JPH0641535A - Liquid crystal composition, liquid crystal element and liquid crystal device - Google Patents

Abstract

PURPOSE:To provide a liquid crystal composition having an inclination angle deltaof smectic phase layer increasing with the lowering of temperature, exhibiting an inflection point on the delta-temperature curve, keeping the state of deltanot equal to 0 even in the further lowering of the temperature, having excellent quick-response and low-temperature storability and useful for a liquid crystal display element, etc. CONSTITUTION:The liquid crystal composition is a ferroelectric liquid crystal composition containing preferably 10-80% of a compound of formula I (each of R1 and R2 is a 1-18C alkyl, etc.; each of X1 and X2 is a single bond, O, COO, etc.; A1 is a group of formula II, etc.; A2 is a single bond or A1). The value of the inclination angle delta of the smectic phase layer of the composition increases with the lowering of temperature from the upper limit of the environmental temperature range (-30 to +70 deg.C, exhibits an inflection point to give a peak, decreases after passing the inflection point and keeps the state of deltanot equal to O even in the further lowering of temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal composition, a liquid crystal element and a liquid crystal device using the same, and more specifically, a liquid crystal using a novel liquid crystal composition having improved response characteristics to electric field and low temperature storage stability. The present invention relates to a liquid crystal element used for a display element, a liquid crystal-optical shutter, etc., and a liquid crystal device using the liquid crystal element for display.

[0002]

2. Description of the Related Art The use of liquid crystal devices having bistability has hitherto been carried out by Clark and Lagawell.
rwall) (JP-A-56-10)
7216, US Pat. No. 4,367,924, etc.).

Bistable liquid crystals are generally chiral smectic C phase (SmC ^* phase) or H phase (SmH ^* phase).
A ferroelectric liquid crystal having is used.

This ferroelectric liquid crystal has a bistable state consisting of a first optical stable state and a second optical stable state with respect to an electric field, and for example, the first optical stable state with respect to one electric field vector. The liquid crystal is aligned in the stable state, and the liquid crystal is aligned in the second optically stable state with respect to the other electric field vector.
Further, this type of liquid crystal has a property (bistability) of taking one of the two stable states described above in response to an applied electric field and maintaining that state when no electric field is applied.

In addition to the above-mentioned characteristic of having bistability, the ferroelectric liquid crystal has an excellent characteristic of high-speed response. This is because the spontaneous polarization of the ferroelectric liquid crystal and the applied electric field act directly to induce the transition of the alignment state.
It is 3 to 4 orders faster than the response speed due to the effect of the dielectric anisotropy and the electric field.

Further, in general, in the case of a liquid crystal element utilizing the birefringence of liquid crystal, the transmittance under orthogonal Nicols is I / I _O = sin ² 4θ _a sin ² (Δnd / λ) π (where I _O Is the incident light intensity, I is the transmitted light intensity, θ _a is the apparent tilt angle defined below, Δn is the refractive index anisotropy, d is the thickness of the liquid crystal layer, and λ is the wavelength of the incident light.) It is represented by. The apparent chilled angle θ _a in the above-mentioned non-helical structure appears as the angle in the average molecular axis direction of the twisted liquid crystal molecules in the first and second alignment states. According to the above equation, the apparent tilt angle θ _a is 2
The maximum transmittance is obtained at an angle of 2.5 °, and it is desirable that the tilt angle θ _a in the non-helical structure that realizes bistability is as close as possible to 22.5 °.

However, the alignment method that has been used so far, particularly the alignment method using a rubbing-treated polyimide film, is applied to the ferroelectric liquid crystal having a non-helical structure and exhibiting the bistability described by Clark and Lagerwall. When applied, it had the following problems.

That is, the apparent tilt angle θ _a in the ferroelectric liquid crystal having a non-helical structure obtained by aligning with a conventional rubbing-treated polyimide film (angle ½ forming the molecular axes of two stable states) Was significantly smaller than the cone angle of the ferroelectric liquid crystal (angle θ of 1/2 of the apex angle of the triangular pyramid shown in FIG. 3). In particular, the apparent tilt angle θ _a in the non-helical ferroelectric liquid crystal obtained by aligning with the conventional rubbing-treated polyimide film is
Generally, it is about 3 ° to 8 °, and the transmittance at that time is 3 at most.
It was about 5%.

Smectic liquid crystals generally have a layered structure, but when the SmA phase transitions to the SmC phase or the SmC ^* phase, the layer spacing shrinks, so that the liquid crystal layer represented by 21 is bent at the center of the upper and lower substrates as shown in FIG. Has a different structure (chevron structure). As shown in the figure, the bending direction is the orientation state (CI that appears immediately after the transition from the high temperature phase to the SmC ^* phase).
(Orientation state) portion 22 and the orientation state (C2) which appears when mixed with the CI orientation state when the temperature is further lowered.
There can be two cases in the case of the (alignment state) portion 23.
After that, when a specific combination of an alignment film having a high pretilt and liquid crystal is used, the above C1 → C2 transition does not easily occur, and depending on the liquid crystal material, the C2 alignment state does not occur at all, and it has been conventionally found in the C1 alignment. In addition to the two stable states with low contrast in which the director of the liquid crystal is twisted between the upper and lower substrates (hereinafter referred to as splay state), another two stable states with high contrast (hereinafter referred to as uniform state) Was found to appear.

Further, these states transit to each other when an electric field is applied. When a weak positive and negative pulse electric field is applied, a transition between the splay 2 states occurs, and when a strong positive and negative pulse electric field is applied, a transition between the uniform 2 states occurs.

By using the uniform 2 state, it is possible to realize a display device which is brighter and has a higher contrast than the conventional one.

Therefore, as the display element, the entire screen is unified in the C1 orientation state, and the high contrast 2 in the C1 orientation is used.
It is expected that a display of higher quality than the conventional one can be realized by using the two states of monochrome display.

As described above, the C1 orientation is not generated.
In order to realize the oriented state, it is necessary to satisfy the following conditions.

That is, as shown in FIG. 3, C1 orientation and C2
The director near the substrate in the orientation is on the cone 31 of FIGS. 3 (a) and 3 (b), respectively. As is well known, the rubbing causes the liquid crystal molecules at the substrate interface to form an angle α (angle formed by the substrate 20 and the liquid crystal molecules 33 in FIG. 3) with respect to the substrate, which is the rubbing direction (see FIG. 2). In addition, in FIG. 3, the liquid crystal molecules hang their heads (the tip becomes floating) in the direction A.
From the above, between the cone angle Θ of the liquid crystal, the pretilt angle α and the layer tilt angle δ (angle formed by the substrate normal 32 of FIG. 3 and the liquid crystal molecular layer 21), in the case of C1 orientation, Θ + δ> α C2 orientation Then, the relation of Θ−δ> α must be established.

Therefore, the condition for producing the C1 orientation without producing the C2 orientation is Θ−δ <α, that is, Θ <α + δ (I).

Further, from a simple consideration of the torque that the molecules at the interface receive when switching from one position to the other by the electric field, α> δ (II) is obtained as a condition under which the interface molecules are likely to switch. .

Therefore, in order to form the C1 orientation state more stably, it is effective to satisfy the relation of the formula (II) in addition to the relation of the formula (I).

As a result of further experiments under the conditions of the formulas (I) and (II), the apparent tilt angle θ _a of the liquid crystal of the conventional liquid crystal device which does not satisfy the conditions of the formulas (I) and (II). In the case of the present invention satisfying the conditions of the formulas (I) and (II), it increases from about 3 ° to 8 ° to about 8 ° to 16 °, and between the cone angle Θ of the liquid crystal, Θ> It was empirically obtained that the relational expression of θ _a > θ / 2 (III) holds.

As described above, (I), (II) and (I
It has been clarified that a display capable of displaying a high-contrast image can be realized if the condition of the formula (II) is satisfied (JP-A-3-252624).

In order to stably form the C1 orientation state and obtain a good orientation, the rubbing directions of the upper and lower substrates are 2 ° to 25 °.
Cross rubbing shifted in the range of ° (crossing angle) is also extremely effective.

By the way, a display device using a chiral smectic liquid crystal element is a display device capable of achieving a large screen and high definition far exceeding that of a conventional CRT or TN type liquid crystal display. As the resolution becomes higher, the frame frequency (one screen forming frequency) becomes lower frequency. Therefore, the screen rewriting speed, the smooth scroll on the character editing and graphics screens, and the moving image display speed such as cursor movement. There was a problem that was slow. A solution to this problem is disclosed in JP-A-60-3.
No. 1120, JP-A No. 1-140198, and the like.

That is, a display panel in which scan electrodes and information electrodes are arranged in a matrix, a means for selecting all or a predetermined number of scan electrodes (selection by this means is called full surface writing), and a total or predetermined number of scan electrodes. It means that a display device having a means for partially selecting (a case of selecting by this means is called partial writing) is used. This enables high-speed display by performing partial moving image display by partial writing, and can achieve both partial writing and full writing.

As described above, the above (I) and (II)
It has been clarified that by driving the liquid crystal element satisfying the conditions of the formulas (III) and (3) with the display device capable of partial writing, a high-contrast image can be realized at a high speed in a large screen and a high definition display.

As described above, the ferroelectric liquid crystal potentially has extremely excellent characteristics, and by utilizing such characteristics, many of the problems of the conventional TN type element are considerably essential. Improvement has been obtained. In particular, it is expected to be applied to high-speed optical optical shutters and high-density large-screen displays. For this reason, extensive research has been conducted on liquid crystal materials having ferroelectricity, but the ferroelectric liquid crystal materials developed to date are sufficient for use in liquid crystal elements, including low-temperature storability and fast response. It is hard to say that they have such characteristics.

[0025]

In practice, when the operating temperature range of the display is set to about 5 to 35 ° C., the ambient temperature of the liquid crystal device itself is set to about 5 to 50 ° C. due to heat accumulation from the periphery of the device. Become. The change in the response speed of a normal ferroelectric liquid crystal with respect to temperature is quite large because it changes greatly depending on the viscosity, and is more than ten times at 5 to 50 ° C, which exceeds the range of adjustment by the drive voltage. Is the current situation. Also, when a large-screen display is put to practical use, it is necessary to be able to output images under the same driving conditions for in-plane temperature distribution of several degrees to several tens of degrees. The temperature dependence of the driving condition is too large.

According to the research conducted by the present inventors, almost the same liquid crystal composition, in which the side chain lengths of some of the constituent liquid crystal compounds are slightly different, does not significantly change the viscosity coefficient and the magnitude of spontaneous polarization. In some cases, the temperature characteristics of the response speed (especially on the low temperature side) were significantly different. It was found that this phenomenon is largely due to the temperature characteristic of the inclination angle δ of the layer near the temperature at which the difference in the temperature characteristic appears.

This is because the net size of the spontaneous polarization director in the substrate normal direction decreases as the inclination of the liquid crystal layer increases, and the effective action with the external electric field decreases. Conceivable.

If the inclination angle δ of the layer shows a decreasing tendency with respect to the temperature drop on the low temperature side where the temperature dependence of the response speed becomes large, the temperature of the response speed is higher than that of the conventional one which increases monotonously. Dependencies are greatly improved.

According to the study by the present inventors, Japanese Patent Application No. 2-3
As disclosed in the specification of No. 07802, the skeleton structure, side chain length, compatibility of the component combination, etc. of the liquid crystal composition constituent components are mentioned as means for adjusting the size of the tilt angle δ of the layer and the temperature characteristics. However, in general, a liquid crystal compound of a type that widens the temperature range of SmA often greatly changes the temperature characteristic of δ.

That is, the angle between the chevron structure layer in the smectic phase of the ferroelectric liquid crystal and the substrate normal is
The “layer inclination angle δ” is a ferroelectric property characterized by having such a temperature characteristic that the value of δ increases with a decrease in temperature and then decreases (has a maximum value). It is possible to provide a liquid crystal element and a display device in which the driving condition is less dependent on temperature by using the liquid crystal composition shown in.

However, according to further studies by the present inventors,
The following new problems were found. Δ mentioned above
When the liquid crystal element using the liquid crystal composition having the maximum temperature characteristic of No. 3 is further cooled over the temperature range used as the display, the value of δ becomes 0 on the low temperature side of the SmC ^* phase.
That is, the layer structure in the smectic phase may show a bookshelf structure from the chevron structure (the temperature at this time is represented by TδS).

In such a liquid crystal composition, the T
When the liquid crystal element is stored at δS or less, the temperature rises again, and even if the temperature reaches the temperature for use as a display, the layer tilt angle δ, the apparent tilt angle (1 / the angle between two extinction positions).
(Defined in Section 2), contrast, the alignment state of liquid crystal molecules, and many other properties change, and cannot return to the initial stage.

This significantly deteriorates the display characteristics of the display, which is a serious problem when the liquid crystal composition or the liquid crystal element is stored and used at a low temperature.

In the smectic phase state, the liquid crystal composition enclosed in the cell stably exists in the smectic phase even at a temperature below the smectic phase → crystallization phase transition temperature in the bulk state. , No crystallization or segregation occurs (supercooled state).

From the above, it was found that the actual lower limit temperature of the storage temperature is often determined by the above-mentioned TδS rather than the melting point.

Further, the layer tilt angle δ, the pretilt angle α of the liquid crystal element, and the cone angle Θ of the liquid crystal have an alignment state satisfying the relations represented by Θ <α + δ and α> δ, and the alignment state The liquid crystal in 2 exhibits at least two optically stable states, and the apparent tilt angle θ _a and the cone angle Θ of the liquid crystal satisfy the relationship of Θ> θ _a > Θ / 2, that is, the C1 uniform state. It was also found that in the above, the above-mentioned changes in contrast and alignment state were more remarkable.

The change in orientation state here means Θ
> Θ _a > θ / 2 conditions that do not satisfy the condition that the orientation state is extremely low appear, or “streak defects” run like stripes in a direction almost perpendicular to the rubbing direction, and different before storage at low temperature. The two stable parts were
After low-temperature storage, they are no longer equivalent, that is, even if both parts are in a stable state at the same time, there is a "deviation of the darkest axis" in which the axes of the extinction positions are slightly different.
The shift of the darkest axis remains because the extinction axis is different even when the temperature rises and the SmA phase is reached.

Therefore, in the present invention, _a liquid crystal composition having a small temperature dependence of driving conditions in a wide temperature range including a room temperature range and having little change in δ, θ _a , C / R and alignment state due to low temperature storage, An object is to provide a liquid crystal element and a display device using these.

[0039]

Means and Actions for Solving the Problems The present inventors define the angle between the layer and the substrate normal in the smectic phase of the ferroelectric liquid crystal used for the liquid crystal element as the “layer tilt angle δ”. It has been found that the above problem can be solved and the display characteristics and the low temperature storage stability of the liquid crystal element can be remarkably improved by the fact that the value of δ has a specific temperature characteristic.

That is, a ferroelectric liquid crystal composition having a smectic phase, which is assumed to be experienced when a liquid crystal device including the liquid crystal composition is used, has a predetermined ambient temperature range (−30 ° C. to 70 ° C.). (° C), the value of the tilt angle δ of the layer in the smectic phase of the liquid crystal composition first increases with a temperature drop from the upper limit of the ambient temperature range,
It has an inflection point that gives a maximum value, and decreases after passing through the inflection point,
By using a liquid crystal composition characterized in that the value of δ does not become 0 with further temperature drop, it is possible to prevent the change of the alignment state in the above environmental temperature range.

Further, as a temperature characteristic of the value of the inclination angle δ of the layer, the value of δ shows a transition point that increases with a decrease in temperature and then decreases, and then further decreases in temperature. When a ferroelectric liquid crystal composition is used in which the value of δ does not become 0 and increases again, the contrast, which exceeds the storage temperature range normally assumed and is stored at a lower temperature, It was also found that there was no change in the alignment state.

That is, in the present invention, when the layer inclination angle in the smectic phase of the ferroelectric liquid crystal is δ, the value of δ is the operating temperature range or storage temperature range (-30 to 70).
Temperature characteristic of having a transition point (hereinafter referred to as a maximum value) that increases with a decrease in temperature and then decreases with decreasing temperature, and the value of δ becomes 0 in the operating temperature range and the storage temperature range. The present invention provides a liquid crystal composition characterized by not being present.

Further, in the present invention, if the inclination angle of the layer in the smectic phase of the ferroelectric liquid crystal is δ, the value of δ increases with a decrease in temperature, and then decreases with a further decrease in temperature. The present invention provides a liquid crystal composition characterized by exhibiting a temperature characteristic having a transition point (hereinafter referred to as a maximum value) and increasing again before the value of δ becomes 0.

In addition, the present invention provides a liquid crystal element comprising a pair of substrates which face each other with the liquid crystal sandwiched therebetween and which have electrodes for applying an electric field to the liquid crystal formed on the opposing surfaces. However, if the inclination angle of the layer in the smectic phase of the ferroelectric liquid crystal is δ, the value of δ increases with the temperature drop in the operating temperature range or the storage temperature range (-30 to 70 ° C). , Showing a temperature characteristic with a transition point (hereinafter referred to as maximum value) that decreases,
Further, the present invention provides a liquid crystal element comprising a liquid crystal composition, wherein the value of δ does not become 0 in the use temperature range and the storage temperature range.

Further, the present invention provides a liquid crystal element comprising a liquid crystal and a pair of substrates which face each other with the liquid crystal sandwiched therebetween and which are provided with electrodes for applying an electric field to the liquid crystal respectively on the opposing surfaces. However, if the inclination angle of the layer in the smectic phase of the ferroelectric liquid crystal is δ, the value of δ increases with a decrease in temperature, and then decreases when the temperature further decreases (hereinafter referred to as the maximum point). The present invention provides a liquid crystal device comprising a liquid crystal composition which exhibits a temperature characteristic having a value) and which increases again before the value of δ becomes zero.

In the present invention, the liquid crystal is opposed to the liquid crystal while sandwiching the liquid crystal, and electrodes for applying a voltage to the liquid crystal are formed on the opposite surfaces, and a uniaxial alignment axis for aligning the liquid crystal. In a liquid crystal element comprising a pair of substrates that have been subjected to an alignment treatment in which they intersect each other at a predetermined angle,
When the pretilt angle α of the liquid crystal element, the cone angle Θ of the liquid crystal, and the tilt angle of the layer in the ferroelectric smectic phase are δ, the alignment state of the liquid crystal satisfies the relations of Θ <α + δ and α> δ. And the liquid crystal in the alignment state exhibits at least two optically stable states, and the apparent tilt angle θ _a and the cone angle Θ of the liquid crystal defined by 1/2 of the angle formed by these optical axes. Has an orientation state satisfying the relationship of Θ> θ _a > Θ / 2, and further, the value of δ of the liquid crystal is experienced when a liquid crystal device including the liquid crystal composition is used. Specified ambient temperature range (-
30-70 ° C), the temperature increases and the temperature decreases,
After that, it exhibits a temperature characteristic that has a transition point (hereinafter referred to as a maximum value) that decreases, and δ
The present invention provides a liquid crystal device made of a liquid crystal composition, wherein the value of is not 0.

Further, according to the present invention, the liquid crystal is opposed to the liquid crystal while sandwiching the liquid crystal, and electrodes for applying a voltage to the liquid crystal are respectively formed on the opposed surfaces, and a uniaxial alignment axis for aligning the liquid crystal. In a liquid crystal element comprising a pair of substrates that have been subjected to an alignment treatment in which they intersect each other at a predetermined angle,
When the pretilt angle α of the liquid crystal element, the cone angle Θ of the liquid crystal, and the tilt angle of the layer in the ferroelectric smectic phase are δ, the alignment state of the liquid crystal satisfies the relations of Θ <α + δ and α> δ. And the liquid crystal in the alignment state exhibits at least two optically stable states, and the apparent tilt angle θ _a and the cone angle Θ of the liquid crystal defined by 1/2 of the angle formed by these optical axes. Has an orientation state satisfying the relationship of Θ> θ _a > Θ / 2, and further, the value of δ of the liquid crystal increases with a decrease in temperature and then decreases with a further decrease in temperature. Provided is a liquid crystal device comprising a liquid crystal composition which exhibits a temperature characteristic having a transition point (hereinafter referred to as a maximum value) and increases again before the value of δ becomes 0. is there.

Further, as a condition useful for increasing the screen rewriting speed (frame frequency) of the liquid crystal element,
The maximum value δ _{MAX of the} value of δ is preferably 20 ° or less, more preferably 15 ° or less.

Further, as one of effective means for giving the liquid crystal composition the temperature characteristic of δ as described above, at least one indane compound represented by the general formula (I) is contained in the liquid crystal composition. It can be included.

[0050]

[Outside 10]

Structures of more preferable compounds among the compounds represented by the general formula (I) are shown below.

[0052]

[Outside 11]

[0053]

[Outside 12] (In the above formula, R ₁ and R ₂ are linear or branched alkyl groups having 1 to 18 carbon atoms, and one or two or more non-adjacent methylene groups in the alkyl group are shown below. And hydrogen atoms may be replaced with F. —O—, —S—,

[0054]

[Outside 13] -CH = CH-, -C≡C-, in which case the general formula (I)
The ratio of the compound is 10 to 8 with respect to the entire composition.
It is preferably 0%, more preferably 20 to 40
% Is desirable. ) Furthermore, the SmC ^* phase is taken in a wide temperature range including room temperature, the response speed and the like can be easily adjusted, and the value with respect to the value of the inclination angle δ of the layer is decreased as the temperature falls within the environmental temperature range. As a means for giving a temperature characteristic having a characteristic that the temperature increases and decreases after passing through the inflection point that gives the maximum value, and does not become 0.
The liquid crystal composition may include a pyrimidine compound represented by the general formula (I) or the general formula (II).

[0055]

[Outside 14] (R ₁ , R ₂ ; C ₁ -C ₂₀ straight-chain or branched alkyl, wherein one or two non-adjacent —CH ₂ — groups are —O.
-,

[0056]

[Outside 15] May be replaced with, and hydrogen of —CH ₂ — is Cl,
It may be substituted with F or CF ₃ .

M and n are 0, 1, and 2, and m + n is 1 or 2. ) In addition, examples of more preferable specific structural formulas of the liquid crystal compound represented by the general formula (II) are shown below.

[0058]

[Outside 16] (In the above formula, R ₁ and R ₂ are linear or branched alkyl groups having 1 to 18 carbon atoms which may have a substituent such as F.)

In this case, the proportion of the compounds of formula (I) and formula (II) is preferably 10 to 80% as a weight percentage with respect to the whole liquid crystal composition. More preferably 20
It is desirable to be -40%.

Other suitable compounds that can be contained include the liquid crystalline compounds represented by the general formulas (III) to (V).

[0061]

[Outside 17] R ₃ , R ₄ ; C ₁ -C ₂₀ linear or branched alkyl, wherein one or two non-adjacent —CH ₂ — groups are —O.
-,

[0062]

[Outside 18] May be replaced with. ) Also has the general formula (III)
A more preferable specific structural formula of the liquid crystal compound represented by is shown below.

[0063]

[Outside 19] (In the above formula, R ₃ and R ₄ are linear or branched alkyl groups having 1 to 18 carbon atoms which may have a substituent such as F.)

[0064]

[Outside 20] Z; -O-, -S-

[0065]

[Outside 21] R ₅ , R ₆ ; C ₁ -C ₂₀ branched or straight-chain alkyl, one or two non-adjacent —CH ₂ — are —O—,

[0066]

[Outside 22] May be replaced with. ) Further, a more preferable specific structural formula of the liquid crystal compound represented by the general formula (IV) is shown below.

[0067]

[Outside 23] (In the above formula, R ₅ and R ₆ are linear or branched alkyl groups having 1 to 18 carbon atoms which may have a substituent such as F.)

[0068]

[Outside 24] (R ₇ ; hydrogen, Cl, F, CF ₃ , (CN) or C _{1 to} C
₂₀ straight-chain or branched alkyl, one or two non-adjacent —CH ₂ — are —O—,

[0069]

[Outside 25] May be replaced with.

R ₈ ; C ₁ -C ₂₀ straight-chain or branched alkyl, wherein one or two non-adjacent --CH ₂ --groups are --O--,

[0071]

[Outside 26] May be replaced with.

X ₁ ; hydrogen or fluorine

[0073]

[Outside 27] X ₂ ; hydrogen, fluorine (CF ₃ , CN) 1; 0, 1) Further, more preferable specific structural formulas of the liquid crystal compound represented by the general formula (V) are shown below.

[0074]

[Outside 28] (In the above formula, R ₇ and R ₈ are linear or branched alkyl groups having 1 to 18 carbon atoms which may have a substituent such as F.)

Further, in the above-mentioned liquid crystal element exhibiting the C1 uniform alignment state, the contrast and the alignment state change remarkably during low temperature storage as described above.

Therefore, according to the present invention, the layer has the C1 uniform orientation state, and the value of the inclination angle δ of the layer increases with a decrease in temperature in the operating temperature range or the storage temperature range of the display device. A liquid crystal device and a C1 uniform characterized in that the liquid crystal composition has a temperature characteristic having a decreasing transition point and has a value of δ not 0 in the use temperature range and the storage temperature range. It has an orientation state, the value of δ increases with a decrease in temperature, and then shows a decrease, and then the value of δ does not become 0 even with a further decrease in temperature, and has a temperature characteristic of increasing again. A liquid crystal device characterized by using a liquid crystal composition.

FIG. 1 is a schematic sectional view showing an example of a liquid crystal element having a chiral smectic liquid crystal layer of the present invention for explaining the structure of a crystal element utilizing ferroelectricity.

In FIG. 1, reference numeral 1 is a chiral smectic liquid crystal layer, 2 is a glass substrate, 3 is a transparent electrode, 4 is an alignment layer, 5 is a spacer, 6 is a lead wire, 7 is a power source, 8 is a polarizing plate, and 9 is a light source. Is shown.

The two glass substrates 2 were each coated with In ₂
A transparent electrode 3 made of a thin film of O ₃ , SnO ₂ or ITO (Indium-Tin Oxide) is covered. A polymer thin film such as polyimide is rubbed on it with gauze or acetate flocking cloth to form an alignment layer for arranging liquid crystals in the rubbing direction. Further, as an insulating material for forming the film, for example, silicon nitride, silicon carbide containing hydrogen, silicon oxide, boron nitride, boron nitride containing hydrogen, cerium oxide, aluminum oxide, zirconium oxide. An insulating layer of inorganic material such as titanium oxide or magnesium fluoride is formed, on which polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate. , An organic insulating material such as polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin or photoresist resin as an orientation control layer,
The orientation control layer may be formed of two layers, or may be a single layer of an inorganic material insulating orientation control layer or an organic material insulating orientation control layer. If this alignment layer is an inorganic type, it can be formed by a vapor deposition method, and if it is an organic type, a solution in which an organic substance is dissolved or its precursor solution (0.1 to 20% by weight in a solvent, preferably 0.2 to 10% by weight) is used. % By weight) and applied by a spinner coating method, a dip coating method, a screen printing method, a spray coating method, a roll coating method, or the like, and cured and formed under predetermined curing conditions (for example, under heating).

The layer thickness of the alignment layer is usually 30Å to 1 μm, preferably 40Å to 3000Å, more preferably 40Å to
1000Å is suitable.

The two glass substrates 2 are held by the spacer 5 at arbitrary intervals. For example, there is a method in which silica beads and alumina beads having a predetermined diameter are used as spacers and sandwiched between two glass substrates, and the periphery is sealed with a sealing material, for example, an epoxy adhesive material. Alternatively, a polymer film or glass fiber may be used as a spacer. A liquid crystal exhibiting ferroelectricity is enclosed between the two glass substrates.

The chiral smectic liquid crystal layer 1 in which the chiral smectic liquid crystal is enclosed is generally 0.5 to 20.
μm, preferably 1 to 5 μm.

Further, this ferroelectric liquid crystal has an SmC ^* phase (chiral smectic C phase) in a wide temperature range including room temperature (particularly low temperature side), and when it is used as an element, it has a driving voltage margin and a driving temperature. A wide margin is desired.

Further, in order to exhibit good uniform alignment and obtain a monodomain state especially when used as an element, the ferroelectric liquid crystal has an isotropic phase to a Ch phase (cholesteric phase)-
It is desirable to have an example of a phase transition system of SmA (smectic phase) -SmC ^* (chiral smectic C phase).

The transparent electrode 3 is connected to an external power source 7 by a lead wire.

A polarizing plate 8 is attached to the outside of the glass substrate 2.

FIG. 1 is a transmission type.

Further, the present invention provides a liquid crystal device comprising the above liquid crystal element and a drive circuit for the liquid crystal element and a light source.

By using the liquid crystal device of the present invention in the display panel section and taking the communication information synchronizing means by the data format as the image information having the scanning line address information and the SYNC signal shown in FIGS. 4 and 5, a liquid crystal display device is obtained. To realize.

In the figure, the symbols are as follows. 101 ferroelectric liquid crystal display device 102 graphics controller 103 display panel 104 scanning line driving circuit 105 information line driving circuit 106 decoder 107 scanning signal generating circuit 108 shift register 109 line memory 110 information signal generating circuit 111 driving control circuit 112 GCPU 113 host CPU 114 VRAM

The image information is generated by the graphics controller 102 on the main unit side and transferred to the display panel 103 according to the signal transfer means shown in FIGS. The graphics controller 102 is a CP
U (central processing unit, hereinafter abbreviated as GCPU 112) and VRAM (memory for storing image information) 114 are used as cores for managing image information and communication between the host CPU 113 and the liquid crystal display device 101, and controlling the present invention. The method is mainly implemented on the graphics controller 102.

A light source is arranged on the back surface of the display panel.

The cone angle Θ, the apparent tilt angle θ _a , the inclination angle δ of the layer, the contrast C / R and the pretilt angle α according to the present invention were measured as follows.

Measurement of cone angle Θ While applying an AC voltage of ± 30 V to ± 50 V, 100 Hz between the upper and lower substrates of the FLC element, the FLC element placed between them is rotated horizontally under the crossed Nicols. The first extinction position (the position where the transmittance is lowest) and the second extinction position are searched for while detecting the optical response with Photomal (manufactured by Hamamatsu Photonics KK). At this time, 1/2 of the angle from the first extinction position to the second extinction position was defined as the cone angle Θ.

Measurement of Apparent Tilt Angle θ _a After applying a single pulse of the threshold value of the liquid crystal, the FLC element placed between them under no electric field and under orthogonal crossed Nicols was rotated horizontally with the polarizing plate to obtain the first tilt angle θ _a . After searching for the extinction position and then applying a pulse having a polarity opposite to that of the above-mentioned single-shot pulse, the second extinction position is searched for under no electric field. The angle ½ from the first extinction position to the second extinction position at this time was defined as θ _a .

Measurement of Layer Inclination Angle δ Basically, the method disclosed by Clark and Lagerwol (Japan Display '86, Sep.
30-Oct. 2, 1986, pp. 456-458)
Alternatively, the method of Ouchi et al. (JJAP, 27 (5)
(1988) pp. L725-728) was used.

A rotating anticathode type X-ray diffractometer manufactured by MAC Science Co. was used as a measuring device, and copper Kα ray was used as an analysis line. For the liquid crystal cell, 80 μm thick glass (trade name: Microsheet, manufactured by Corning Incorporated) was used as the substrate glass to reduce the absorption of X-rays as much as possible, and the other ordinary cell forming steps were used as they were. To measure the layer spacing of liquid crystal, apply bulk liquid crystal on the sample glass and perform 2 as in the case of normal powder X-ray diffraction.
It was determined by performing θ / θscan.

The tilt angle δ was measured by forming a cell with a gap of 80 μm using the same 80 μm thick glass as a spacer as described above, and gradually cooling from the isotropic phase while applying a magnetic field in the direction parallel to the substrate in the electromagnet to perform horizontal alignment. A treated cell was prepared.

An X-ray detector was fitted to the diffraction angle 2θ for which the above-mentioned layer spacing was obtained, the cell was θ-scanned, and δ was calculated by the method described in the above document.

Further, instead of the 80 μm magnetic field orientation cell,
Using LP-64 (manufactured by Hitachi Chemical Co., Ltd.) as an alignment film and rubbing-treated cells with a cell gap of 1.2 μm,
Approximately the same value of δ can be obtained in the temperature range of about -20 ° C to 60 ° C.

As an alignment film, SP-71 described later is used.
Almost the same value was obtained when 0 or SP-510 was used (the pretilt angle when these cells were used was 1 to 3 °).

However, instead of the above alignment film, LQ-1
When 802 (manufactured by Hitachi Chemical Co., Ltd.) is used, the pretilt angle of the cell is 8 to 25 °, and the value of δ in that cell is 0.
It showed a large value of about 2 to 2 °. In this case, the value of δ is a unique value for each liquid crystal element.

In the following examples, unless otherwise specified, the value of δ was measured with the 80 μm gap cell oriented in the magnetic field.

Further, according to Rieker et al., The inclination angle δ of the layer is
And the layer spacings d _c and d _A of SmC ^* and SmA have the following relationship. ("" Ch
evron "Local Layer Structu
re in Surface-Stabilized
Ferroelectric Smatic-CC
ells ”, Phys. Rev. Lett., 59,
p. 2658 (1987) cos δ = d _C / d _A

Measurement of Contrast C / R While applying a driving waveform of Vp _-p = 30V between the upper and lower substrates of the liquid crystal element, the liquid crystal element disposed under the crossed Nicols was rotated horizontally with the deflection plate, and Then, the first extinction position is searched for by the photomul, and the liquid crystal element is fixed at that position.

Then, the drive waveform was changed to rewrite the observed portion to the "bright state", and the contrast was defined as the ratio of the output voltage of the photomultiplier at that time and the output voltage at the extinction position.

Measurement of Pretilt Angle α The pretilt angle α was measured by the crystal rotation method.
(J.J.A.P. V. 119 (1980) No. S
It was calculated according to “Hort Notes 2031)”. Also
As a liquid crystal for measuring the pretilt angle, a ferroelectric liquid crystal (chip
So-10-made CS-1014) is a compound represented by the following structural formula
A standard liquid crystal was prepared by mixing 20% by weight of the substances.

[0108]

[Outside 29]

The liquid crystal composition used as the standard liquid crystal exhibited an SmA phase at 10 to 55 ° C. The measurement procedure is a helium-neon laser having a polarization plane that makes an angle of 45 ° with the rotation axis while rotating the liquid crystal panel injecting the standard liquid crystal on the plane perpendicular to the upper and lower substrates and including the alignment treatment axis (rubbing axis). The light was irradiated from the direction perpendicular to the rotation axis, and the transmitted light intensity was measured by a photodiode through a polarizing plate having a transmission axis parallel to the incident polarization plane on the opposite side. Then, the pretilt angle α was obtained by a simulation in which the following theoretical curve, Formulas 3 and 4, were fitted to the spectrum of the transmitted light intensity generated by the interference.

[0110]

[Outside 30] N _o: ordinary refractive index N _e: extraordinary refractive index phi: rotation angle of the liquid crystal panel T (φ): transmitted light intensity d: cell thickness lambda:
Incident light wavelength

[0111]

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.

In the following examples, all "parts" indicate "parts by weight".

In addition, the liquid crystal compositions A to L used in the following examples contain the above-mentioned indane compounds, pyrimidine compounds and compounds represented by the general formulas (III) to (V) at appropriately different ratios. It is a mixed liquid crystal compound obtained by mixing.

To give some specific examples, Liquid Crystal Composition I was prepared by mixing the compounds shown below in the proportions shown below.

[0115]

[Outside 31]

[0116]

[Outside 32]

The liquid crystal composition K was prepared by mixing the compounds shown below in the proportions shown below.

[0118]

[Outside 33]

[0119]

[Outside 34]

Further, the liquid crystal composition represented by X is a liquid crystal composition in which the following liquid crystal compounds are mixed in respective proportions.

[0121]

[Outside 35]

[0122]

[Outside 36] Table 1 shows the phase transition temperatures of the liquid crystal compositions A to L and X, the indane compound content ratio, and the pyrimidine compound content ratio.

[0123]

[Table 1]

Reference Example 1 δ measured by X-ray diffractometry using a liquid crystal material CS-1017 manufactured by Chisso Co., Ltd. such that the temperature characteristic of the inclination angle δ of the layer monotonically increases with a decrease in temperature. The temperature characteristics of the value (°) of are shown in (Table 1-1).

The upper limit of the temperature at which the measurement of the temperature characteristic experiments carried out in the examples, reference examples and comparative examples described below should be started is "SmC phase ← → SmA phase transition temperature" -5 ° C. Yes, the lower limit is the lower limit of the stated measurement data.

[0126]

[Table 2]

Next, two 0.7 mm thick glass plates were prepared, an ITO film was formed on each glass plate, a voltage application electrode was prepared, and SiO ₂ was vapor-deposited on the electrode to form an insulating layer. And A silane coupling agent [KBM-602 manufactured by Shin-Etsu Chemical Co., Ltd.] 0.2% isopropyl alcohol solution was spun on a glass plate at a rotation speed of 2000 r. p. m spinner applied for 15 seconds and surface-treated. After this, 12
A heat drying treatment was performed at 0 ° C. for 20 minutes.

A polyimide resin precursor [Toray Industries, Inc. SP-5] was applied on a glass plate with an ITO film which had been further surface treated.
10] Rotate the 1.5% dimethylacetamide solution at a rotation speed of 20.
00r. p. m spinner for 15 seconds. After the film formation, the film was heat-condensed and baked at 300 ° C. for 60 minutes. At this time, the film thickness of the coating film was about 250Å.

The coating film after firing was rubbed with an acetate flocked cloth, then washed with an isopropyl alcohol solution, and silica beads having an average particle diameter of 2 μm were sprayed on one glass plate, and then rubbed. The axes were made parallel to each other, and glass plates were laminated using an adhesive sealant [Rixon Bond (Chisso Corporation)] and dried by heating at 100 ° C. for 60 minutes to prepare a cell. Was about 2 μm as measured by a Berek phase plate.

Liquid crystal composition CS-1017 was injected into this cell in an isotropic liquid state, and the liquid crystal composition CS-1017 was injected at 25 ° C. at 20 ° C./h from the isotropic phase.
A liquid crystal element was produced by gradually cooling to.

By using this liquid crystal element, by applying a voltage of peak-to-peak voltage Vpp = 20 V, an optical response (transmission light amount change 0 to 90%) under orthogonal Nicols is detected and a response speed (hereinafter optical response) is detected. The speed) was measured.

The results are shown in (Table 1-2).

[0133]

[Table 3] * ^Values in parentheses () are temperature characteristics every 10 ° C (f ^10/20 ,
f ^20/30 , f ^30/40 ) are shown.

In the above element, the liquid crystal composition CS-1
017 in place of liquid crystal compositions B, D, J, and K,
An experiment was conducted to measure a similar response speed.

The results are shown in Table 2-1.

[0136]

[Table 4]

From the above results, the liquid crystal composition in which the temperature characteristic of the inclination angle δ of the layer has a maximum value with respect to the temperature drop and then tends to decrease, the original δ continues to increase with the temperature drop. The temperature dependence of the response speed is reduced as compared with the liquid crystal composition CS-1017, and the temperature characteristics of the response speed are improved.

(Example 1-5, Comparative Example 1-9) Next, in order to improve the temperature dependence of the response speed of the liquid crystal element, a liquid crystal composition in which the temperature characteristics of the tilt angle δ of the layer were adjusted, and An example in which the display characteristics are deteriorated due to low temperature storage will be described.

The above-mentioned liquid crystal compositions AF, which are "liquid crystal compositions exhibiting temperature characteristics in which the value of the layer inclination angle δ increases with a decrease in temperature and then decrease,"
And X were adjusted.

The compositions and phase transition temperatures of A to F and X are shown in Table 1 above.

The temperature characteristics of each inclination angle δ are shown in FIGS. 6 and 7.

Here, 0.7 m used in (Reference Example 1)
A cell having 80 μm thick glass manufactured by Corning Incorporated was used in place of the m thick glass, and LP-64 manufactured by Toray Industries, Inc. was used in place of the polyimide resin precursor SP-510.

The thickness of the orientation control film at this time is about 50Å,
The cell thickness was about 1.2 μm.

The liquid crystal compositions A to F and X were injected into the cell by the method described above, and the tilt angles δ, θ _a and C / R of the layer at 25 ° C. were measured by the method described above.

The value of the inclination angle δ of the layer measured by using the LP-64 orientation control film and a cell having a cell thickness of 1.2 μm is as follows.
Cell thickness 80 μm in the temperature range of approximately −20 to 60 ° C.
The value of the non-aligned film cell of No. 1 was almost the same as the value specific to the liquid crystal composition measured in the cell in which the magnetic field was aligned.

Thereafter, each cell was cooled to 0 ° C. at a rate of 1 ° C./min and held for 15 minutes, then heated again to 25 ° C. at the same rate, and δ, θ _a , and C / R were measured. Compared with the value.

Similarly, an experiment was conducted in which the low temperature storage temperature was -30 ° C. The results are shown in (Table 3-1) and (Table 3-2).

[0148]

[Table 5]

[0149]

[Table 6]

From the above experimental results, when the storage temperature is lower than Tδs described above, phenomena such as changes in δ and θ _a and _a decrease in contrast occur, and the display characteristics of the display are deteriorated. confirmed.

However, in these experiments, segregation and crystallization of the liquid crystal composition in the cell did not occur.

Further, in the cell using this alignment control film LP-64, the phenomenon of "streak defects" and "deviation of the darkest axis" due to low temperature storage did not occur.

The pretilt angle α of the liquid crystal element at this time is
Was about 2 ° and the orientation was in the splayed state of C2.

(Example 6, Comparative Example 10-16) Next, C1
The results of studying changes in display characteristics due to low temperature storage in a uniform orientation state are shown.

Here, in the cell prepared in (Reference Example 1), 1.1 mm thick glass was used instead of 0.7 mm thick glass, and Hitachi Chemical Co., Ltd. LQ-1802 was used instead of polyimide resin precursor SP-510. Was used to create a cell.

At this time, the thickness of the orientation control film of the cell is 250.
Å, Sergiyap was 1.2 μm.

In the above cell, the above-mentioned liquid crystal compositions A to E,
X as Iso. Injected in the state, subjected to aging treatment at about 100 ° C. for 5 hours and then gradually cooled, and observed alignment state and apparent tilt angle, B, C, D, and X were 10 ° C. to 5 ° C.
It was confirmed that the C1 uniform condition was satisfied at 5 ° C., and the alignment state with high contrast was exhibited. In addition, E showed C1 uniform orientation only between 30 degreeC and 45 degreeC.

At this time, the pretilt angle α of the liquid crystal element using the LQ1802 alignment film was about 18 °. (Table 4-
The cone angle Θ, the apparent tilt angle θ _a , and the layer inclination angle δ at 25 ° C. are shown in 1).

[0159]

[Table 7]

Next, the ferroelectric liquid crystal cell was cooled from room temperature to 0 ° C. or −10 ° C. at a rate of 1 ° C./min, left in a dark place for 200 hours, and then again at a rate of 1 ° C./min. A low temperature storage test of raising the temperature to room temperature was performed, and changes in the apparent tilt angle θ _a , contrast C / R, and alignment state before and after the test were observed.

The respective results are shown in (Table 4-2) and (Table 4-3).
It was shown to.

[0162]

[Table 8]

[0163]

[Table 9] In the change of orientation state, I and II are as follows.

I: C1 splay The portion in the alignment state appears, and the uniformity of the alignment state is broken.

II: Along with I, a “streak defect” running in a stripe shape in a direction almost perpendicular to the lapping direction generated at the boundary between domains having different tilt angles δ of the alignment layer, the direction of the darkest axis, and
The phenomenon that the central angle of the apparent tilt angle θ _a is different between the area that was at the one darkest position and the area that was at the other darkest position during low temperature storage, “deviation of the darkest axis” appears.

Note that θ _a was measured at the portion where the above C1 splay alignment state did not appear.

From the above experimental results, it can be seen that even in the C1 uniform orientation state, there is no change in θ _a and the contrast when the storage temperature is higher than T δs.

However, when low-temperature storage is performed at a temperature of T δs or lower, θ _a is changed, the contrast is lowered, the orientation state is changed, and a portion in the C1 splay orientation state appears. Axis misalignment occurs,
A phenomenon occurs, which does not occur in the C2 splay orientation, but causes great damage to the display characteristics of the display.

(Examples 7-14, Comparative Examples 17-18) Next, the value of the inclination angle δ of the layer was "increased with a decrease in temperature and then decreased when the temperature was further decreased. An example of an experiment conducted on the low temperature storage stability of some liquid crystal compositions showing the temperature characteristics thereof and increasing again before the value of δ becomes 0 is shown.

As shown in FIG. 7, when the indane compound and the pyrimidine compound are compounded in the liquid crystal composition, the temperature characteristic of δ increases with a decrease in temperature and then decreases with a further decrease in temperature. It has been confirmed that the temperature characteristic has a transition point of increasing and the value of δ increases again before the value of δ becomes 0 ”.

Next, the orientation control film LQ prepared in Example 1 was prepared.
Liquid crystal compositions F to I, and X for comparison with Iso. Phase injection, aging treatment at about 100 ℃ for 5 hours, then slowly cooled to about 10-50 ℃
When the alignment state in 1 and the apparent tilt angle were observed, all liquid crystal materials showed C1 uniform alignment.

The pretilt angle α of the liquid crystal element at this time is
Was 19 °.

Next, each of the above ferroelectric liquid crystal cells was cooled from room temperature to -10 ° C or -30 ° C at a rate of 1 ° C / minute, left in a dark place for 200 hours, and then again at a rate of 1 ° C / minute. A low-temperature storage test was conducted in which the temperature was raised to room temperature at 25 ° C., and changes in the apparent tilt angle, contrast, and alignment state before and after that were observed at 25 ° C.

The respective results are shown in (Table 5-3) and (Table 5-4).
It was shown to.

[0175]

[Table 10]

[0176]

[Table 11] In the change of orientation state, I and II are as follows.

I: A portion in the C1 splay alignment state appears.

II: Along with I, a “streak defect” running in a stripe shape in a direction substantially perpendicular to the rubbing direction, the direction of the darkest axis, and the apparent central angle of the tilt angle θ _a are The "deviation of the darkest axis", which is a different phenomenon, appears in the area in the darkest position and the area in the other darkest position.

Note that θ _a was measured at the portion where the above C1 splay alignment state did not appear.

From the above results, the temperature characteristic of δ shows a temperature characteristic having a transition point of “increasing with a decrease in temperature and then decreasing with further decrease in temperature, and before the value of δ becomes zero. In the liquid crystal material of the “increasing again” type, there is no transition that changes the chevron structure to a bookshelf structure, and thus the storage stability at low temperatures is significantly improved.

Further, when the liquid crystal composition G was stored at -30 ° C., the apparent tilt angle was slightly increased and the contrast was increased, but the display characteristics of the display are not particularly adversely affected. Absent.

(Examples 15-17, Comparative Examples 19-21)
Up to this point, attention has been paid to the value of δ as a physical property value peculiar to the liquid crystal composition. Next, description will be made regarding an experiment conducted by prescribing the liquid crystal element configuration and paying attention to the temperature characteristic of δ in the liquid crystal element. .

Here, (Example 1-5, Comparative example 1-9)
In the cell having a cell gap of 1.2 μm using 80 μm-thick glass prepared in step 1, an X-ray measurement cell was prepared by using the LQ1802 alignment control film described above instead of the LP-64 alignment film.

The above-mentioned liquid crystal compositions J, K and L were injected into this cell, aged at about 100 ° C. for 5 hours, then gradually cooled to 25 ° C., and the inclination angle δ of the layer and the apparent angle were obtained by the method described above. The tilt angle θ _a and the contrast C / R were measured.

The pretilt angle α of the liquid crystal element at this time
Was 19 °, and it was confirmed that the orientation was C1 uniform.

The orientation state, the apparent tilt angle, and the contrast in the X-ray measuring cell used here are as follows.
The alignment state, the apparent tilt angle, and the contrast in the cell using the 1.1 mm thick glass are not different.

FIG. 8 shows the temperature characteristics of the layer inclination angle δ in the element structure at this time.

In the experiment, each cell was cooled to −10 ° C. at a rate of 1 ° C./min and held for 24 hours, and then again cooled at the same rate for 25 hours.
The temperature was raised to ℃ and δ, θ _a and C / R were measured and compared with the initial values.

Similarly, an experiment was conducted by setting the low temperature storage temperature to -30 ° C.

The results are shown in (Table 6-1) and (Table 6-2).

[0191]

[Table 12]

[0192]

[Table 13]

The symbols for changes in the alignment state are the same as before.

From the above results, when the liquid crystal element structure is defined and the low temperature storage at a temperature higher than the temperature Tδs at which the value of δ in the liquid crystal element becomes 0, θ _a , C / R and the orientation state are all no change.

However, if low temperature storage is performed at Tδs or less,
Since θ _a , C / R, and orientation state change, the display characteristics of the display deteriorate.

That is, in order to reduce the temperature dependence of the response speed of the liquid crystal element in the liquid crystal display device and prevent the deterioration of the display characteristics due to the low temperature storage, "the value of δ increases as the temperature decreases, A liquid crystal composition having a decreasing transition point ”and a temperature (Tδs) at which the value of δ becomes 0 is lower than a temperature at which the liquid crystal composition may be stored.

Alternatively, in the liquid crystal element structure,
“The value of δ increases with a decrease in temperature, and then shows a temperature characteristic with a transition point that decreases when the temperature further decreases, and increases again before the value of δ becomes zero.”
It was found that the liquid crystal element should be designed so as to have such a temperature characteristic of δ.

[0198]

INDUSTRIAL APPLICABILITY The liquid crystal composition of the present invention, the liquid crystal element, and the liquid crystal device using them have a very excellent display in which the temperature dependence of the response speed is reduced and the display characteristics are not deteriorated by storage at low temperature. It can be carried out.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a liquid crystal element of the present invention.

FIG. 2 is an explanatory diagram showing C1 and C2 orientations.

FIG. 3 is an explanatory diagram showing a relationship among a cone angle, a pretilt angle, and a layer tilt angle in C1 and C2 orientations.

FIG. 4 is a block diagram showing a liquid crystal device and a graphics controller of the present invention.

FIG. 5 is a timing chart of image information communication between the liquid crystal device of the present invention and the graphics controller.

FIG. 6 is a tilt angle δ of a layer of each liquid crystal composition used in Examples.
It is a figure which shows the temperature characteristic of.

FIG. 7 is a tilt angle δ of a layer of each liquid crystal composition used in Examples.
It is a figure which shows the temperature characteristic of.

FIG. 8 is a tilt angle δ of a layer of each liquid crystal composition used in Examples.
It is a figure which shows the temperature characteristic of.

[Explanation of symbols]

 1 Chiral Smectic Liquid Crystal Layer 2 Glass Substrate 3 Transparent Electrode 4 Alignment Layer 5 Spencer 6 Lead Wire 7 Power Supply 8 Polarizing Plate 9 Light Sources 20a, 20b Substrate Surface 21 Liquid Crystal Layer 22 C1 Alignment 23 C2 Alignment A Rubbing Direction 31 Cone Angle 32 Substrate Normal 33 liquid crystal molecules 101 ferroelectric liquid crystal display device 102 graphics controller 103 display panel 104 scanning line driving circuit 105 information line driving circuit 106 decoder 107 scanning signal generating circuit 108 shift register 109 line memory 110 information signal generating circuit 111 driving control circuit 112 GCPU 113 Host CPU 114 VRAM

Front Page Continuation (72) Inventor Yu Mizuno 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Akio Yoshida 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (31)

[Claims] 1. A ferroelectric liquid crystal composition having a smectic phase, wherein a predetermined ambient temperature range (−30 ° C. to 70 ° C.) that is assumed to be experienced when a liquid crystal device including the liquid crystal composition is used. C.), the tilt angle δ of the layer in the smectic phase of the liquid crystal composition
Value has an inflection point that first increases with a decrease in temperature from the upper limit of the ambient temperature range and gives a maximum value, decreases after passing through the inflection point, and even for further temperature drop. δ is 0
A liquid crystal composition which is characterized in that it does not become. 2. If the tilt angle of the layer in the smectic phase of the ferroelectric liquid crystal is δ, the value of δ has an inflection point that first increases with a decrease in temperature and gives a maximum value, A liquid crystal composition characterized in that after passing through the inflection point, it decreases, and δ does not become 0 even with further temperature drop. 3. The liquid crystal composition according to claim 1, wherein the value of δ increases again before the value of δ becomes 0 with a decrease in temperature. 4. The liquid crystal composition according to claim 1, wherein the maximum value of the layer tilt angle δ is 20 ° or less. 5. The liquid crystal composition according to claim 1, wherein the maximum value of the layer tilt angle δ is 15 ° or less. 6. The liquid crystal composition according to claim 1, wherein the liquid crystal composition contains at least one or more indane compounds represented by the following general formula (I). The following general formula (I) 7. A compound represented by the general formula (I) is contained in the composition in an amount of 10 to 80%.
The liquid crystal composition described. 8. The composition according to claim 6, which comprises 10 to 40% of the compound represented by the general formula (I).
The liquid crystal composition described. 9. The liquid crystal composition according to claim 6, which contains at least one or more pyrimidine compounds represented by the general formula (I) and the following general formula (II). [Outside 2] (R ₁ , R ₂ ; a straight-chain or branched alkyl group having 1 to 20 carbon atoms, which is one or two-
A CH ₂ — group is —O—, [External 3] May be replaced with, and hydrogen of the —CH ₂ — group is C
It may be substituted with 1, F or CF ₃ . m and n are 0,
1, 2 and m + n is 1 or 2. ) 10. The ferroelectric liquid crystal composition according to claim 9, wherein the composition contains 10 to 80% of the compounds represented by the general formulas (I) and (II). 11. The ferroelectric liquid crystal composition according to claim 9, wherein both 10 to 80% of the compounds represented by the general formulas (I) and (II) are contained in the composition. 12. A ferroelectric liquid crystal composition having a smectic phase, wherein a predetermined ambient temperature range (−30 ° C. to 70 ° C.) assumed to be experienced when a liquid crystal device including the liquid crystal composition is used. (° C), the value of the tilt angle δ of the layer in the smectic phase of the liquid crystal composition first increases with the effect of temperature from the upper limit of the ambient temperature range, and has an inflection point giving a maximum value, A liquid crystal device comprising a liquid crystal composition, which is characterized in that after passing through the inflection point, it decreases and δ does not become 0 even with further temperature drop. 13. A ferroelectric liquid crystal composition having a smectic phase, wherein a predetermined ambient temperature range (−30 ° C. to 70 ° C.) assumed to be experienced when a liquid crystal device including the liquid crystal composition is used. (° C), the value of the tilt angle δ of the layer in the smectic phase of the liquid crystal composition first increases with the effect of temperature from the upper limit of the ambient temperature range, and has an inflection point giving a maximum value, A liquid crystal device comprising a liquid crystal composition, which is characterized by decreasing after passing through the inflection point and further increasing before δ becomes 0 with respect to further temperature drop. 14. The liquid crystal element according to claim 13, wherein the value of δ increases again before it becomes 0 as the temperature decreases. 15. The liquid crystal composition according to claim 11, wherein the maximum value of the tilt angle δ of the layer is 20 ° or less. 16. The liquid crystal composition according to claim 10, wherein the maximum value of the tilt angle δ of the layer is 15 ° or less. 17. The liquid crystal composition according to claim 10, wherein the liquid crystal composition contains at least one kind of indane compound represented by the following general formula (I). The following general formula (I) 18. The liquid crystal device according to claim 15, wherein the compound represented by the general formula (I) is contained in the composition in an amount of 10 to 80%, more preferably 20 to 40%. 19. The general formula (I) and the following general formula (II):
16. The liquid crystal device according to claim 15, containing at least one kind of the pyrimidine compound shown in FIG. [Outside 5] (Wherein R ₁ and R ₂ are C _{1 to} C ₂₀ linear or branched alkyl, and one or two non-adjacent —CH ₂ — groups are —O—, May be replaced with, and hydrogen of —CH ₂ — is Cl,
It may be substituted with F or CF ₃ . m and n are 0 and 1,
2 and m + n is 1 or 2. ) 20. The composition contains 20 to 80% of a compound represented by the general formula (I) and 5 to 80% of a compound represented by the general formula (II). 17
The liquid crystal element described. 21. A liquid crystal and electrodes sandwiching the liquid crystal and facing each other, electrodes for applying a voltage to the liquid crystal are respectively formed on the facing surfaces, and uniaxial alignment axes for aligning the liquid crystal are predetermined to each other. In a liquid crystal device including a pair of substrates subjected to alignment treatment intersecting at an angle of, the pretilt angle α of the liquid crystal device, the cone angle Θ of the liquid crystal, and the tilt angle of the layer in the ferroelectric smectic phase are δ. At this time, the liquid crystal has an alignment state satisfying the relations represented by Θ <α + δ and α> δ, and the liquid crystal in the alignment state exhibits at least two optically stable states, and the angle formed by the optical axes thereof. The apparent tilt angle θ _a and the cone angle Θ of the liquid crystal, which are defined by ½ of the above, have an alignment state satisfying the relationship of Θ> θ _a > Θ / 2. When the liquid crystal element provided is used In certain circumstances the temperature range which is assumed to experience (-30 ~ 70 ° C.), the inclination angle of the layers in the smectic phase of said liquid crystal composition δ
The value of increases first with a decrease in temperature from the upper limit of the ambient temperature range, has an inflection point that gives a maximum value, decreases after passing through the inflection point, and becomes δ for further temperature decrease. A liquid crystal element comprising a liquid crystal composition, characterized in that is never 0. 22. A liquid crystal and electrodes sandwiching the liquid crystal and facing each other, electrodes for applying a voltage to the liquid crystal are respectively formed on the facing surfaces, and uniaxial alignment axes for aligning the liquid crystal are predetermined to each other. In a liquid crystal device including a pair of substrates subjected to alignment treatment intersecting at an angle of, the pretilt angle α of the liquid crystal device, the cone angle Θ of the liquid crystal, and the tilt angle of the layer in the ferroelectric smectic phase are δ. At this time, the liquid crystal has an alignment state satisfying the relations represented by Θ <α + δ and α> δ, and the liquid crystal in the alignment state exhibits at least two optically stable states, and the angle formed by the optical axes thereof. The apparent tilt angle θ _a and the cone angle Θ of the liquid crystal, which are defined by 1/2 of the above, have an alignment state satisfying the relationship of Θ> θ _a > Θ / 2, and The value increases with decreasing temperature, A liquid crystal composition characterized by exhibiting a temperature characteristic having a transition point (hereinafter referred to as a maximum value) which decreases as the temperature further lowers, and increasing again before the value of δ becomes zero. A liquid crystal element that consists of objects. 23. The value of δ increases again before the value of 0 becomes 0 as the temperature decreases.
The liquid crystal element described. 24. The maximum value of the inclination angle δ of the layer is 20 °.
The liquid crystal element according to any one of claims 19 to 21, wherein: 25. The maximum value of the inclination angle δ of the layer is 15 °
The liquid crystal element according to any one of claims 19 to 21, wherein: 26. The liquid crystal composition comprising the following general formula (I):
22. The liquid crystal device according to claim 19, which contains at least one kind of the indane compound shown in FIG. The following general formula (I) 27. A compound represented by the general formula (I) is contained in the composition in an amount of 5 to 80%.
6. The liquid crystal device according to item 6. 28. The general formula (I) and the following general formula (II)
27. The liquid crystal device according to claim 26, which contains at least one kind of the pyrimidine compound shown in FIG. [Outside 8] R ₁ and R ₂ ; linear or branched alkyl group having 1 to 20 carbon atoms, one or two non-adjacent —CH
₂ -group is -O-, May be replaced with, and hydrogen of the —CH ₂ — group is C
It may be substituted with 1, F or CF ₃ . m and n are 0,
1, 2 and m + n is 1 or 2. 29. The ferroelectric liquid crystal composition according to claim 28, wherein both 10 to 80% of the compounds represented by the general formulas (I) and (II) are contained in the composition. 30. The ferroelectric liquid crystal composition according to claim 28, wherein the composition contains 20 to 40% of the compounds represented by the general formulas (I) and (II). 31. The liquid crystal device according to claim 10,
A liquid crystal device characterized in that the liquid crystal element has at least a drive circuit and a light source.