JPH049197B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a liquid crystal composition used in a TN type liquid crystal display. In recent years, the performance of liquid crystal display devices has improved and their application fields are expanding.In addition to conventional calculators, wristwatches, clocks, etc., they are now being used in large outdoor display devices with a wide operating temperature range, automobile dashboards, and pockets. It has come to be applied to high-performance displays with a large amount of information such as computers, word processors, and information terminal devices such as televisions, but in order to further expand its uses, it is necessary to maintain display quality while maintaining display quality. ,
Increasing display density is an important issue. New ideas to increase display density include the TET method using amorphous silicon and the dual-frequency drive method using dielectric dispersion of liquid crystals, but the former has problems in terms of reliability and cost, and the latter The disadvantage is that the characteristics of low voltage and low power consumption, which are characteristics of liquid crystal display devices, are lost. In the case of a liquid crystal display device, a selection waveform is repeatedly applied to selection electrodes in a line-sequential manner, but in order to increase display density, it is necessary to increase the number of selection electrodes (equal to the number of time divisions N). However, with conventional liquid crystals, the number of time divisions is small and display density cannot be increased. In order to solve these problems, the present inventors investigated increasing the display density using the voltage averaging method conventionally used in calculators and the like, and arrived at the present invention. That is, an object of the present invention is to provide a liquid crystal composition that can obtain a large number of time divisions.
The objective is to increase the steepness of the voltage-luminance characteristic, which is a related characteristic of the liquid crystal composition. The liquid crystal composition of the present invention has the general formula (In the formula, R ₁ is C _o H _2o+1 , R ₂ is C _o H _2o+1 or C _o
It represents H _2o+1 O, and n represents an integer of 1 to 8. )
10 to 80% by weight of the liquid crystal compound component (A) consisting of one or more of the compounds represented by |△
The highly dielectric anisotropic liquid crystal compound component (B) with ε|≧5 is
10-60% by weight, no pyrimidine ring |△ε|
The low dielectric anisotropic liquid crystal compound component (C) with <5 is 10~
It is characterized by containing 80% by weight. Further, in detail, the liquid crystal composition of the present invention is that the first is a composition consisting of components (A), (B), and (C), and the second is a composition consisting of components (A), (B), and (C). The third composition is a composition containing 50% by weight or less of a liquid crystal compound component (D) having a clearing point of over 100°C; The above first or second composition is changed to 10% by weight or less. To explain each component in more detail, component (A) is a liquid crystal compound represented by the general formula () described above, and is usually a component having a low dielectric anisotropy of |△ε|<5. be. The content of component A is preferably 20 to 70% by weight, more preferably 40 to 60% by weight. It is preferable that component A is composed of a plurality of compounds, and the more preferable number of compounds is 3 to 8. Component (B) is a general formula or [In the formula, R ₃ is C _o H _2o+1 (n is an integer from 1 to 8),
C _o H _2o+1 O (n is an integer from 1 to 8), C _o H _2o+1
COO (n is an integer from 1 to 8), C _o H _2o+1 OCH ₂ (n
is an integer from 1 to 6), C _o H _2o+1 CO (n is an integer from 1 to 6)
) or C _o H _2o+1 OCH ₂ CH ₂ O (n is an integer from 1 to 6),

【ceremony

【formula】

[Formula] (tras-disubstituted cyclohexane ring) or

[Formula] (trans-di-substituted metadioxane ring),

【ceremony

[Formula] or

[Formula] Y is - COO−, −COS−, −CH=N−,

[Formula] −N=N−, −CH ₂ −CH ₂ −, or −CH ₂ O−,
Z is H, F, Cl, Br, I or -CN, R _{1 is} Co
H _2o+1 (n is an integer of 1 to 8). ] Consists of one or more compounds selected from the group of compounds having a cyano terminal group represented by the following. The content of component B is preferably 10 to 50% by weight, more preferably 15 to 40% by weight. Component (C) has the general formula or [In the formula, R ₄ and R ₅ are C _o H _2o+1 , C _o H _2o+1 O, _Co
H _2o+1 COO, C _o H _2o+1 OCO, C _o H _2o+1 OCH ₂ , C _o
H _2o+1 OCH ₂ CH ₂ O, F, Cl, or Br (n is 1
integer up to 8),

【ceremony

【formula】

[Formula] or

In [Formula], the two rings are the same or different rings, Y is -COO-, -COS-, -CH=N-,

[Formula] -N=N-, -CH ₂ -CH ₂ -, or -CH ₂ O-. ] Consists of one or more compounds selected from the group of compounds shown below. The preferred content of component C is 10 to 50% by weight, and the more preferred content is 15 to 40% by weight. Component (D) is the general formula or, [In the formula, R ₆ is C _o H _2o+1 , C _o H _2o+1 O, or _Co
H _2o+1 COO (n is an integer from 1 to 8), R ₇ is C _o
H _2o+1 , C _o H _2o+1 O, C _o H _2o+1 COO, −CN, F,
Cl, Br or (n is an integer from 1 to 8),

【ceremony

[Formula] or

[Formula], each ring is the same or different, X is a single bond or COO-, R ₈ is C _o H _2o+1 , C _o H _2o+1 O, -CN, F, Cl, Br, or, I, l, and m each represent 0 or 1. ] Consists of one or more compounds selected from the group of compounds shown below. The preferred content of component D is 30% by weight or less based on the total of components A, B, C and D. Component (E) is the general formula [In the formula, R ₉ is C _o H _2o+1 (n is an integer from 0 to 24),

【ceremony

[Formula] or

[Formula] p represents 0 or 1] This is a liquid crystal analog compound represented by the following formula. The liquid crystal composition of the present invention is characterized by steep voltage-luminance characteristics, excellent visual characteristics, and a significantly large number of time divisions. Therefore, by using the composition of the present invention, 1
Display devices for information terminals that can display multiple lines using LSIs, and TN-type liquid crystal displays that can display television images and have improved display density by enabling high time-division driving, which was previously considered difficult. can be provided. In other words, in the conventional voltage averaging method, it is said that the duty rate of 1/16 is the limit from the viewpoint of display quality. is at the same time
Previously, LSI had to be used for the number of rows, but by using the liquid crystal composition of the present invention, one
Multi-line display is possible with this LSI. The liquid crystal composition of the present invention can be manufactured by mixing predetermined amounts of each component.
It is preferable to create one. The steepness of the voltage-luminance characteristic is an important characteristic necessary for a liquid crystal when performing high time division driving of a liquid crystal display. This steepness is a factor that determines the display contrast and the number of time divisions. In the case of a simple matrix, scanning electrodes and signal electrodes are perpendicular to each other, and a liquid crystal material is sandwiched between the electrodes, and voltage is applied optimally using a voltage averaging method. If the effective voltage value at the selected point is V _po and the effective voltage value at the non-selected point is V _pff , it is expressed by the following equation. Here, b is the bias ratio, and N is the number of time divisions (number of scanning lines). V ₀ is the peak value of the applied voltage, and the condition for maximizing V _po /V _pff is b = √
It becomes N+1. At this time, V _po /V _pff =√N+1/√N−1. Here, V _pff is the voltage at which the light transmittance becomes 10% (V ₁₀ , 0°) [threshold voltage] when viewed from the vertical axis in the actual display panel, and V _po is the voltage at which the light transmittance when viewed from the vertical axis becomes 10% (threshold voltage). Voltage at which the transmittance of light becomes 50% (V ₅₀ , 0°)
Assuming [ON voltage], the parameter -α of the steepness of the voltage-luminance characteristic is as follows. Therefore, as the time division number N increases, α approaches 1. In other words, as α approaches 1, the voltage -
This indicates that the brightness characteristics are steep, and is an evaluation characteristic of materials that can display a large amount of information. Further, the maximum number of time divisions N _nax is obtained from α using the following equation. N _nax = (a ² +1/a ² -1) ² The larger N _nax indicates that higher time division is possible. Viewing angle characteristics are generally determined by the transmittance of light from an axis tilted 40° from the axis perpendicular to the LCD panel.
Let the voltage at 10% be V _10,40 °, and let β be the parameter indicating the viewing angle characteristic, and define it as shown in the following equation. β=V ₁₀ , 0°/V ₁₀ , 40° The closer this β is to 1, the better the viewing angle characteristics are. As a parameter for performing an evaluation that takes into account the steepness of the voltage-luminance characteristic and the viewing angle characteristic, γ is defined as shown in the following equation. γ=α×β The closer both α and β are to 1, the closer to the ideal state it is, and the closer γ is to 1, the better the characteristics of the liquid crystal composition. The composition of the present invention will be explained below using Examples and Comparative Examples. Examples 1 to 17, Comparative Examples 1 to 6 The components used in the Examples and Comparative Examples are as follows. The following was used as component A. The following was used as component B. As component C, the following was used. The following was used as component D. The following was used as component E. Each component was mixed in a predetermined amount as shown in the table to prepare a composition. Characteristic values of this were measured using a predetermined method. The results are shown in the table.

【table】

【table】

【table】

【table】

【table】

【table】

[Table] Examples 1 to 17 are compositions with a threshold voltage of 1.7 V or more that are used for applications with a time division number of 16 or more, but Table 4 shows compositions that have a threshold voltage of 1.7 V or more for use in applications where the number of time divisions is 16 or more. This shows that A) significantly improves the steepness.

Claims (1)

[Claims] 1. General formula (In the formula, R ₁ is C _o H _2o+1 , R ₂ is C _o H _2o+1 or C _o
10 to 80% by weight of a liquid crystal component (A) consisting of one or more compounds represented by H _2o+1 O and n is an integer of 1 to 8, and the general formula or (In the formula, R ₃ is C _o H _2o+1 , C _o H _2o+1 O, C _o H _2o+1 COO, C _n H _2n+1 OCH ₂ , C _n H _2n+1 CO, or C _n H _2n+1 OCH ₂ CH ₂ O, n represents an integer of 1 to 8, m represents an integer of 1 to 6, and [Formula] is [Formula] [Formula] (trans-disubstituted cyclohexane ring) , or [Formula] (trans-disubstituted metadioxane ring), [Formula] is [Formula] or [Formula], Y is -COO-, -COS-, -CH=N-, [Formula] -N =N-, _{-CH2CH2- ,} or _-CH2O- , Z is H, F, Cl, Br,
I or -CN, R ₁ represents C _o H _2o+1, respectively), and one selected from the group of highly dielectric anisotropic liquid crystal compounds where |△ε|≧5, or 10 to 60% by weight of component (B) consisting of two or more types, and the general formula (In the formula, R ₄ and R ₅ are C _o H _2o+1 , C _o H _2o+1 O, _Co
H _2o+1 COO, C _o H _2o+1 OCO, C _o H _2o+1 OCH ₂ , C _o
H _2o+1 OCH ₂ CH ₂ O, F, Cl, or Br;
[Formula] represents [Formula] (trans-disubstituted cyclohexane ring) or [Formula] (trans-disubstituted metadioxane ring),
These two rings may be the same or different rings, and Y is -COO-, -COS-, -CH=N-,
[Formula] -N=N-, -CH ₂ CH ₂ - or - CH ₂ O-, n is an integer from 1 to 8), and |△ε|<5 1. A liquid crystal composition comprising 10 to 80% by weight of component (C) consisting of one or more selected from the group of anisotropic liquid crystal compounds. 2 Claim 1 containing 50% by weight or less of a liquid crystal compound component (D) having a clearing point exceeding 100°C
Compositions as described in Section. 3 Component (D) is a general formula Or general formula (In the formula, R ₆ is C _o H _2o+1 , C _o H _2o+1 O, or _Co
H _2o+1 COO, R ₇ is C _o H _2o+1 . C _o H _2o+1 O, C _o
H2o ₊₁ represents COO, -CN, F, Cl, Br or respectively, n represents an integer from 1 to 8,
[Formula] is [Formula] or [Formula], each ring may be the same or different, and X is a single bond or -COO-
, R ₈ is C _o H _2o+1 , C _o H _2o+1 O, −CN, F,
The composition according to claim 2, comprising one or more compounds selected from the group of compounds represented by Cl, Br, or Cl, Br, or 1 and 0 or 1, respectively. 4 Component (B) as a general formula (In the formula, R ₉ represents C _o H _2o+1 , n represents an integer from 0 to 24, [formula] represents [formula] or [formula], and p represents 0 or 1, respectively). The composition according to any one of claims 1 to 3, which contains 10% by weight or less of component (E) consisting of at least one liquid crystal analog compound.