JP3168399B2 - Liquid crystal element and liquid crystal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal element used for a light valve used in a flat panel display, a projection display, a printer, and the like, and a liquid crystal device using the same.

[0002]

2. Description of the Related Art A CRT is known as the most widely used display. It is widely used as a video output for televisions and VTRs, or as a monitor for personal computers. However, due to the characteristics of the CRT, flicker and scanning fringes due to insufficient resolution lower the visibility of a still image, and the phosphor deteriorates due to burn-in. Recently, CRT
It can be seen that the electromagnetic waves generated by the harmful effects on the human body, which may harm the health of the VDT worker. And
Because of its structure, it has a large volume behind the screen,
It may hinder home space savings and may not be able to fulfill its responsibility as a display in the advanced information society.

As a solution to such a disadvantage of the CRT, there is a liquid crystal display element. For example, M. Shut (M.
Schadt) and W. Helfrich (W. He)
Ifrich), "Applied Physics Letters" (Applied Physics Letter)
s ") Volume 18, Issue 4 (issued February 15, 1971)
Twisted pages shown on pages 127-128
A device using a twisted nematic liquid crystal is known. One is a simple matrix type liquid crystal element which has an advantage in cost. This liquid crystal element has a problem that crosstalk occurs in time-division driving using a matrix electrode structure with a high pixel density, so that the number of pixels is limited. In addition, since the response speed is as slow as several tens of milliseconds or more, the use as a display has been limited. In recent years, a liquid crystal element called a TFT has been developed for such a simple matrix type. Since this type creates a transistor for each pixel, it solves the problems of crosstalk and response speed, but the larger the area, the more industrially it is extremely difficult to create a liquid crystal element without defective pixels. Difficult and costly, if possible.

As an improvement over the disadvantages of the conventional liquid crystal device, the use of a bistable liquid crystal device has been proposed by Clark and Lagerwell.
all). (JP-A-56-107
216, U.S. Pat. No. 4,367,924) As the liquid crystal having this bistability, a ferroelectric liquid crystal having a chiral smectic C phase or a chiral smectic H phase is generally used. Since the ferroelectric liquid crystal performs inversion switching by spontaneous polarization, the ferroelectric liquid crystal has a very fast response speed and can exhibit a bistable state with memory properties. Further, since the viewing angle characteristics are also excellent, it is considered that they are suitable as a high-speed, high-definition, large-area display element or light valve. Recently, a chiral smectic antiferroelectric liquid crystal device having three stable states has been proposed by Chandani, Takezoe et al. (Japanese Journal of Applied Physics).
of Applied Physics) 27, 198
8 years, L729).

In such a chiral smectic liquid crystal element, for example, as described in “Structure and Physical Properties of Ferroelectric Liquid Crystal” (Corona Co., Atsuo Fukuda, Hideo Takezoe, 1990), a zigzag alignment defect is formed. This causes a problem that the contrast is remarkably reduced due to the occurrence of. This defect is due to the fact that the layered structure of the chiral smectic liquid crystal carried between the upper and lower substrates forms two types of chevron-like structures. Recently, there has been a movement to eliminate the chevron structure that causes low contrast and to exhibit a layered structure called a bookshelf (hereinafter, this structure is referred to as a bookshelf) or a structure similar thereto, thereby realizing high contrast (for example, "Next-generation liquid crystal display and liquid crystal material", edited by CMC Corporation, Atsuo Fukuda, 1992). One method is to use a naphthalene-based liquid crystal material. In this case, a tilt angle of 10 is used.
Degree, and an ideal maximum transmittance can be obtained.
There is a problem that it is very small as compared with 5 degrees and has a low transmittance, and there is also a problem that the bookshelf structure does not appear reversibly with respect to temperature. As another typical example, there is a method of inducing a bookshelf structure by applying a high electric field from the outside to a liquid crystal element having a chevron structure, but this method also has instability to external stimuli such as temperature. It is a problem. These bookshelf types are still being discovered, and there are various other problems for practical use.

Further, a liquid crystal compound having a perfluoroether side chain as a bookshelf or a liquid crystal having a substantially similar structure (US Pat. No. 5,262,082;
International Patent Application WO 93/22396, 1993 4th International Conference on Ferroelectric Liquid Crystal P-46, Marc D. Radc
life et al.) are disclosed. This liquid crystal can show a bookshelf or a structure with a small layer tilt angle near it without using an external field such as an electric field.
Suitable for high-definition, large-area liquid crystal elements and display devices. However, further improvements are required in terms of the speed, alignment, contrast, drive stability and the like of the liquid crystal element. In addition, there is a need for a method of improving a plurality of characteristics and an invention for higher performance as well as improvement of each characteristic.

For example, in order for a liquid crystal device using this polyfluorinated liquid crystal to exhibit desired electro-optical characteristics, an alignment state in which the liquid crystal between the substrates switches between two stable states stably and with good reproducibility. And that the alignment state is uniform over the entire pixel or display screen.

In general, in order to align a chiral smectic liquid crystal, a polymer film of horizontal alignment (or tilt alignment) such as polyimide (PI), polyvinyl alcohol (PVA), or polyamide (PA) is formed on a substrate surface. A pair of substrates rubbed in substantially the same direction is used. In this case, the temperature of the liquid crystal to be used is decreased due to a temperature drop, and isotropic (Iso) phase → cholesteric (Ch) phase (chiral nematic (N ^* ) phase) → smectic A (SmA) phase → chiral smectic C (SmC ^* ) phase. If it changes, since the orientation is uniformed in the Ch phase, S
The orientation in the mC ^* phase tends to be uniform. However, for example, a polyfluorinated liquid crystal has a phase transition of Iso phase → SmA phase → S
Since it occurs in the order of the mC ^* phase, during the transition from the Iso phase to the SmA phase (I / A transition), generation of a batone (a kind of liquid crystal nucleus) occurs.
Since the process of growth and bonding is performed, a shift in the layer normal direction in the smectic phase, a defect in the Battone bonding portion, and the like occur, and it is difficult to obtain uniform orientation.

According to experiments by the present inventors, such a C
For the liquid crystal lacking the h phase, only one of the opposing substrates was rubbed, and the substrate surface on the side where rubbing was not performed was subjected to a vertical alignment treatment without forming an alignment film, whereby uniform alignment was obtained. This is because the liquid crystal grows from the substrate surface on the rubbed side near the I / A transition temperature and goes through a transition process of reaching the opposing substrate. In fact, it has been confirmed that the I / A transition temperature of a cell in which both surfaces are horizontal alignment films is higher than the I / A transition temperature of a cell in which both surfaces are vertically aligned by 0.5 ° C. or more.

[0010]

As described above, in order to uniformly align the ferroelectric liquid crystal, particularly when the liquid crystal does not have a Ch phase, the asymmetrical relationship between the rubbing process of the horizontal alignment film and the vertical alignment process is required. The configuration is valid. However, when the properties of the opposing substrate surfaces are different from each other, the bistable state of the ferroelectric liquid crystal is destroyed, and the electro-optical switching characteristic (driving threshold characteristic) between the two stable states becomes asymmetric, which causes a reduction in the driving margin. Become.

In the experiments by the present inventors so far, in the above-mentioned polyfluorinated liquid crystal, a thin film of a polymer film such as polyimide is used as an alignment control film, and a vertical alignment agent is used as another alignment control film. When used, when switching between two stable states by an external electric field, the spontaneous polarization Ps
The threshold voltage differs between the two states, that is, the state where the dipole moment of the liquid crystal faces the orientation film side (here, the polymer film side) (first state) and the state where the dipole moment faces the liquid crystal inside side (second state). First
The switching from the state to the second state may have a lower asymmetric threshold value. Presumably, the reason is that the polyfluorinated liquid crystal is more strongly regulated (has a strong interaction) by the vertical alignment agent than by the polymer film as described above. In a system having such a threshold asymmetry, the driving method is practically limited in order to more effectively adapt to a write operation from both sides.
Further, a deterioration phenomenon peculiar to the system having threshold asymmetry is likely to occur.

In view of the above problems, the present invention provides a liquid crystal element which improves the above threshold asymmetry, realizes good bistability, has high reliability and driving stability, and a liquid crystal device using the element. It is intended to provide.

[0013]

According to the present invention, there are provided an upper and lower substrate having an electrode film formed thereon, an alignment control film formed on each electrode film, and a ferroelectric liquid crystal sandwiched between the upper and lower substrates. in the liquid crystal device having the basic components, the strong induction
The conductive liquid crystal is composed of a fluorocarbon terminal and a hydrocarbon powder.
End portions, the two end portions being joined by a central nucleus
And a smectic mesophase or potential smectic
70% by weight or less of fluorine-containing liquid crystal compounds having an intermediate phase
And a fluorine-containing liquid crystal.
Of the compounds, at least
The compound containing ether oxygen in one chain is prepared by the above-mentioned liquid crystal composition.
Liquid crystal composition containing at least 30% by weight based on the total amount of
A chiral smectic liquid crystal composition, which produces a difference in surface energy at the liquid crystal interface between at least each substrate, and gradually changes from an isotropic phase to a chiral smectic C (SmC ^* ) phase without applying an electric field between the upper and lower substrates. This is a liquid crystal element that has solved the above-mentioned problems by controlling the initial alignment when cooling is performed so that the spontaneous polarization dipole moment of the liquid crystal molecules is directed to a substrate having a higher surface energy.

When a thin film of a polymer film such as polyimide is used as the alignment control film, the dipole moment of liquid crystal molecules and the electric interaction between the polymer surface (dipole-dipol) are used.
It is considered that the regulating force acts in a state where the dipole moment faces the polymer alignment film side (first state) due to the interaction. On the other hand, on the side of the vertical alignment agent, the regulation force of the substrate surface against the polyfluorinated liquid crystal molecules is often stronger than the other substrate surface. In the present invention, in a device configuration including a pair of substrates provided with a polymer alignment film and a vertical alignment film, respectively, and provided with a difference in surface energy near an interface with liquid crystal in each substrate, the alignment film is substantially formed. Set the substrate side to have a high surface energy state,
Preferably, the surface potential is set to be higher on the substrate having a lower surface energy, and the dipole moment of the liquid crystal is regulated and adjusted so as to be more stable. It destabilizes the regulating force on the vertical alignment agent side surface in the state facing the side (second state), and as a result, cancels out the asymmetry in the voltage application direction of the switching threshold between the stable states due to the asymmetric configuration. It has been found that the relationship between the two stable states is symmetrical, and that high reliability and drive stability are exhibited.

[0015]

In the present invention, the ether oxygen in the chain is
Oxygen that forms the main chain in the perfluoroether chain.

[0019] Preferably in the present invention, the fluorocarbon terminal chain of the fluorine-containing liquid crystal compounds comprising at least one chain ether oxygen in the fluorocarbon terminal _{chain, -V (C x F 2x O} ) z C y F 2y ₊₁
an integer x from 1 is independently in each of the C _x F _2x O to 10, y is an integer from 1 to 10, z is an integer from 1 to 10, V is a single bond, -COO-C _r H _2r- ,
_{-O-C r H 2r -,} - O- (C s H 2s O) t -C r 'H
_{2r '-, - OSO 2 -} , - SO 2 -, - SO 2 -C r H 2r
_{-, - C r H 2r -} , - C r H 2r -N (C p H 2p + 1) -SO 2
_{-, - C r H 2r -N} (C p H 2p + 1) -CO-, r and r 'is an integer of independently 1 to 20, s is independently in each of the C _s H _2s O Is an integer from 1 to 10, t is an integer from 1 to 6, and p is an integer from 0 to 4.

[0018]

FIG. 1 shows an example of the liquid crystal device of the present invention. Reference numeral 1 denotes a liquid crystal layer composed of a chiral smectic liquid crystal composition. Usually, the layer thickness is preferably 5 μm or less in order to exhibit bistability. 2 is a substrate, glass,
Plastic or the like is used. 3 is a transparent electrode such as ITO. Reference numeral 4 denotes an orientation control layer, which requires a uniaxial orientation control layer on at least one substrate. In addition, polyimide is used for at least one orientation control layer. As a forming method, a polyamic acid as a polyimide precursor is usually formed on a substrate by solution coating, followed by heat treatment to form a polyimide film. By rubbing the surface with a fibrous material such as velvet, cloth or paper, a polyimide orientation control layer is obtained.

In the present invention, an element having an asymmetric alignment film configuration is used. When the chiral smectic liquid crystal composition is used in a device having an asymmetric alignment film configuration having a polyimide alignment control film, the device has good driving characteristics in a very wide temperature range, and has high reliability and good driving stability. It is possible. As the alignment film, as a specific structure of the polyimide used from the viewpoint of characteristics, a polyimide including a repeating unit represented by the following general formula P is preferable.

[General formula P] (-K-P ¹ -L ¹ -M ^1- (L ² ) _a -P ^2- )

[0021]

Embedded image Or an alkylene group having 1 to 20 carbon atoms, wherein P ¹ ,
P ² represents an imide bond. M ¹ represents a single bond or —O—, and a represents 0, 1, or 2. )

Further, specific structures of these polyimides include, for example, the following repeating unit structures.

[0023]

Embedded image

In addition to the orientation control layer, an insulating layer or another organic or inorganic layer may be formed as a short-circuit preventing layer for the upper and lower substrates. Reference numeral 5 denotes a sealing material for bonding the substrates. In addition, gap control spacers (not shown) such as silica beads are provided between the substrates. 8
Is a polarizing plate, and 9 is a light source. Switching is performed in response to a switching signal from a signal power supply (not shown), and functions as a light valve such as a display element. Further, when the three transparent electrodes are arranged in a matrix with upper and lower crosses, pattern display and pattern exposure become possible, and they are used, for example, as displays for personal computers and word processors, and as light valves for printers.

The perfluoroether liquid crystal compound used in the liquid crystal composition used in the present invention is described in US Pat. No. 5,262,082 and International Patent Application WO 93/223.
96, 1993 4th International Conference on Ferroelectric Liquid Crystal P-46
(Marc D. Radcliffe et al.), Comprising a fluorocarbon end portion and a hydrocarbon end portion and comprising at least one ether oxygen in the chain in the fluorocarbon end chain, wherein both end portions are linked by a central nucleus. And a fluorine-containing liquid crystal compound having a smectic mesophase or a latent smectic mesophase.

The compound having a latent smectic mesophase as used herein means a compound having a smectic mesophase or a compound having another potential smectic mesophase, even if the compound does not itself exhibit a smectic mesophase. Refers to compounds that, under appropriate conditions, express a smectic mesophase. It can be represented by the following general formula II.

[General formula II]

[0028]

Embedded image A, b and c are each independently 0 or 1 to 3
Represents an integer. However, a + b + c is at least 2.

M and N are each independently -COO-,-
COS -, - COSe -, - COTe -, - (CH 2 C
H ₂ ) _d- (d represents an integer of 1 to 4), -C≡C-,
-CH = CH -, - CH = N -, - CH 2 -O -, - C
O-, -O-, or a single bond, and the orientation may be any.

Each of X, Y and Z is independently -H, -C
l -, - F, -Br, -I, -OH, -OCH 3, -C
H ₃ , —CF ₃ , —OCF ₃ , —CN, and —NO ₂ . L, m, and n each independently represent an integer of 0 to 4.

[0031] G is _{-COO-C e H 2e -,} - O-C e H 2e
_{-, - O (C e "} H 2e" O) t -C e 'H 2e' -, - C e H
_{2e -, - OSOO -, -} SOO -, - SOOC e H
_{2e -, - C e H 2e} -N (C p H 2p + 1) -SOO -, - C e
_{H 2e -N (C p H 2p} + 1) -CO- (e, e ' represents an integer of from 1 independently to 20, p is an integer from 0 to 4 .e "is respectively ( Ce _{" H2e"} O) independently represents an integer of 1 to 10, and t represents an integer of 1 to 6.)

[0032] A is _{-O- (C f H 2f -O)} u -C f 'H
_{2f '+ 1, - (C} f H 2f -O) u -C f' H 2f '+ 1, -C f H 2f -
_{R ', - O-C f} H 2f -R', - COO-C f H 2f -
_{R ', - OCO-C f} H 2f -R' (R ' is -Cl, -
_{F, -CF 3, -NO 2,} -CN, -H, -COO-C f '
_{H 2f '+ 1, -OCO-} C f'' represents a _{+ 1, f, f' H} 2f each independently represents an integer of 1 to 20. u is 1 to 10
Is an integer. A represents a linear or branched chain.

[0033] R is - (C _x F _2x O) a _z C _y F _{2y + 1,}
x is an integer from 1 to 10 independently for each C _x F _2x O, y is an integer from 1 to 10, and z is an integer from 1 to 10. )

Further, specific structural examples of the perfluoroether liquid crystal compound include compounds having the following structures.

[0035]

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[0036]

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[0037]

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In the present invention, the liquid crystal contains a fluorocarbon terminal portion and a hydrocarbon terminal portion, and at least one ether oxygen in the chain is contained in the fluorocarbon terminal chain, and both terminal portions are bound by a central nucleus. A fluorine-containing liquid crystal compound having a smectic mesophase or a latent smectic mesophase, a compound having at least one or more ether oxygen atoms in one chain, a compound having at least one or more ether oxygen atoms in two chains, Those containing a compound having at least one ether oxygen in the three chains are preferably used. When these three types of compounds are contained, good driving characteristics, high reliability, and driving stability can be obtained over a characteristically wide temperature range. In order to obtain these effects, at least one compound having one or more ether oxygen atoms in the chain is 10% by weight or more, and at least one compound having two or more ether oxygen atoms in the chain is 10% or more.
It is preferable that at least 10% by weight of at least one compound having at least one kind of ether oxygen in the chain is contained by 10% by weight or more. Further, in order to obtain a sufficient contrast and response speed, a bookshelf or a structure having a small layer tilt angle close to the bookshelf is preferable. Therefore, the liquid crystal composition of the present invention contains 50% by weight or more of a perfluoroether liquid crystal compound. It is preferably contained. Further, a perfluoroalkyl liquid crystal compound can be contained from the viewpoint of good compatibility with the perfluoroether liquid crystal compound. Further, as other components,
It is possible to contain a so-called hydrocarbon type liquid crystal compound having no perfluorocarbon chain. The chiral smectic liquid crystal composition of the present invention contains a chiral compound.

Specific examples of the perfluoroalkyl liquid crystal compound described above include those described in JP-A-2-142755 and those having the following structures.

[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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[0049]

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[0050]

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In the chiral smectic liquid crystal composition of the present invention, other compounds such as dyes and pigments,
Additives such as antioxidants and ultraviolet absorbers can also be included.

The liquid crystal element of the present invention constitutes a liquid crystal device having various functions. The data format of the image information having the scanning line address information shown in FIGS.
A liquid crystal display device is realized by using communication synchronization means using N signals. The reference numerals in the figure are as follows.

101 Chiral smectic liquid crystal display device 102 Graphic controller 103 Display panel 104 Scan line drive circuit 105 Information line drive circuit 106 Decoder 107 Scan signal generation circuit 108 Shift register 109 Line memory 110 Information signal generation circuit 111 Drive control circuit 112 GCPU 113 Host CPU 114 VRAM

The generation of image information is performed by the graphic controller 102 on the main unit side, and is transferred to the display panel 103 according to the signal transfer means shown in FIGS. The graphic controller 102 is a CPU
(Central processing unit, abbreviated as GCPU) and VRAM
(Image information storage memory) Host CPU 1 with 114 as a core
13 manages image information and communicates with the liquid crystal display device 101. Note that a light source is disposed on the back surface of the display panel.

The display device of the present invention exhibits excellent driving characteristics and reliability because the liquid crystal element as a display medium has good switching characteristics as described above.
A large area display image can be obtained.

As a method of driving the liquid crystal element of the present invention, for example, JP-A-59-193426 and JP-A-59-19
The driving method disclosed in Japanese Patent No. 3427, Japanese Patent Application Laid-Open No. 60-156046, Japanese Patent Application Laid-Open No. 60-156047 or the like can be applied.

FIG. 6 is an example of a waveform diagram of the above driving method. FIG. 5 is a plan view of an example of a chiral smectic liquid crystal panel on which matrix electrodes are arranged. FIG.
In the liquid crystal panel 51, the scanning lines of the scanning electrode group 52 and the data lines of the information electrode group 53 are wired so as to cross each other, and a chiral smectic liquid crystal is arranged between the scanning line and the data line at the intersection. Have been.

In FIG. 6A, S _S applies a selected scanning waveform to be applied to a selected scanning line, S _N applies an unselected scanning waveform that is not selected, and I _S applies to a selected data line. A selected information waveform (black) and _IN indicates a non-selected information signal (white) applied to an unselected data line. In the drawing, (I _S -S _S ) and (I _N -S _S ) are voltage waveforms applied to the pixels on the selected scanning line, and the pixels to which the voltage (I _S -S _S ) is applied are black. Taking the display state, the voltage (I _N −
The pixel to which S _S ) is applied takes a white display state.

FIG. 6B shows the driving waveform shown in FIG. 6A, which is a time-series waveform when the display shown in FIG. 4 is performed.

In the driving example shown in FIG. 6, the minimum application time Δt of the unipolar voltage applied to the pixels on the selected scanning line
There corresponds to the write phase t ₂ time period of a one-line clearing phase t ₁ is set to 2? T.

The values of the parameters V _S , V _I and Δt of the drive waveform shown in FIG. 6 are determined by the switching characteristics of the liquid crystal material used.

[0062] Figure 7 shows the transmittance change T, then namely V-T characteristic when changing the left driving voltage and the bias ratio was kept constant to be described later (V _S + V _I). Where Δ
t = 50 μsec, bias ratio V _I / (V _I + V _S ) = 1
/ 3. The positive side of FIG. 7 is shown in FIG.
_N- S _s ), and the waveform shown by (I _s -S _s ) is applied to the negative side.

Here, V ₁ and V ₃ are called an actual drive threshold voltage and a crosstalk voltage, respectively. Also, V ₂ <V ₁ <V ₃
In this case, ΔV = V ₃ −V ₁ is referred to as a voltage margin, which is a parameter of a voltage width capable of driving the matrix. V ₃ is a chiral smectic liquid crystal display device driving on, it may be said that generally present. Specifically, a voltage value causing switching by V _B in the waveform of FIG. _{6 (A) (I N -S} S). Of course, it is possible to increase the value of V ₃ by increasing the bias ratio, increasing the bias ratio corresponds to a large amplitude of a data signal, an increase in flickering in image quality, contrast Is undesirably caused.

According to our study, the bias ratio is 1/3 to 1/4.
The degree was practical. By the way, if the bias ratio is fixed, the voltage margin ΔV strongly depends on the switching characteristics of the liquid crystal material and the element configuration, and it goes without saying that an element having a large ΔV is very advantageous for matrix driving.

Similarly, the above-mentioned voltage is kept constant,
It is also possible to drive by changing the voltage application time Δt. The above-described voltage may be used as the voltage application time as it is, and in this case, the voltage application time threshold is Δt
₁ , the voltage application time crosstalk value is Δt ₂ and Δt
₂₋ Δt ₁ = ΔT is called a voltage application time margin.

At such a certain temperature, two states of "black" and "white" can be written to the selected pixel depending on the two directions of the information signal. The voltage margin or the voltage application time margin capable of maintaining the “white” state varies depending on the liquid crystal material and the element configuration, and is unique. Also,
Since the driving margin shifts due to a change in the environmental temperature, in the case of an actual display device, it is necessary to set optimal driving conditions for the liquid crystal material, the element configuration, and the environmental temperature.

[0067]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

[Example 1]

[0069]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Tables 1 and 2 below show examples of the polymer film (uniaxial alignment control film) and the vertical alignment agent, and their surface potentials and surface energies, which are cited in the examples.

[0071]

[Table 1]

[0072]

[Table 2]

The values of the surface potential and the surface energy change when the state of the film changes. In the present embodiment, the following relationship was satisfied.

Surface potential relationship: A <D <B, E <C Absolute value of surface potential: film thickness thick> thin Surface energy relationship: polymer film> vertical alignment agent

An example of a method for manufacturing a liquid crystal element will be described below.

70 nm as a transparent electrode by sputtering
A pair of glass substrates on which an ITO (indium oxide: tin) film having a thickness of 1 mm is formed is prepared, and NMP (polyamide acid LP-64 (manufactured by Toray Industries, Inc.), a polyimide precursor, is formed on the ITO film of one substrate. N-methylpyrrolidone): n-BC
The (n-butyl cellosolve) mixed solution was spin-coated. The coating solution was prepared by adjusting LP-64 to 1% by weight in a mixed solvent of NMP: n-BC = 2: 1, and spinning was performed at 45 rpm for 20 seconds. This substrate is 80
After drying the solvent for 5 minutes in an oven at
The mixture was heated and baked in an oven at a temperature of 1 ° C. for 1 hour to imidize. The obtained polyimide film was about 10 nm thick, and this film was rubbed to form an alignment film.

The rubbing was carried out by using a nylon cloth wrapped around a roller having a diameter of 10 cm.
Rubbing was performed twice (one way) in the same direction at a pressure of 0.4 mm for pushing the cloth against the surface of the alignment film at a feed rate of 10 mm / sec. Thereafter, an IPA (isopropyl alcohol) solution in which silica beads having an average particle size of 2.0 μm are dispersed at 0.008% by weight is spin-coated on the surface of the substrate under the conditions of 25 rotations / sec and 10 seconds, and the distribution density is 300 μm.
Bead beads spacers of about pieces / mm ² were sprayed.

The other substrate on the opposite side is the ITO of the substrate.
A 0.5% by weight solution of a silane coupling agent (ODS-E) in ethyl alcohol was spin-coated on the film at 45 rpm for 20 seconds to perform vertical alignment treatment. Thereafter, a thermosetting liquid adhesive was applied on the substrate by printing.

The two substrates thus obtained were bonded to face each other, and thermally cured in an oven at 150 ° C. for 90 minutes to form a cell.

The liquid crystal composition was injected into the cell thus prepared at an isotropic phase temperature, and was gradually cooled to an SmC ^* phase to obtain a liquid crystal element.

[0081]

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[0082]

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The liquid crystal composition used in the present invention is shown below.

The present liquid crystal composition (weight ratio; compound A / B / C)
/D/E=46.4/15.5/30.9/5.2/
2.0) are shown below.

[0085]

(Equation 1) Tilt angle (30 ° C.) = 24.4 ° Spontaneous polarization (30 ° C.) Ps = -31.1 (nC / cm ² )

The liquid crystal device manufactured as described above is placed under crossed Nicols, and an experimental driving waveform (V = 20 V fixed, pulse width is changed) is applied to change the first state to the second state and the second state. The switching threshold from the state to the first state was measured. The results are shown in Table 3 below.

[0087]

[Table 3]

From the above, it has been found that by controlling the direction of the dipole moment in the initial orientation state to the first state side, the switching asymmetry is eliminated and good driving characteristics are exhibited.

[0089]

As described above, according to the present invention,
In a liquid crystal element consisting of a liquid crystal cell with an asymmetric configuration using a polyfluorinated liquid crystal material, the switching threshold between bistable two states can be made equal and symmetric, and good driving characteristics can be obtained, and high reliability and driving can be achieved. A stable liquid crystal device is realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross-sectional structure of a liquid crystal element of the present invention.

FIG. 2 is a block diagram illustrating a display device including a liquid crystal element of the present invention and a graphics controller.

FIG. 3 is a diagram showing a timing chart of image information communication between a display device and a graphics controller.

FIG. 4 is a schematic diagram of a display pattern when actual driving is performed with the time-series driving waveform shown in FIG.

FIG. 5 is a plan view of a liquid crystal panel on which matrix electrodes are arranged.

FIG. 6 is a diagram showing an example of a driving waveform used for driving the liquid crystal element of the present invention.

FIG. 7 is a graph (VT characteristic diagram) showing a change in transmittance when a drive voltage is changed according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal layer 2 Substrate 3 Transparent electrode 4 Alignment control layer 5 Sealing material 8 Polarizer 9 Light source 101 Chiral smectic liquid crystal display device 102 Graphic controller 103 Display panel 104 Scan line drive circuit 105 Information line drive circuit 106 Decoder 107 Scan signal generation circuit 108 Shift register 109 line memory 110 information signal generation circuit 111 drive control circuit 112 GCPU 113 host CPU 114 VRAM

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yukio Hanyu 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Makoto Mori 3-30-2 Shimomaruko, Ota-ku, Tokyo K Inside Canon Inc. (72) Inventor Koji Noguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Shinichi Nakamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masahiro Terada 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-63-158521 (JP, A) JP-A-63-73223 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/1337 510

Claims (10)

(57) [Claims] 1. A liquid crystal device having upper and lower substrates each having an electrode film formed thereon, an alignment control film formed on each electrode film, and a basic component of ferroelectric liquid crystal sandwiched between the upper and lower substrates. The ferroelectric liquid crystal contains a fluorocarbon terminal portion and carbon
A hydrogen hydride end portion, wherein both end portions are
Bound, smectic mesophase or potential smear
70 groups of fluorine-containing liquid crystal compounds having a metic phase
A liquid crystal composition containing at least
Of the contained liquid crystal compounds,
A compound containing ether oxygen in at least one chain
Liquid crystal composition containing at least 30% by weight based on the total amount of the liquid crystal composition
Is a chiral smectic liquid crystal composition comprising at least a difference in surface energy at the liquid crystal interface between each substrate, and from an isotropic phase to a chiral smectic C (SmC ^* ) in a state where no electric field is applied between the upper and lower substrates.
A liquid crystal device characterized in that the initial alignment when the phase is gradually cooled is controlled so that the spontaneous polarization dipole moment of the liquid crystal molecules is directed to a substrate having a higher surface energy. 2. The liquid crystal device according to claim 1, wherein a surface potential difference occurs between the upper and lower substrates, and the surface potential value of the substrate having a lower surface energy value is higher. 3. The liquid crystal device according to claim 1, wherein at least one of the alignment control films is made of an organic polymer. 4. The liquid crystal device according to claim 1, wherein at least one of the alignment control films is made of polyimide. 5. One of the alignment control films is rubbed.
An alignment control film, and the other is a vertical alignment film.
5. The liquid crystal element according to any one of 4. 6. The liquid crystal device according to claim 2, wherein the substrate having the lower surface potential has a negative surface potential. 7. The fluorine-containing liquid crystal compound containing at least one ether oxygen in the chain in the fluorocarbon terminal chain, wherein the fluorocarbon terminal chain has -V (C _x F
_2x O) _z C _y F represented by _{2y + 1,} x is each C _x F _2x O
To an integer from 1 independently to 10, y is an integer from 1 to 10, z is an integer from 1 to 10, V is a single _{bond, -COO-C r H 2r -} , - O-C _r H _2r- , -O-
_{(C s H 2s O) t} -C r 'H 2r' -, - OSO 2 -, - SO
_{2 -, - SO 2 -C r} H 2r -, - C r H 2r -, - C r H 2r -
_{N (C p H 2p + 1} ) -SO 2 -, - C r H 2r -N (C
_{p H 2p + 1) -CO-,} r and r 'is an integer of independently 1 to 20, s is an integer from 1 independently each C _s H _2s O to 10, t is An integer from 1 to 6, and p is an integer from 0 to 4 .
7. The liquid crystal element according to any one of 6 . 8. The compound according to claim 1, wherein the fluorine-containing liquid crystal compound is a compound represented by the following general formula II .
A liquid crystal device according to. [General formula II] A, b, and c each independently represent 0 or an integer of 1 to 3. However, a + b + c is at least 2. M, N
Are independently -COO-, -COS-, -COS
e -, - COTe -, - (CH 2 CH 2) d - (d is an integer of from 1 4), - C≡C -, - CH = CH -, -
CH = N—, —CH ₂ —O—, —CO—, —O—, a single bond, and the orientation may be any. Each X,
Y and Z are independently -H, -Cl-, -F, -Br, -I,
_{-OH, -OCH 3, -CH 3,} -CF 3, -OCF 3, -
CN, representing the -NO _2. L, m, and n each independently represent an integer of 0 to 4. G is _{-COO-C e H 2e -,} - O
_{-C e H 2e -, - O} (C e "H 2e" O) t -C e 'H
_{2e '-, - C e H} 2e -, - OSOO -, - SOO -, -
_{SOOC e H 2e -, - C} e H 2e -N (C p H 2p + 1) -SO
_{O -, - C e H 2e} -N (C p H 2p + 1) -CO- (e, e '
Each independently represents an integer from 1 to 20, and p is 0
Represents an integer from to 4. e "is the respective (C _e" H
_2e "O) independently represents an integer of 1 to 10, t is an integer from 1 to 6.) Represents .A is a -O- (C _f H _2f
−O) _u −C _{f ′} H _{2f ′ + 1} , − (C _f H _2f −O) _u −C _{f ′
H 2f '+ 1, -C f} H 2f -R', - O-C f H 2f -R ', -
_{COO-C f H 2f -R '} , - OCO-C f H 2f -R'
(R 'is _{-Cl, -F, -CF 3, -NO} 2, -CN, -
_{H, -COO-C f 'H} 2f' + 1, -OCO-C f 'H
_{2f '+ 1} , and f and f' each independently represent an integer of 1 to 20. u is an integer of 1 to 10. ),
A may be linear or branched. R is _{- (C x F 2x O)} z C
_y F _{2y + 1} , x is independently an integer from 1 to 10 for each C _x F _2x O, y is an integer from 1 to 10 and z is an integer from 1 to 10 . ) 9. The liquid crystal device according to claim 8, wherein the compound represented by the general formula II is a compound comprising a phenylpyrimidine core. 10. A liquid crystal device using the liquid crystal element according to claim 1.