JPS6013883A - Liquid crystal composition and liquid crystal display - Google Patents

Abstract

PURPOSE:To obtain a liquid crystal composition suitable for the time-sharing driving with low driving voltage, and giving high contrast without using a yellow filter, by using a cyclohexanecarboxylic acid ester liquid crystal of a specific formula and an acyloxy-containing ester liquid crystal of a specific formula as the base components. CONSTITUTION:The objective liquid crystal composition contains (A) the compound of formula I (R1 is 2-6C straight-chain alkyl; R2 is 1-6C straight-chain alkyl; the sum of the C atoms of R1 and R2 is preferably 8-10), the compound of formula II (R3 is 3-6C straight-chain alkyl; R4 is 1-5C straight-chain alkyl), the compound of formula III (R5 is 2-8C straight-chain alkyl) and/or the compound of formula IV (R9 is 2-8C straight-chain alkyl) and if necessary (B) the compound of formula V (R6 is 2-4C straight-chain alkyl) and/or the compound of formula VI (R7 is 3-5C straight-chain alkyl; R8 is 2-7C straight- chain alkyl). A liquid crystal display device drivable by time-sharing driving with a driving voltage of <=10V and a duty ratio of <=1/32 can be produced by using the above liquid crystal composition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nematic liquid crystal composition that exhibits positive dielectric anisotropy and has no absorption in visible light. 0 [Prior art] TN-type liquid crystal mixture based on a nematic liquid crystal mixture having excellent time-sharing characteristics capable of sufficiently performing time-sharing driving up to a duty ratio of at least 1/32 at a driving voltage of 10 V or less Static drive and time-division drive are known as methods for driving liquid crystal display devices, but time-division drive can reduce the number of lead extractions, so it can: simplify the structure of the liquid crystal cell, and simplify the output of the liquid crystal cell and drive circuit. This is advantageous in terms of reduction in the number of parts connected to other parts, and (2) simplification of the drive circuit. Furthermore, if an attempt is made to display an even larger capacity, the number of read outputs will further increase, which will require time-divisional driving with a small duty ratio.

However, when time-division driving is performed, there is a problem in that the driving voltage is limited due to the relationship with the liquid crystal.

For example, if the selected waveform of the time division drive waveform is shown in Fig. 1 (α),
The half-selection waveform is shown in FIG. 1 (6), and FIG. 2 shows the relationship between the voltage of the liquid crystal cell and the light transmittance corresponding to this waveform. However, in Figure 2, graphs 1 and 2 indicate the angle (viewing angle) between the liquid crystal cell and the viewing direction when the selection waveform (α) and half-selection waveform (&) are applied to the liquid crystal cell, respectively. The relationship between voltage and light transmittance when the angle is 80 degrees and 50 degrees is shown. Furthermore, vth-1 and Vth-2 indicate threshold voltages at light transmittances of 30% and 80%, respectively. At this time, the driving voltage width Vd that allows time-division driving to be performed with practically sufficient display contrast and viewing angle range is vth-+≦Vd<Vth-2.

On the other hand, the drive voltage fluctuates due to changes in battery voltage over time or variations in the circuit, etc. Therefore, as a measure to allow fluctuations in the drive voltage, the voltage margin (M) is determined as shown in the following formula, where Va is the drive voltage. Vc = -((vth-2)-1-(vth-1))0 can express the suitability for time-division driving of liquid crystals.However, generally speaking, the smaller the duty ratio, the smaller the selection waveform and half-selection waveform. Since the effective voltage ratio becomes smaller, V
The difference between th-,1 and Vth-2 decreases and merges:/:
(M) also decreases. Furthermore, if the duty ratio is further reduced, Vth-1) Vth-2, ka'') M<0, and time-division driving at this duty ratio becomes practically impossible.

Therefore, in order to display a large capacity with high quality, a liquid crystal that can perform time-division driving with a smaller duty ratio and a wider voltage margin is required.

From this point of view, conventionally, mixed liquid crystals mainly composed of azoxy liquid crystals have been used. However, azoxy liquid crystal deteriorates when exposed to visible light, so a yellow filter was used to block out harmful light.For this reason, the display color was limited to yellow, and various color displays were not possible. 〇-As non-azoxy liquid crystals that do not require color filters, mixed liquid crystals mainly composed of the following are known.

R-◎-〇-〇N )-〇-ON R-◎-coo-◎-0N RO-◎-COO-◎-R Ryo-coo-0-68 R-◇-◎-〇N However, R indicates a straight-chain alkyl group 0 However, in a mixed liquid crystal that combines these liquid crystals, time-division driving with a duty ratio smaller than 1/16 results in a negative margin, and it is necessary to perform time-division driving with a duty ratio smaller than 1/16. [Objective of the Invention] The object of the present invention is to provide an excellent method capable of practically sufficient time-division driving with a data ratio of up to 1/32 at low voltage. Another object of the present invention is to provide a liquid crystal composition having time-division characteristics.Another object of the present invention is to provide a liquid crystal display device capable of displaying a large capacity with high quality using such a liquid crystal composition.

Still another object of the present invention is to provide a bay crystal display device using such a liquid crystal composition, which requires less burden on the driving circuit. Still another object of the present invention is to provide a bay crystal display device that uses such a liquid crystal composition and which requires less burden on the drive circuit. To provide a liquid crystal composition for a display device that is easy to read and has a wide viewing angle range. In view of the above objectives, the present inventor has conducted various studies and studies and has found a liquid crystal composition that satisfies all of the above objectives. be. That is, the present invention has the general formula % (2) (4) where R1 is a linear alkyl group having 2 to 6 carbon atoms R2 1
~6 R3 3-6 R number 1-5 R5 2-8 R6 2-4 R7 3-5 R8 2-7 R9 is a straight chain alkyl having 2 to 8 carbon atoms Compounds of each group represented by (i), (3), (3), (4
), (5), 5(6) in a suitable combination.

Compounds (1), (2), (3) used in the present invention
), (4), (5), and (6) are all stable, and unlike azoxy liquid crystals, they do not absorb in the visible light range, so they do not require a yellow filter to prevent photodeterioration. Therefore, it not only enables bright display but also has the excellent advantage of being applicable to various color displays. In the present invention, compound (1) mainly improves the viewing angle range of a liquid crystal display device using such a liquid crystal composition. It has the effect of expanding
This has the effect of making crosstalk less likely to occur on the low viewing angle side in time-division driving.

In particular, when the concentration of the component of compound (1) in which the sum of the carbon numbers of R1 and R2 is 8 to 10 is increased, the above-mentioned effects are further increased.

Furthermore, compound (2) mainly has the effect of improving contrast at a constant viewing angle in time-division driving.

Moreover, compound (3) has the effect of lowering the driving voltage◇Compound (6) may be used instead of compound (3). Compared to compound (6), compound (3) has the effect of widening the viewing angle range and making crosstalk less likely to occur, in addition to these effects, similar to compound (1).

Compounds (4) and (5) raise the clearing point of the liquid crystal and have the following formula: % Formula % However, R represents a straight-chain alkyl group.

The liquid crystal shown in this figure has the effect of improving comparative contrast and widening the viewing angle range.

Compound (6) can be used in place of compound (3), and has the effect of lowering driving voltage 1 and increasing contrast.

The liquid crystal composition of the present invention comprises the above compounds (1), (2)
, (3) αnd10r(6), respectively, and as an example to be described later using Table 2, compound (4) and/o for clearing point adjustment.
r (5) was added and shown.

Table 1-1 Table 1-2 Table 1-3 Examples Table 2 shows examples in which the liquid crystal compositions of the present invention were constructed using the compounds shown in Table 1.

Table 2-2 In Table 2, the circle mark indicates that no crystallization was observed even after the cell containing the composition of the present invention was left at -60°C for 4 days. '7th-1゜Vth-2,M, the response time is v - ((-z) v (When driving the liquid crystal in a time-division manner with a duty ratio of 1/N (N is a positive integer), the non-selection period and the selection period The ratio of the voltage applied to the liquid crystal is 1: (JT
+1) drive method).

This figure shows the characteristics when driven with a waveform with a data ratio of 1/32. In any of the examples, practically sufficient display contrast and viewing angle range were obtained.Compounds 1 to 0 in Table 2 are the same compounds as in Table 1. Hereinafter, in Examples 0 to explain Examples in detail, 1 is a component in which the sum of carbon numbers of R1 and R2 is 8 or more in compound (1) (58.0% of the total) and compound (2) (total 2
8. This is a liquid crystal composition based on a compound (3) with positive dielectric anisotropy and a compound (4) that increases the clearing point.The voltage exceeds 10'V, but the margin M is the best at 4.5%, and time-division driving with a duty ratio of 1/48 is also possible. When the definite crystal composition of Example 1 is driven at a duty ratio of 1/48, vth-+ is 1268
V, vth-2 is 12.89 V, and the margin M is 16%.

Compounds (4) and (5) are added to adjust the clearing point, and the clearing point can also be adjusted by adding a compound such as terphenyl, but compounds (4) and
lor (5) has other effects of increasing the contrast and widening the viewing angle range.

Examples 2 and 5 have almost the same composition as Example 1, but the concentration of compound (3) is 17.0% in Examples 2 and 3, compared to 10.5% in Example 1. is increasing. As a result, the driving voltage is approximately 8 V, which is lower in Examples 2 and 5 than in Example 1. On the other hand, the response speed of Example 1 is faster. In addition, compound (4) s added for clearing point adjustment.
(5) is 3.5% in Example 1 and 10.5% in Example 2.
0%, and Example 6 contains compound (5) in addition to compound (4), making the total amount 16.0%, which is more mixed than Examples 1 to 6. As a result, the clearing point was 55% in Example 1. .0%
, 58.0% in Example 2, 60.0% in Example 3
It can be seen that the clearing point is high.

The fourth embodiment also has a positive margin of 1.5% at a drive duty ratio of 1/32. By comparing Example 4 with Example 2, it is possible to understand the effect of the margin M (C) of the component in which the sum of the carbon numbers of R1 and R2 is 8 or more on compound (1). Comparing with Example 2, the compositions of compounds (2) to (4) are the same, and compound (1)
Both are 51. Same Owt%, but compound (1)
have different compositions. In Example 4, the linear alkyl groups R1 and R
Compound (1) has a total of 8 to 10 carbon atoms, accounting for 51.0 wt% of the total, whereas in Example 2, compound (1) accounts for 51.0 wt% of the total. .0 vv
t%, but those in which the sum of the carbon numbers of R1 and R2 is 8 to 10 account for only 34 Owt% of the total. Therefore, the driving voltage of the fourth embodiment is lower than that of the second embodiment, and the response speed of the fourth embodiment is also faster than that of the second embodiment. On the other hand, when looking at the drive margin MK, the drive margin M of the second embodiment is larger, being 15% in the fourth embodiment and 2.4% in the fourth embodiment.

Example 5 is a composition in which compound (3) in Example 4 is replaced with ester (6)K having a cyano group.The driving margin M takes a positive value of 1.0%, and even under such pressure, It can be seen that a liquid crystal composition for high duty use can be constructed. However, as is clear from comparing Example 5 with Example 4, Example 5 has a higher clearing point and faster response speed than Example 4, but on the other hand, the drive margin is lower. M
Regarding this, Example 4 is 15% while Example 5 is 1.0%, and the margin M of Example 4 is higher than that of Example 5.
bigger. In addition, when compounds (3) and (6) are mixed together, when the amount of compound (3) is smaller than (6), the properties are close to those of Example 5 and are intermediate between Examples 4 and 5.
It is obvious that when the amount of compound (6) is less than that of (3), it exhibits characteristics that are close to Example 4 and intermediate between Examples 4 and 5, and when it is half and half, it exhibits characteristics that are approximately intermediate between Examples 4 and 5. It is.

Furthermore, in Examples 4 and 5, compounds (4) and (5) were exchanged, but as mentioned above, compounds (4) and (
5) both exhibit almost the same effects, and there is almost no change in the effects due to this.

Examples 1 to 5 of the liquid crystal compositions of the present invention each contain at least one component of compounds (1) and (2). By including one component, it is possible to obtain a positive margin with driving at a duty ratio of 1/32. Furthermore, as shown in Examples 1 to 5, the liquid crystal composition of the present invention does not crystallize at low temperatures and has a high clearing point temperature, so it can be used in a wide temperature range and has no practical problems. These effects were obtained by containing at least one component of compounds (1) and (2) each in the liquid crystal composition of the present invention, as shown in Examples 1 to 5.

The liquid crystal compositions of Examples 1 to 4 were obtained by adding compounds (3) and (4) αnd10 r (5) to the liquid crystal compositions of the present invention containing at least one component of compounds (1) and (2), respectively. By containing at least one component, the driving margin M is made larger than that of the rod.

It is also possible to construct a liquid crystal composition with a small duty ratio by using compound (6) instead of compound (3) as in Example 5. However, as in Example 1, compound (6) can be used instead of compound (6). 3) can also be used to construct a liquid crystal composition with a small duty ratio. Examples 1 to 4 constructed in this way
The liquid crystal compositions have a larger drive margin M than the liquid crystal composition of Example 5.

From this, it can be seen that the drive margin is increased by including compound (3).

Further, the liquid crystal compositions of Examples 1 to 5 mainly contained compound (1), and further contained linear alkyl group R in compound (1).
It contains many compounds in which the sum of the carbon numbers of 1 and R2 is 8 to 10. In addition, as shown in Table 2, compounds (1) in which the sum of the carbon numbers of linear alkyl groups R1 and R2 occupying the entire liquid crystal composition are 8 to 10 (in Table 2, compound (1)
, ■, ■, 0) in Example 1 is 5 B, Owt
%・Example 2 was 151. Owt% Example 3 is 45.
Owt%・Examples 4 and 5 (34.0 wt%, Example 5 and 4s !1t 2 t') Compounds in which the sum of the carbon numbers of linear alkyl groups R1 and R7 is 8 to 10 (1 )
The proportion of the liquid crystal composition in the entire liquid crystal composition increases, and Example s
, 4, 3, 2, 1. The Vc drive margin M is large. Here, the drive margin M is made larger than in Example 5 by using the compound (3) instead of the metal material (6) in Example 4 & Mahihi. Moreover, the liquid crystal composition of Example 1 is
The drive margin M4 is the largest among the 5, and is large, not only with 1/32 duty drive but also with 1/48 duty drive. It takes a positive value and can be driven. These & good hardware (1).

(2+ , (3) , (4), (5) , (6
) by appropriately adjusting the ratio of
This shows that it is possible to construct a liquid crystal composition that can obtain a large value of O.Also, in all Examples 1 to 5 of the liquid crystal compositions shown in Table 2, the ``Deity ratio η32'' and the drive margin M are positive, and the ``Deity ratio η'' is positive. The type of liquid and crystalline paraboloid to be used, which can be used in applications with a small size, is determined experimentally and theoretically from Examples 1 to 5, depending on the size of the drive margin, drive voltage, and liquid crystal material. From the overall point of view of cost etc.
It is better to compare the advantages and disadvantages and use a type of liquid crystal composition suitable for each application.

In addition, when the liquid crystal 1 composition of the present invention shown in Examples 1 to 5 is driven at a duty ratio of 1/62,
The response interval at 5°C is on the order of 10.0g5c, which has the advantage that there is no problem in practical use in terms of response speed.Also, even when driven at a duty ratio of 1/62, the driving voltage is i' Low, near ov. Lowering the voltage is not only advantageous in simplifying the power supply and downsizing the device;
It is also very advantageous in manufacturing integrated circuits for driving. Integrated circuits are generally manufactured using 0-MOS from the viewpoint of ease of manufacturing and low power consumption, but manufacturing becomes extremely difficult as the driving voltage increases. Since the liquid crystal composition of the present invention does not require a particularly high drive voltage, it is easy to manufacture a 0-MOS drive circuit, and has advantages in terms of the 0-MOS drive circuit, which has a high yield and is low in cost.

As explained above, the liquid crystal display device using the liquid crystal composition according to the present invention has a duty ratio of 1/32 at low voltage,
In addition, it has excellent time division characteristics that allow practical time division driving up to 1/48, so not only can large capacity displays be performed with high quality, but it also does not require a yellow filter. It has advantages such as bright display and color display, and has great practical value.0

[Brief explanation of the drawing]

FIG. 1 shows an example of a time-division driving waveform, in which (α) shows a selection waveform and (e) shows a half-selection waveform. Figure 2 is a diagram for explaining the relationship between voltage and light transmittance.

Claims (1)

[Claims] 1) Each group of metal compounds (1), (21, (3) represented by the general formula % formula % (1) (2) (6)
A liquid crystal composition 0 characterized by containing at least one of each of and/or (6>). However, R1 is a straight chain alkyl group having 2 to 6 carbon atoms. R2 is a straight chain alkyl group having 1 to 6 carbon atoms. R8 is carbon. Number 3 to 6 R4 is a straight chain alkyl group having 1 to 5 carbon atoms R0 is a straight chain alkyl group having 2 to 8 carbon atoms 2) Compound (1) is the sum of the carbon numbers of straight chain alkyl groups R1 and R2 The liquid crystal composition according to claim 1, characterized in that the main component is a compound having 8 to 10. 3) Compounds of each group represented by the general formula % formula % (4) a% d / or
A liquid crystal composition according to claims 1 and 2, characterized in that it contains at least one component of (5). However, Ro is a straight chain alkyl group having 2 to 4-1 carbon atoms. R7 is a straight chain alkyl group having 3 to 5 carbon atoms. R8 is 2 to 7 carbon atoms. 4) Using the liquid crystal composition described in claims 1 to 3. However, when the driving voltage is approximately 10V or less, the duty ratio is approximately 1/3.
A liquid crystal display device characterized in that it is time-divisionally driven up to 2 times. 5) Compound (3) atLd/or (6),
Using the liquid crystal composition according to claims 1 to 3 using compound (3), the data-ty ratio is about 1/32 to 1.
Liquid crystal display device 0 characterized by time-division driving up to /48