JPH1114991A - Liquid crystal element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the influence of antielectric field effect and crosstalk between pixels. SOLUTION: On one substrate 2, an orientation control film 10 is fold which has uniaxial orientation characteristics to limpid crystal molecules and on the other substrate 3, a film 7 is formed which has nonuniaxial orientation characteristics to the liquid crystal molecules. This film 7 has a polycrystalline structure which has nearly no crystal grain boundary in its film thickness direction and crystal grain boundaries in its film surface direction. Consequently, the film 7 has low volume resistivity along the film thickness and high volume resistivity along the film surface. Those volume resistivity values are set within a specific range to prevent the influence of antielectric field effect and crosstalk between pixels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical modulator using liquid crystal, and more particularly to a computer terminal display, a word processor, a typewriter, a television receiver, a video camera viewfinder, a projector light valve, a liquid crystal printer light valve, and the like. Liquid crystal element used in a liquid crystal device, particularly, a liquid crystal element exhibiting good display characteristics using a liquid crystal exhibiting a chiral smectic phase such as a ferroelectric liquid crystal or an antiferroelectric liquid crystal driven by utilizing the action of spontaneous polarization. About.

[0002]

2. Description of the Related Art Conventionally, a CRT has been known as a display for displaying various information.
It is widely used in TVs and VTRs that output moving images, or in monitors of personal computers.

However, this CRT has a problem in that, due to its characteristics, flicker and scanning stripes due to lack of resolution lower visibility and cause deterioration of a fluorescent lamp due to burn-in for a still image. is there. Also, recently, electromagnetic waves generated by a CRT adversely affect the human body,
It has been found that DT workers may be harmed. Further, the CRT requires a space behind the screen due to its structure, which hinders space saving in offices and homes.

There is a liquid crystal element as a display for solving such a drawback of the CRT. As one of the liquid crystal devices, twisted nematic (twisted nematic) is used.
The use of nematic (TN) liquid crystals is known and is described in the Applied Physics Letters by M. Schadt and W. Helfrich.
Physics Letters), Vol. 18, No. 4 (issued on Feb. 15, 1971), pp. 127-12.
8 ".

As one of the liquid crystal elements using the TN liquid crystal, there is a simple matrix type which has an advantage in cost. However, this type of liquid crystal element is not suitable for a liquid crystal element having a high pixel density. Since crosstalk occurs during the division driving, the pixel density is limited.

In recent years, a liquid crystal element called a TFT has been developed for such a simple matrix type. In this TFT, since a transistor is formed for each pixel, the problems of crosstalk and response speed can be solved. However, as the area becomes larger, defective pixels are more likely to occur and the yield decreases. is there.

In recent years, a display device of a type that controls transmitted light by combining with a polarizing element utilizing the refractive index anisotropy of ferroelectric liquid crystal molecules has been proposed by Clark and Lagerwall. (JP-A-56-107216, U.S. Pat.
67924, etc.). This ferroelectric liquid crystal generally has a chiral smectic C phase (S
mC *) or H-phase (SmH *), in which state one of a first optically stable state and a second optically stable state is taken in response to an applied electric field, and an electric field is applied. When there is no property to maintain the state (ie,
(Bistable memory property), and also exhibits a very fast response speed due to inversion switching by spontaneous polarization. In addition, because the visual characteristics are also excellent, especially high speed,
It is considered to be suitable as a high-definition, large-screen display element or light valve.

[0008] Similarly, a liquid crystal exhibiting antiferroelectricity is known as a technique for forming a display element utilizing the refractive index anisotropy and spontaneous polarization of liquid crystal molecules. This antiferroelectric liquid crystal generally has a chiral smectic CA phase (SmCA *) in a specific temperature range. In this state, when no electric field is applied, the average optically stable state is in the normal direction of the smectic layer. It has the property that the average optical stable state is inclined from the layer normal direction by application. In addition, the antiferroelectric liquid crystal also performs switching by coupling of spontaneous polarization and electric field, so that it exhibits a very fast response speed and is expected as a high-speed display element or light valve.

In order to maintain good contrast in a liquid crystal device using such a ferroelectric liquid crystal or antiferroelectric liquid crystal, it is necessary to obtain a defect-free alignment state. As a liquid crystal element for improving a liquid crystal alignment state, a pair of substrates is arranged at a position separated by a predetermined distance, and a liquid crystal is sandwiched between them. An alignment control film having uniaxial alignment characteristics is formed on the other substrate, and an alignment control film having different characteristics and types having non-uniaxial alignment characteristics with respect to liquid crystal molecules is formed on the other substrate. 61-209
No. 30 and other publications. According to this liquid crystal element, the orientation of the liquid crystal can be controlled in a high order from the side of the substrate that has been subjected to the uniaxial orientation treatment, and a favorable liquid crystal alignment state can be easily obtained.

[0010]

However, in such a liquid crystal device, although the alignment state is apparently good, an asymmetrical characteristic appears in the switching, or the ferroelectric liquid crystal has a favorable bistable property. In some cases, the so-called switching memory performance may be reduced.

In particular, the symmetry of the switching characteristics is important for widening the driving margin, and it is necessary to maintain the symmetry of the switching characteristics even if driving is continued for a long time.

In addition, especially in a liquid crystal device using a ferroelectric liquid crystal or an antiferroelectric liquid crystal, in performing halftone display, an anti-electric field effect induced by spontaneous polarization of the liquid crystal itself is a serious problem. It has become. That is, a desired halftone may be destabilized due to a reason that the internal ions unevenly distributed in response to the spontaneous polarization form an electric field, and hysteresis may occur in an optical response to an externally applied voltage. This is because ions are localized in a direction that stabilizes each state with respect to the direction of spontaneous polarization of liquid crystal molecules when displaying “black state” or “white state”. Because the voltage applied to the liquid crystal portion in the previous state ("white" or "black") differs even when the voltage Vw applied after a short reset ("black erasure") is equally applied due to the difference It is thought to happen.

As an extremely inconvenient phenomenon due to the above-described anti-electric field effect, for example, when the “black state” is set to the reset direction and the “white state” is written, the “white state” Cannot be latched, and a so-called switching failure occurs, in which the signal is returned to the “black state”. This phenomenon is a fatal defect even in a liquid crystal element that does not require a halftone at a pixel level.

As a countermeasure against the above-described anti-electric field effect,
For example, in JP-A-63-12020, etc.,
A method of reducing the impedance of an alignment control film constituting a ferroelectric liquid crystal element, that is, a method of coping with switching failure due to a so-called anti-electric field is disclosed. In addition, Japanese Unexamined Patent Application Publication No.
In JP-A-153321, many examples of an organic conductive film for lowering the impedance of an alignment control film are disclosed. Furthermore, Japanese Patent Application Laid-Open No. 64-49023 discloses that a thin film orientation layer is formed for passivation for preventing short circuit with reduced impedance, but at present, there is no sufficient solution.

As described above, the electro-optical characteristics of the liquid crystal device using the chiral smectic liquid crystal are controlled by the change of the threshold value caused by the control of the alignment state and the anti-electric field generated by the spontaneous polarization Ps, and by the neglected state. However, there are problems to be improved with respect to optical response instability, etc. In this respect, the antiferroelectric liquid crystal element has the same problem.

Therefore, an object of the present invention is to provide a liquid crystal element exhibiting a good alignment state.

Another object of the present invention is to provide a liquid crystal element which can sufficiently prevent the influence of the anti-electric field effect and crosstalk between pixels.

Still another object of the present invention is to provide a liquid crystal device capable of suppressing the asymmetric characteristic of the switching threshold.

Still another object of the present invention is to provide a liquid crystal element whose manufacturing cost is reduced.

[0020]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made in consideration of the above circumstances, and includes a pair of substrates arranged at a predetermined distance, a liquid crystal sandwiched between the pair of substrates, And wherein at least one of the substrates has uniaxial alignment characteristics with respect to liquid crystal molecules, at least one of the pair of substrates has almost no crystal grain boundary in the film thickness direction and the film surface direction. And a film having a polycrystalline structure having a plurality of crystal grain boundaries.

In the present invention, it is particularly preferable that one of the substrates has uniaxial alignment characteristics with respect to liquid crystal molecules and the other opposing substrate has non-uniaxial alignment characteristics with respect to liquid crystal molecules. A substrate having a uniaxial orientation characteristic is provided with a film having a polycrystalline structure having few crystal grain boundaries in the film thickness direction and having a plurality of crystal grain boundaries in the film surface direction as described above. .

In this case, it is preferable that the film having the polycrystalline structure is formed of a polycrystalline metal oxide or a polycrystalline semiconductor to which conductivity controlling impurities are added.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS.
An embodiment of the present invention will be described.

FIG. 1 is a cross-sectional view showing a preferred embodiment of the liquid crystal device according to the present invention. Liquid crystal element 1 shown in FIG.
Is provided with a pair of light-transmitting substrates 2 and 3 that are disposed at a predetermined distance from each other.
A liquid crystal 5 is sandwiched between the three. One translucent substrate 2 has uniaxial alignment characteristics for liquid crystal molecules, and the other translucent substrate 3 has non-uniaxial alignment characteristics for liquid crystal molecules. (Hereinafter, the translucent substrate 2 on the side having uniaxial alignment characteristics with respect to the liquid crystal molecules is referred to as the “uniaxial alignment side substrate 2”, and the translucent substrate 3 on the side having non-uniaxial alignment characteristics with respect to the liquid crystal molecules. Is referred to as “non-uniaxially oriented substrate 3.” Further, as described above, the uniaxially oriented substrate 2 and the non-uniaxially oriented substrate 3
Is referred to as an “asymmetric configuration”). According to the present embodiment, a uniform alignment state is realized by using an asymmetric liquid crystal element and using an appropriate liquid crystal material (details will be described later).

It should be noted that "uniaxial orientation characteristics" in this specification
Means a uniaxial alignment state of liquid crystal molecules (for example, a uniaxial horizontal alignment state).

In this embodiment, an electrode 6 and a film 7 are formed on the surface of the non-uniaxially oriented substrate 3, and the film 7 has a non-uniaxially oriented characteristic with respect to, for example, liquid crystal molecules. (I.e., having no uniaxial alignment property with respect to liquid crystal molecules) and function as a non-uniaxial alignment film. This film 7
Has a polycrystalline structure having no (or almost no) crystal grain boundaries in the film thickness direction and a large number of crystal grain boundaries in the film surface direction depending on the setting of the film formation conditions. As described above, the film 7 is configured so that there is no (or almost no) crystal grain boundary in the film thickness direction, and the resistance (volume resistance) in the film thickness direction is suppressed low. I have. Further, since the film 7 has a structure having many crystal grain boundaries in the film surface direction, the resistance (volume resistance) in the film surface direction can be increased. That is, the film 7 in the present embodiment
Indicates a resistivity anisotropy in the film thickness direction and the film surface direction.

Here, the reason why the resistance in the film thickness direction is reduced will be described with reference to the “SETO model” which is famous for a polycrystalline structure model.
Is significantly inhibited by a potential barrier formed at a crystal grain boundary in a polycrystalline material, but if there is no crystal grain interface in the film thickness direction as in the present embodiment,
The carrier traveling in the thickness direction does not pass through the crystal grain boundaries,
This is because the resistance is reduced because only the crystalline characteristics appear.

The film 7 on the non-uniaxially oriented substrate
Is preferably formed of a polycrystalline metal oxide or a polycrystalline semiconductor, and in particular, formed of a polycrystalline metal oxide or a polycrystalline semiconductor to which a conductivity controlling impurity is added, and Try to control conductivity.

Here, as the polycrystalline metal oxide film, Zn
O, CdO, ZnCdOx Group 12 (Group number by IUPAC inorganic chemical nomenclature; the same applies hereinafter) oxide film, GeO
₂ , SnO ₂ , GeSnOx, TiO ₂ , ZrO ₂ , T
An iZrOx Group 4 or 14 oxide film or the like is preferable. Also,
As the polycrystalline semiconductor film, a Group 14 semiconductor of Si and SiC is preferable. Further, as the conductivity controlling impurity, for example, a group 13 element B, Al, or G as an n-type impurity (donor: an impurity that enhances electron conduction) for a group 12 oxide is used.
a and In are p-type impurities (acceptors: impurities that enhance hole conduction), Cu and A, which are Group 1 and 11 elements.
g, Au, and Li are used. For Group 4 or 14 oxides or semiconductors, P, As, Sb, and Bi as Group 15 elements are used as n-type impurities, and B, Al, Ga, and In as Group 13 elements are used as p-type impurities. . By adding the conductivity control impurity to the film 7 in this manner, fine control of the surface potential (the surface potential detected on the surface of the uniaxially oriented substrate 2 or the non-uniaxially oriented substrate 3 as described later) can be finely controlled. The absolute value of the difference between the two surface potentials (the difference between the surface potential detected on the surface of the uniaxially oriented substrate 2 and the surface potential detected on the surface of the non-uniaxially oriented substrate 3) is reduced to a small value (100
mV or less, preferably 50 mV). When the surface potential of the uniaxially oriented substrate 2 is positive, a donor is added, and when the surface potential is negative, an acceptor is added. Further, the concentration of the impurity added depends on the type of the material and its crystallization state (the degree of crystal defect density), but the rough rule of thumb is that the concentration of free electrons or free holes in the material is 1%.
What is necessary is just to set it as about 0 < ¹¹ > -10 < ¹⁴ > / cm < ³ >. When a polycrystalline material is used, the actual addition amount is preferably 10 ¹⁷ to 10 ²⁰ / cm ³ (about 0.01% to 1% with respect to the base material) in consideration of the impurity addition efficiency. . The amount of change in the surface potential with respect to the amount of impurity added is equivalent to about 50 mV with an increase of one digit.

The resistance (volume resistance) in the film thickness direction of the film 7 is 10 ⁴ Ωcm to 10 ⁸ Ωcm, particularly 10 ⁴ Ωcm to 1ΩΩ.
A range of 0 ⁷ Ωcm is preferred. As a result, the delay time constant given by the resistance * capacitance product can be reduced, and the effect of the anti-electric field effect due to the chiral smectic liquid crystal having a high Ps can be prevented. The resistance (volume resistance) in the film surface direction of the film 7 is preferably in the range of 10 ⁶ to 10 ⁹ Ωcm. Thereby, crosstalk between pixels can be sufficiently prevented. Note that the resistance (volume resistance) of the film 7 may be adjusted by selecting its material.

As described above, the uniaxially oriented substrate 2 has uniaxially oriented characteristics with respect to liquid crystal molecules.
An electrode 9 is formed on the surface of the uniaxially oriented substrate 2 and a uniaxially oriented film (hereinafter, referred to as an “alignment control film”) having a uniaxially oriented property on liquid crystal molecules is formed on the surface of the electrode 9.
Preferably, 10 is formed. The orientation control film 10 may exhibit uniaxial orientation characteristics by performing a predetermined process (for example, rubbing process), or may have uniaxial orientation characteristics without such a process.

A specific example of a material which exhibits uniaxial orientation characteristics by performing a predetermined treatment is a polymer material which can be used as an alignment film exhibiting uniaxial orientation characteristics when used alone, preferably two or more organic polymer materials. It may be mixed and used.
As such an alignment control film 10, a film obtained by uniaxially aligning an organic polymer film is preferable.
Examples include polyimide, nylon, and polyvinyl alcohol.

As the alignment control film 10 having uniaxial alignment characteristics, a film having a structural unit represented by the following general formula [P] is particularly preferably used.

[0034]

Embedded image In addition, specific structures of these polyimides include, for example, the following repeating unit structures.

[0035]

Embedded image

[0036]

Embedded image In the present invention, preferably, according to the alignment characteristics of the liquid crystal material to be used, one that has been subjected to uniaxial alignment treatment with a film made of an organic material such as polyimide as described above on one substrate as an alignment control film, and used on the other substrate Alternatively, a film (coating film) in which the above-described oxide ultrafine particles or the like are dispersed in a base material can be used.

On the other hand, as a material of the electrodes 6 and 9,
In addition to tin oxide and indium oxide, a transparent conductor such as ITO (indium tin oxide) is preferable. In the case of forming an element that does not require translucency, Cr,
A metal such as Al or Ta may be used.

Next, the liquid crystal composition used in the present invention will be described.

The liquid crystal 5 used in the present invention is preferably a liquid crystal exhibiting a chiral smectic phase, particularly a liquid crystal exhibiting a ferroelectric property or a liquid crystal exhibiting an antiferroelectric property, in which the action of spontaneous polarization is applied to driving. However, a nematic liquid crystal or the like may be used.

For example, as a liquid crystal exhibiting a chiral smectic phase (a liquid crystal exhibiting ferroelectricity or a liquid crystal exhibiting antiferroelectricity), a phase transition series isotropic phase → SmA → SmC from high temperature to low temperature. * → It is preferable to use a material that becomes a crystal phase and has a spontaneous polarization of 30 nC / cm ² (at a temperature of about 30 ° C.) and a tilt angle of about 24 degrees.

Further, in the liquid crystal device of the present invention, in order to improve the brightness at the time of display, when the liquid crystal takes the SmC * phase, a bookshelf structure in which the smectic layer is vertically parallel to the substrate, or It is preferable to use a liquid crystal material having a structure with a smectic layer inclination close to the above.
As a liquid crystal material having such a smectic layer structure, for example, a composition containing a fluorine-containing liquid crystal compound having a structure in which a fluorocarbon terminal portion and a hydrocarbon terminal portion are bonded to a central nucleus and exhibiting a smectic phase or a potential smectic phase Is mentioned. Such fluorine-containing compounds are specifically described in US Pat.
2,587, U.S. Pat. No. 5,262,082, WO93 / 22936, and the like can be used.

More specifically, the compound is a nuclear fluorine-containing compound and is, for example, an isotropic phase at a temperature lowering as described above → SmA
A liquid crystal material exhibiting a phase transition such as → SmC * → crystal phase (in particular, not exhibiting a cholesteric phase) may be used.

According to the present embodiment, the liquid crystal element is
Since only one side of one substrate 2 has an asymmetric configuration in which uniaxial alignment processing is performed, the liquid crystal (particularly, ferroelectric or antiferroelectric liquid crystal) is aligned in a temperature region of SmA in particular, and the uniaxial alignment processing in one substrate 2 is performed. The growth is performed as uniaxial molecular growth from the surface to which S has been applied, and a good orientation state can be obtained in the SmC * phase. In particular, when a liquid crystal that does not exhibit the cholesteric phase is used,
By performing good orientation control during the (isotropic phase) → SmA phase transition, a uniform orientation state can be realized.

In the fluorine-containing liquid crystal compound, the terminal portion of the fluorocarbon is a group represented by -D ¹ -C _xa F _2xa -X (provided that xa is 1 to 20;
It represents -H or -F, D ¹ is, -CO-O- (C
_{H 2) ra -, - O-} (CH 2) ra -, - (CH 2) ra -,
_{-O-SO 2 -, - SO} 2 -, - SO 2 - (CH 2) ra -,
_{-O- (CH 2) ra -O- (} CH 2) rb -, - (CH 2)
_{ra -N (C pa H 2pa +} 1) -SO 2 -, or - (CH _{2) ra
-N (C pa H 2pa + 1} ) represents the -CO-. ra and rb
Is independently 1 to 20, and pa is 0 to 4. ),
Alternatively, a group represented by -D ^2- (C _xb F _2xb -O) _za -C _ya F _{2ya + 1} (where xb is each of (C
_xb F _2xb -O) is independently 1 to 10, and ya is 1 to
10, za is 1 to 10, and D ² is -CO-
_{O-C rc H 2rc, -O} -C rc H 2rc -, - C rc H 2rc -,
_{-O- (C sa H 2sa -O)} ta -C rd H 2rd -, - O-SO
_{2 -, - SO 2 -,} - SO 2 -C rc H 2rc -, - C rc H 2rc
_{-N (C pb H 2pb + 1} ) -SO 2 -, - C rc H 2rc -N (C
_pb H _2pb + 1) -CO-, selected from a single bond, rc and r
d is independently 1 to 20, sa is independently 1 to 10 for each (C _sa H _2sa -O), and ta is 1
And pb is 0-4. ) Can be used.

Particularly preferably, a fluorine-containing liquid crystal compound represented by the following general formula (I) or (II) can be used.

[0046]

Embedded image Represents

Ga, ha and ia each independently represent an integer of 0 to 3 (provided that ga + ha + ia is at least 2).

Each of L ¹ and L ² is independently a single bond, —CO
-O-, -O-CO-, -COS-, -S-CO-,-
CO-Se-, -Se-CO-, -CO-Te-, -T
_{e-CO -, - CH 2} CH 2 -, - CH = CH -, - C≡
C -, - CH = N - , - N = CH -, - CH 2 -O-,
-O-CH ₂ -, - CO- or represent -O-.

Each of X ¹ , Y ¹ , and Z ¹ is a substituent of A ¹ , A ² , and A ³ and independently represents —H, —Cl, —F, —Br, —
_{I, -OH, -OCH 3, -CH} 3, -CN, or -NO
₂ and each of ja, ma and na independently represents an integer of 0-4.

J ¹ is —CO—O— (CH ₂ ) _ra —, —O
_{- (CH 2) ra -,} - (CH 2) ra -, - O-SO 2 -,
_{-SO 2 -, - SO 2 -} (CH 2) ra -, - O- (CH 2)
_{ra -O- (CH 2) rb -} , - (CH 2) ra -N (C pa H
_2pa + 1) -SO ₂ -, or _{- (CH 2) ra -N (} C pa H
_{2pa + 1} ) represents -CO-. ra and rb are independently 1
-20 and pa is 0-4.

R ¹ is _{-OC qa} H _{2qa -OC qb} H
_{2qb + 1, -C qa H 2qa} -O-C qb H 2qb + 1, -C qa H 2qa -
_{^{R 3, -O-C qa H}} 2qa -R 3, -CO-O-C qa H 2qa -
R ³ or —O—CO—C _qa H _2qa —R ³ , which may be linear or branched (where R ³ _{is-
O-CO-C qb H 2qb} + 1, -CO-O-C qb H 2qb + 1, -
_{H, -Cl, -F, -CF 3} , -NO 2, represents a -CN, qa and qb are 20 independently).

R ² represents C _xa F _2xa -X (X represents -H or -F, and xa is an integer of 1 to 20).

[0053]

Embedded image Represents

Gb, hb and ib are each independently 0 to 3
(Where gb + hb + ib is at least 2).

Each of L ³ and L ⁴ is independently a single bond, —CO
-O-, -O-CO-, -CO-S-, -S-CO-,
-CO-Se-, -Se-CO-, -CO-Te-,-
Te-CO -, - (CH 2 CH 2) ka - (ka is 1
4), -CH = CH-, -C≡C-, -CH = N-,-
_{N = CH -, - CH 2} -O -, - O-CH 2 -, - CO-
Or -O-.

Each of X ² , Y ² , and Z ² is a substituent of A ⁴ , A ⁵ , and A ⁶ and independently represents —H, —Cl, —F, —Br, —
_{I, -OH, -OCH 3, -CH} 3, -CF 3, -O-C
F ₃ , —CN, or —NO ₂ , and each jb, m
b and nb each represent an integer of 0 to 4.

J ² represents —CO—O—C _rc H _2rc —, —O—
_{C rc H 2rc -, - C} rc H 2rc -, - O- (C sa H 2sa -
O) _ta -C _rd H _2rd- , _-O -SO _2- , -SO ₂ -,-
_{SO 2 -C rc H 2rc -,} - C rc H 2rc -N (C pb H 2pb + 1)
_{-SO 2 -, - C rc H} 2rc -N (C pb H 2pb + 1) -CO-
_Where rc and rd are independently 1-20, sa is independently 1-10 for each (C _sa H _2sa -O), ta is 1-6, pb is 0-4. is there.

R ⁴ is -O- (C _qc H _2qc -O) _wa- C _{qd
H 2qd + 1, - (C} qc H 2qc -O) wa -C qd H 2qd + 1, -C
_qc H _2qc -R ⁶ , _{-OC qc} H _2qc -R ⁶ , -CO- _OC
qc H _2qc -R ^6, or represents _{-O-CO-C qc H 2qc} -R 6, linear, may be either branched (Here, R
⁶ is _{-O-CO-C qd H 2qd} + 1, -CO-O-C qd H
_{2qd + 1, -Cl, -F,} -CF 3, -NO 2, represents -CN, or -H, qc and qd are independently an integer of 1 to 20, the wa is an integer of 1 to 10).

R ⁵ is (C _xb F _2xb -O) _za -C _ya F
_{2ya + 1} is represented by (wherein, the formula xb is 1 to 10 independently of each _{(C xb F 2xb -O),} ya is 1
And za is 1-10).

The compound represented by the above general formula (I) is
JP-A-2-142755, U.S. Pat.
2,587.
Specific examples of such compounds are listed below.

[0061]

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[0062]

Embedded image

[0063]

Embedded image

[0064]

Embedded image

[0065]

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[0066]

Embedded image

[0067]

Embedded image

[0068]

Embedded image

[0069]

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[0070]

Embedded image

[0071]

Embedded image

[0072]

Embedded image The compound represented by the above general formula (II) is disclosed in International Publication W
O93 / 22396 and JP-T-7-506368. Specific examples of such compounds are listed below.

[0073]

Embedded image

[0074]

Embedded image

[0075]

Embedded image

[0076]

Embedded image

[0077]

Embedded image By the way, in the liquid crystal element 1 of the present invention, selection of materials for the alignment control film 10, the film 7, and other components (for example, a transparent electrode, a short prevention film, and other functional films) in each of the substrates 2 and 3 are performed. By adjusting the type, the surface potential detected on the surface of the uniaxially oriented substrate 2 (accurately,
The absolute value of the difference between the surface potential generated on the orientation control film 10) and the surface potential detected on the surface of the non-uniaxially oriented substrate 3 (accurately, the surface potential generated on the film 7) is less than 100 mV, preferably 50 mV. And more preferably less than 30 mV, to make the both surface potentials substantially equal. Similarly, by adjusting the materials of the orientation control film 10 and the film 7, the polarities of the surface potentials of the two substrates 2 and 3 are made the same.

In general, when the absolute value of the surface potential difference is large (specifically, in the case of 100 mV to 200 mV),
Switching asymmetrical characteristics that affect the drive margin tend to appear, and in an element whose absolute value exceeds 250 mV, switching failure often occurs and the bistable potential collapses. When the absolute value of the potential difference is small (for example, when the absolute value of the surface potential difference is smaller than 50 mV, or when the surface potential polarity is the same in both substrates 2 and 3 and the absolute value of the surface potential difference is 50 to 100 mV) In this case, the asymmetric characteristic of the switching threshold can be suppressed. In addition, it is possible to suppress the influence of the substrate surface on the dipole of the liquid crystal molecules when left unattended, and prevent monostable over time. In particular, the absolute value of the difference between the surface potentials of the two substrates 2 and 3 is 30 mV.
In the following, when both surface potentials are made substantially equal, the switching symmetry is stably maintained.

Here, the meaning of the term “surface potential” used in this specification, a method of measuring the surface potential, and the action caused by the surface potential will be described in detail.

As used herein, “surface potential”
Means the potential due to the polarity of the film itself, the electric double-layer potential due to carrier transfer between the underlying films, and the complex potential induced on the film surface by the potential due to the ionic molecules contained in the film. .

For the measurement of the surface potential, for example,
Reports from Ito and Iwamoto (Tokyo Tech.)
5 p352-358 (1993), Journal
ofElectrostatics 33 p147-
158 (1994)). This report is about polyimides, and in this report Ito et al.
`` In the polyimide film, the surface potential changes greatly depending on the type of the underlying metal film, and the direction and amount of the change correspond to the work function of the metal film, and the surface potential changes depending on the polyimide film thickness and the carrier From the point of saturation at about 5 nm, which is the tunnel limit, the cause of the surface potential in the polyimide film is mainly the electric double layer due to carrier movement between the electrodes. "

As a method of measuring the surface potential, a vibration capacitance type, a sector type, and a pyroelectric type are known as a capacitive method, and in the present embodiment, Trek Corporation Capacitance type surface voltmeter (320B)
) Was used to measure the surface potential.

Here, according to the experiments performed by the present inventors, it has been found that the measured value of the surface potential greatly changes depending on the polar molecules adsorbed on the surface. In air atmosphere, it is mainly susceptible to water molecules, especially for highly hygroscopic materials.
There are cases where the measured value in a vacuum atmosphere and the measured value in an air atmosphere are significantly different. By the way, when preparing a liquid crystal element, the liquid crystal is injected under vacuum heating. By this vacuum heating, the adsorbed water molecules on the surface are desorbed, and in some cases, the molecules in the liquid crystal component are adsorbed and fixed. It is considered that a high surface potential is developed. Therefore, in this embodiment, the measurement of the surface potential is performed in an atmosphere equivalent to the liquid crystal injection environment of the device.

FIG. 2 shows a vibration capacitance type surface voltmeter (vibration capacitance type (320B type) manufactured by Trek Corporation) used in the present embodiment.

This surface voltmeter 20 is
1 and a chamber 2 by an evacuation system 22.
1 is evacuated, and a gas such as dry nitrogen can be charged by the gas introduction system 23.

A substrate sample heating table 25 for mounting a sample is disposed inside the chamber 21. The substrate sample heating table 25 is provided with a temperature control device 26 installed outside the vacuum chamber. To heat the sample to a predetermined temperature.

Reference numeral 27 indicates a sample whose surface potential is to be measured. This sample 27 is various candidate materials used for the alignment control film and the like. In order to make the same condition as the actual liquid crystal element, the electrode 30 is formed on the surface of the substrate 29 and the sample is formed on the surface of the electrode 30. 27 are formed.

Reference numeral 31 denotes a probe for measuring the surface potential. The probe 31 is constituted by a preamplifier, a vibrator 32, and a sensor electrode 33 attached to the vibrator 32. And the vibrator 32
Is obtained by oscillating the sensor electrode 33 so that the sample 2
The capacity between the 7-electrode 33 is modulated.
Surface potential measurement control device 3 installed outside vacuum chamber
5 is connected.

On the other hand, the vibrator 32 and the sensor electrode 33
Is attached to a biaxial distance displacement device 36, which maintains the distance between the sample 27 and the sensor electrode 33 at an appropriate distance of about 0.5 to 5 mm, Can be moved along the sample surface.

On the other hand, reference numeral 37 denotes a liquid crystal, reference numeral 39 denotes a container for holding the liquid crystal 37, and reference numeral 50 denotes a sample heating table for heating and evaporating the liquid crystal 37. Like the substrate sample heating table 25, it is connected to a temperature controller 26. With these, a liquid crystal atmosphere is created in the chamber 21 to expose and adsorb the liquid crystal component molecules to the sample surface.

The conditions for measuring the surface potential are in accordance with the standard liquid crystal injection conditions in the present invention. For example, the degree of vacuum in the chamber is set to 10 ^-1 to 10 ^-3 Torr, and the temperature is set to 80 to 100 ° C. The sample was heated for 15 minutes to 2 hours, and then cooled to room temperature for measurement.

When measuring the surface potential, the sensor electrode 33 is moved along the sample surface by the biaxial displacement device 36, so that the electrode portion exposed without being covered by the sample 27 (electrode exposed portion) ) And the surface potential of the sample 27 were measured, and the value obtained by subtracting the former (the surface potential of the electrode-exposed portion) from the latter (the surface potential of the sample 27) was used as the measurement result.

According to the present inventor, it is apparent that the surface potential varies greatly in the range of approximately +500 to -500 mV depending on the material of the sample (the orientation control film or the film on the substrate on the non-uniaxial orientation side). became.

In the case of an asymmetric liquid crystal element,
There is a difference between the surface potential of the uniaxially oriented substrate and the surface potential of the non-uniaxially oriented substrate. An internal potential is generated due to the difference in the surface potential. For the concept of the internal potential, see FIG. I will explain.

In the figure, reference numerals 61 and 62 denote translucent substrates. One translucent substrate 61 is provided with a layer 63 having a uniaxial orientation characteristic, and the other translucent substrate 62 is provided. Has a layer 64 having non-uniaxial orientation characteristics.
The substrates 61 and 62 are arranged at a predetermined distance from each other, but no liquid crystal is arranged between them. In this case, both layers 63 and 64 have surface potentials 65 and 66, respectively.
And an internal potential 67 is generated correspondingly. According to the measurement results of the surface potential described above, it is recognized that the value of the internal voltage reaches as much as ± 1 V.

It is considered that the existence of the internal voltage is effectively the same as the case where the DC offset voltage is constantly applied between the upper and lower electrodes (not shown) of the cell. Therefore,
In order to experimentally verify the effect of this internal voltage on the switching threshold, cells having a symmetrical configuration (for example, an alignment control film made of the same material formed on both substrates and subjected to the same treatment on the alignment control film) And the surface potential difference is zero), a DC offset voltage is superimposed between the upper and lower electrodes of the cell, and the change in the switching threshold is measured.
It was confirmed that a threshold change occurred at a DC offset voltage of about ± 50 mV to about one hundred and several tens mV.

Here, the surface potential difference (absolute value) of both substrates and the asymmetric characteristic of the switching threshold will be described.

When the surface potential difference (absolute value) of both substrates is small (for example, when the absolute value of the surface potential difference is smaller than 50 mV, or when the surface potential polarity is the same in both substrates and the absolute value of the surface potential difference is 50 to 50 mV). (In the case of 100 mV), the switching asymmetric characteristic hardly appears regardless of the surface potential characteristics on both substrate surfaces. In this case, the absolute value of the switching threshold difference indicating the switching asymmetry is 1. 0 V or less (threshold difference -1.
0 to 1.0 V). Conversely, when the absolute value of the surface potential difference is large (specifically, 100 mV to 200 m
V) tends to exhibit switching asymmetric characteristics. In particular, in a device in which the absolute value of the surface potential difference exceeds 250 mV, switching failure occurred in many cases, and collapse of the bistable potential was observed. The direction of the polarity of the surface potential difference and the direction of the asymmetric characteristic of the switching threshold value were almost the same.

As described above, according to the present invention, the absolute value of the difference between the surface potential detected on the surface of the uniaxially oriented substrate 2 and the surface potential detected on the surface of the non-uniaxially oriented substrate 3 is determined. By making it smaller than 100 mV, the asymmetric characteristic of the switching threshold can be suppressed.

With reference to FIGS. 4A to 4D, a particularly desirable configuration in the present invention will be described.

In the liquid crystal device shown in FIG. 9A, a layer 63 having uniaxial alignment characteristics is formed on one translucent base material 61.
A layer 6 having non-uniaxial orientation characteristics is formed on the other light-transmitting substrate 62.
4, in which the surface potentials 65, 66 generated in the layers 63, 64 are of the same polarity, and the internal potential 67 corresponding to the difference is less than 50 mV (absolute value). is there. The liquid crystal element shown in FIG.
The surface potentials 65 and 66 generated in each of the layers 63 and 64 have different polarities, and the internal potential 67 corresponding to the difference therebetween.
Is less than 50 mV (absolute value). further,
The liquid crystal element shown in FIG. 9C is an element in which an additional film 68 such as a short-circuit prevention layer is provided between one of the translucent bases 61 and the layer 63, and has an internal potential 67 of 50 mV (absolute). value)
It is a smaller element. Further, in the liquid crystal element shown in FIG. 4D, the absolute value of the difference between the surface potentials 65 and 66 is 50 m.
V element or less.

As described above, in the configuration of the liquid crystal element of the present invention, the surface of the layer having uniaxial alignment characteristics with respect to the liquid crystal molecules and the surface of the layer having non-uniaxial alignment characteristics with respect to the liquid crystal molecules are located between the surfaces. Maintaining proper surface property relationships is important to provide a uniform bistable potential with respect to switching ferroelectric or antiferroelectric liquid crystals after alignment.

Further, as a measure of the characteristics at the liquid crystal side interface between the translucent substrates 61 and 62, when a chiral smectic liquid crystal, particularly a ferroelectric liquid crystal or an anti-ferroelectric liquid crystal is used, especially when a ferroelectric liquid crystal is used. It is also important that the direction of the spontaneous polarization during the SmA → SmC * transition is directed toward the substrate (outward property) or toward the bulk of the liquid crystal (center of the liquid crystal layer) (inward property). . It has been recognized that such a property strongly correlates with the surface potential polarity at the liquid crystal side interface of each substrate. In other words, by adjusting these outward or inward properties, the symmetry of switching is ensured, and the bistable potential of switching can be stably equalized.

As a result, for example, it is possible to suppress the occurrence of an alignment defect or a defect domain from a foreign substance defect such as a spacer or another step (for example, a step between pixels), and to obtain a good memory characteristic or margin characteristic. It can be realized.

Next, the above-described surface potential polarity will be described.

The surface potential polarity is generally caused by contact charging generated by contact between an organic film or inorganic film and a metal, or generation of a potential on the surface as a charge in which ions or the like existing in the film are distributed. It is thought that it can be seen in.

In the present invention, the surface potential polarity detected on the surface of the uniaxially oriented substrate 2 and the non-uniaxially oriented substrate 3
The dipole of chiral smectic liquid crystal or antiferroelectric liquid crystal is affected by the magnitude or direction of the two polarities of the surface potential polarity detected on the surface, and the switching characteristics of the liquid crystal fluctuate It is inevitable. Therefore, in the liquid crystal device of the present invention, by appropriately controlling such a relationship of the surface potential polarity itself, preferably, the orientation state of the liquid crystal, switching characteristics, and the like are improved particularly by making the surface potential polarity the same. be able to.

In the liquid crystal element 1 (structure shown in FIG. 1) according to the present invention, the resistance (volume resistance) of the film 7 in the thickness direction is 10 ⁴
Although it is in the range of 10 to 10 ⁸ Ωcm, a preferable range of such a resistance value will be described in detail.

The upper limit (10 ⁸ Ωcm) is defined by a time constant condition as to whether or not the previous state of display is electrically released (reset). In other words, in driving a ferroelectric liquid crystal having bistability, a reset signal (generally for adjusting to a “black” state) is input before a desired pixel state is determined. In order not to affect the image quality in such a case, it is preferable to set the reset signal within a width of about 100 μsec at most. In order to electrically release (reset) the previous state within such a width (within 100 μsec), the resistance (volume resistance) in the film thickness direction of the film 7 is about 10 ⁸ Ωcm.
It is necessary that:

This will be described mathematically as follows.

The equivalent circuit time constant γ is (C1c + Ca)
* R1c * Ra / (R1c + Ra) C1c; capacity of liquid crystal, Ca; capacity of film (film 7) on substrate on non-uniaxial alignment side, R1c: resistance of liquid crystal, Ra: film on substrate on non-uniaxial alignment side (film 7) ), Where (C1c + Ca) ≒ Ca, R
When a "R1c, γ ≒ CaRa = ε a ε 0 ρ a; a ([rho _a film resistivity in the substrate of a non-uniaxial alignment side).

The time constant γ is equal to 10 as described above.
Since Nakere must smaller than 0μsec, the _{ε a ε 0 ρ a <100μsec} .

Then, the liquid crystal film thickness: 2 μm, the thickness of the film (film 7) on the non-uniaxially oriented substrate: 1000 °, the liquid crystal dielectric constant: 6, the dielectric constant ε of the film (film 7) on the non-uniaxially oriented substrate _{If a is} 10, it is roughly estimated that ρ <10 ⁸ Ωcm.

On the other hand, the lower limit (10 ⁴ Ωcm) is set so as to prevent a current from flowing to an adjacent pixel to cause a voltage drop when the liquid crystal element has a matrix structure.
It is determined from the viewpoint of preventing crosstalk between lines.

For example, in the case where a matrix of 1000 * 1000 pixels is formed, if the sheet resistance of the electrode stripe to be used is about 1 Ω / □, 100
The resistance value up to the 0th pixel is about 1 kΩ. Actually, in the current transparent electrode forming technology, such a level can be obtained. On the other hand, assuming that the width between adjacent electrode stripes is about 10% of the stripe width, the current direction to the adjacent stripe electrodes is 1/10000 of the sheet resistance of the film (film 7) on the non-uniaxially oriented substrate. Value, 1000
In order to keep the voltage drop rate at the 1st pixel below 1/100, the sheet resistance between the stripe electrodes needs to be 10 ⁶ times larger. That is, the sheet resistance of the film is 1
The resistance is required to be about ^{9 9} Ω / □, for example, the film resistivity of a film having a thickness of 500 、 ５ is 5 × 10 ³ Ωcm or more, preferably 10 ⁴ Ωcm or more.

Next, means for measuring the resistance (volume resistance) of a film such as the film 7 will be described with reference to FIGS.

FIG. 5 shows a system for measuring the resistance (volume resistance) in the film thickness direction.
Is a film to be measured, which is measured by flowing a current between the electrode 72 and the electrode 73. Here, one electrode 72 is an electrode made of Al and having a diameter of 1 mmφ, and the other electrode 73 is an electrode made of ITO.

FIG. 6 is a diagram showing a system for measuring the resistance (volume resistance) in the film surface direction of the film. Reference numeral 74 denotes a film to be measured. The measurement is performed by passing a current during the measurement.

In the present invention, a predetermined inorganic film may be provided closer to the substrate than the film 7 (for example, between the film 7 and the electrode 6) to further increase the breakdown voltage. Thereby, the durability of the element can be increased.

Examples of such an inorganic film include ZnO, Sn
A vapor-deposited film formed by various sputtering methods such as O ₂ or TaOx is suitable. For example, by adjusting the gas pressure of an oxygen gas, an argon gas or the like, or by adjusting the RF power, the resistivity in the film thickness direction can be adjusted to 10%. ⁴ to 10 ⁸ Ωcm
A film having a thickness of about 1000 to 2000 mm controlled optimally can be used optimally.

When such an inorganic film is provided, the upper limit of the resistance (volume resistance) in the film thickness direction is, like the film 7,
Approximately 10 ⁸ Ω because it is necessary to cancel the state before switching.
cm is preferable.

On the other hand, the same applies to the lower limit value and the upper layer film. For example, even if the liquid crystal portion is short-circuited due to the incorporation of a conductive foreign substance or the like, it flows in the thickness direction of the deposited film. By suppressing the current, it is derived based on a condition for preventing a defect in image quality from being noticeable in or around the short portion. As an example of a typical idea, when an electric path is generated in a liquid crystal portion in a film thickness direction by a foreign substance having a thickness of about the cell, in order to reduce the above-described voltage drop rate between pixels to 1/100, The resistance of this portion is required to be 100 times the resistance of 1 kΩ from the feeding portion to the pixel end. If the short area is 2 μm * 2 μm and the thickness of the inorganic film is 1000 °, ρ _min * 1 * 10 ⁻⁵ /
From (2 * 10 ^-4 ) ² ≧ 1 * 10 ⁵ (Ω) (ρ _min : lower limit value of resistance), ρ _min ≧ 4 * 10 ² (Ωcm), and
For example, assuming a path at a plurality of locations, about 10 ⁴ Ωcm
The above resistance (volume resistance) is required.

[0123]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to specific embodiments. (Embodiment 1) First, Embodiment 1 of the present invention will be described with reference to FIGS.

In this example, a liquid crystal device having the structure shown in FIG. 1 was prepared. That is, the liquid crystal element 1 includes a uniaxially oriented substrate 2 and a non-uniaxially oriented substrate 3 arranged at positions separated by a predetermined distance.
A liquid crystal 5 is sandwiched between the three. Further, an electrode 9 and an alignment control film 10 are formed on the surface of the uniaxial alignment side substrate 2, and the alignment control film 10 is treated to uniaxially align the liquid crystal 5. Further, an electrode 6 and a film 7 are formed on the surface of the non-uniaxial alignment side substrate 3 so as to have non-uniaxial alignment characteristics with respect to liquid crystal molecules.

Next, a method for manufacturing the liquid crystal element 1 will be described.

First, a general DC sputtering apparatus and an ITO
An ITO film is sputtered on the surfaces of the substrates 2 and 3 using a target of (indium tin oxide). In this sputtering, the power of the sputtering apparatus was set to 1 W / cm ² and the sputtering gas was Ar
Mixed gas of O ₂ and O ₂ (Ar: 90 SCCM, O ₂ : 10S)
(CCM), the discharge time was 2.5 minutes, and the thickness of the ITO film was 700 °. Then, the ITO film is patterned into a desired shape by a normal wet etching method,
Electrodes 6 and 9 were made.

Next, the surface of one substrate (uniaxially oriented substrate) 2 was spin-coated with nylon diluted with formic acid (0.2 wt%) at 3000 rpm for 20 seconds.
This was baked at 180 ° C. for 60 minutes to form an orientation control film (nylon film) 10 having a thickness of 50 °. Thereafter, the orientation control film 10 was subjected to rubbing three times in one direction at a rotation speed of 1000 rpm, a pushing amount of 0.3 mm, a feed speed of 5 mm / sec.

Also, the other substrate (non-uniaxially oriented substrate) 3
A film 7 made of an Al-doped ZnO film was formed to a thickness of 1000.degree. The target was ZnO: 95.5% and A
l ₂ O ₃ : 0.5% is used and the power is 5
W / cm ² and the substrate heating temperature was 200 ° C. The sputtering gas is a mixed gas of Ar and O ₂ (Ar: 9).
0 SCCM, O ₂ : 10 SCCM) and the pressure is 3 m
Torr and the discharge time was 2 minutes.

When the substrate 3 was observed using a cross-sectional TEM (transmission electron microscope), it was found that the film 7 had almost no crystal grain boundaries in the film thickness direction, and a plurality of crystal grain boundaries in the film surface direction. It had a polycrystalline structure.

Next, the alignment control film 10 of the uniaxial processing side substrate 2
A solution containing 2.2 μm-diameter SiO ₂ fine particles was applied to the surface by spin coating, and heated to disperse and fix the SiO ₂ fine particles on the surface of the orientation control film 10. Further, a solution containing adhesive particles (particles made of an epoxy resin having a particle size of about 5 μm) was applied by a spin coating method, and heated again to disperse and fix the adhesive particles.

Further, using a printing machine, a sealant is applied to a desired position of the substrate 3 on the non-uniaxial processing side, and this is applied at 90 ° C. for 5 minutes.
Prebaked for minutes.

Further, the substrate 2 and the substrate 3 were pressed at a pressure of 50 gf / cm ² using a press machine, and heated at 110 ° C. for 90 minutes while applying the same pressure with an air cushion. The sealing agent was cured, and the two substrates 2 and 3 were bonded to form an empty cell.

Thereafter, the empty cell formed in the above operation is placed in a normal load-lock type vacuum chamber, and 10 ⁻³ T
After evacuation to orr, the liquid crystal was similarly immersed in a liquid crystal storage tank heated to 95 ° C. in a vacuum so as to provide an injection port, and the liquid crystal was injected into the empty cell.

For the liquid crystal element formed by the above process, first, as shown in FIG. 7, the non-uniaxial processing side substrate 3 (more precisely, the electrode 6) is grounded, and the uniaxial processing side substrate 2 ( To be precise, the test was performed by applying a signal voltage to the electrode 9) side.

FIG. 8 shows the relationship (VT characteristic) of the light transmittance when the write signal voltage is applied and the voltage is changed in the evaluation of the device. The difference between the direction of the arrow and the direction of the return shown in the figure is an amount called hysteresis. Ideally, it is desirable to be "0". However, in practice, it is sufficient if the driving voltage is about 5% or less.

The solid line U1 and the broken line U2 indicate which direction the spontaneous polarization of the liquid crystal molecules is oriented at the time of black reset. For example, when Ps is negative, U1 indicates the direction toward the non-uniaxial alignment side.
U2 is directed to the uniaxial orientation side. When the respective states of U1 and U2 are set to the black state, it is desirable that the amount of deviation between the respective voltage thresholds is ideally also “0”.
It is said that symmetry was obtained at this time. On the other hand, the threshold shift amount is also called asymmetry, and if the value is practically less than about ± 1 V, the bistable potential is not extremely disturbed, and a change over time such as writing failure or burn-in is caused. Is suppressed.

The V of the liquid crystal element according to the embodiment of the present invention shown in FIG.
In the -T characteristic, the hysteresis is suppressed to 0.8 V and the asymmetry is suppressed to 0.3 to 0.4 V, which is well within the required range.

Further, when the produced liquid crystal element is driven,
No afterimage was seen, and it was confirmed that a quick response was obtained.
Further, in this liquid crystal element, no flicker or growth of a defective display area is observed, and extremely good bistability is obtained, and progress of image sticking and monostability is sufficiently suppressed, and high reliability is obtained. confirmed. Further, there was a sufficient margin for the drive voltage. (Embodiment 2) Next, Embodiment 2 will be described with reference to FIG.

First, a general DC sputtering apparatus and an ITO
An ITO film is sputtered on the surfaces of the substrates 2 and 3 using a target of (indium tin oxide). In this sputtering, the power of the sputtering apparatus was set to 1 W / cm ² and the sputtering gas was Ar
Mixed gas of O ₂ and O ₂ (Ar: 90 SCCM, O ₂ : 10S)
(CCM), the discharge time was 2.5 minutes, and the thickness of the ITO film was 700 °. Then, the ITO film is patterned into a desired shape by a normal wet etching method,
Electrodes 6 and 9 were made.

Next, the surface of one substrate (uniaxially oriented substrate) 2 was spin-coated with nylon diluted with formic acid (0.2 wt%) at 3000 rpm for 20 seconds.
This was baked at 180 ° C. for 60 minutes to form an orientation control film (nylon film) 10 having a thickness of 50 °. Thereafter, the orientation control film 10 was subjected to rubbing three times in one direction at a rotation speed of 1000 rpm, a pushing amount of 0.3 mm, a feed speed of 5 mm / sec. Further, an ordinary load-lock type parallel plate RF plasma CVD apparatus is used, and the surface of the other substrate (non-uniaxially oriented side substrate) 3 is n-type polycrystalline Si.
A film 7 made of C: H was formed to a thickness of 2000 mm. The frequency was 13.56 MHz and the substrate heating temperature was 2
The temperature was set to 00 ° C., and the power was set to 300 mW / cm ² . Silane (SiH ₄ ): 40 SCC
M, isobutane (iC ₄ H ₁₀ ): 300 SCCM, hydrogen diluted 0.1% phosphine (PH ₃ / H ₂ : 0.1%):
Using a mixed gas of 10 SCCM, the pressure is 0.2 Torr
And the discharge time was 30 minutes.

Observation of the substrate 3 using a cross-sectional TEM (transmission electron microscope) revealed that the cross section of the film 7 had almost no crystal grain boundaries in the film thickness direction, and a plurality of crystal grains in the film surface direction. It had a polycrystalline structure with boundaries.

Next, the orientation control film 10 of the uniaxial processing side substrate 2
A solution containing 2.2 μm-diameter SiO ₂ fine particles was applied to the surface by spin coating, and heated to disperse and fix the SiO ₂ fine particles on the surface of the orientation control film 10. Further, a solution containing adhesive particles (particles made of an epoxy resin having a particle size of about 5 μm) was applied by a spin coating method, and heated again to disperse and fix the adhesive particles.

Further, using a printing machine, a sealant is applied to a desired position of the non-uniaxial processing side substrate 3 and this is applied at 90 ° C. for 5 minutes.
Prebaked for minutes.

Further, the substrate 2 and the substrate 3 were pressed with a press machine at a pressure of 50 gf / cm ² and heated at 110 ° C. for 90 minutes while applying the same pressure with an air cushion. The sealing agent was cured, and the two substrates 2 and 3 were bonded to form an empty cell.

Thereafter, the empty cell formed by the above operation is placed in a normal load lock type vacuum chamber, and 10 ⁻³ T
After evacuation to orr, the liquid crystal was similarly immersed in a liquid crystal storage tank heated to 95 ° C. in a vacuum so as to provide an injection port, and the liquid crystal was injected into the empty cell.

FIG. 9 is a diagram showing the VT characteristics of the liquid crystal element prepared as described above. From this figure, the hysteresis is suppressed to 0.8 V and the asymmetry is suppressed to 0.3 to 0.4 V. It is well within the required range.

When the formed liquid crystal element is driven, no afterimage is seen, and a high responsiveness is obtained. Further, in this liquid crystal element, no flicker or growth of a defective display area is observed, and extremely good bistability is obtained. Burn-in and progress of monostability are sufficiently suppressed, and high reliability is obtained. Further, there was a sufficient margin for the drive voltage.

[0148]

As described above, according to the present invention,
A good alignment state can be obtained, the effect of the anti-electric field effect and crosstalk between pixels can be sufficiently prevented, and the asymmetric characteristic of the switching threshold can be suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating one embodiment of a liquid crystal element according to the present invention.

FIG. 2 is a schematic diagram showing the entire configuration of a vibration capacitance type surface electrometer.

FIG. 3 is a schematic diagram for explaining the concept of an internal potential in a liquid crystal element.

FIG. 4 is a schematic diagram for explaining an example of a state of an internal potential in the liquid crystal element of the present invention.

FIG. 5 is an explanatory diagram showing a resistance (volume resistance) measuring system in a film thickness direction of a film on a substrate on a non-uniaxial orientation side.

FIG. 6 is an explanatory diagram showing a resistance (volume resistance) measurement system in a film surface direction of a film on a substrate on a non-uniaxial orientation side.

FIG. 7 is a cross-sectional view showing a measurement system for surface potential.

FIG. 8 shows a liquid crystal element according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating hysteresis and switching asymmetry.

FIG. 9 is a diagram showing hysteresis and switching asymmetry of a liquid crystal element according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal element 2 Uniaxial alignment side substrate (substrate) 3 Non-uniaxial alignment side substrate (substrate) 5 Liquid crystal 7 Film 10 Alignment control film (Uniaxial alignment film)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shuzo Kaneko 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Katsutoshi Nakamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside the corporation

Claims (13)

[Claims] 1. A liquid crystal display device comprising: a pair of substrates disposed at a predetermined distance from each other; and a liquid crystal interposed between the pair of substrates, wherein at least one of the substrates has a uniaxial alignment characteristic with respect to liquid crystal molecules. In a liquid crystal device having at least one of a pair of substrates, a film having a polycrystalline structure having almost no crystal grain boundaries in the film thickness direction and having a plurality of crystal grain boundaries in the film plane direction is provided. Characteristic liquid crystal element. 2. One of the substrates has a uniaxial alignment characteristic with respect to liquid crystal molecules, and the other substrate has a non-uniaxial alignment characteristic with respect to liquid crystal molecules, and at least the substrate having the non-uniaxial alignment characteristic includes: 2. The liquid crystal device according to claim 1, comprising the film having the polycrystalline structure. 3. The method according to claim 1, wherein the film on the substrate having the non-uniaxial orientation characteristic is formed of a polycrystalline metal oxide or a polycrystalline semiconductor to which a conductivity control impurity is added. 3. The liquid crystal device according to 2. 4. An absolute value of a difference between a surface potential detected on the surface of the substrate having the uniaxial orientation characteristic and a surface potential detected on the surface of the substrate having the non-uniaxial orientation characteristic is 100 mV. 3. The liquid crystal device according to claim 2, wherein: 5. An absolute value of a difference between a surface potential detected on the surface of the substrate having the uniaxial orientation characteristic and a surface potential detected on the surface of the substrate having the non-uniaxial orientation characteristic is 50 mV. The liquid crystal device according to claim 4, wherein 6. An absolute value of a difference between a surface potential detected on the surface of the substrate having the uniaxial orientation characteristic and a surface potential detected on the surface of the substrate having the non-uniaxial orientation characteristic is 30 mV. The liquid crystal device according to claim 4, wherein 7. A surface potential detected on the surface of the substrate having the uniaxial orientation property and a surface potential detected on the surface of the substrate having the non-uniaxial orientation property are substantially equal to each other; The liquid crystal device according to claim 4, wherein: 8. The surface potential polarity detected on the surface of the substrate having the non-uniaxial orientation characteristic and the surface potential polarity detected on the surface of the substrate having the uniaxial orientation characteristic have the same polarity. The liquid crystal device according to claim 4, wherein: 9. The film of the substrate having the non-uniaxial orientation characteristic has a volume resistivity in a thickness direction of 10 ⁴ to 10 ⁷ Ωc.
3. The liquid crystal device according to claim 2, wherein m is set to m, and a volume resistance in a film surface direction is set to 10 ⁶ to 10 ⁹ Ωcm. 10. The liquid crystal device according to claim 1, wherein the liquid crystal is a liquid crystal exhibiting a chiral smectic phase. 11. The liquid crystal device according to claim 10, wherein the liquid crystal is a liquid crystal that does not exhibit a cholesteric phase. 12. The liquid crystal composition comprising at least one fluorine-containing compound exhibiting a smectic phase or a potential smectic phase having a structure in which a fluorocarbon terminal portion and a hydrocarbon terminal portion are bonded to a central nucleus. The liquid crystal device according to claim 11, wherein: 13. The liquid crystal device according to claim 10, wherein the liquid crystal is a liquid crystal exhibiting ferroelectricity.