JPS58142965A - Liquid crystal composition - Google Patents

Abstract

PURPOSE:To provide a liquid crystal composition containing specific ester compounds and a chiral nematic liquid crystal at specific ratios, exhibiting quick response even at a low voltage, having broad temperature and voltage margins and high chemical stability, and suitable for a liquid crystal valve of a printer. CONSTITUTION:The objective composition is composed of (A) a mixture of ester compounds comprising 40-60wt% compound of formulaI(R and R' are 1-8C straight-chain alkyl), 0-20wt% compound of formula II, 0-20wt% compound of formula III, 5-20wt% compound of formula IV and 0-15wt% compound of formula V and (B) 0-5wt% chiral nematic liquid crystal. A liquid crystal panel suitable as a liquid crystal light valve for the optical ON-OFF control can be manufactured by inserting the liquid crystal composition between a pair of oppositely placed glass plates each having a NESA electrode at the inner side. The ON-OFF control can be carried out by applying a signal containing a component having higher frequency than the cross frequency (fc) of the liquid crystal material and a signal containing lower frequency component than fc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an optical 0N-0? by applying to a liquid crystal panel signals of wavenumber components lower than to and higher frequency components than f and o of the sandwiched liquid crystal material. This invention relates to liquid crystal light pulp that performs ν control. More specifically, the present invention relates to a liquid crystal light pulp in which the light response speed of the panel is significantly increased by using a new liquid crystal composition.

BACKGROUND ART In recent years, there has been rapid progress in increasing the capacity of information processing, increasing the speed of calculations, and popularizing office automation equipment. Printers, which are one of the terminal equipment for computer systems, are also required to be high speed, high print quality, and low price, but there is currently no product on the market that satisfies these requirements. , its appearance is strongly desired.

Printing device N (Japanese Unexamined Patent Publication No. 56-93568), which uses liquid crystal light pulp in the optical signal generating section and applies electrophotographic technology,
The above points have reached a practical level and are attracting attention.

First, FIG. 1 shows an outline of the configuration of the above-mentioned liquid crystal light pulp type printing apparatus. Optical writing is performed on the photosensitive drum 102 by an optical signal generating section 101 using liquid crystal light pulp. At this time, the photosensitive drum 102 is charged in advance by a four-way charger 110. At this time, when printing characters, the optical signal is usually such that light is generated corresponding to the character part. This forms an electrostatic latent image, which is developed with toner by a magnetic brush developer 9104S. The developing method at this time is usually reversal development. Thereafter, the toner is transferred onto plain paper 104 by a transfer corona discharge number 105 and fixed by a fixing device 106.

The toner remaining on the photosensitive drum after transfer is removed by the blade 108.
The charge is removed by the charge removal lamp 109, and the electrostatic latent image is removed by the charge removal lamp 109. Figure 2 shows the configuration of the optical signal generator, light source 2.
The light emitted from 01 is subjected to o m - o ]P-p control in the liquid crystal panel section (211 to 21B), and the transmitted light is imaged on the photoreceptor by the condensing lens 221. The LCD panel is
The seal 2 is sandwiched between two polarizing plates 211 and consists of a NESA electrode 213 formed on a glass plate 212 by coating by vapor deposition, sputtering, dipping, etc., and further formed by photoetching, and a metal thin film 216 used as an optical mask.
A liquid crystal 218 is held between the liquid crystal panel 17 and the liquid crystal panel.

The third w is a front view of the liquid crystal panel, which is composed of a micro-shutter 502 that transmits and blocks light, and a light mask section 501 that constantly blocks light.

Next, the driving principle of liquid crystal light pulp will be explained.

No. 411 shows signals applied to the liquid crystal panel and transmitted light characteristics. However, what is shown here is the case of dynamic driving. When a signal with a frequency component higher than fc is applied to the liquid crystal during the opening period te [Fig. 4 &)
], the panel transmits light, and then when a signal with a frequency component lower than fo is applied to the liquid crystal for a period of T, the panel blocks light (Fig. 4b)). T is the selection period, and the date in this case is T.

/ Ts. It is already known that the orientation state of liquid crystal molecules can be controlled by the frequency of the applied signal, so the details are omitted, but this phenomenon is that the sign of the dielectric anisotropy of the liquid crystal is reversed by the frequency of the applied signal. Based on nature.

FIG. 5 shows the frequency dependence of the dielectric constant Hz in the long axis direction and the dielectric constant C1 in the short axis direction of liquid crystal molecules.

We have explained the driving principle of the 0 or more liquid crystal light pulp in which the sign of the dielectric anisotropy Δε is reversed at the crossing frequency *to<ε◆ = frequency Wk above C). When used in the optical writing section of a copying device, in order to achieve high speed, high print quality, and even high reliability, many constraints must be met. 4T,), high light energy must be supplied onto the photosensitive drum.

In order to satisfy this requirement, it is possible to improve the characteristics to some extent depending on the details, the light source optical system around the panel, and the driving method, but it largely depends on the basic characteristics of the liquid crystal.

In order to realize an excellent liquid crystal light pulp, the following items are listed as basic characteristics required of a liquid crystal material.

t High-speed response with low voltage.

211 degrees, wide voltage margin.

5. High reliability can be ensured.

2. Liquid crystal materials for liquid crystal driving are used for displays, etc., and excellent products have been produced in the past.
1 milliJ seconds or less) has not yet been fully developed, and liquid crystal materials that satisfy all of the above-mentioned characteristics are not well known.

The present invention improves the characteristics of a liquid crystal material for liquid crystal light pulp used in printing devices, etc., and has the following objectives: 1. High-speed response at low voltage.

2. Wide temperature and voltage margins.

3. High reliability can be ensured.

The object of the present invention is to provide a liquid crystal material for dual-frequency driving that satisfies the above requirements in a well-balanced manner.

Below, we will explain these requirements.

t High-speed response with low voltage.

Xa is used in the drive circuit to reduce the size and cost of the finished product.
etc., the upper limits of drive voltage and drive frequency are constrained. Furthermore, since power consumption reduction is inversely proportional to the square root of the anisotropy, it is necessary to increase the absolute value of the dielectric anisotropy at the driving frequency in order to obtain a high-speed response. It is also required to have low viscosity. Furthermore, since the driving frequency cannot be made too high, the FO at the operating temperature must also be appropriately low.There is no liquid crystal material that satisfies these requirements with a single component, so a number of components are mixed to achieve a good balance of each characteristic. It will satisfy you. First, to.

Although the adjustment of viscosity, these two properties are contradictory to each other. Among the components in the composition provided by the present invention, R-■-000-〇-OR' R-罷-ooo- ◎-RI -ooo-ρ-RI N [However, R and R' represent straight-chain alkyl having 1 to 8 carbon atoms] Both f and viscosity of the composition are low to a practical level. It has the ability to

Next, a component that adjusts the dielectric anisotropy at low frequencies, and
It is a component that adjusts dielectric anisotropy at high frequencies, but there are many known liquid crystals or compounds with a molecular structure similar to liquid crystals that have a large absolute value of positive dielectric anisotropy. There are very few cases where the absolute value of dielectric anisotropy is large. Furthermore, in both cases, if constraints are imposed such as a small melting point, a wide liquid crystal temperature range, and not having adverse effects on fo, viscosity, etc., the types will be further limited. 0 Among the components of the composition provided by the present invention, RO-◎-000-◎-000-HE-OMI L, where R represents a straight-chain alkyl having 1 to 8 carbon atoms] is a positive It has very large dielectric anisotropy and low fo.

Furthermore, among the components of the composition, [wherein R represents a straight-chain alkyl having 1 to 8 carbon atoms] has a large absolute value of negative 1 anisotropy and is not compatible with other components. is also excellent.

Next, regarding the chiral nematic liquid crystal among the components of the composition provided by the present invention, in the case of a T1 display panel, this component is added in a small amount to prevent reverse tilt,
Many examples of using this component are known, such as using it for guest-host display to improve contrast, and display systems that apply the memory effect of liquid crystals to which the component is added. It is also well known that some devices improve response speed by utilizing the helical force of chiral nematic liquid crystal, that is, the force of returning to a helical structure.In the present invention, the reason for adding chiral nematic liquid crystal is that it In the 62w 1-wave drive method, which has the same effect as mentioned above, that is, the effect of improving response speed, driving is based on a signal having a higher frequency component than fO, that is, the liquid crystal molecules are aligned square to the cell surface. In some cases, it has the effect of particularly speeding up the process.

The inventors of the present invention have determined that by blending the above-mentioned components in appropriate proportions, the absolute values of Δ8L and ΔM (in particular, in the conventional composition, increasing the absolute value of 6gm takes into consideration the balance with other properties). By adding chiral nematic liquid crystal, we were able to dramatically increase the response speed at operating temperatures and voltages.

In the case of liquid crystal compositions, it is expected that the interaction between different components, rather than a single component, will have a considerable influence on the viscosity, fo, and ultimately the response speed. It seems that this is working towards improving the properties of the material, and I look forward to future research on the physical or quantum mechanical interpretation of this point.

The above is the reason why the components according to the present invention were used to satisfy characteristic 1.

2. Wide temperature and voltage margins.

First, regarding the temperature margin, Figure 6 shows the temperature dependence of the dielectric anisotropy of the liquid crystal. This is the dielectric anisotropy at 6gg.
Although Δ01 increases rapidly as the temperature rises, it is a basic characteristic of liquid crystals, so in actual use, a humidity range with a small change in Δ01 is selected. When extremely high speed is required, it is necessary to lower the viscosity of the liquid crystal in a certain high temperature range. Based on the undeniable fact that Δ11 fluctuates quite a bit due to temperature envy, and in order to maintain a wide temperature margin, it is necessary to adopt a range in which the light transmission characteristics of the liquid crystal are saturated. becomes. That is, under a constant voltage, the response is fast and the light transmission curve is saturated, and it is a prerequisite that the above-mentioned characteristic 1 is satisfied. The voltage margin can also be considered in the same way.

5. High reliability can be ensured.

Many studies and experiments have been conducted on the chemical-optical or electrochemical addressability of liquid crystals.Since the liquid crystals according to the present invention are all ester-based liquid crystals, they have high optical reliability and Due to aging and other factors, the reliability has been evaluated as being at a sufficient practical level.

In order to meet the above-mentioned properties 1 and 2.3 in a well-balanced manner and at a practical level, the present invention has developed a liquid crystal material with excellent properties as a composition by appropriately selecting the blending ratio of each of the above-mentioned components. I was able to create. That is, the composition is as shown in Table 1.

[However, in the above table, R, B / represents a linear alkyl having 1 to 8 carbon atoms.] Table 1 Next, the details of the present invention will be explained with reference to examples.

EXAMPLE The liquid crystal compositions listed in Table 2 were prepared and their basic properties and light transmission properties were investigated.

Table 2 [However, the book in the table is 0. has the structure HHHHHHHH + 1 1 11 1 1 - O-0-0-0-0-0-0'-H+111111 HH-0-HHHHHH] Figure 7 shows the dielectric properties of the liquid crystal compositions shown in Table 2. shows the frequency dependence of the rate. However, the measurement temperature was 30°C.

This liquid crystal was sealed in a test cell with a cell thickness of 5μ, and a paper waste wave signal (30V, IKH), a high frequency signal (50'TI) was
, 150KHm), the repetition period is 15, as shown in Figure 8, which shows the light transmission characteristics.
Repeated responses are possible with ~2 tests and an opening time of α4 to α5@m. However, the rubbing angle of the cell used at this time was 7
0°, and the polarization directions of the polarizing plates sandwiching the cell were set at right angles to each other. The measured concentration was 40°C.

Next, a printing experiment was conducted using this liquid crystal light pulp. The same liquid crystal cell as in the above measurement was used, and the iron-driving properties were also the same. The light source has the structural formula 0@Mgmu4tOt@
: A high-intensity fluorescent lamp using a T ba phosphor is used as the photoreceptor! Be sensitized with ・was used. The parts are arranged as shown in Figure 1, and the surface movement speed of the photosensitive drum is 5.
cll/1111c. When I drove the liquid crystal light pulp and performed optical writing, the 0N-01FI
Corresponding to F, a clear image could be formed. The present embodiment is an example of the use of the liquid crystal light pulp provided by the present invention, and is applicable to optical writing devices other than printing devices, displays, etc.

Furthermore, the liquid crystal composition used in this example is an example, and even if each component is replaced with a homolog of the component, the blending ratio may be within the range of the blending ratio in the table described in the claims. The present invention is not limited to this example, as the present inventor has already conducted experiments to find that excellent characteristics similar to those of this example can be achieved even if the values are changed.

As mentioned above, the present invention utilizes the dielectric dispersion of liquid crystal,
In liquid crystal light pulp driven by 2Ml wave drive and high-speed switching, we have succeeded in improving the responsiveness of the liquid crystal material, and in practical use, we have dramatically improved the writing speed, humidity, voltage margin, etc. of printing devices. The effect of the present invention is significant.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of a liquid crystal light pulp printing apparatus. FIG. 2 is a schematic diagram of liquid crystal light pulp. FIG. 5 is a top view of a liquid crystal panel used for liquid crystal light pulp. FIG. 4 shows the signals applied to the liquid crystal light pulp and the photoresponse characteristics at that time. FIG. 5 shows the frequency characteristics of the dielectric constant of liquid crystal. The sixth WJ is the temperature characteristic of dielectric anisotropy of liquid crystal. FIG. 7 shows the frequency characteristics of the dielectric constant of the liquid crystal composition used in this example. FIG. 8 shows the optical path and other characteristics of the liquid crystal light pulp according to this example. Agent Patent Attorney Mogami ・Re1 Figure 1 Figure 2 Figure 311 Figure 4 Figure 5 Figure 6 Figure 7 1111 Hours (LA6) 00 Figure 8

Claims (1)

[Claims] A liquid crystal panel in which two glass plates having NESA electrodes on the inside are placed facing each other and a liquid crystal material is sandwiched between them is provided with a liquid crystal panel having a frequency higher than that of the crossed debris wave (hereinafter abbreviated as FO) of the liquid crystal material. In a liquid crystal light modulator that controls the intensity of transmitted light by applying a signal having a component and a signal having a frequency & that is lower than fo singly or in a superimposed manner, the liquid crystal material has the following composition: A liquid crystal composition comprising: [However, in the above table, R and R' represent straight chain alkyl having 1 to 8 carbon atoms]