(F,F)-F 12.0% 5-HB-CL 8.0% 5-HHB-CL 4.0% 3-HB-CL 9.0% 5-H2B(F)-F 10.0%, a transparent point was T NI =62.2 (°C), a viscosity at 20°C was η 20 =18.2(mPa·s), a refractive anisotropy at 25°C was Δn=0.100, a dielectric anisotropy at 20°C was Δε=5.2. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.14(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25 °C of 98.4%. Example 10 Concerning a liquid crystal composition consisted of 5-H4HB-OCF 3 8.0% 4-H2BB(F)-F 9.0% 5-H2BB(F)-F 8.0% 3-HH2B-OCF 3 4.0% 3-H2HB-OCF 3 4.0% 3-HBB(F,F)-OCF 2 CFHCF 3 8.0% 3-HBB(2F)-OCF 2 CFHCF 3 4.0% 3-HBB(F,F)-F 12.0% 5-HHEB-OCF 3 3.0% 3-HHEB(F,F)-F 8.0% 5-HB-CL 7.0% 5-HHB-CL 5.0% 5-H2B(F)-F 10.0% 2-HEB-F 10.0%, a transparent point was T NI =60.6 (°C), a viscosity at 20°C was η 20 =20.0(mPa·s), a refractive anisotropy at 25°C was Δn=0.105, a dielectric anisotropy at 20°C was Δε=5.6. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =1.97(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25 °C of 98.3%. Example 11 Concerning a liquid crystal composition consisted of 3-PyB(F)-F 12.0% 7-HB(F)-F 11.0% 2-HHB(F)-F 7.0% 3-HHB(F)-F 7.0% 5-HHB(F)-F 7.0% V-HHB(F)-F 2.0% V2-HHB(F)-F 2.0% 2-HBB(F)-F 8.0% 3-HBB(F)-F 8.0% 5-HBB(F)-F 7.0% 3-HHEB-F 5.0% 5-HHEB-F 5.0% 3-HBEB-F 6.0% 3-PyBB-F 7.0% 4-PyBB-F 6.0%, a transparent point was T NI =81.0 (°C), a viscosity at 20°C was η 20 =26.8(mPa·s), a refractive anisotropy at 25°C was Δn=0.128, a dielectric anisotropy at 20°C was Δε=8.7, an elastic constant K 3 at 25 °C was 12.2(PN), K 1 was 9.88(PN) and an elastic constant ratio K 3 /K 1 was 1.23. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =1.87(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.1%. Example 12 Concerning a liquid crystal composition consisted of V-HHB(F,F)-F 3.0% 3-HHB(F,F)-F 5.0% 3-HH2B(F,F)-F 10.0% 5-HH2B(F,F)-F 10.0% 3-HBB(F,F)-F 26.0% 5-HBB(F,F)-F 26.0% 3-HHEB(F,F)-F 10.0% 3-HBEB(F,F)-F 2.0% 5-HBEB(F,F)-F 2.0% 3-HHBB(F,F)-F 6.0%, a transparent point was T NI =82.5 (°C), a viscosity at 20°C was η 20 =32.0(mPa·s), a refractive anisotropy at 25°C was Δn=0.113, a dielectric anisotropy at 20°C was Δε=10.6. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =1.72(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.7%. Example 13 Concerning a liquid crystal composition consisted of 7-HB(F,F)-F 3.0% 2-HHB(F)-F 2.0% 3-HHB(F)-F 3.0% 5-HHB(F)-F 3.0% 2-HBB(F)-F 9.0% 3-HBB(F)-F 9.0% 5-HBB(F)-F 8.0% 3-HBB-F 4.0% 5-HBB-F 3.0% 3-HBB(F,F)-F 15.0% 5-HBB(F,F)-F 15.0% 3-HB-O2 7.0% 3-HH-4 4.0% 3-HB(F)TB-2 5.0% 3-HB(F)TB-3 5.0% 3-HB(F)TB-4 5.0%, a transparent point was T NI =92.1 (°C), a viscosity at 20°C was η 20 =27.6(mPa·s), a refractive anisotropy at 25°C was Δn=0.140, a dielectric anisotropy at 20°C was Δε=5.5, an elastic constant K 3 at 25°C was 12.9(PN), K 1 was 10.9(PN) and an elastic constant ratio K 3 /K 1 was 1.18. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.30(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 99.0%. Example 14 Concerning a liquid crystal composition consisted of 3-PyB(F)-F 16.0% 7-HB(F)-F 12.0% 2-HHB(F)-F 12.0% 3-HHB(F)-F 12.0% 5-HHB(F)-F 12.0% 3-PyBB-F 8.0% 4-PyBB-F 8.0% 5-PyBB-F 8.0% 2-PyB-2 2.0% 2-PyBH-3 3.0% 3-PyBH-3 3.0% 4-PyBH-3 4.0%, a transparent point was T NI =83.8 (°C), a viscosity at 20°C was η 20 =50.9(mPa·s), a refractive anisotropy at 25°C was was Δn=0.140, a dielectric anisotropy at 20°C was Δε=9.0, an elastic constant K 3 at 25°C was 15.3(PN), K 1 was 16.6(PN) and an elastic constant ratio K 3 /K 1 was 0.92. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.15(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.3%. Example 15 Concerning a liquid crystal composition consisted of 3-PyB(F)-F 11.0% 5-PyB(F)-F 12.0% 3-HHEB-F 5.0% 5-HHEB-F 5.0% 3-HBEB-F 6.0% 3-PyBB-F 8.0% 4-PyBB-F 8.0% 5-PyBB-F 8.0% 3-HB-02 20.0% 3-HEB-04 1.4% 4-HEB-02 1.0% 5-HEB-01 1.0% 3-HEB-02 0.9% 5-HEB-02 0.7% 2-PyBH-3 4.0% 3-PyBH-3 4.0% 4-PyBH-3 4.0%, a transparent point was T NI =81.2 (°C), a viscosity at 20°C was η 20 =27.8(mPa·s), a refractive anisotropy at 25°C was Δn=0.159, a dielectric anisotropy at 20°C was Δε=7.9, an elastic constant K 3 at 25°C was 14.0(PN), K 1 was 14.0(PN) and an elastic constant ratio K 3 /K 1 was 1.00. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =1.98(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.1%. Example 16 Concerning a liquid crystal composition consisted of 2-PyB-F 2.0% 3-PyB(F)-F 10.0% 5-PyB(F)-F 11.0% 3-HHEB-F 5.0% 5-HHEB-F 5.0% 3-HBEB-F 6.0% 3-PyBB-F 8.0% 4-PyBB-F 8.0% 5-PyBB-F 6.0% 3-PyB-01 2.0% 3-HB-02 20.0% 3-HEB-04 2.0% 5-HEB-1 2.0% 10-BEB-2 1.0% 2-PyBH-3 4.0% 3-PyBH-3 4.0% 4-PyBH-3 2.0% 3-PyBB-2 2.0%, a transparent point was T NI =80.0 (°C), a viscosity at 20°C was η 20 =28.7 (mPa·s), a refractive anisotropy at 25°C was Δn= 0.1700, a dielectric anisotropy at 20°C wasΔ ε=7.0, an elastic constant K 3 at 25°C was 13.8(PN), K 1 was 13.7(PN) and an elastic constant ratio K 3 /K 1 was 1.01. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.08(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.1%. Example 17 Concerning a liquid crystal composition consisted of 7-HB(F)-F 8.0% 7-HB(F,F)-F 10.0% 2-HBB(F)-F 13.0% 3-HBB(F)-F 13.0% 5-HBB(F)-F 12.0% 3-HB(F)TB-2 6.0% 3-HB(F)TB-3 6.0% 3-HB(F)TB-4 6.0% 3-H2BTB-2 4.0% 3-H2BTB-3 4.0% 3-HBB(F,F)-F 9.0% 5-HBB(F,F)-F 9.0%, a transparent point was T NI =83.4 (°C), a viscosity at 20°C was η 20 =30.8 (mPa . s), a refractive anisotropy at 25°C was Δn=0.146, a dielectric anisotropy at 20°C was Δε=6.2, an elastic constant K 3 at 25°C was 10.9(PN), K 1 was 10.4(PN) and an elastic constant ratio K 3 /K 1 was 1.05. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.08(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 99.0%. Example 18 Concerning a liquid crystal composition consisted of 7-HB(F,F)-F 7.0% 2-BTB-01 11.0% 3-HB-02 3.0% 2-HBB(F)-F 12.0% 3-HBB(F)-F 11.0% 5-HBB(F)-F 10.0% 3-HBB(F,F)-F 10.0% 5-HBB(F,F)-F 11.0% 3-H2BTB-2 3.0% 3-H2BTB-3 4.0% 3-HB(F)TB-2 6.0% 3-HB(F)TB-3 6.0% 3-HB(F)TB-4 6.0%, a transparent point was T NI =96.1 (°C), a viscosity at 20°C was η 20 =35.9(mPa·s), a refractive anisotropy at 25°C wasΔn=0.179, a dielectric anisotropy at 20°C was Δε=5.5. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.52(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.7%. Example 19 Concerning a liquid crystal composition consisted of 7-HB(F,F)-F 3.0% 2-HHB(F)-F 2.0% 3-HHB(F)-F 3.0% 5-HHB(F)-F 3.0% 2-HBB(F)-F 9.0% 3-HBB(F)-F 9.0% 5-HBB(F)-F 8.0% 3-HBB-F 3.0% 5-HBB-F 3.0% 3-HBB(F,F)-F 15.0% 5-HBB(F,F)-F 15.0% 3-HB-02 7.0% 3-HH-4 4.0% 3-HB(F)TB-2 5.0% 3-HB(F)TB-3 5.0% 3-HB(F)TB-4 4.0% 2-BTB-1 1.0% 3-HHB-F 1.0%, a transparent point was T NI =91.3 (°C), a viscosity at 20°C was η 20 =27.0 (mPa·s), a refractive anisotropy at 25°C was Δn=0.146, a dielectric anisotropy at 20°C was Δε=5.3, an elastic constant K 3 at 25°C was 12.0(PN), K 1 was 10.1 (PN) and an elastic constant ratioK 3 /K 1 was 1.19. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.27(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.8%. Example 20 Concerning a liquid crystal composition consisted of 2-HHEBB(F,F)-F 5.0% 3-HB-CL 5.0% 2-HHB(F)-F 10.0% 3-HHB(F)-F 10.0% 5-HHB(F)-F 10.0% 2-HBB(F)-F 10.0% 3-HBB(F)-F 10.0% 5-HBB(F)-F 10.0% 2-HBB-F 5.0% 3-HBB-F 5.0% 3-HBB(F,F)-F 8.0% 3-HHBB(F,F)-F 3.0% 3-HB(F)VB-2 5.0% 3-HB(F)VB-3 4.0%, a transparent point was T NI =115.0(°C), a viscosity at 20°C was η 20 =27.7 (mPa . s), a refractive anisotropy at 25°C was Δn=0.134, a dielectric anisotropy at 20°C was Δε=5.7. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.51(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 99.4%. Example 21 Concerning a liquid crystal composition consisted of 5-HHEBB(F,F)-F 5.0% 5-H2B(F)-F 10.0% 7-HB(F)-F 3.0% 7-HEB-F 2.0% 2-HHB(F)-F 10.0% 3-HHB(F)-F 10.0% 5-HHB(F)-F 10.0% 2-HBB(F)-F 6.0% 3-HBB(F)-F 6.0% 5-HBB(F)-F 6.0% 2-H2HB(F)-F 6.0% 3-H2HB(F)-F 6.0% 5-H2HB(F)-F 6.0% 3-HBB-1 8.0% 101-HBBH-3 2.0% 101-HBBH-4 2.0% 3-HEBEB-F 2.0%, a transparent point was T NI =103.5(°C), a viscosity at 20°C was η 20 =25.9 (mPa·s), a refractive anisotropy at 25°C was Δn=0.100, a dielectric anisotropy at 20°C was Δε=5.0. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.63(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 99.0%. Example 22 Concerning a liquid crystal composition consisted of 2-HHEBB(F,F)-F 10.0% 5-HHEBB(F,F)-F 3.0% 2-HHB-OCF 3 14.0% 3-HHB-OCF 3 13.0% 5-HHB-OCF 3 12.0% 3-HH2B-OCF 3 5.0% 5-HH2B-OCF 3 5.0% 3-HBB(F)-F 16.0% 5-HBB(F)-F 16.0% 3-HBB(F)-OCF 2 CF 2 H 4.0% 3-HBB(F)-OCF 2 CFHCF 3 2.0% 3-HHB(F)-F 10.0% 5-HHB(F)-F 10.0% 2-HBB(F)-F 5.0% 3-HBB(F)-F 5.0% 5-HBB(F)-F 6.0% 2-H2HB(F)-F 6.0% 3-H2HB(F)-F 6.0% 5-H2HB(F)-F 6.0% 3-HBB-1 10.0% 101-HBBH-3 2.0% 101-HBBH-4 2.0% 3-HEBEB-F 2.0%, a transparent point was T NI =139.3(°C), a viscosity at 20°C was η 20 =27.9(mPa·s), a refractive anisotropy at 25°C was Δn=0.117, a dielectric anisotropy at 20°C was Δε=5.8. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.66(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.3. Example 23 Concerning a liquid crystal composition consisted of 5-HHEBB(F,F)-F 5.0% 2-HHB-OCF 3 10.0% 3-HHB-OCF 3 10.0% 5-HHB-OCF 3 10.0% 3-HH2B-OCF 3 10.0% 5-HH2B-OCF 3 10.0% 4-H2BB(F)-F 13.0% 5-H2BB(F)-F 10.0% 3-HBB(F,F)-F 7.0% 3-HHB(F,F)-F 7.0% 3-HBB(F)-OCF 2 CFHCF 3 2.0% 3-HBB(F,F)-OCF 2 CFHCF 3 2.0% 5-HBBH-3 2.0% 5-HB(F)BH-3 3.0%, a transparent point was T NI =130.6(°C), a viscosity at 20°C was η 20 =24.6 (mPa . s), a refractive anisotropy at 25°C was Δn=0.110, a dielectric anisotropy at 20°C was Δε=5.6. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.83(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.8. Example 24 Concerning a liquid crystal composition consisted of 5-H4HB-OCF 3 5.0% 4-H2BB(F)-F 5.0% 5-H2BB(F)-F 5.0% 3-HHB-OCF 3 5.0% 5-HBB(F,F) -OCF 2 CFHCF 3 5.0% 3-HBB-OCF 2 CFHCF 3 5.0% 3-HBB(F,F)-F 10.0% 5-HBB(F,F)-F 10.0% 3-HBEB-F 15.0% 3-HBEB(F,F)-F 10.0% 3-HB-CL 10.0% 3-HHB-CL 5.0% 3-HH2BB(F,F)-F 5.0% 3-HH-4 5.0%, a transparent point was T NI =99.1 (°C), a viscosity at 20°C was η 20 =28.2 (mPa·s), a refractive anisotropy at 25°C was Δn=0.119, a dielectric anisotropy at 20°C was Δε=8.2. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.08(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.3%. Example 25 Concerning a liquid crystal composition consisted of 5-H4HB-OCF 3 12.0% 5-H4HB(F,F)-CF 3 8.0% 3-H4HB(F,F)-CF 3 14.4% 5-H4HB(F,F)-F 5.6% 3-HB-CL 7.8% 5-HB-CL 3.2% 4-H2BB(F)-F 8.0% 5-H2BB(F)-F 7.0% 3-HHB-OCF 3 8.0% 3-H2HB-OCF 3 4.0% 3-HBB(F,F)-OCF 2 CFHCF 3 8.0% 5-HHEB-OCF 3 1.6% 3-HBEB(F,F)-F 5.0% 101-HH-3 1.4% 5-H2B(F)-F 2.0% 3-HHB-01 2.0% 3-HHEBB-F 2.0%, a transparent point was T NI =68.2 (°C), a viscosity at 20°C was η 20 =24.2(mPa·s), a refractive anisotropy at 25°C was Δn=0.100, a dielectric anisotropy at 20°C was Δ ε =7.3. The liquid crystral composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.14(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.4%. Example 26 Concerning a liquid crystal composition consisted of 3-PyB(F)-F 13.0% 7-HB(F)-F 12.0% 2-HHB(F)-F 12.0% 3-HHB(F)-F 12.0% 5-HHB(F)-F 12.0% 2-HBB(F)-F 8.0% 3-HBB(F)-F 8.0% 5-HBB(F)-F 6.0% 2-PyBH-3 5.0% 3-PyBH-3 5.0% 4-PyBH-3 5.0% 3-HB(2F,3F)-4 2.0%, a transparent point was T NI =78.2 (°C), a viscosity at 20°C was η 20 =32.2 (mPa . s), a refractive anisotropy at 25°C was Δn=0.132, a dielectric anisotropy at 20°C was Δε=6.2. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.12(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.0%. Example 27 Concerning a liquid crystal composition consisted of 3-PyB(F)-F 16.0% 3-HB-O2 18.0% 3-HB-O4 5.0% 2-HHB(F)-F 3.0% 3-HHB(F)-F 4.0% 5-HHB(F)-F 4.0% 2-HBB(F)-F 4.0% 3-HBB(F)-F 4.0% 5-HBB(F)-F 4.0% 2-PyBB-F 9.0% 3-PyBB-F 9.0% 4-PyBB-F 9.0% 5-PyBB-F 9.0% 3-HHB(2F,3F)-4 2.0%, a transparent point was T NI =82.2 (°C), a viscosity at 20°C was η 20 =50.2 (mPa . s), a refractive anisotropy at 25°C was Δn=0.165, a dielectric anisotropy at 20°C was Δε=8.5. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.25(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.3%. Example 28 Concerning a liquid crystal composition consisted of 3-PyB(F)-F 13.0% 7-HB(F)-F 4.0% 2-HHB(F)-F 15.0% 3-HHB(F)-F 15.0% 5-HHB(F)-F 14.0% 2-HBB(F)-F 8.0% 3-HBB(F)-F 8.0% 5-HBB(F)-F 8.0% 2-PyBH-3 9.0% 3-PyBH-3 4.0% 3-HBB(2F,3F)-4 2.0%, a transparent point was T NI =86.7 (°C), a viscosity at 20°C was η 20 =28.7 (mPa . s), a refractive anisotropy at 25°C was Δn=0.103, a dielectric anisotropy at 20°C was Δε=5.8. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.32(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.7%. Example 29 Concerning a liquid crystal composition consisted of 5-HB-CL 22.0% 2-HBB(F)-F 12.0% 3-HBB(F)-F 12.0% 5-HBB(F)-F 12.0% 4-HHB-CL 10.0% 3-HBB(F,F)-F 15.0% 5-HBB(F,F)-F 15.0% 3-HB(2F,3F)H-4 2.0%, a transparent point was T NI =66.7 (°C), a viscosity at 20°C was η 20 =22.7(mPa·s), a refractive anisotropy at 25°C was Δn=0.105, a dielectric anisotropy at 20°C was Δε=5.1. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =2.37(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.2%. Example 30 Concerning a liquid crystal composition consisted of 3-H2HB(F,F)-F 5.0% 5-H2HB(F,F)-F 5.0% 3-HH2B(F,F)-F 6.0% 4-H2BB(F,F)-F 10.0% 3-HBB(F,F)-F 29.0% 5-HBB(F,F)-F 29.0% 3-HBEB(F,F)-F 3.0% 5-HBEB(F,F)-F 3.0% 3-HHEB(F,F)-F 10.0% 3-HBPn-4 1.0%, a transparent point was T NI =63.9 (°C), a viscosity at 20°C was η 20 =35.1 (mPa . s), a refractive anisotropy at 25°C was Δn=0.102, a dielectric anisotropy at 20°C was Δε=9.6. The liquid crystal composition was sealed in a cell for OCB having a thickness of 6.0 µm, and a transition voltage (V CR ) at which a splay-alignment being transited to a bend-alignment was determined, to obtain V CR =1.60(V). Also, a voltage holding ratio of the liquid crystal composition was determined, to obtain a voltage holding ratio at 25°C of 98.3%. Effect of the Invention As shown in Examples, there can be realized an active driving OCB element with a low voltage driving property, a high contrast, a wide viewing angle and a high reliability according to the invention.

Claims: An active driving OCB (Optically Compensated Bend or Birefringence) liquid crystal display element, wherein a) a sealed cell formed of two substrates having transparent electrodes is used, b) a nematic liquid crystal mixture having a positive dielectric anisotropy and a high resistance is contained in the cell, c) rubbing directions of aligned membranes coated on the two upper and lower substrates are made in the same direction (a twist angle of 0°), d) an arrangement is made such that one angle constituted by a pre-tilt direction of liquid crystals on the aligned membranes and the substrates being + and the other being -, e) a biaxial phase different film is arranged on the top of the upper substrate of the upper and lower substrates in the cell, and polarized plates are arranged above and below the cell containing the arranged biaxial phase different film, and f) respective pixels in the sealed cell are switched, characterized in that the said nematic liquid crystal composition contains at least one compound having (a) terminal group structure(s) of the following general formula (I) (wherein, X denotes F, Cl, CF 3 , OCF 3 , CF 2 H, OCF 2 H, OCF 2 CF 2 H, OCF 2 Cl or OCF 2 CFHCF 3 , Q 1 and Q 2 denote independently each other H or F.) as the first component. A liquid crystal display element according to Claim 1, characterized in that the compound of the general formula (I) being one expressed by the general formulae (I-a), (I-b) and (I-c) (whrein, R 1 denotes an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, of which optional one or non-adjacent two or more than two methylene (-CH 2 ) group(s) may be optionally substituted by (an) oxygen atom(s) or -CH=CH-; X denotes F, Cl, CF 3 , OCF 3 , CF 2 H, OCF 2 H, OCF 2 CF 2 H, OCF 2 Cl or OCF 2 CFHCF 3 ; Q 1 and Q 2 denote independently each other H or F; Z 1 , Z 2 , Z 3 , Z 4 , Z 5 and Z 6 denote independently each other -CH 2 CH 2 -, -(CH 2 ) 4 -, -COO-, -CF 2 O-, -CH=CH- or a single bond; A, B, C, D and E denote independently each other trans-1,4-cyclohexylene, pyrimidine-2,5-diyl, 1,4-cyclohexenylene or 1,4-phenylene optionally substituted with F at a branching H.). A liquid crystal display element according to Claim 1 or 2, characterized in that an amount of the first component used is from 50 to 100% by weight based on the total weight of the liquid crystal composition. An active driving OCB (Optically Compensated Bend or Birefringence) liquid crystal display element, wherein a) a sealed cell formed of two substrates having transparent electrodes is used, b) a nematic liquid crystal mixture having a positive dielectric anisotropy and a high resistance is contained in the cell, c) rubbing directions of aligned membranes coated on the two upper and lower substrates are made in the same direction (a twist angle of 0° ), d) an arrangement is made such that one angle constituted by a pre-tilt direction of liquid crystals on the aligned membranes and the substrates being + and the other being -, e) a biaxial phase different film is arranged on the top of the upper substrate of the upper and lower substrates in the cell, and polarized plates are arranged above and below the cell containing the arranged biaxial phase different film, and f) respective pixels in the sealed cell are switched, characterized in that the said nematic liquid crystal composition contains at least one compound having (a) terminal group structure(s) of the following general formula (I) (wherein, X denotes F, Cl, CF 3 , OCF 3 , CF 2 H, OCF 2 H, OCF 2 CF 2 H, OCF 2 Cl or OCF 2 CFHCF 3 , Q 1 and Q 2 denote independently each other H or F.) as the first component and that at least one compound selected from the group of compound shown by the general formulae (II), (III) and (IV) is contained as the second component: R 2 -(G)-Z 7 -(J)-R 3 (wherein, R 2 and R 3 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-; G and J denote independently each other trans-1,4-cyclohexylene, 1,4-phenylene, or pyrimidine-2,5-diyl; and Z 7 denotes -CH 2 CH 2 -, -COO-, -CH=CH-, -C≡C- or a single bond.), R 4 -(K)-Z 8 -(L)-Z 9 -(M)-R 5 (wherein, R 4 and R 5 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-; K denotes trans-1,4-cyclohexylene, 1,4-phenylene or pyrimidine-2,5-diyl; L and M denote independently each other trans-1,4-cyclohexylene or 1,4-phenylene optionally substituted by F at one branching H; Z 8 and Z 9 denote independently each other -CH 2 CH 2 -, -CH=CH-, -C≡C-, -COO- or a single bond), and (wherein, R 6 and R 7 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-, and Q 3 denotes H or F.). A liquid crystal display element according to Claim 4, characterized in that the amount of the second component used is 40% or less than 40% by weight based on the total weight of the liquid crystal composition. An active driving OCB (Optically Compensated Bend or Birefringence) liquid crystal display element, wherein a) a sealed cell formed of two substrates having transparent electrodes is used, b) a nematic liquid crystal mixture having a positive dielectric anisotropy and a high resistance is contained in the cell, c) rubbing directions of aligned membranes coated on the two upper and lower substrates are made in the same direction (a twist angle of 0° ), d) an arrangement is made such that one angle constituted by a pre-tilt direction of liquid crystals on the aligned membranes and the substrates being + and the other being -, e) a biaxial phase different film is arranged on the top of the upper substrate of the upper and lower substrates in the cell, and polarized plates are arranged above and below the cell containing the arranged biaxial phase different film, and f) respective pixels in the sealed cell are switched, characterized in that the said nematic liquid crystal composition contains at least one compound having (a) terminal group structure(s) of the following general formula (I) (wherein, X denotes F, Cl, CF 3 , OCF 3 , CF 2 H, OCF 2 H, OCF 2 CF 2 H, OCF 2 Cl or OCF 2 CFHCF 3 , Q 1 and Q 2 denote independently each other H or F.) as the first component and that at least one compound selected from the group of compound shown by the general formulae (II), (III) and (IV) is contained as the second component: R 2 -(G)-Z 7 -(J)-R 3 (wherein, R 2 and R 3 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-; G and J denote independently each other trans-1,4-cyclohexylene, 1,4-phenylene, or pyrimidine-2,5-diyl; and Z 7 denotes -CH 2 CH 2 -, -COO-, -CH=CH-, -C≡C- or a single bond.), R 4 -(K)-Z 8 -(L)-Z 9 -(M)-R 5 (wherein, R 4 and R 5 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-; K denotes trans-1,4-cyclohexylene, 1,4-phenylene or pyrimidine-2,5-diyl; L and M denote independently each other trans-1,4-cyclohexylene or 1,4-phenylene optionally substituted by F at one branching H; Z 8 and Z 9 denote independently each other -CH 2 CH 2 -, -CH=CH-, -C≡C-, -COO- or a single bond.), and (wherein, R 6 and R 7 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-, and Q 3 denotes H or F.) and that one or more than one compound(s) selected from the group of compounds shown by the general formulae (VI-a), (VI-b), (VI-c), (VI-d) and (VI-e) is (are) contained as the third component: (wherein, R 8 denotes an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-, R 9 denotes an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom or -CH=CH-, CF 3 or CF 2 H; Z 10 and Z 11 denote independently each other -CH 2 CH 2 -, -COO- or a single bond.). A liquid crystal display element according to Claim 6, characterized in that an amount of the third component used is 20% or less than 20% based on the total weight of the liquid crystal composition. A liquid crystal display element according to any of Claims 1 to 7, characterized in that a nematic phase range in the liquid crystal composition is 60°C or above 60°C, an optical anisotropy Δn is 0.1 or more than 0.1, an elastic constant ratio K 3 /K 1 of a splay mode and a bend mode is 1.7 or less than 1.7, and a dielectric anisotropy Δε is 5.0 or more than 5.0. Use of a liquid crystal composition in an active driving OCB (Optically Compensated Bend or Birefringence) liquid crystal display element, wherein a) a sealed cell formed of two substrates having transparent electrodes is used, b) a nematic liquid crystal mixture having a positive dielectric anisotropy and a high resistance is contained in the cell, c) rubbing directions of aligned membranes coated on the two upper and lower substrates are made in the same direction (a twist angle of 0° ), d) an arrangement is made such that one angle constituted by a pre-tilt direction of liquid crystals on the aligned membranes and the substrates being + and the other being -, e) a biaxial phase different film is arranged on the top of the upper substrate of the upper and lower substrates in the cell, and polarized plates are arranged above and below the cell containing the arranged biaxial phase different film, and f) respective pixels in the sealed cell are switched, characterized in that the said nematic liquid crystal composition contains at least one compound having (a) terminal group structure(s) of the following general formula (I) (wherein, X denotes F, Cl, CF 3 , OCF 3 , CF 2 H, OCF 2 H, OCF 2 CF 2 H, OCF 2 Cl or OCF 2 CFHCF 3 , Q 1 and Q 2 denote independently each other H or F.) as the first component. Use of a liquid crystal composition in an active driving OCB (Optically Compensated Bend or Birefringence) liquid crystal display element, wherein a) a sealed cell formed of two substrates having transparent electrodes is used, b) a nematic liquid crystal mixture having a positive dielectric anisotropy and a high resistance is contained in the cell, c) rubbing directions of aligned membranes coated on the two upper and lower substrates are made in the same direction (a twist angle of 0° ), d) an arrangement is made such that one angle constituted by a pre-tilt direction of liquid crystals on the aligned membranes and the substrates being + and the other being -, e) a biaxial phase different film is arranged on the top of the upper substrate of the upper and lower substrates in the cell, and polarized plates are arranged above and below the cell containing the arranged biaxial phase different film, and f) respective pixels in the sealed cell are switched, characterized in that the said nematic liquid crystal composition contains at least one compound having (a) terminal group structure(s) of the following general formula (I) (wherein, X denotes F, Cl, CF 3 , OCF 3 , CF 2 H, OCF 2 H, OCF 2 CF 2 H, OCF 2 Cl or OCF 2 CFHCF 3 , Q 1 and Q 2 denote independently each other H or F.) as the first component and that at least one compound selected from the group of compound shown by the general formulae (II), (III) and (IV) is contained as the second component: R 2 -(G)-Z 7 -(J)-R 3 (wherein, R 2 and R 3 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-; G and J denote independently each other trans-1,4cyclohexylene, 1,4-phenylene, or pyrimidine-2,5-diyl; and Z 7 denotes -CH 2 CH 2 -, -COO-, -CH=CH-, -C≡C- or a single bond.), R 4 -(K)-Z 8 -(L)-Z 9 -(M)-R 5 (wherein, R 4 and R 5 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-; K denotes trans-1,4-cyclohexylene, 1,4-phenylene or pyrimidine-2,5-diyl; L and M denote independently each other trans-1,4-cyclohexylene or 1,4-phenylene optionally substituted by F at one branching H; Z 8 and Z 9 denote independently each other -CH2CH2-, -CH=CH-, -C≡C-, -COO- or a single bond.), and (wherein, R 6 and R 7 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-, and Q 3 denotes H or F.). Use of a liquid crystal composition in an active driving OCB (Optically compensated Bend or Birefringence) liquid crystal display element, wherein a) a sealed cell formed of two substrates having transparent electrodes is used, b) a nematic liquid crystal mixture having a positive dielectric anisotropy and a high resistance is contained in the cell, c) rubbing directions of aligned membranes coated on the two upper and lower substrates are made in the same direction (a twist angle of 0° ), d) an arrangement is made such that one angle constituted by a pre-tilt direction of liquid crystals on the aligned membranes and the substrates being + and the other being -, e) a biaxial phase different film is arranged on the top of the upper substrate of the upper and lower substrates in the cell, and polarized plates are arranged above and below the cell containing the arranged biaxial phase different film, and f) respective pixels in the sealed cell are switched, characterized in that the said nematic liquid crystal composition contains at least one compound having (a) terminal group structure(s) of the following general formula (I) (wherein, X denotes F, Cl, CF 3 , OCF 3 , CF 2 H, OCF 2 H, OCF 2 CF 2 H, OCF 2 Cl or OCF 2 CFHCF 3 , Q 1 and Q 2 denote independently each other H or F.) as the first component and that at least one compound selected from the group of compound shown by the general formulae (II), (III) and (IV) is contained as the second component: R 2 -(G)-Z 7 -(J)-R 3 (wherein, R 2 and R 3 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-; G and J denote independently each other trans-1,4-cyclohexylene, 1,4-phenylene, or pyrimidine-2,5-diyl; and Z 7 denotes -CH 2 CH 2 -,-COO-, -CH=CH-, -C≡C- or a single bond.), R 4 -(K)-Z 8 -(L)-Z 9 -(M)-R 5 (wherein, R 4 and R 5 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-; K denotes trans-1,4-cyclohexylene, 1,4-phenylene or pyrimidine-2,5-diyl; L and M denote independently each other trans-1,4-cyclohexylene or 1,4-phenylene optionally substituted by F at one branching H; Z 8 and Z 9 denote independently each other -CH 2 CH 2 -, -CH=CH-, -C≡C-, -COO- or a single bond), and (wherein, R 6 and R 7 denote independently each other an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-, and Q 3 denotes H or F.) and that one or more than one compound(s) selected from the group of compounds shown by the general formulae (VI-a), (VI-b), (VI-c), (VI-d) and (VI-e) is (are) contained as the third component: (wherein, R 8 denotes an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom(s) or -CH=CH-, R 9 denotes an alkyl group or a fluoroalkyl group with from 1 to 10 carbon atoms, in which optional one or non-adjacent two or more than two methylene group(s) may be substituted by (an) oxygen atom or -CH=CH-, CF 3 or CF 2 H; Z 10 and Z 11 denote independently each other -CH 2 CH 2 -, -COO- or a single bond.).

Inventors: MATSUSHITA TETSUYA, MURAOKA TOSHIHIKO, MURASHIRO KATSUYUKI, NAKAGAWA ETSUO, TAKESHITA FUSAYUKI, MATSUSHITA, TETSUYA, MURAOKA, TOSHIHIKO, MURASHIRO, KATSUYUKI, NAKAGAWA, ETSUO, TAKESHITA, FUSAYUKI
Applicants: CHISSO CORP, CHISSO CORPORATION
Application year: 1996
Main classification: C09K19
IPC codes: G02F1, C09K19