JPS6157934A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To obtain a liquid crystal element small in hysteretic effect of liquid crystal for high frequency and suitable for two-frequency driving by using a liquid crystal composition having an absolute value of dielectric constant smaller at high frequency than at low frequency. CONSTITUTION:As the result of examining shutter characteristics by using a liquid crystal element prepared by mixing a compound that forms the base of the liquid crystal composition, a compound that gives dielectric characteristic, a compound for adjusting viscosity and a compound that lowers the whole dielectric characteristics to the negative side, a liquid crystal element of ¦rho@@@@@@@@@$000''xsirhoBETA@@@@@@@dispersion phenomenon of smaller value of ¦DELTAepsilon¦ at high frequency was obtained. DELTAepsilonH¦>2.0 at high frequency and epsilonL>3.5 at low frequency and shows dielectric dispersion phenomenon of smaller value of ¦DELTAepsilon¦ at high frequency was obtained. Greater values of ¦DELTAepsilonL¦/¦epsilonH¦ are desirable to make hysteretic effects for high frequency small. However, if this value is too large, the viscosity of liquid crystal composition becomes too high for practical use. Therefore, it is desirable to make the value of ¦epsilonL¦/¦DELTAepsilonH¦ within the range of 1.2-5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a liquid crystal element suitable for two-frequency driving.

[Technical background of the invention]

Recently, liquid crystal elements have been used for image display on television receivers and computer displays, and for optical writing in optical writing printers used as computer terminals and office equipment. There is.

The liquid crystal element used for image display, optical writing, etc. has minute shutter sections arranged at close intervals to control the transmission of light. It is constructed by forming transparent electrodes on a transparent substrate so as to face each other.

The liquid crystal element used for the image display and the like is normally driven by selectively applying a voltage equal to or higher than the threshold voltage of the electro-optic effect and a voltage lower than the threshold voltage to the shutter section.

However, in such a driving method, for example, in the case of a liquid crystal element using a liquid crystal composition with positive dielectric anisotropy, liquid crystal molecules are aligned perpendicularly to the substrate by applying a voltage higher than the threshold value. Sometimes, the applied voltage causes the liquid crystal molecules to behave immediately, but when the liquid crystal molecules are aligned parallel to the substrate by applying a voltage lower than the threshold, the liquid crystal molecules move between the liquid crystal composition and the alignment film of the substrate. Since the liquid crystal molecules are aligned only by the alignment regulating force acting on them, the behavior of the liquid crystal molecules is slow, so there is a problem that the shutter section cannot be driven to open and close at high speed.

Therefore, if it is necessary to drive multiple shutter sections at high speed and with high contrast,
A two-frequency drive method that utilizes the dielectric dispersion phenomenon of liquid crystal is employed.

In this two-frequency driving method, when a high frequency electric field is applied to the liquid crystal, the liquid crystal molecules try to align perpendicular to the electric field, and when a low frequency electric field is applied, the liquid crystal molecules try to align parallel to the electric field. The TN type (twisted nematic type, in which the polarizing axes of the polarizing plates are arranged perpendicular to each other) liquid crystal element with a positive display using this driving method uses the phenomenon that the shutter part opens ( When a low frequency is applied, the shutter closes (opaque), and in the case of a GH type (guest-host) liquid crystal element, when a high frequency is applied, the shutter closes (opaque).
Coloring), the shutter opens when low frequency is applied (light transmission...
(uncolored).

1 [Problems in the Background Art] However, when driving a liquid crystal element with two frequencies, a high frequency (100 KHz or more) and a low frequency are applied to the liquid crystal, but if the high frequency is applied for a long time, the next low frequency There is a problem that the responsiveness of the liquid crystal to the application of is deteriorated.

This is due to the hysteresis effect of the liquid crystal, and the hysteresis effect of the liquid crystal is particularly large for high frequencies, so the longer the high frequency is applied, the stronger the influence of the high frequency remains, and even when the next low frequency is applied. This is because the liquid crystal immediately stops responding.

In other words, when driving a liquid crystal element with two frequencies, the liquid crystal
By applying high and low frequencies, the liquid crystal molecules behave so as to be aligned parallel and perpendicular to the substrate, but in this case, the liquid crystal molecules are not aligned completely parallel and perpendicular to the substrate, but to some extent. It behaves in the range of angles. However, when the high frequency is applied for a long time, the applied electric field accumulates and acts on the liquid crystal, causing the liquid crystal molecules to be strongly aligned parallel to the substrate. Therefore, even when the next low frequency is applied, the liquid crystal molecules immediately become unable to stand up.

For this reason, when a conventional liquid crystal element is driven at two frequencies, in the case of a positive display TN type liquid crystal element, the operation when the shutter section switches from the open state to the closed state becomes slow, and the G
In the case of an H-type liquid crystal element, the operation of the shutter section when switching from the closed state to the open state is delayed, and for this reason, for example, in an optical writing printer, the light on the photosensitive drum is not irradiated. When a liquid crystal element used as an optical writing element is driven at two frequencies using a development-type electrophotographic process in which toner is attached to a certain area, in the case of a TN type liquid crystal element, the printing pixels are affected by the delay in the shutter closing operation. The beginning of the page is blurred or not printed,
In the case of a GH type liquid crystal element, the end portion of the printed pixel becomes trailing due to the delay in the opening operation of the shutter section.

This phenomenon occurs when the liquid crystal element is time-divisionally driven at two frequencies, in which the shutter portion formed by the facing portion of the electrode formed on one substrate and the electrode formed on the other substrate is arranged in a matrix. It appears more prominently because the applied electric field has more high-frequency components.

(Purpose of the Invention) This invention is an attempt to solve the above-mentioned problems, and its purpose is that even if a high frequency is applied for a relatively long time, the next application of a low frequency will immediately cause the liquid crystal to display. It is an object of the present invention to provide a liquid crystal element suitable for two-frequency driving, which can cause molecules to rise and open and close a shutter section with good responsiveness and at high speed.

(Summary of the Invention) That is, the present invention uses a liquid crystal composition exhibiting a dielectric dispersion phenomenon in which the value of |Δε| at high frequencies is smaller than the value of |Δε| at low frequencies. This prevents the hysteresis effect of the liquid crystal from appearing to a large extent with respect to high frequencies.

To explain the liquid crystal composition used in this invention, FIG. 1 shows the frequency f (KH
This liquid crystal composition for two-frequency driving has a frequency ft- in the low frequency vA range showing a constant Δε, and a frequency f in the high frequency range fH fL=fc/10 f+-+ =10-fc (fc is the crossing frequency where Δε crosses O, 100KH
z or less) is ΔεL>3.5 1ΔεH1>2.0, and the ratio of 1ΔεLl and 1ΔεH1 is 1Δε
It shows the dielectric dispersion phenomenon where t, l/lΔεH1>1.0.

This liquid crystal composition has a small hysteresis effect at high frequencies,
Moreover, the rising and falling time of liquid crystal molecules is very short, 0.5 msec or less, and the responsiveness is excellent.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings, taking as an example a liquid crystal element used for optical writing in an optical writing printer.

First, let me explain the configuration of an optical writing printer.
In FIG. 2, 1 is a photoconductive photosensitive drum, 2 is a charger that uniformly charges the surface of the photosensitive drum 1, and 3 is an optical recording section that performs optical writing on the charged surface of the photosensitive drum 1. The optical recording unit 3 is driven by a recording system (IlaI 14) that controls timing and the like based on recorded information such as images, and irradiates the surface of the photosensitive drum 1 with light to erase charges on the light-irradiated portion of the photosensitive drum surface. By doing so, optical writing is performed.

The electrostatic latent image formed on the surface of the photosensitive drum by optical writing in the optical recording section 3 is developed with toner by the developing device 5 .

Further, the recording paper 6 is fed by a string feeding roll 7,
After being temporarily stopped by a standby roll 8, the toner image on the surface of the photosensitive drum is sent to a transfer section 9 in synchronization with the toner image on the surface of the photosensitive drum, and the toner image on the surface of the photosensitive drum is transferred onto the paper 6 at the transfer section 9. Ru. This paper 6 is separated by a separation unit 10
The toner is separated from the photosensitive drum 1 at , the toner acid is fixed in a fixing device 11 , and then sent out by a paper discharge roller 12 .

Note that the photosensitive drum 1 having the toner image transferred to the paper 6 is subjected to a snow remover 13 to neutralize the toner charge, and then to a cleaner 1.
4, residual toner is cleaned, and surface charges are neutralized by an eraser 15.

As shown in FIG. 3, the optical recording section 3 includes a light source 16,
It consists of a liquid crystal element 20 for optical writing and an imaging lens 17, and the light from the light source 16 is irradiated onto the surface of the photosensitive drum via the liquid crystal element 20 and the imaging lens 17.

The liquid crystal element 20 is horizontally elongated along the axial direction of the photosensitive drum 1, so the liquid crystal element 20 has a large number of minute shutter parts arranged at close intervals along its length to control the transmission of light. It was formed by

That is, FIGS. 4 to 9 show the liquid crystal element 20, and here a GH type liquid crystal element is shown.

To explain the structure of this liquid crystal element 20, 21°22
are a pair of upper and lower transparent substrates made of glass plates with a thickness of about Q and 7 mm, and the pair of transparent substrates 21 and 22 are connected to an outer sealing material 23 in the shape of an oblong frame as shown in FIGS. 5 and 8.
a and 2II for both sides of the outer sealing material 23a.
A pair of inner sealing members 23b parallel to each other are formed on the inner side with an interval d of about In1.

23b.

The distance e between this pair of inner sealing materials 23b, 23b
is approximately 1 ma+, and this inner sealing material 23b.

For example, the length of the narrow gap between 23b is 249+++ in the case of a liquid crystal element for a printer that records on paper with a maximum of 84 plates.
It is said to be m. Moreover, the inner sealing material 23b.

Both ends of the outer sealing material 23a are connected to both sides of the outer sealing material 23a, and a space 30 is formed between the inner sealing materials 23b, 23b between the substrates 21 and 22, and the portion surrounded by the both sides of the outer sealing material 23a. It is said to be .30. In addition, in FIG. 5, 31.31 is a pair of substrates 21.
, 22 is an air hole for letting the air between the substrates 21 and 22 escape to the outside when polymerizing and bonding the substrates 21 and 22.
．． 31 is sealed with a sealing material 32.32 applied after the substrate 21.22 is twisted. Therefore, the space 30.
30 is filled with air (clean air) left behind when the substrates 2.1.22 are bonded.

Further, both ends of the narrow gap between the inner sealing materials 23b and 23b are communicated with wide gaps at both ends surrounded by the outer sealing material 23a, and the narrow gap and the wide gap between the substrates 21 and 22 are connected to each other. The gap is filled with a liquid crystal composition 24 containing a dichroic dye. Note that 33 is a liquid crystal injection hole provided at one end of the outer sealing material 23a, and this liquid crystal injection hole 33 allows air between the substrates 21. The liquid crystal injection hole 33 also serves as an air hole for the liquid crystal to escape, and after the liquid crystal composition 24 is injected (injected using a vacuum injection method), the liquid crystal injection hole 33 is sealed by applying a sealing material 34 four times. .

Further, one of the pair of substrates 21 and 22 is
1 (hereinafter referred to as the segment substrate), as shown in FIGS. 5 and 7, the inner sealing material 23b,
In the narrow gap between the electrodes 23b, a large number of segment electrodes 81, 81, .

82, 32,... are arranged in two rows,
On the inner surface of the other board 22 (hereinafter referred to as the common board),
As shown in FIG. 6, two strip-shaped common electrodes [C1 and C2 each having a width of 3 mm are formed in parallel with a minute interval of about 30 μm, facing each segment electrode row of the segment substrate 21.

These segments are poles S1, Sl,..., S2゜8
2,... and the common N poles C1, C2 are both transparent electrodes, and these segment electrodes S1゜Sl,...
, 82, S2, . . . and the common electrode CI.

Shutter portions a, a, . . . for controlling transmission of light are formed in the portions facing C2.

The two rows of segment electrodes 31, 81, . . .

82 , S2 , . . ., segment electrodes 81 . S, 1. ... are arranged 1/2 pitch shifted from the segment electrodes 82 1 , 82 , . . . in the other row, and therefore the shutter parts a, a, .
... are arranged in two rows with a 1/2 pitch shift.

The reason why the shutter parts a, a, ... are arranged in two rows with a 1/2 pitch shift is that the light that passes through the shutter parts a, a, ... of one row is aligned in one row. Between the rows of irradiation points on the surface of the photosensitive drum that were irradiated, the shutter parts a, a of the other row
, . . . to form an electrostatic latent image with high dot density on the surface of the photosensitive drum. Note that these shutter parts a, a.

... is the case of a liquid crystal element for a printer that records on paper with a maximum of 84 plates, and 587 liquid crystal elements are arranged in one column, and the arrangement pitch (shutter Part a, distance between the centers of a Kn) Pl.

P2 is each about 200 μm, and the shutter portions a, a, a, . . . in one row and the shutter portions a in the other row.

The distance between the centers of a, . . . is approximately 260 μm.

Also, segment electrodes 81, Sl in one row.

. . . and the other column's segment electric 4US2,82.・・・
・ means that the common connection electrodes 25 and 2 that are adjacent to each other with a 1/2 pitch deviation are approximately in rotation with the segment electrodes.
5. . . , and the drive circuit connection leads 26.2G, . In this way, the segment electrodes S1, 81, . . . in one column are commonly connected to the segment electrodes S2, 82, . s1゜..., S
This is because if the drive circuit connection leads were individually derived from 2, S2, . Now, the segment electrodes 31 1 , 31 , . . . in one column and the segment electrodes 1 fi 32 . S2. . . . are connected in common, and common electrodes CI and C2 are opposed to each segment electrode row to drive the liquid crystal element in a time-division manner.

Note that the segment electrodes 81, 81, . . .

82, 82, . . . and common connection electrodes 25, 25.・
...and drive circuit connection lead 26.26. ···teeth,
It is integrally formed of a transparent conductive material such as indium oxide.

Also, in Figures 7 and 9, 27.27°...
* represents the common connection electrode 25.25. ... and the drive circuit connection leads 2G, 2G, ... are low resistance metal films made of chromium, gold, etc., and these metal films 27.27. . . . are common connection electrodes 25.25.
...Part and drive circuit connection lead 26.26.・・・
・Provided to reduce the electrical resistance of the part.

Note that the drive circuit connection leads 26.26. ···teeth,
The drive circuit connection leads 26, 26. Metal covering...11!27.
27. ... is drive circuit connection lead 26.2G, ...
・Drive circuit connection terminal portions 26a, 26a,...
Covered except for.

Further, in FIGS. 6 and 9, reference numeral 28.28 indicates a shutter portion a above the common electrodes CI and C2.

It is a low resistance metal film deposited except for a, . . . , and this gold Jiml! ! 28.28 is the common electrode 015. C
In order to reduce the electrical resistance of the shutter parts a and a.

... is provided to regulate the light transmission area.

28a, 28a,... are these metal films 28.28
A light transmitting part (transparent common electrode CI,
The light transmitting portions 28a, 28a, . . . have vertical and horizontal lengths ff11.
, l (see FIG. 7) are each approximately 90 μm square.

Note that the segment electrodes si, si, . . .

82, 82,... and common electrodes CI, C2
The film thickness is 200-300 people, metal film 27.27. ...
and 28, 28 thickness is about 1700 people.

29, 29 are liquid crystal alignment films formed on the inner surfaces of both substrates 21.22, and the film thickness of these alignment films 29.29 is 200~200.
There are 400 people.

Furthermore, the segment board 21 and the common board 22 are
Alignment film 29°29 in each shutter part a, a,...
The outer sealing material 23 is arranged so that the distance between the shutter parts a, a, . . .
a and inner sealing materials 23b, 23b.

Note that in this embodiment, the shutter section a.

Each segment electrode si, s+ forming a,...
.

The filling area of the liquid crystal composition 24 is narrowed by providing the inner sealing materials 23b, 23b on both sides of the arrangement portion of . . . , 82, 82, . When widening the segment electrodes 81 , 81 , . . . , 82 , when applying a high frequency signal,
S2.

...'s lead 26.26. ... liquid crystal composition 2
This is because a high frequency current flows through the common electrode FAc1.02 through the common electrode FAc1.02 and promotes heat generation in the common electrodes C1 and C2. ..., S2,
S2.

...'s lead 26.26. ...and common electrode CI
, C2 are opposed to each other, heat generation of the common electrodes C1 and C2 can be reduced by preventing the liquid crystal composition from intervening as much as possible in the portions facing the common electrodes C1 and C2. In addition, in this embodiment, the segment electrodes Sl, 81, ..., $2゜82,
Since both sides of the liquid crystal substance filled part where the liquid crystal material is arranged have a double wall structure consisting of an inner sealing material 23b and an outer sealing material 23a, fine dust, moisture, etc. can not enter into the liquid crystal layer from the outside. This can be completely prevented.

On the other hand, in FIG. 5, so and so are the segment electrodes 31, 81, . . . , S2, S2, .
These are horizontally elongated auxiliary segment electrodes formed on both ends of the arrangement portion of . A margin erasing shutter section is formed opposite to l1C1 and C2. This margin erasing shutter section is located at both ends of the photosensitive drum (portions corresponding to the margins on both sides of the recording paper) where the light passing through the two rows of shutter sections a, a, . . . used for optical writing is not irradiated. This is to erase the electrical charges on both ends of the photosensitive drum by irradiating it with light, leaving the margins on both sides of the recording paper white.This margin erasing shutter section is always open (light transmission). Driven. Moreover, in FIG. 5, St.

St is a test segment electrode formed on the outside of the auxiliary segment electrodes tiso, 3o, and these test segment electrodes ist, st also face the common ItUC1, C2 of the common board 22 and connect the shutter portion to the test 1. is forming. 23c and 23c are test segment electrodes st and st provided on both sides of both substrates 21 and 22.
This is a spacer that maintains the distance between the two.

Note that the auxiliary segment voltages +hso, so;B and the test segment voltages ist, st are connected to the common It! of the common board 22. ! In order to face 7C1 and C2, the common terminal of the common board 22! The metal films 28 and 28 deposited on UC1 and C2 are used for the auxiliary segment electrodes mso and so of the common snow surfaces C1 and C2 and the test segment electrodes s.
Parts 28b, 28b and 2 opposite to t, st
8c and 28c are covered (
(See Figure 6).

Further, in FIG. 8, 35 is a polarizing plate.

This liquid crystal element 20 has a liquid crystal element 20 as shown in FIG.
From the drive circuit 40 connected to each segment Ti pole 31
, Sl,..., 82, 82,... and the common electrodes CI, C2 and are time-divisionally driven at two frequencies, basically as shown in Figure 10. The liquid crystal composition is controlled by applying an electric field having such a waveform to the liquid crystal composition. That is, the shutter part a.

When a, . . . are open (light transmission), each segment electrode 81 , 81 , .
A driving voltage having a waveform as shown in FIG. 10(a) is applied between the common electrodes CI and C2, and the shutter parts a and a are connected to each other.

... is closed (opaque), each segment electrode 8
1, 81, . . . , 82, 82, . . . and the common electrodes CI, C2, a driving voltage having a waveform as shown in FIG. 10(b) is applied. In addition, in Figure 10,
1 cycle T1 for controlling shutter parts a, a,...
The shutter section is opened and closed by the activation signal (signal in the time period T2), and is held open or closed by the activation signal (signal in the time period T2).

To explain the specific drive signals for controlling this liquid crystal element, in FIG. 11, C0M1 is a common signal applied to one common electrode C1, and C0M2 is a common signal applied to the other common electrode C2. Yes, this common signal C0M1.

C0M2 has the same waveform, but the phase is changed to T2°T3
It is applied at a period of T1 with a shift of (T2, T3 - 1 msec). Furthermore, 5EG1 to 5EG4 are segment signals that are applied to the commonly connected segment electrodes 81 and S2 in synchronization with the application of the common signal, and the segment signal 5EGI is the segment signal that is applied to the segment electrodes 81 and 82 and the common electrode C1, The segment signal 5EG2 is applied when both of the two facing shutter parts a and a are closed, and the segment signal 5EG2 is applied when the segment electrode 81.82 and the common electrode ff1c1.02 are facing each other. Common N to which the common signal C0M1 is applied among the shutter parts a and a
Segment signal 5EG is applied when the shutter on the pole C1 side is opened and the other shutter is opened.
3 is a common electrode C2 to which the common signal C0M2 is applied.
The segment signal 5EG4 is applied when one shutter section is closed and the other shutter section is opened.
It is applied when both shutter sections are opened.

In FIG. 11, only the low frequency component 0 is shown by a pulse waveform, and the high frequency component 0 is shown by hatching. Furthermore, fL and fo indicate signals that are inverted and applied.

FIG. 12 shows segment electrodes Sl of each shutter part a, a.
, S2 and the common electrodes CI, C2, the waveform of the electric field applied to the liquid crystal composition is shown in FIG.
) shows the electric field applied to the liquid crystal when the segment) signal 5EGI is applied to the segment electrode 31°S2. At this time, during the time period T2, a closed starting electric field (high frequency ) is applied, and during the time period T3, an electric field is applied to hold the liquid crystal molecules in a lying state. Further, at the end of the time period T3, an open starting electric field (low frequency) is applied to make the liquid crystal molecules stand up, and then, in the time period T2 again, a closing starting electric field is applied. Note that when the opening rib electric field is applied, the liquid crystal molecules stand up and the shutter section opens, but since the time Δt is very short, the opening of the shutter section does not affect optical writing, and in this case By momentarily standing up the liquid crystal molecules immediately before applying a closed starting electric field, it is possible to prevent the liquid crystal molecules from becoming strongly aligned parallel to the substrate each time a closed starting electric field is applied. .

Furthermore, FIG. 12(b) shows the electric field applied to the liquid crystal when the segment signal 5EG2 is applied to the segment electrodes S1 and S2. The same electric field as above is applied to the liquid crystal in the shutter section, and the opening starting electric field (low frequency) that makes the liquid crystal molecules stand up and its hold are applied to the liquid crystal in the shutter section on the common electrode C2 side to which the common signal C0M2 is applied. An electric field is applied.

This also applies to the case of FIG. 12(C) in which the segment signal 5EG3 is applied to the segment electrodes 81 and 82.

Further, FIG. 12(d) shows the electric field applied to the liquid crystal when the segment signal 5EG4 is applied to the segment electrode 81°S2. A starting electric field (low frequency) and its holding electric field are applied.

Next, the liquid crystal composition 24 filled in this liquid crystal element will be explained.

The table below shows examples of this liquid crystal composition 24.

Of the liquid crystal compounds 1 to 21 in this table, the compounds in group 1 serve as the base of the liquid crystal composition, and the compounds in group 1 have low viscosity and excellent compatibility with other compounds. (However, Δε is small and no dielectric dispersion phenomenon is shown). The liquid crystal substances of group (2) exhibit a dielectric dispersion phenomenon in which Δε on the low frequency fL side is positively large and 1Δε1 on the high frequency fH side is relatively small.This compound is mixed to give the liquid crystal composition dielectric properties. Ru. Compounds of Group ■ may be used in cases where the desired dielectric properties cannot be achieved by 1q simply by mixing a compound of Group ■ with a compound of Group ■, which is the base, or where the viscosity of the liquid crystal composition increases due to mixing of compounds of Group ■. (However, it is not necessary to mix the compounds of group 1 if the desired dielectric properties can be obtained by mixing only the compounds of group 2). In addition, the compounds of group Ⅰ are mixed to lower the overall dielectric properties of the liquid crystal composition to the negative side and lower fc, and the compounds of group IV have a large Δε on the negative side and a high viscosity. .

1.2% by weight of each of the following two types of dyes are added as dichroic dyes to each of the liquid crystal compositions (1) to (6) above, and the liquid crystal element 20 having the above structure is filled with this liquid crystal composition. It was used for optical writing in the optical writing printer mentioned above. Note that the emission wavelength band of the light source of the optical recording section of the printer is 543±2.
0 mm, and the absorption wavelength band of the dichroic dye is 560 mm.
±40mm.

This liquid crystal element is driven by the drive signal having the waveform shown in FIG. When the shutter characteristics were investigated, the results shown in the table below were obtained.

As can be seen from this table, in all of the liquid crystal elements filled with the liquid crystal composition of each example, the time required for the shutter section to switch from opening to closing, that is, the rise time of liquid crystal molecules due to low frequency application after high frequency application. It is extremely short, less than 0.5 msec. This is because the values of |Δε| at high frequencies of the liquid crystal compositions are all 1ΔεH1>2.0.

In addition, when the value of 1ΔεHl of the liquid crystal composition is large, the time required for the shutter section to switch from open to closed becomes shorter, but on the other hand, the high frequency Ill history effect becomes stronger, which affects the shutter characteristics, resulting in poor response and stability. However, in all of the liquid crystal compositions of the above examples, the value of |Δε| at low frequency is ΔεL>3.5, and the ratio of 1ΔεL1 and 1Δεu l is 1ΔεL
Since it shows a dielectric dispersion phenomenon where 1/1ΔεH1>1.0, that is, the value of 1ΔεI at high frequencies is smaller than the value of |Δε| at low frequencies, the hysteresis effect at high frequencies is You can prevent it from appearing in a big way.

In addition, to reduce the history effect for high frequencies, 1Δε
The larger the value of L1/1Δεn I, the better, but (ΔεL
If the value of 1/1ΔεH1 is large, the viscosity of the liquid crystal composition becomes too high to be practical.
The value of ΔεHl is preferably in the range of 1ΔεL1/1ΔεH1×5.

As shown in this table, when looking at the shutter characteristics of the liquid crystal elements filled with the liquid crystal compositions of each example, the shutter characteristics of the liquid crystal elements filled with the liquid crystal compositions of examples (1) and (2) are the best; The shutter characteristics of the liquid crystal elements filled with the liquid crystal compositions of Examples (3) and (6) were second to this.

In other words, as a liquid crystal element for two-frequency drive, 1ΔεL
It is optimal to use a liquid crystal composition having a value of l/;ΔεH1 in the range of 1.2 to 5. Note that the shutter characteristics of the liquid crystal elements filled with the liquid crystal compositions of Examples (4) and (5) are worse than those of the liquid crystal elements filled with the liquid crystal compositions of other Examples, but these liquid crystal elements are also better than those of conventional liquid crystal elements. The shutter characteristics are good compared to .

In this way, the liquid crystal elements shown in the solid line examples have an IU value of |Δε| at high frequencies that is higher than the value of |Δε| at low frequencies.
uses a liquid crystal composition that exhibits a smaller dielectric dispersion phenomenon, and in this liquid crystal element, even when high frequency is applied for a long time, liquid crystal molecules rise immediately when low frequency is applied, so the shutter part is The liquid crystal compositions can be opened and closed with good responsiveness and at high speed, and each of the liquid crystal compositions has a temperature of 1ΔεH1.

Since the values of both 1ΔεL1 are relatively large, this liquid crystal element can be driven with a low voltage.

Note that in the above embodiment, a liquid crystal element used for optical writing of an optical writing printer was described, but this invention
It can also be applied to liquid crystal elements used for image display in television receivers, computer displays, etc., and of course can be applied not only to GH type liquid crystal elements but also to TN type liquid crystal elements.

〔Effect of the invention〕

The liquid crystal element of the present invention uses a liquid crystal composition exhibiting a dielectric dispersion phenomenon in which the value of |Δε| at high frequencies is smaller than the value of |Δε| at low frequencies. Therefore, even if a high frequency wave is applied for a relatively long time, the next application of a low frequency wave will immediately cause the liquid crystal molecules to rise, allowing the shutter section to open and close with good responsiveness and at high speed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the dielectric characteristics of the liquid crystal composition used in this invention. FIGS. 2 and 3 are a schematic diagram of an optical writing printer that performs optical writing using a liquid crystal element, and a configuration diagram of its optical recording section. 4 to 12 show an embodiment of the present invention, in which FIG. 4 is a plan view of a liquid crystal element, and FIG.
6 and 6 are plan views of the segment substrate and common substrate of the liquid crystal element, FIG. 7 is an enlarged plan view of the segment electrode forming portion of the segment substrate, and FIG. 8 is a plan view of the liquid crystal element along A-AI in FIG. 7. 9 is an enlarged view of the shutter part in FIG. 8, FIG. 10 is a driving waveform diagram of the liquid crystal element, FIG. 11 is a waveform diagram of the common signal and segment signal, and FIG. 12 is a diagram of the waveforms applied to the liquid crystal. It is a waveform diagram of an electric field. 21, 22...Substrate, 31.32...Segment electrode, CI, C2...Common electrode, a...Shutter section. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Δε Figure 2 Figure 3 Figure 9 Figure 10; □T1 Procedural amendments Showa (10) Application No. 59-179881 2, Name of the invention Liquid crystal element 3, Relationship with the person making the amendment Patent pressure H'''' (144) Casio Computer Co., Ltd. 11, Agent 5, Spontaneous amendment 7, Contents of amendment + 11 Details On page 26 of the book, line 9 from the bottom, it says “543±2
0 朋” was corrected to ``543±20 nmJ. (2) On page 26 of the specification, line 8 from the bottom, “56o±4
0tL! 1" should be corrected to "560±40 nm J.

Claims (1)

[Claims] In a liquid crystal element driven at two frequencies, the value of |Δε| at high frequencies is higher than the value of |Δε| at low frequencies as a liquid crystal composition.
A liquid crystal element characterized by using a liquid crystal composition having dielectric properties exhibiting a dielectric dispersion phenomenon where the value of | is smaller.