JPH08262447A - Liquid crystal element - Google Patents

Abstract

PURPOSE: To provide a liq. crystal element having a good liq. crystal oriented state and stabilized optical responsiveness and improved in the asymmetry of switching. CONSTITUTION: A liq. crystal 8 is held between a couple of opposed substrates 1 and 2, the substrate 1 has a uniaxial orientation characteristics, and the substrate 2 has a non-uniaxial orientation characteristics in the liq. crystal element. The absolute value of the difference between the surface potential detected on the surface (interface with liq. crystal) of the substrate 1 having the uniaxial orientation characteristics and the surface potential detected on the surface (interface with liq. crystal) of the substrate 2 having the non-uniaxial orientation characteristics is controlled to <=50mV.

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 a liquid crystal, such as a computer terminal display, word processor, typewriter, television receiver, video camera viewfinder, projector light valve, liquid crystal printer light valve, and the like. A liquid crystal element used in a liquid crystal element that exhibits good display characteristics, particularly using a liquid crystal exhibiting a chiral smectic phase such as a ferroelectric liquid crystal or an antiferroelectric liquid crystal that is driven by utilizing the action of spontaneous polarization. Regarding

[0002]

2. Description of the Related Art Conventionally, a CRT has been known as a display which has been used most widely, and is used in a TV and a V.
It is widely used for video output such as TR, or as a monitor for personal computers. However, due to the characteristics of the CRT, for a still image, flicker or scanning stripes due to insufficient resolution may reduce the visibility, or the fluorescent lamp may deteriorate due to burn-in. Recently, it has been found that the electromagnetic waves generated by CRTs have a bad influence on the human body.
There is a risk that the health of the DT worker will be impaired. Furthermore, because of the large volume behind the screen due to its structure, it is difficult to save space in offices and homes.

There is a liquid crystal display element as a means for solving such a drawback of the CRT. For example, "Applied Physics L" by M. schadt and W. Helfrich.
eters) Vol. 18, No. 4 (February 15, 1971)
Issued on page 127-128, Twisted nematic
c; TN) liquid crystal is known.

As one of the liquid crystal elements using the TN liquid crystal, there is a simple matrix type which is superior in cost. This liquid crystal element has a problem that crosstalk occurs during time-divisional driving with a matrix electrode structure having a high pixel density, so that the number of pixels is limited.

In recent years, a liquid crystal element called TFT has been developed for such a simple matrix type. Since this type creates a transistor in each pixel, problems of crosstalk and response speed are solved, but it is industrially very difficult to create a liquid crystal element without a defective pixel as the area increases. It is difficult and very costly, if possible.

As a means for improving the drawbacks of the conventional liquid crystal element, a display element of the type that controls transmitted light rays by combining with a polarizing element by utilizing the anisotropy of refractive index of ferroelectric liquid crystal molecules is proposed. Proposed by Clark and Lagerwall (JP 56-107216, U.S. Pat. No. 436).
7924 specification). This ferroelectric liquid crystal generally has a chiral smectic C phase (Sm) in a specific temperature range.
C ^* ) or H phase (SmH ^* ), in which, in response to an applied electric field, one of a first optical stable state and a second optical stable state is taken, and an electric field is applied. It has a property of maintaining its state when there is no, that is, a bistable memory property, and exhibits very fast response speed because it performs inverting switching by spontaneous polarization. Further, since it has excellent visual characteristics, it is considered to be particularly suitable as a high speed, high definition, large screen display element or a light valve.

Similarly, a liquid crystal exhibiting antiferroelectricity is known as a technique for constructing a display element by utilizing the refractive index anisotropy of liquid crystal molecules and spontaneous polarization. This antiferroelectric liquid crystal generally has a chiral smectic CA phase (SmCA ^* ) in a specific temperature range. In this state, the average optical stable state is in the smectic layer normal direction when no electric field is applied. The average optical stable state is inclined from the layer normal direction by application. In addition, antiferroelectric liquid crystals also perform switching due to coupling of spontaneous polarization and electric field, and therefore exhibit extremely fast response speed, and are expected as high-speed display elements or light valves.

[0008]

In a display panel equipped with a liquid crystal element using a ferroelectric liquid crystal or an antiferroelectric liquid crystal, one of the best ways to obtain a good contrast is to obtain a defect-free alignment state. It has become a challenge. As a cell structure for satisfactorily forming such a liquid crystal alignment state, for example, as described in JP-A-61-29303, an alignment control layer having asymmetrical, that is, different characteristics and types is provided on the upper and lower substrates. The configuration is included. One of the upper and lower electrode substrates has a uniaxial alignment property with respect to liquid crystal molecules, and the other has a non-uniaxial alignment property, so that the liquid crystal alignment can be controlled in a highly ordered manner from the uniaxially aligned substrate side. It is possible to easily obtain a good liquid crystal alignment state.

However, when such a structure in which the upper and lower liquid crystal interfaces are changed, the alignment state is apparently good, but asymmetric characteristics occur in switching, or good bistable ferroelectric liquid crystal is obtained. Sex may be hindered,
In some cases, so-called switching memory property is reduced.

To solve this problem, Japanese Patent Laid-Open No. 62-2359
No. 28, JP-A-63-228230 and the like adjust the polarities of the upper and lower surfaces, but further improvement is required to totally stabilize the behavior of the liquid crystal.
In particular, it is necessary to use a liquid crystal element having a simple structure and a low manufacturing cost.

In particular, the symmetry of the switching characteristics is important for widening the drive margin, and moreover, the symmetry of the switching characteristics must be maintained even if the driving is continued for a long time.

In addition to this, particularly in a display panel provided with a liquid crystal element using a ferroelectric liquid crystal or an antiferroelectric liquid crystal, an anti-electric field induced by the spontaneous polarization of the liquid crystal itself is exhibited particularly when performing halftone display. The effect is a serious problem.
That is, there is a case in which a desired halftone is made unstable due to the reason that the internal ions unevenly distributed corresponding to the spontaneous polarization form an electric field, and a hysteresis is caused in the optical response to an applied voltage applied from the outside. this is,
With respect to the direction of spontaneous polarization of liquid crystal molecules when displaying "black state" or "white state", uneven distribution of ions occurs in the direction that stabilizes each state. , Even when the voltage Vw applied after a short period of reset (“black erase”) is equally applied, it occurs because the voltage applied to the liquid crystal portion in the previous state (“white” or “black”) is different. It is considered.

As an extremely inconvenient phenomenon due to the anti-electric field effect as described above, for example, even if the "black state" is set as the reset direction and the "white state" is written, the "white state" is generated at the desired voltage level. Cannot be latched, and a so-called switching failure occurs in which it is swung back to the “black state”. This phenomenon becomes a fatal defect even in a display panel that does not require halftone at the pixel level.

As a countermeasure against the above-mentioned anti-electric field effect,
For example, in Japanese Patent Application Laid-Open No. 63-121020, etc.,
A method of reducing the impedance of an orientation control film forming a ferroelectric liquid crystal element, that is, a method of coping with a switching failure due to a so-called anti-electric field is disclosed. In addition, JP-A-2-
In Japanese Patent No. 153321, many kinds of organic conductive films for lowering the impedance of the orientation control film are disclosed. Further, Japanese Patent Application Laid-Open No. 64-49023 discloses that a thin film orientation layer is formed for passivation for prevention of short circuit with low impedance, but the present situation is that it has not been sufficiently solved.

As described above, the electro-optical characteristics of the liquid crystal element using the chiral smectic liquid crystal are such that the control of the alignment state and the anti-electric field generated by the spontaneous polarization Ps and the threshold change caused by the pre-standing state. , There are issues to be solved such as unstable optical response.

[0016]

The present invention has been made in consideration of the above circumstances, and its object is to provide good switching characteristics and orientation characteristics that can withstand long-time driving at low cost. An asymmetric alignment-treated liquid crystal element,
A liquid crystal element that exhibits a particularly favorable liquid crystal alignment state, reduces switching asymmetry characteristics, and secures stability of two states of liquid crystal (particularly ferroelectric or antiferroelectric liquid crystal), and has stable optical response characteristics. Is to provide.

A further object of the present invention is to provide an anti-electric field induced by the spontaneous polarization of the liquid crystal itself, especially when performing halftone display using the ferroelectric liquid crystal or the anti-ferroelectric liquid crystal. An object of the present invention is to provide a liquid crystal element that prevents the effects of effects and enables excellent halftone display.

The above object of the present invention is to sandwich a liquid crystal between a pair of substrates facing each other, and one substrate has a uniaxial orientation characteristic.
The other substrate is a liquid crystal element having non-uniaxial alignment characteristics, and the surface potential detected on the surface of the substrate having the non-uniaxial alignment characteristics (the surface in contact with the liquid crystal) and the uniaxial alignment treatment have been performed. The absolute value of the difference from the surface potential detected on the surface of the side substrate (the surface in contact with the liquid crystal) is smaller than 50 mV (the surface potential difference is larger than −50 mV and smaller than 50 mV).
It is characterized by the following.

A further object of the present invention is to sandwich a liquid crystal between a pair of opposed substrates, one substrate having uniaxial alignment characteristics with respect to liquid crystal molecules, and the other substrate with respect to liquid crystal molecules. A liquid crystal device having non-uniaxial alignment characteristics, and a volume resistance of 10 ⁴ Ω at least on the substrate side having non-uniaxial alignment characteristics.
The problem is solved by a liquid crystal element provided with a film in the range of 10 cm to 10 ⁸ Ωcm.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, a liquid crystal element using a liquid crystal exhibiting a chiral smectic phase, particularly a liquid crystal exhibiting ferroelectricity or a liquid crystal exhibiting antiferroelectricity, having an asymmetric structure, that is, one of In a liquid crystal device having uniaxial (alignment) characteristics for liquid crystal molecules on the liquid crystal side of the substrate and non-uniaxial alignment characteristics for liquid crystal molecules on the other substrate, the spontaneous polarization of the liquid crystal molecules at the interface on the substrate side having the respective characteristics By adjusting the tendency of the direction (characteristic called outward property or inward property), the symmetry of switching is ensured, and the bistable potential of switching can be stabilized and equalized.

As a result, in the above liquid crystal element, for example, it is possible to suppress alignment defects or generation of defect domains from foreign matter defect parts such as spacers or other steps (eg, step differences between pixels), and a good memory is obtained. It becomes possible to realize the characteristic or the margin characteristic.

In the present invention, "uniaxial alignment property" means a uniaxial alignment state of liquid crystal molecules (for example, uniaxial horizontal alignment state), and "non-uniaxial alignment property" means liquid crystal molecules excluding uniaxial alignment state. It means any alignment state (for example, vertical alignment state, random alignment state).

In the liquid crystal device of the present invention, preferably, the surface potential polarities of both substrates are the same, and the above-mentioned relationship between the surface potential and the value and the absolute value of the difference are 100 mV or less (surface potential difference −100 mV to 100 mV). ), More preferably less than 50 mV in absolute value (surface potential difference greater than −50 and 5).
(Less than 0 mV). Further, by making the absolute value of the surface potential difference between both substrates more preferably 30 mV or less and most preferably substantially the same, the switching symmetry can be stably maintained.

In the liquid crystal element of the present invention, specifically, in one substrate, a layer having a uniaxial orientation controllability for appropriately treated or untreated liquid crystal (orientation control layer) is provided on the other substrate. In the substrate, a layer that imparts non-uniaxial alignment characteristics to the liquid crystal is provided, and the liquid crystal is sandwiched between these substrates (interlayer). Then, these alignment control layer, non-uniaxial orientation imparting layer, further by other components in each substrate, for example, transparent electrode, short-circuit prevention film, by optimally adjusting the selection and type of material of other functional film, The surface potentials on both substrates described above are controlled.

FIG. 1 schematically shows an example of a liquid crystal element (cell cross-sectional structure of the present invention. In the cell structure shown in FIG. 1, a liquid crystal 8 is sandwiched between a pair of substrates 1 and 2. ,
On the inner surface of one of the substrates, an electrode 3 and an alignment control layer 4 which has been treated to uniaxially align the molecules of the liquid crystal 8 inside the cell.
However, the inner surface of the substrate (the surface in contact with the liquid crystal layer) has a uniaxial alignment property for aligning liquid crystal molecules in a predetermined direction.

On the other substrate 2, an electrode 5 and a film having the characteristics described later, for example, a film (preferably a coating film) in which ultrafine oxide particles or ultrafine metal particles are dispersed in an oxide matrix or polymer matrix. If necessary, a treatment portion 7 is formed on the film 6 by coating a known silane coupling agent, and the inner surface of the substrate has a non-uniaxial orientation property with respect to liquid crystal molecules.

Here, the film thickness of the film 6 is preferably 30.
It is 0Å or 5000Å. The film 6 has a material composition selected, for example, in order to adjust the polarity, resistance, surface property, etc. on the substrate side where the film exists, and is formed as a film containing various metals or metal oxides. preferable. Further, the film 6 has a volume resistance value of 10 measured in the sheet direction (layer direction), preferably by the method described below, in order to prevent the influence of the anti-electric field effect due to the chiral smectic liquid crystal having high Ps. ⁴ Ωcm to 10 ⁸ Ωcm, more preferably 10 ⁴ to 10 ⁷ Ωc
It is in the range of m.

As a material for the electrodes 3 and 5, a transparent conductor such as tin oxide, indium oxide, or ITO is preferable, and in the case of forming an element which does not require translucency, Cr, Al, or Ta is used. Metals such as can be used.

The orientation control layer 4 is preferably an organic polymer film of polyimide, nylon, polyvinyl alcohol, or the like, or a conductive polymer film of polyaniline, polypyrrole, or the like, which is uniaxially oriented. In particular, a film made of a known material that is uniaxially oriented by rubbing is preferable. In addition to the organic polymer film, a film of an inorganic material such as a silicon oxide film formed by oblique vapor deposition can be used as the orientation control layer 4. In this case, by adjusting the conditions of the oblique deposition, the uniaxial orientation property is obtained without performing the rubbing treatment described above. As the film thickness, for example, a thin film of about 30 Å to 300 Å is desirable.

On the other hand, the treatment section 7 provided as needed on the surface of the substrate having non-uniaxial orientation controllability includes, for example, the above-mentioned coating treatment of the silane coupling agent, and a silane coupling agent which is volatile with respect to the substrate. And the vapor deposition film formed of an amorphous inorganic material, or the coating film formed under the adhesion condition of preferably 50 Å or less.

The processing section 7 may be provided as necessary as described above, and the surface of the film 6 can also be used as a surface having non-uniaxial orientation characteristics. In addition, it is preferable that the surface of the film 6 is exposed everywhere due to the discontinuous treatment portion 7.

As the liquid crystal layer 8, a material having a spontaneous polarization effect such as a liquid crystal exhibiting a chiral smectic phase, particularly a liquid crystal exhibiting ferroelectricity or a liquid crystal exhibiting antiferroelectricity is widely used, and the device structure of the present invention is used. However, other nematic liquid crystals can also be applied.

In the device structure of the present invention, when a liquid crystal exhibiting a chiral smectic phase and exhibiting a ferroelectric property or a liquid crystal exhibiting an antiferroelectric property is used, the phase transition sequence is an isotropic phase from high temperature to low temperature. It is particularly effective from the viewpoint of orientation when applying a material that becomes SmA → SmC ^* → crystal phase.

In the liquid crystal element of the present invention, in order to improve the brightness at the time of display, a bookshelf structure in which the smectic layer is vertically aligned with the substrate when the liquid crystal takes the SmC ^* phase, or near vertical It is preferable to use a material having a structure with a smectic layer inclination. As the liquid crystal material having such a smectic layer structure, for example, a fluorine-containing liquid crystalline compound having a structure in which a fluorocarbon terminal portion and a hydrocarbon terminal portion are bonded to a central nucleus, and showing a smectic phase or a latent smectic phase can be mentioned. Regarding the fluorine-containing compound, specifically, US Pat. No. 5,082,587 and US Pat.
The fluorine-containing compounds described in 262,082, International Publication WO93 / 22936 and the like can be used.

More specifically, the fluorine-containing compound is, for example, an isotropic phase → SmA when the temperature is lowered as described above.
A liquid crystal material that exhibits a phase transition such as → SmC ^* → crystalline phase (in particular, does not exhibit a cholesteric phase) can be appropriately selected and used.

The device structure of the present invention as described above is basically an asymmetric structure in which only one side of one substrate is uniaxially oriented, and the liquid crystal (especially ferroelectric or antiferroelectric liquid crystal), especially SmA. Orientation in the temperature region is carried out as uniaxial molecular growth from the surface of one of the substrates 1 which has been subjected to the uniaxial orientation treatment, and a good orientation state can be obtained in the SmC ^* phase.

In particular, in the case of using the above-mentioned liquid crystal which does not exhibit a cholesteric phase, in order to realize a uniform alignment state by well controlling the alignment during the phase transition from I (isotropic phase) to SmA under cooling. The asymmetric liquid crystal element structure of the invention is more preferable.

The surface potential and the measuring method defined in the present invention will be described in detail below with respect to the action caused by the surface potential.

The surface potential defined in the present invention means that the surface potential of the membrane depends on the polarity depending on the polarity of the membrane, the electric double layer potential associated with the carrier movement between the underlying films, the potential due to the ionic molecules contained in the membrane, and the like. It is a complex electric potential that has been induced and is a measurement value detected by the measurement method described below.

Regarding the measurement of the surface potential according to these definitions, for example, a report from Ito and Iwamoto (Tokyo Institute of Technology) on polyimide, which is generally known as an alignment film material for liquid crystals (Journal of Japan Electrostatic Society 17,5 p352-358). (199
3), Journal of Electrostati
cs 33 p147-158 (1994)). Ito et al. Show that the surface potential of a polyimide film 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 thickness of the polyimide film. From the point of saturation at a carrier tunnel limit of about 5 nm, it is concluded that the cause of the surface potential in the polyimide film is mainly the electric double layer due to the carrier transfer between the electrodes.

Regarding the method of measuring the surface potential, the vibration capacitance type, the sector type, and the pyroelectric type are known as the capacitive method. In the present invention, a vibration capacitance type surface potential meter (320B type) manufactured by Trek Co., Ltd. was used for the measurement. Specifically, the uniaxial processing side that directly contacts the liquid crystal,
Various potential materials for the film on the non-uniaxially processed side were formed by using a transparent electrode material, a short-circuit prevention film, etc. as a base film as in the cell configuration, and the surface potential was measured. It was revealed that the surface potential was generated in the range of +500 to -500 mV.

According to the experiments conducted by the present inventors, the measured value of the surface potential greatly changes depending on the polar molecule adsorbed on the surface.
In an air atmosphere, water molecules are predominantly susceptible to the influence of water molecules, and particularly in a material having a high hygroscopic property, the measured value in a vacuum atmosphere and the measured value in an air atmosphere may be significantly different from each other. Regarding the surface of the liquid crystal element, liquid crystal injection is often performed under vacuum heating, and after the adsorbed water molecules on the surface are desorbed, the molecules in the liquid crystal component are adsorbed and fixed in some cases and a new surface potential is expressed. It is thought that

Therefore, it is desirable to measure the surface potential in an atmosphere equivalent to the liquid crystal injection environment of the device.

FIG. 2 shows a schematic view of a surface potential measuring system applied in the present invention (the model surface potential meter is a vibration capacitance type (320B type) manufactured by Trek Corporation). The measurement is performed in the vacuum chamber 35. Reference numeral 32 is a vacuum exhaust system, and 33 is a gas introduction system such as dry nitrogen. The surface potential measurement sample 21 basically has the same underlying structure as the device. The same substrate 23 under the same conditions as the device,
The electrodes are formed on the same electrode 22 and arranged on the substrate sample heating table 30. The sample heating table 30 is connected to a temperature control device 31 installed outside the vacuum chamber.

Reference numeral 24 is a surface potential measuring probe, which is composed of a sensor electrode 25, a preamplifier, and a vibrator 26 for vibrating the electrode to modulate the capacitance between the sample and the electrode. The surface potential measurement probe is installed outside the vacuum chamber. It is connected to the control device 27.

The specific surface potential measurement conditions adopted in the present invention are in accordance with the standard liquid crystal injection conditions in the present invention, for example, under reduced pressure of 10 ^{-1 to -3} torr and at 80 to 100 ° C.
The sample was heated for 15 minutes to 2 hours and then cooled to room temperature for measurement. The distance between the sample surface and the sensor electrode 25 is maintained at an appropriate distance of about 0.5 to 5 mm by the biaxial distance displacement device 34. First, the surface potential of the electrode exposed portion adjacent to the sample surface is measured, and then the biaxial. The distance displacement device 34 moves the sensor electrode 25 onto the sample surface to measure the surface potential. The surface potential of the sample is obtained as a value obtained by subtracting the measured value of the exposed portion of the electrode as the reference potential from the measured value on the surface of the sample.

In the present invention, as described above, in some systems, the surface potential in the state where the liquid crystal component molecules are adsorbed under the liquid crystal injection is considered to control the internal potential generated between the substrates in the liquid crystal cell. In practice, it is desirable to perform the comparative measurement and to perform the measurement under the condition that the correlation with the characteristic is better. Reference numeral 28 shown in FIG. 2 denotes liquid crystal, and 29 denotes a heating / evaporating vessel, which is installed on the sample heating table 30. If necessary, a liquid crystal atmosphere can be formed to expose and adsorb liquid crystal component molecules on the sample surface.

With reference to FIG. 3, the concept of the internal potential generated due to the difference in the surface potentials of the liquid crystal side interfaces of the two substrates facing each other in the liquid crystal element having the asymmetric structure of the present invention will be described.

In the figure, reference numerals 41 and 42 denote substrates (electrode substrates), on each of which a layer 33 having a uniaxial orientation characteristic and a layer 44 having a non-uniaxial orientation characteristic made of different materials are formed. The cells are opposed to each other with a certain distance therebetween to form a cell. When such electrode substrates 41 and 42 constitute an empty cell in a short-circuited state, that is, when liquid crystal is not injected between the substrates, surface potentials 45 and 46 are generated in the layers 43 and 44, corresponding to the internal potentials of both substrates. An electric potential 47 is generated.

According to the above-described measurement result of the surface potential, the value of the internal voltage generated corresponding to the difference of the surface potential reaches up to ± 1 V at least in the empty cell in which the upper and lower electrodes are short-circuited before the liquid crystal injection. Is recognized.

It is considered that the existence of the internal voltage due to this surface potential difference is effectively the same as the DC offset voltage being constantly applied between the upper and lower electrodes of the cell. Therefore, in order to experimentally verify the influence of the surface potential difference on the switching threshold of the internal voltage, a cell having a symmetrical structure, for example, a cell in which an alignment control layer having the same material and treatment is formed on both substrates, DC offset voltage is ± 50 when the change in switching threshold is measured by superposing a DC offset voltage between the upper and lower electrodes.
It was confirmed that the threshold value changed at about mV to ± 100 tens of mV.

Next, based on the surface potential measurement values of various alignment control films, the surface potential difference and the asymmetrical characteristic of the switching threshold in the liquid crystal cell having the above-mentioned asymmetric structure by the combination of various alignment control films were compared. The polarity of the surface potential difference and the direction of the asymmetric characteristic of the switching threshold were almost the same, and a significant correlation was also found between the absolute value of the surface potential difference and the degree of the asymmetric characteristic of the switching threshold. That is, the area where the absolute value of the surface potential difference is small, especially 50 m
In an element in a range smaller than V, switching asymmetrical characteristics rarely appear regardless of surface potential characteristics on both substrate surfaces, and conversely ± 100 mV to ± 200 m
In most cases, the elements having a surface potential difference of V tended to exhibit asymmetric characteristics that affect the drive margin. Also, the surface potential polarity is the same on both substrates,
Moreover, even when the absolute value of the surface potential difference is 100 mV or less, switching asymmetry tends to be hardly exhibited. In these cases, the switching threshold difference indicating the asymmetry of switching is an absolute value of 1.0 V or less (threshold difference-1.
It can be adjusted to a level of 0-1.0V). On the other hand, in the element in which the absolute value of the surface potential difference exceeds 250 mV, switching failure often occurred and collapse of the bistable potential was observed.

As described above, the present invention verifies that the surface potential of the vertical alignment control film is important as the controlling factor of the asymmetrical characteristics of the switching threshold in the cell having the asymmetrical structure of the vertical alignment control film, and the asymmetric cell structure is obtained. It was also found that it is possible to suppress the asymmetric characteristic of the switching threshold by controlling the surface potentials at the liquid crystal side interfaces of the upper and lower substrates.

A particularly desirable configuration in the present invention will be described with reference to FIGS. (A) is the electrode substrate 4
When the layer 43 having the uniaxial orientation property and the layer 44 having the non-uniaxial orientation formed on the layers 1 and 42 are formed of different materials, the surface potentials 45 and 46 generated in the respective layers have the same polarity. , And the internal potential 47 corresponding to the difference is 5
An element that is less than 0 mV (absolute value), (b) shows a surface potential of 4
An element in which 5, 46 have different polarities and an internal potential 47 corresponding to the difference is less than 50 mV (absolute value),
(C) is a result of disposing an additional film 48 such as a short-circuit prevention layer between the electrode substrate 41 on one substrate side and the orientation control film layer 43 in the element of (b), resulting in a surface potential 4 of the orientation control layer 43.
5 is different from (b), the element whose internal potential 47 is smaller than 50 mV (absolute value), (d) is the layer 43,
This is an element in which the absolute values of the surface potentials 45 and 46 generated in 44 are each 50 mV or less.

As described above, in the structure of the liquid crystal element of the present invention, an appropriate surface is provided between the surface having the uniaxial alignment property with respect to the liquid crystal molecules and the surface having the non-uniaxial alignment property of the other substrate 2 facing the other surface. It is important to maintain the relationship of properties in order to provide a uniform bistable potential for switching of the ferroelectric liquid crystal or antiferroelectric liquid crystal after alignment.

Further, when a chiral smectic liquid crystal, particularly a ferroelectric liquid crystal or an antiferroelectric liquid crystal is used, as a measure of the characteristics at the liquid crystal side interface of the uniaxially oriented substrate and the non-uniaxially treated substrate, the ferroelectricity is particularly high. SmA for liquid crystal
The property of whether the spontaneous polarization tends toward the substrate side (outward property) or the bulk of the liquid crystal (center of the liquid crystal layer) side (inward property) at the SmC ^* transition is also important. It is recognized that such properties strongly correlate with the surface potential polarity of the liquid crystal side interface of each substrate.

The surface potential polarity is caused by a contact charge generally generated by contact between an organic film or an inorganic film and a metal, or a potential generated on the surface as a charge in which ions existing in the film are distributed. It is thought to be visible in.

As the substrate structure of the liquid crystal element in the present invention, the above-mentioned alignment film, coating film, vapor deposition film or the like may be laminated on a transparent electrode made of, for example, ITO. At this time, the dipole of the antiferroelectric or ferroelectric liquid crystal, which is a chiral smectic liquid crystal, is affected by the magnitude of the surface potential polarity of both the uniaxially oriented substrate and the non-uniaxially oriented substrate, or the relationship in direction. Further, it is inevitable that the switching characteristics of the liquid crystal change. Therefore, in the liquid crystal element of the present invention, by appropriately controlling the relationship between the surface potential polarities themselves on both the substrates, preferably,
In particular, by making the surface potential polarities the same, it is possible to improve the alignment state of the liquid crystal and the switching characteristics.

In the structure of the liquid crystal element of the present invention, in addition to controlling the surface potential value on both substrates or adjusting the surface potential polarity (adjusting to the same polarity) as described above, it is more preferable for both substrates to be respectively. By making the absolute value of the surface potential of (1) smaller, particularly 100 mV or less, it is possible to suppress the influence of the substrate surface on the dipoles of the liquid crystal molecules when standing and prevent monostabilization with time.

As described above, in the liquid crystal element of the present invention,
In order to obtain a good alignment state and a uniform potential for switching, it is important to adjust the surface material and the like on both the non-uniaxially oriented substrate side and the uniaxially oriented substrate side. From this point, it is recognized that, on the liquid crystal side surface of the substrate, an element of interfacial tension which is determined by a dispersion component of the surface energy is important as a potential element of so-called latch in addition to the polar element.

In the liquid crystal element of the present invention, the dispersion term of the surface energy of the surface side substrate having the non-uniaxial orientation property is as small as the surface energy in the vicinity of the SmA → SmC ^* transition of the liquid crystal used, and specifically, Is within 5 dyne / cm as the difference, and the actual value is 30 d
When it is yne / cm or less, or when it is larger than the surface energy of the substrate having the uniaxial orientation characteristic and is in the range of 40 dyne / cm or more as an actual value, good switching characteristics are often obtained, which is preferable.

The meaning of the preferable range of the surface energy is that when the surface energy is low (preferably 30 dyne / cm or less), the liquid crystal has a so-called vertical alignment property with respect to the surface side of the substrate having the non-uniaxial alignment property. By exhibiting the wettability, the liquid crystal in the vicinity of the interface with the surface becomes fixed, and the switching potential is determined inside the liquid crystal (on the liquid crystal bulk side).
On the contrary, when the surface energy is large (40 dy is preferable)
(ne / cm or more), it is considered that the liquid crystal near the interface is fixed due to the so-called horizontal alignment wettability, so that the switching potential on the inner side (liquid crystal bulk side) is determined.

The surface property of the substrate-side surface having such non-uniaxial orientation characteristics can be adjusted by the material or shape of the surface.

On the other hand, the value of the surface energy dispersion component term on the side of the substrate having the uniaxial orientation property is substantially 40 dyne / cm or more in order to obtain good uniaxial horizontal orientation and to determine the stable switching potential. It is preferable to set it in the range of 42 dyne / cm or more, and it is preferable to select the material of the orientation control film so as to make such setting.

Next, the measurement of the surface energy of each substrate of the liquid crystal device of the present invention by the macroscopic surface state will be described.

Examples of the reagent having a contact angle of droplets include A: α-bromonaphthalene, B: methylene iodide,
C: Use water etc. And after measuring the contact angle by each A, B, C etc., as an example, the Japan Adhesion Society magazine, Vol. 8, N
o. 3 (1972) P131-Kitasaki et al., "Fowkes
It is possible to pay attention to the dispersion component of the surface energy obtained by the calculation formula described in "Expansion of formula and evaluation of surface tension of polymer solid." Although there are component terms such as components and hydrogen-bonding components, these are closely related to the surface polarity of the film, and the correlation with the above-mentioned favorable properties is preferably evaluated by noting only the value of the dispersion component. be able to.

In the liquid crystal device having the structure shown in FIG. 1 of the present invention, the film 6 has the polarity or surface state (surface energy) on the surface of the substrate having the non-uniaxial alignment property with respect to the liquid crystal molecules as described above. Is effective as an adjusting material for controlling the volume resistance value, and it may be easy to adjust the effect satisfactorily due to its components and characteristics.

In the present invention, a film made of a specific material can be used as the film 6 in order to more appropriately control the surface potential of the surface. As a specific example, SiO _x , TiO _x , Zr
O _x, in other oxides molten matrix, the base material such as silica or siloxane polymer, ZnO, CdO, ZnCdO _x
Group II element oxides such as GeO ₂ , SnO ₂ , GeS
Ultrafine particles of oxides such as oxides of group IV elements such as nO _x , TiO ₂ , ZrO ₂ , and TiZrO _x , or ultrafine particles of metal such as Pd are dispersed, and film properties and resistance values are also obtained. The prepared film is preferably a coating film.

The oxide or the like as described above may be added with a conductivity control impurity. Examples of such conductivity control impurities include group III elements B, Al, Ga, and In, which are n-type impurities (donors: impurities that enhance electron conduction) with respect to group II oxides, and p-type impurities (acceptors: hole conduction). (Impurities that increase the) are group I elements Cu, Ag, Au, and Li. See also IV
P which is a group V element as an n-type impurity with respect to the group oxide,
Examples of p-type impurities include As, Sb, and Bi, and group III elements such as B, Al, Ga, and In. When such a film is used, as described above, the upper layer thereof, that is, the surface side on the liquid crystal side, may be subjected to a surface treatment with, for example, a silane coupling material, for the purpose of controlling the fine surface state, if necessary. it can.

The effect of using ultrafine particles (particle size 30Å to 300Å, preferably 150Å or less) will be described in more detail.

First, a film containing the above ultrafine particles is a relatively thick film (300 Å to 5000 Å, preferably 1 Å).
By forming the ultra fine particles at a rate of 000Å or more), a plurality of ultrafine particles are randomly stacked.

Since such ultrafine particles generally have a high hardness, such a stack structure exhibits a strong withstand voltage performance against a vertical short circuit caused by, for example, mixing of foreign matter into the liquid crystal cell. In the general probe measurement conducted by the present inventors, as an example demonstrating the above matters, a withstand voltage of about 25 V was shown at a film thickness of 1400 Å in which antimony-doped SnO _x was dispersed in silica.

Further, the film containing the ultrafine particles has an appropriately low resistance (preferably a volume resistance of 10 ⁴ to 10 ⁸ Ω · cm).
Because there is no big charge up,
This also contributes to the increase in breakdown voltage.

Further, since the film containing the ultrafine particles can be formed as a thick film, when a color filter is formed in the electrode underlayer structure for forming the film, switching of a thin film transistor (TFT) or the like is performed. A film having a uniaxial orientation property formed on the opposite side as a cell by appropriately absorbing a step or the like that may occur due to the formation of an element or the presence of a metal wiring. Satisfactorily transmits the orientation function of, or suppresses defective domains during driving.

In addition, the film containing the ultrafine particles is effective in that it can be controlled as the film thickness, film quality and other parameters from the viewpoint of adjusting the polarity value as described above.

In addition, since the film in which the fine particles are dispersed is filled with minute irregularities having a moderate hardness as a characteristic of the surface, various treatments are applied to the substrate side surface having non-uniaxial characteristics. However, uniaxiality is not imparted, and there is an effect that characteristics can be improved without disturbing the alignment of the liquid crystal.

In the present invention, two or more kinds of materials, for example, different base materials and / or particles of the above-mentioned fine particle dispersion curtain, are used as the material in order to accurately adjust various characteristics including the surface potential of the film 6. A mixture of a plurality of the used systems can be used.

In particular, the absolute value of the difference between the surface potentials on the inner surfaces of both substrates described above is small, for example, 100 mV or less (-100 mV).
~ 100 mV), more preferably less than 50 mV (-50
greater than mV to less than 50 mV),
The polymer material forming the coating film 6 is selected so that the polarities of the surface potentials are the same on both the upper and lower substrates, and blended at an appropriate mixing ratio. By doing so, the response of the ferroelectric liquid crystal or the anti-ferroelectric liquid crystal to the external field of the dipole (Ps) is improved.

Further, in the liquid crystal element of the present invention, the film 6 may be a passivation film formed of a laminated structure of a plurality of films on the side of the substrate having non-uniaxial orientation characteristics.

In such a passivation film, when an arbitrary electrode (for example, ITO) is used as a reference, the potential generated on the surface by contact with the electrode (that is, the surface potential) is the surface potential of each single-layer film constituting the laminated film. It is preferable to design so as to take an intermediate value of (surface potential when formed as a single layer on an arbitrary electrode).

Further, the difference (absolute value) between the surface potential generated in the laminated passivation film on the substrate side having the non-uniaxial orientation characteristic and the surface potential generated in the orientation control film on the substrate side having the uniaxial orientation characteristic is calculated as follows. Small, preferably 50m
A stable chiral smectic liquid crystal switching characteristic can be obtained by making the value smaller than V, particularly preferably substantially equal.

Further, it is preferable that the lower layer forming the laminated passivation film, that is, the layer on the substrate side is a polycrystalline metal oxide film or a polycrystalline semiconductor film to which a conductivity control impurity is added if necessary. In this case, the volume resistance in the film thickness direction of the lower layer of the passivation film is 10 ⁴ to 10 ⁸
It is preferable that Ωcm and the volume resistance in the film surface direction are 10 ⁶ to 10 ⁹ Ωcm so that resistivity anisotropy is exhibited in the film thickness direction and the film surface direction.

The lower layer of the above-mentioned laminated passivation film is a film in which fine particles to which conductivity controlling impurities are added, if necessary, are dispersed and which has an insulating material or other material as a base material, preferably a coating film. Can be In this case, it is desirable that the volume resistance of the passivation film be in the range of 10 ⁴ to 10 ⁸ Ωcm.

The lower layer is preferably 500 to 200.
Set to 0Å.

In such a laminated film, at least one layer can be provided with the function of "having a high withstand voltage to prevent short circuit", and another function can be provided to the other layers, which is seen as a device characteristic. For example, it can meet the specifications required in several aspects.

Particularly, if the surface potential generated in the laminated passivation film is set to an intermediate value of the surface potentials that can occur in the respective layers forming the laminated passivation film, the surface potential of the laminated film will be the surface of the opposing uniaxial orientation control film. It is easy to design to match the electric potential. This control makes it easier to secure the bistable state of the liquid crystal.

The lower layer constituting the laminated passivation film is a polycrystalline metal oxide film to which a conductivity control impurity is added,
Alternatively, by using a polycrystalline semiconductor film, fine control of the surface potential becomes possible, and 100 mV (absolute value) or less,
A value smaller than 50 mV is preferably realized.
At the same time, the operation of lowering the resistance of the film is performed at the same time, so that the resistance * capacitance product, which is a factor of the delay time constant of the device, can be reduced. Further, the volume resistivity is 10 ⁴ to 10 ^{8 in the} film thickness direction.
Crosstalk between pixels is prevented by providing anisotropy in the range of Ωcm and 10 ⁶ to 10 ⁹ Ωcm in the film surface direction.

The lower layer of the laminated passivation film is
When the film is formed of a film using an insulating material containing ultrafine particles to which conductivity controlling impurities are added as a matrix, the surface potential can be finely controlled as described above, and a value of 100 mV or less (absolute value) can be easily realized. At the same time, the operation of lowering the resistance of the film is performed at the same time, so that the resistance * capacitance product, which is a factor of the delay time constant of the device, can be reduced. This has a volume resistance of 10 ⁴
It is appropriately performed by setting the range of 10 ⁸ Ωcm.

In the present invention, the material of the polycrystalline metal oxide film used for the laminated film on the non-uniaxially processed substrate side is Zn.
Group II oxides of O, CdO and ZnCdO _x , GeO ₂ , S
nO ₂ , GeSnO _x , TiO ₂ , ZrO ₂ , TiZrO _x
As the group IV oxide and the material of the polycrystalline semiconductor film,
Group IV semiconductors such as Si and SiC can be cited. As impurities for controlling conductivity, group III elements B, Al, Ga, and In are used as n-type impurities (donor: an impurity that enhances electron conduction) for group II oxides, and p-type impurities (acceptors: holes). Cu, Ag, Au, and Li which are group I elements are used as impurities for enhancing conductivity. For group IV oxides or semiconductors, group V elements P, As, Sb, and Bi are used as n-type impurities, and group III elements B, Al, Ga, and In are used as p-type impurities.

On the other hand, with respect to the film used in the present invention, in which the ultrafine particles to which the conductivity control impurities are added are dispersed,
As the matrix material, SiO _x , TiO _x , ZrO _{x and} other oxide-melting matrix materials, silica, and siloxane polymer, and as ultrafine particles, ZnO, CdO, ZnCdO _x
Group I oxides, GeO ₂ , SnO ₂ , GeSnO _x , Ti
Group IV oxides of O ₂ , ZrO ₂ , and TiZrO _x are used. The conductivity control impurity is n with respect to the group II oxide.
Group impurities B, Al, Ga, and In are group-type impurities (donors: impurities that enhance electron conduction), and group I elements Cu, Ag, and Au are p-type impurities (acceptors: impurities that enhance hole conduction). , Li are used.
For group IV oxides or semiconductors, group V elements P, As, Sb, and Bi are used as n-type impurities, and group III elements B, Al, Ga, and In are used as p-type impurities.

As a standard for adding impurities in the passivation film, a donor is added when the surface potential of the substrate having the uniaxial orientation property is positive, and an acceptor is added when the surface potential is negative. The concentration of impurities added varies depending on the type of material and the crystallization state (the amount of crystal defect density), but a rough guideline is that the concentration of free electrons or free holes in the material is 10
^It may be set to be about ¹¹ to 10 ¹⁴ / cm ³ .
At this time, the surface potential can be simultaneously changed by about 100 mV.

When a polycrystalline material is used, it is preferably 10 ¹⁷ to 10 ²⁰ / cm in consideration of impurity addition efficiency.
³ (about 0.01% to 1% with respect to the base material) is the actual addition amount. The amount of change in surface potential with respect to the amount of added impurities corresponds to about 50 mV with an increase of one digit.
The conductivity control impurity may not be added to at least one layer constituting the multi-layered passivation film depending on the setting of the conductivity.

On the other hand, in the liquid crystal device having the structure example as shown in FIG. 1 of the present invention, the uniaxial alignment property is exhibited even when used individually as the alignment control layer 4 on the substrate 1 side having the uniaxial alignment property with respect to the liquid crystal molecules. Polymer materials that can serve as an alignment film,
Preferably, a mixture of two or more organic polymer materials can be used to finely adjust the surface potential value between the upper and lower substrates, the relationship of polarities, or the alignment control of the liquid crystal.

As the material of the orientation control layer 4, a material obtained by mixing at least two materials selected from organic polymer materials such as polyimide, polyvinyl alcohol, polyaniline, polypyrrole and nylon is used. The film thickness is preferably about 30Å to 300Å.

Then, it is preferable to rub the film of the above-mentioned mixed material in order to have a uniaxial orientation characteristic.

In the present invention, in consideration of the liquid crystal alignment state obtained in the element structure shown in FIG. 1 as described above, the alignment property near the interface of the alignment film 4-liquid crystal layer 8 on the substrate side having the uniaxial alignment property is improved. High-quality liquid crystal molecule orientation is exhibited, and liquid crystal interface on the substrate side (interface of 7 and 8) having non-uniaxial orientation characteristics
In, it is assumed that the interface state is somewhat disordered or is fixed (the liquid crystal molecules move slowly) (see FIG. 5).

Here, the optical response hysteresis and the like, which are particularly problematic in performing switching failure or gradation display, can be explained as follows from an electrical aspect.

FIGS. 6a and 6b are views for explaining the function and effect of the device structure of the present invention with respect to the alignment state of liquid crystal molecules shown in FIG.
FIG. 7 and FIG. 8 show the difference in element configuration between the present invention and the conventional case in an equivalent circuit manner. 6a and 6b, the disordered alignment interface of liquid crystal molecules in the liquid crystal element and the interface portion with weak insulation are clearly shown. In the equivalent circuits shown in FIGS. 7 and 8, C _LCB and R _LCB are assumed to be capacitance and resistance of the liquid crystal bulk part, respectively, and
_LCS and _RLCS are assumed to be capacitance and resistance near the interface of the liquid crystal as shown in FIGS. 6a and 6b. In addition, 1 of the present invention
One characteristic low resistance conduction path R _S is shown. Figure 5
Further, the "disordered array interface" shown in FIG. 6 is regarded as a partial impedance of the liquid crystal as shown in FIG. 8 in an equivalent circuit, and extremely as a substantially insulating layer-like portion ( _RLCS ).
On the other hand, the accumulation center position of ions or other charges, which is considered to be the cause of the electrical history of whether the previous state was "black" or "white", is modeled as the "disordered interface".
Spontaneous polarization on the liquid crystal bulk side (inside the liquid crystal layer) (P
s) It is easy to think that it is near the aligned edge. Therefore, if the liquid crystal interface is insulative as in the conventional case (assuming that the interface on the substrate side having the non-uniaxial orientation property is simply insulative), the C _LC (capacitance ) Or R _LC (resistance) determines the influence of the electrical history of the previous state, and as a result, the history is not released and switching failure is considered to occur.

On the other hand, as shown in FIG. 6, in the element structure of the present invention, the film 6 on the substrate side having the non-uniaxial orientation characteristic.
Is preferably 10 ⁴ Ωcm, which has a relatively small resistance value.
By forming a film, preferably a coating film, set to about 10 ⁸ Ωcm, the above-mentioned insulating layer-like liquid crystal interface apparently disappears.

For example, this state shows that the impedance of the element of the present invention provided with such a film is on the low frequency side (1 mH).
It is confirmed by observing (z to 10 Hz) that the real part resistance of the Cole-Cole plot, which is considered to be the liquid crystal part, decreases.

That is, in the present invention, through the weak insulating portion which is considered to exist everywhere in the “disordered array interface”,
It is considered that the electrical history can be released in the film thickness direction or the sheet direction (see FIG. 6b). Alternatively, it is considered that the film 6 can directly reduce the resistance of the interface layer. FIG. 7 is an equivalent circuit representation at this time, and a low resistance conduction path (Rs) corresponding to the film 6 is formed. In this way, it becomes possible to prevent the occurrence of switching failures.

In the present invention, in order to effectively realize the above effects, for example, a low resistance film is a coating film, and the surface state of the coating film is at least 20.
It is desirable to include surface irregularities of 0 Å or more (for example, measured values when observed by SEM or the like). In order to form such irregularities appropriately and uniformly, for example, a film in which conductive particles having a particle diameter of 30 to 300Å are dispersed in a base material (binder) is preferably applied.

It was found that approximately 10 or more layers of liquid crystal molecules are necessary for the appropriate range of the irregularities on the surface of the coating film due to rough estimation of the average film thickness of the "disordered alignment interface". Then, it is based on the experimental result that the thickness of the insulating layer which can be calculated from the magnitude of the hysteresis seen as a phenomenon is about 200 Å or more, relative to the actual magnitude of the spontaneous polarization of the liquid crystal. Such an experiment result shows that, for example, instead of the coating film, an insulating layer having several different thicknesses is provided in the cell, the change in the hysteresis amount at this time is measured, and the hysteresis at the extrapolated value at the film thickness of 0 is measured. It is obtained by the correlation between the quantity and Ps.

In the above description, the insulating interface has been treated as a “disordered interface” as a model, but the insulating interface is on the substrate side having liquid crystal and non-uniaxial orientation characteristics. It is like an electric double layer formed on the material surface, or it is due to a trapping interface or a high resistance surface state that is considered to be directly related to the vicinity of the surface of the substrate having non-uniaxial orientation characteristics. There may be cases. However, also in these cases, the phenomenon description similar to the above description is established, and the effect when the resistance of the film 6 is lowered can be similarly expressed.

In the liquid crystal element of the present invention, as described above, preferably the volume resistance is 10 on the non-uniaxially oriented substrate side.
^A low resistance film in the range of ⁴ to 10 ⁸ Ωcm, more preferably a coating film, is formed, and the preferable range of the resistance value will be described in detail.

(Upper limit value / 10 ⁸ Ω · cm) The upper limit value is defined by the time constant condition of whether or not the previous state of display is electrically released. In driving a bistable ferroelectric liquid crystal, a reset signal (generally for aligning to a "black" state) is usually input before determining a desired pixel state. In order to prevent the image quality from being affected by matrix driving, this reset period is at most 1
It is preferable that the time is within about 00 μsec. It is about 10 ⁸ Ω to release the previous state electrically within such width.
It is required that the resistivity be cm or less. This is based on the following estimation.

Equivalent circuit time constant: (C1c + Ca) * R
1c * Ra / (R1c + Ra), C1c; liquid crystal capacitance Ca; coating film capacitance R1c; liquid crystal resistance Ra; coating film resistance, where liquid crystal film thickness is 2 um, coating film film thickness is 1000 Å,
If the liquid crystal dielectric constant is -6 and the coating film dielectric constant is -10 (C1c
+ Ca) ≈Ca, Ra << R1c, time constant≈Ca
Since it is Ra, it is estimated from γ to ε _a ε ₀ ρ _a <100 μsec that ρ _a <10 ⁸ Ωcm (γ: time constant, ε _a : dielectric constant of coating film, ρ _a : coating film) Resistivity).

(Lower limit value / 10 ⁴ Ωcm) The lower limit value of the resistance of the above-mentioned coating film is under the condition that the previous state is electrically released, and in addition, in the case of the matrix constitution, the lower limit value is It is defined by preventing unnecessary voltage drop or line-to-line crosstalk due to the flow of current.

For example, when a matrix of 1000 * 1000 pixels is formed and the resistance value from the feeding point to the 1000th pixel is, for example, the sheet resistance of the electrode stripe to be used is about 1Ω / □, it is about 1 kΩ. Further, actually, in the present transparent electrode forming technology, such a thing can be obtained. On the other hand, if the distance between the adjacent electrode stripes is about 10% of the stripe width, the resistance value is 1/10000 of the sheet resistance of the coating film as the current direction to the adjacent stripe electrodes, and the voltage drop at the 1000th pixel. Rate 10
If it is attempted to keep it at 1/0 or less, the sheet resistance between the stripe electrodes must be 10 ⁶ times larger. That is,
The sheet resistance of the coating film is required to be about 10 ⁹ Ω / □, and for example, the coating film resistivity of 500 Å film thickness is 5 * 10 ³
Ωcm or more, preferably 10 ⁴ Ωcm or more.

Next, the means for measuring the volume resistance value of the film in the present invention will be described with reference to the drawings.

FIG. 9 shows a system for measuring the resistance in the film thickness direction of the object and the film, and 71 is the film to be measured,
The measurement is performed by passing a current through the electrode 73 made of ITO to the electrode 72 made of A1 (for example, 1 mmφ). FIG. 10 shows a system for measuring the resistance of the target film in the sheet direction, where 74 is the film to be measured, and the electrode 7
The measurement is performed by passing an electric current by 5,76.

In the liquid crystal device of the present invention, the volume resistance is 10 ⁴ Ωcm to 10 ⁸ Ωcm on the substrate having the non-uniaxial orientation property.
When the above film is provided, the durability of the element can be increased by providing an inorganic film for further increasing the breakdown voltage between the lower layer of the film and, for example, the ITO electrode film.

Examples of such an inorganic film include ZnO and Sn.
Evaporated films formed by various kinds of sputtering such as O ₂ or TaO _x are suitable. For example, the resistivity in the film thickness direction can be adjusted by adjusting the gas pressure of oxygen gas, argon gas, or the like, or by adjusting the RF power. A film having a film thickness of 1000Å to 2000Å controlled to 10 ⁴ to 10 ⁸ Ωcm can be optimally used.

As a preferable resistance condition of the film for the purpose of increasing the withstand voltage, the upper limit value is a condition for releasing the pre-switching state like the upper film, and is about 10 ⁸ Ω.
It is about cm.

On the other hand, the lower limit value also applies to the upper layer film under the same conditions. For example, even if the liquid crystal portion is in a short-circuited state due to the mixing of a conductive foreign substance, it flows in the film thickness direction of the vapor deposition film. By suppressing the current, it is derived under the condition that the defect in the image quality is not remarkable in the short-circuited portion or its periphery. As an example of a typical way of thinking, when an electric path is generated in the liquid crystal portion in the film thickness direction due to a foreign substance having a thickness of about the cell, in order to reduce the voltage drop rate between pixels to 1/100, The resistance of this portion needs to be 100 times the resistance of 1 kΩ from the power feeding portion to the pixel end. If the short area is 2 μm * 2 μm and the thickness of the inorganic film is 1000 Å, then ρ _min * 1 * 10 ⁻⁵ / (2 * 10 ⁻⁴ ) ² ≧ 1 * 10
^{From 5} (Ω) (ρ _min : lower limit of resistance), ρ _min ≧ 4 * 1
The volume resistivity is 0 ² (Ωcm). For example, assuming paths at a plurality of locations, a volume resistivity of about 10 ⁴ Ωcm or more is required.

In the liquid crystal device of the present invention, the device performance can be further improved by using the conductive alignment film as the alignment control layer provided on the side substrate having the uniaxial alignment property. Examples of such a conductive alignment film include a charge transfer complex obtained by doping polypyrrole, polyaniline or the like with TCNQ (tetracyanobenzoquinodimethane) or the like, a material made conductive by doping with sulfuric acid or the like, ordinarily an insulator. Doping the polyimide with an organic acid such as LiCF ₂ SO ₃ or an inorganic acid, etc.
A film obtained by subjecting a film having conductivity of about 0 ⁴ to 10 ⁸ Ωcm to a uniaxial orientation process such as a rubbing process can be given.

In the case of using the inorganic film formed on the substrate having the non-uniaxial orientation property or the conductive alignment film formed on the substrate having the uniaxial orientation property as described above, the polarities of both substrates in the element structure of the present invention are used. Select a combination that maintains a positive correlation. That is, in a liquid crystal device, a conductive alignment film is formed on a substrate having uniaxial alignment characteristics, and an inorganic film is formed on a substrate having non-uniaxial alignment characteristics, and the surface potential value on both substrates is controlled or The conductive alignment film and the inorganic film are selected so that the surface potentials are set to the same polarity.

[0118]

EXAMPLES The present invention will be described in more detail with reference to concrete experimental examples.

In the liquid crystal element structure according to the experimental example of the present invention, specific examples of the respective constituent members will be listed below with reference to the structure shown in FIG.

(1) Substrate (see FIG. 1, reference numerals 1 and 2):
(Common to uniaxial orientation characteristic side and non-uniaxial orientation characteristic side) Single-sided or double-sided soda-lime glass substrate having an ITO (700Å or 1500Å) film (see FIG. 1, symbols 3 and 5) as a transparent electrode (2) Alignment control layer ( (See FIG. 1 and reference numeral 4): 2 spin coat films of polyamic acid (LP-64)
A layer obtained by rubbing a 30 Å-thick polyimide film obtained by baking at 70 ° C.-A layer in which 5 monolayers of LP64 were laminated by the LB method and then baked-A spin coat film of a formic acid dispersion of polypyridine was 180
A layer obtained by rubbing a 100 Å film that has been baked at ℃ (3) Configuration on the substrate side having non-uniaxial orientation characteristics (a) Coating film (see FIG. 1, reference numeral 6): ・ Antimony-doped SnO ₂ ultrafine particles (grains) Diameter about 100
Å) dispersed siloxane (SiO _x ) baked polymer film (about 900Å film thickness) ・ SinO ₂ ultrafine particles similar to the above dispersed in a composite of titanium oxide, zirconium oxide, silicon oxide, etc. (b) Surface treatment (Refer to code 7):-Spin coating treatment of silane coupling material-Coating film of the same material as the alignment treatment film of (2) without orientation control-No surface treatment (4) Liquid crystal: from high temperature side Isotropic phase → S towards the low temperature side
Ferroelectric liquid crystal having spontaneous polarization of 20 nC / cm ² and a tilt angle of about 22 degrees having a phase transition sequence of mA → Sm * C → crystalline phase.

The volume resistance values of both A and B of the coating film (3) -a measured in the sheet direction and the film thickness direction by the above-mentioned method are both about 10 ⁴ Ωcm.

As described in the above example, according to the liquid crystal element of the present invention, the influence on the history of the previous state is extremely small (for example, as the optical response hysteresis, 1 V or less at the maximum). Threshold difference), the asymmetry of switching between bistable states is reduced (eg the difference between the threshold when switching from the first stable state to the second stable state and the threshold for switching in the opposite direction). Is 0.5
(V or less), variation in threshold is reduced even when driven for a long period of time or left for a long time (for example, variation threshold width is 1 V or less), and stable characteristics are obtained.

The present invention will be described in more detail below with reference to specific experimental examples.

Experimental Example 1 In this experimental example, a liquid crystal element having a structure shown in FIG. 1 was manufactured as follows.

Table 1 shows the film thickness and surface of the film having the uniaxial orientation property (4 in FIG. 1) and the film having the non-uniaxial alignment property (6 in FIG. 1) with respect to the liquid crystal molecules used in the experimental examples. The potential measurement values are shown together. The materials and preparation methods described in the table are as follows.

As a uniaxial orientation control layer, a polyimide film obtained by baking a spin coat film of A polyamic acid (LP-64, manufactured by Toray Industries, Inc.) at 200 ° C.,
Film thickness 5 nm Polyimide film obtained by baking a spin-coated film of polyamic acid having a structure in which an alkyl chain is further added to the imide ring of the main chain structure of BLP-64 at 200 ° C., film thickness 5 n
m

As a material for the film 6 on the substrate side having a non-uniaxial orientation property 6 and the processing portion 7, a 1 silane coupling agent (ODS-E, manufactured by Chisso Co.) 1 wt.
Baked at 80 ° C. for 1 hour, film thickness 2.5 nm b1 antimony-doped SnO ₂ ultrafine particles (particle size of about 1
0 nm) dispersed silica or siloxane (SiO _x ).
Of fired film thickness 70 nm b2, same thickness 140 nm c1 surface-treated antimony-doped SnO ₂ ultrafine particles (particle size: about 10 nm) dispersed in polysiloxane (GR651L, USA Techneglas Inc.
(Manufactured by Showa Denko), average film thickness 30 nm c2, average film thickness 70 nm d1 polysiloxane SiO _x (GR651L, US T
echneglas Inc. (Manufactured by Showa Denko), average thickness 3 nm

[0128]

[Table 1]

(Experimental Example 1-1) In this Experimental Example 1-1, as a film having a uniaxial orientation characteristic (4 in FIG. 1), -22
A surface potential of 0 mV and a relatively large negative polarity was detected L
An element having P64 (material A in Table 1) as a constituent element will be described.

LP6 was formed on the surface of an ITO film having a thickness of about 150 nm formed as a transparent electrode on a glass substrate having a thickness of 1.1 mm.
4 thin films were formed. Then, using a roller having a diameter of 80 mm with a nylon cloth wrapped around the thin film, the number of rotations of the roller was 1000 rpm, and the pushing amount was 0.3 mm.
The rubbing treatment was performed under the conditions of a relative feed rate of 10 mm / sec with respect to the substrate and a feed number of 4 times to impart uniaxial orientation characteristics.

As the layer having the non-uniaxial orientation characteristic (6 in FIG. 1), a1, b1, b2 and c1 in Table 1 were used.

Each non-uniaxial processing side substrate and LP6
The substrate having 4 uniaxial orientation control films was laminated with 2.0 μm bead spacers to make a total of 4 types of cells. To these cells, from the high temperature side to the low temperature side,
A chiral smectic liquid crystal (ferroelectric liquid crystal) having a spontaneous polarization of 30 nC / cm ² (at a temperature of about 30 ° C.) and a tilt angle of about 24 degrees, which has a phase transition sequence of liquid phase → SmA → SmC ^* → crystalline phase, is heated under reduced pressure. After injecting under, it was slowly cooled (2 ° C./min) under normal pressure to prepare four kinds of liquid crystal elements having good uniaxial orientation.

Switching voltage thresholds were measured for two stable states under the conditions of a bipolar rectangular pulse and a pulse width of 20 μsec for these four types of elements. FIG. 11 shows the relationship between the switching threshold value difference between the two stable states and the surface potential on the substrate side having the non-uniaxial orientation characteristic. The vertical axis represents the switching threshold difference of the device, and the horizontal axis represents the surface potential value on the side having non-uniaxial orientation characteristics. In the figure, each measurement point is indicated by ◯ when the switching threshold asymmetry characteristic is at a good level, and by Δ when it is insufficient. The arrow points indicate the surface potential of LP64, which is a uniaxial alignment control film.

As is clear from FIG. 11, a strong correlation is recognized between the switching threshold value difference and the surface potential measurement value. In the device using the silane coupling agent a1 described as a conventional typical asymmetrical configuration cell, -110 mV
Surface potential difference (hereinafter defined as {uniaxial side surface potential}-{non-uniaxial side surface potential}) is detected and the switching threshold difference is relatively large at -0.8V, whereas the surface potential difference is -0.8V.
The element using b1 having a small absolute value of 40 mV has a switching threshold difference of −0.4 V, which is about twice as thick as b1, and the element using b2 having a smaller surface potential difference of −20 mV has a switching threshold difference. Shows an almost ideal symmetry characteristic of -0.1V. Conversely, the surface potential difference is -320 mV
In the device using c1, which is very large, no switching failure was observed, but it showed a very large switching threshold difference of −1.4V.

According to the correlation shown in FIG. 11, the surface potential difference is controlled to an appropriately small width (-100 mV to 100 mV or less), its polarity is adjusted, and the switching threshold difference is within ± 1.0 V. It is suggested that it can be suppressed to a low level.

Not only the correlation of the absolute values of the switching thresholds, but also the polarity of the switching threshold difference is consistent with the direction in which the switching threshold increases from the stable state in which the surface potential difference is applied as the internal potential. However, it strongly suggests that this switching threshold difference may be caused by the surface potential difference.

(Experimental Example 1-2) In this Experimental Example, the material B of Table 1 in which +50 mV and a positive surface potential was detected was used as a constituent element as a film having uniaxial orientation characteristics (4 in FIG. 1). The element will be described.

Material B was formed on the surface of an ITO film having a thickness of about 150 nm formed as a transparent electrode on a glass substrate having a thickness of 1.1 mm.
A thin film was formed. Then, using a roller having a diameter of 80 mm wound with a nylon cloth, a roller rotation speed of 1000 rpm, a pushing amount of 0.3 mm, a relative feed speed to the substrate of 10 mm / sec, and a feed number of 4
The rubbing treatment was performed under the same condition to give uniaxiality.

A substrate-side layer having non-uniaxial orientation properties (see FIG.
6) in Table 1 includes a1, b1, b2, c1, c in Table 1.
2, d1 was used. Each non-uniaxial substrate and material B
A total of 6 types of cells were prepared by laminating a substrate having a uniaxial alignment control film with a bead spacer of 2.0 μm. Six kinds of liquid crystal elements having good uniaxial orientation were obtained by injecting the same liquid crystal as in Experimental Example 1-1 into these cells under reduced pressure heating and then slowly cooling (2 ° C./min) under normal pressure. It was created.

Switching voltage thresholds were measured for these six types of devices in two stable states under conditions of a bipolar rectangular pulse and a pulse width of 20 μsec. FIG. 12 shows the relationship between the switching threshold value difference between the two stable states and the surface potential of the substrate on the non-uniaxial orientation characteristic side. The vertical axis represents the switching threshold difference of the device, and the horizontal axis represents the surface potential value of the substrate on the side having non-uniaxial orientation characteristics. In the figure, each measurement point is ○ when the asymmetry characteristic of the switching threshold is at a good level, Δ when there is a considerable problem, × when there is a significant problem causing switching failure, and good asymmetry characteristic. Not only that, but ◎ indicates that the decrease in deterioration with time is particularly well suppressed. The arrow points indicate the surface potential of the material B that is a uniaxial orientation control film.

As is clear from FIG. 12, the LP of Experimental Example 1-1 was placed between the switching threshold value difference and the surface potential measurement value.
A strong correlation similar to that with 64 is observed. That is, as the surface potential of the layer having the non-uniaxial orientation property approaches the surface potential of the opposite side material B (uniaxial orientation control film),
It is observed that the switching threshold difference tends to zero, and b1, b2, a having a smaller surface potential than the material B are used.
The polarity of the switching threshold difference observed in the device having the element L is corresponding to that of the material B1 having a positive surface potential.
The polarity is opposite to that of P64.

Silane coupling agent a1 which is known as an alignment treatment layer on one substrate of a typical asymmetric constitutional cell.
+15 in the cell using
The surface potential difference is 0 mV and the positive polarity, and accordingly, the switching threshold difference is +1.1 V, which shows the positive polarity. LP
For b1 and b2, which showed good switching threshold asymmetry characteristics with respect to 64, the surface potential difference was +230 mV and +250 mV, respectively, when the opposite side was the material B1, and both were in a switching failure state, and the measurement of the threshold value was impossible. could not. Conversely, the surface potential difference is relatively small c
1 (surface potential difference -50 mV), c2 (same -20 mV),
When d1 (same +20 mV) is used, the switching threshold difference is small as 0V, 0.4V, and 0V, respectively, and in particular, the element using c1 or d1 realizes an ideal symmetrical characteristic. In particular, the correlation shown in FIG. 12 suggests that the surface potential difference can be adjusted to a small width of −100 mV to 100 mV and the switching threshold difference can be suppressed to a small level within the range of ± 1.0V.

Further, it has been found that especially in the device using d1, the change with time of the switching threshold, which is likely to occur uniquely in the asymmetrical configuration cell, is well suppressed. This tendency is d1
The surface potential difference on both sides is 100 mV
And the absolute value of each surface potential is 50 m
It was a feature commonly recognized in devices having V or less. The present inventors interpret this result as the potential generated between the electrode and the alignment film being an important factor for the change over time in the threshold value.

As described in the above two experimental examples, as the surface potential of the substrate having the non-uniaxial orientation characteristic approaches the surface potential of the substrate having the uniaxial orientation characteristic on the opposite side (that is, the surface potential difference between the two is zero). The tendency of the switching threshold difference to approach zero, the tendency of the applied direction of the internal potential due to the surface potential difference to coincide with the direction of the generation of the switching threshold difference, and the detected value of the surface potential on the uniaxial side and the non-uniaxial side are If both are small, preferably both are 10
It has been verified that when the voltage is 0 mV or less, the deterioration characteristic over time peculiar to the asymmetrical structure cell is suppressed particularly well.

It has also been clarified that the switching threshold difference is further eliminated when the surface potentials on both substrates have the same polarity.

In addition, in each of the samples of Experimental Examples 1-1 and 1-2, the system using c1, c2, and d1 in the layer provided on the substrate side having the non-uniaxial orientation property in Experimental Example 1-2,
Compared with each sample of Experimental example 1-1, monostabilization over time was suppressed. This is because the samples of Experimental Example 1-2 have the same surface potential and the absolute value of the surface potential difference between both substrates is smaller (less than 50 mV), and the surface potentials of both substrates are absolute values. It is presumed that this is due to the fact that it was adjusted to a small value of 100 mV or less, and that the influence of the substrate surface potential over time on the dipoles of liquid crystal molecules was small.

Experimental Example 2 A liquid crystal element having a structure shown in FIG. 1 was produced as follows.

Specific examples of each component used in the configuration of the liquid crystal element according to Experimental Example 2 of the present invention will be listed below. Some of the members are the same as those used in the experimental example.

(1) As a substrate (see FIG. 1, reference numerals 1 and 2): (common to uniaxial orientation processing side and non-uniaxial processing side) ITO (700Å or 1500Å) film as a transparent electrode (FIG. 1,
A single-sided or double-sided polished soda-lime glass substrate on which reference numerals 3 and 5 are formed.

(2) Substrate surface having uniaxial orientation characteristics (see FIG. 1, reference numeral 4): A layer obtained by rubbing a polyimide film 1 having a film thickness of 50 Å obtained by firing a spin coat film of polyamic acid (LP-64) at 200 ° C. A layer (thickness 50Å) obtained by baking and rubbing the coating film 2 of a polyimide-based material having a structure in which an alkyl portion is further added as a main chain structure to the imide ring of the main chain structure of LP-64 at 200 ° C. 1 spin coat film of nylon 6.6 formic acid dispersion
A layer obtained by rubbing a 50Å film baked at 80 ° C.

(3) Substrate having non-uniaxial orientation characteristics Coating film (see FIG. 1, reference numeral 6): b1. Antimony-doped SnO ₂ ultrafine particles (particle size about 1
00Å) dispersed silica or siloxane (SiO
_x ) Fired film (about 700Å film thickness) e1. A film (thickness 900Å) in which the same SnO ₂ ultrafine particles as described above are dispersed in a composite (MOF) such as titanium oxide and silicon oxide c1. Polysiloxane (GR651L (US Techn
Eglas Inc.)) in the same film as S
Fired film in which nO _x ultrafine particles are dispersed (however, surface treatment is applied to SnO _x ultrafine particles) (film thickness 300Å)

The firing temperature of each of b1, c1 and e1 was set to about 200.degree.

(4) Liquid crystal: Spontaneous polarization having a phase transition sequence of isotropic phase → SmA → SmC ^* → crystal from the high temperature side to the low temperature side, 30 nC / cm ² (in temperature of about 30 ° C.), tilt angle Chiral smectic liquid crystal that is about 24 degrees.

Each of the coating films b1, e1, c1 of (3) above is a mixture of the ultrafine particles for imparting conductivity and adjusting the polarity.
For both 1 and c1, the volume resistance in the film thickness direction measured by the method described above was 10 ⁵ Ωcm.

A liquid crystal element having the configuration shown in FIG. 1 was manufactured using the above-described components, and the substrate side having non-uniaxial orientation characteristics was grounded for each element, and the signal voltage was applied to the substrate side having uniaxial orientation characteristics. Was applied, VT characteristics were measured, and hysteresis and switching asymmetry were evaluated.

The constitution of the members of each experimental example and the evaluation results are also shown in Table 2 below.

[0157]

[Table 2]

According to the liquid crystal element of the present invention as described in the above-mentioned embodiments, the difference in surface potential between the two substrates is reduced, and the surface potentials have the same polarity. The influence on the history is made extremely small (for example, as the optical response hysteresis, the maximum is 1 V).
The following threshold difference) reduces the asymmetry of switching between bistable states (for example, the threshold for switching from the first stable state to the second stable state and the threshold for switching in the opposite direction). As a result, the generation of defective domains and the like was suppressed. Further, it was confirmed that the threshold variation was reduced even when the device was driven for a long period of time or left standing (for example, the variation threshold width was 1 V or less), and stable characteristics were obtained.

(Experimental Example 3) FIG. 13 schematically shows a liquid crystal element (cell cross-sectional structure) according to Experimental Example 3 of the present invention. In the cell structure shown in the figure, the liquid crystal 9 is interposed between the pair of substrates 91 and 92.
8 is sandwiched between the electrodes 93,
And an alignment control layer 94 that has been treated to uniaxially align the liquid crystal 98 inside the cell, and an electrode 95 and two-layered passivation films 96 and 97 as non-uniaxially treated sides on the other substrate 92. There is. The manufacturing process is described below.

First, on the substrates 91 and 92, a general D
With a C sputtering system, an ITO target was used, power was 1 W / cm ² , and sputtering gas was Ar: 90 SC.
A 700Å ITO film was deposited by flowing CM, O ₂ : 10 SCCM and discharging for 2.5 minutes. After that, the ITO film was patterned into a desired shape by ordinary wet etching to form the electrodes 93 and 95 of each substrate.

Subsequently, on the substrate 1 side, polyamic acid (LP-64) was spin-coated on the electrode 93 under the conditions of 2700 rpm and 20 seconds, and this was baked at 200 ° C. for 60 minutes,
A polyimide film having a thickness of 50Å was formed. Then, the polyimide film was subjected to rubbing treatment at a rotation speed of 1000 rpm, a pushing amount of 0.4 mm, a feed speed of 5 mm / sec, and three times in one direction to form an orientation control film 94.

On the other hand, on the electrode 95 of the substrate 2, a normal RF
Using a target of ZnO: 100%, a sputtering apparatus was used to discharge at a power of 5 W / cm ² , a substrate heating temperature of 200 ° C., a sputtering gas Ar: 90 SCCM, O ₂ : 10 SCCM and a pressure of 3 mTorr for 1 minute to deposit a ZnO film of 1000 Å. Thereby, the passivation film lower layer 96 was formed. Subsequently, a solution in which ultrafine SnO _x oxide particles (particle size: about 100 Å) were dispersed in a SiO _x oxidization-melting base material was spin-coated, and baked at 200 ° C. for 90 minutes to apply 1500 Å. Thereby, the passivation film upper layer 97 was formed.

Then, a solution containing fine particles of SiO _{2 having a} diameter of 2.2 μm was spin-coated on the orientation control film 94 of the substrate 91 on the uniaxially processed side after heating to disperse and fix it, and subsequently trepal particles (adhesive particles having a particle diameter of about 5 μm). ) Spin coat the solution,
Heat to disperse and adhere.

On the other hand, the substrate 92 was coated with a sealant at a desired position by using a printing machine and prebaked at 90 ° C. for 5 minutes. The resulting substrate 92 is used as the substrate 9
1 was bonded and pressure-bonded with a press at a pressure of 50 gf / cm ² . Further, with the same pressure being applied with an air cushion, heating was performed at 110 ° C. for 90 minutes to cure the sealant.

After that, the empty element completed by the above work is put into a normal load-lock type vacuum chamber, and 10 ^-5 T
After evacuation to orr, the liquid crystal 98 was heated to 95 ° C. in a vacuum of 10 ⁻² Torr so as to have an injection port, and the liquid crystal 98 was filled in the empty element in the same manner as in Experiments 1 to 4. Injected.

In such a liquid crystal element, the surface potential at the liquid crystal interface of each substrate was measured and found to be -220V on the uniaxial orientation side (alignment control film 94) and -120V on the non-uniaxial orientation side (passivation film 96.97). It was

With respect to the liquid crystal element formed by the above process, the characteristics of one pixel are shown in FIG. 13. First, the non-uniaxial side substrate (electrode 95) is grounded (99), and the uniaxial orientation processed substrate (electrode 93) side is signaled. A voltage was applied and (100) investigation was performed.

FIG. 14 shows the relationship (VT characteristics) when the voltage is changed in the light transmittance when a write signal voltage is applied in the evaluation of the element. The difference between the going and returning of the arrow shown in the figure is a quantity called hysteresis, and ideally it is desirable to be "0", but in practice it may be about 5% or less of the drive voltage.

Further, the solid line U1 and the broken line U2 indicate which direction the spontaneous polarization of the liquid crystal molecules is facing at the time of black reset. For example, when Ps of the liquid crystal is negative, U is when facing the non-uniaxial side.
1, U2 is when facing the uniaxial orientation side. This U1 and U
Ideally, the amount of deviation between the voltage thresholds of each of the two cases when the two states are black is ideally “0”, and symmetry is obtained at this time. On the other hand, the threshold shift amount is also called asymmetry, and if the value is practically less than plus or minus 1 V, the bistable potential is not extremely disturbed, and changes over time such as defective writing and burn-in occur. Is suppressed.

In the VT characteristic of the liquid crystal element of Experimental Example 5 of the present invention shown in FIG. 14, the hysteresis is suppressed to 0.8 V and the asymmetry is suppressed to about 0.5 V, which is within the necessary range. .

Further, a liquid crystal panel in which matrix pixels were formed by the elements in Experimental Example 5 was produced. When such a panel is driven, no afterimage can be seen, fast response is obtained, flicker, growth of defective display area, etc. are not seen, extremely good bistability is obtained, burn-in, progress of monostability, etc. are sufficiently performed. The result is that it is suppressed and high reliability is obtained. There was also a sufficient margin for the drive voltage. At the same time, even if a voltage of 30 V was applied between the electrodes of the upper and lower substrates, no pixel in which a short circuit occurred was seen.

(Experimental Example 4) Also in this example, a liquid crystal element having the same sectional structure as in Experimental Example 3 was prepared under the following conditions.

First, the electrodes 93 and 95 of the respective substrates were formed on the substrates 91 and 92 under the same conditions as in Experimental Example 5.

Subsequently, on the substrate 91 side, polyamic acid (LP-64) was spin-coated on the electrode 93 at 2700 rpm for 20 seconds, and this was baked at 200 ° C. for 60 minutes to form a polyimide film having a thickness of 50 Å. Formed. After that, a rubbing treatment was performed on the polyimide film at a rotation speed of 1000 rpm, a pushing amount of 0.4 mm, a feed speed of 5 mm / sec, and three times in one direction to form an alignment control film 94.

On the other hand, on the electrode 95 of the substrate 92, a normal load-lock type parallel plate type RF plasma CVD apparatus was used and the substrate was heated at 200 ° C. at a frequency of 13.56 MHz.
Power 300 mW / cm ² , silane (S
iH ₄ ): 40 SCCM, isobutane (iC ₄ H ₁₀ ): 3
00SCCM, hydrogen diluted 0.1% phosphine (PH ₃ /
H ₂ : 0.1%): 10 SCCM, pressure 0.2 Torr
Discharge for 30 minutes at 200 n-type polycrystalline SiC: H
0Å accumulated. Thereby, the passivation film lower layer 96
Was formed.

Subsequently, a solution prepared by dispersing SnO _x oxide ultrafine particles (particle diameter of about 100 Å) in a SiO _x oxidization-melting base material was spin-coated on this, followed by baking at 200 ° C. for 90 minutes, and 1500 Å Applied. Thereby, the passivation film upper layer 97 was formed.

Subsequently, the substrate 91 was processed in the same manner as in Experimental Example 3.
After bonding Nos. 92 and 92, liquid crystal was injected to prepare a liquid crystal element.

In such a liquid crystal element, the surface potential at the liquid crystal interface of each substrate was measured and found to be -220 V on the uniaxially processed side (alignment control film 94) and -130 V on the non-uniaxially processed side (passivation film 96.97). It was

When the VT characteristic of the liquid crystal element according to this experimental example was evaluated, the hysteresis was 0.6 as in the experimental example 3.
The V and asymmetry are suppressed to about 0.5 V, which is within the required range. In addition, when a matrix panel was manufactured using the element of the experimental example and its driving was evaluated, as in the experimental example 3, a fast response without afterimage, flickering, and extremely good bistability with no defective display region growth,
The result shows that it has a high reliability in which seizure and monostable progression are suppressed. Also, a sufficient margin was obtained for the driving voltage. At the same time, the breakdown voltage between the upper and lower substrate electrodes is 3
0V or more was obtained.

(Experimental Example 5) In this experimental example, a liquid crystal element having the same sectional structure as in Experimental Example 4 was prepared under the following conditions and methods.

First, the electrodes 93 and 95 of the respective substrates were formed on the substrates 91 and 92 under the same conditions as in Experimental Example 4.

Subsequently, on the substrate 91 side, 2700 rp of polyamic acid (LP-64: 0.7 wt%) was formed on the electrode 93.
Spin coating was performed under conditions of m and 20 seconds, and this was baked at 200 ° C. for 60 minutes to form a polyimide film having a thickness of 50 Å. After this, the rotation speed is 1000 rpm and the pushing amount is 0.4.
mm, feeding speed 5 mm / sec, rubbing treatment three times in one direction is performed on the polyimide film to obtain an orientation control film 94.
Was formed.

On the other hand, on the electrode 95 of the substrate 92, a silica solution in which antimony-doped SnO ₂ ultrafine particles (particle size of about 100Å) was dispersed was spin-coated at 1500 rpm for 20 seconds, and baked at 200 ° C. for 60 minutes. By doing so, a film having a thickness of 1500 Å was formed. Thereby, the passivation film lower layer 96 was formed.

Subsequently, a siloxane solution as a surface treatment layer was spin-coated at 1500 rpm for 20 seconds, and baked at 200 ° C. for 60 minutes to give a thickness of 50.
A Å polysiloxane film was formed. Thereby, the passivation film upper layer 97 was formed.

Then, after the substrates 91 and 92 were bonded together under the same method and conditions as in Experimental Example 5, liquid crystal was injected to prepare a liquid crystal element.

When the surface potential of the liquid crystal element was measured, it was -220V on the uniaxial orientation side and -100V on the non-uniaxial side.

The VT characteristics of the liquid crystal device of the present experimental example formed by the above process were evaluated in the same manner as in Experimental Example 5. The hysteresis was 0.4 V and the asymmetry was 0.5 V.
And is within the required range.

Further, a liquid crystal panel having matrix pixels formed by the elements of the experimental example was manufactured, and its driving was evaluated. As a result, afterimage was not visible, fast response was obtained, flicker, growth of defective display area, etc. It was not observed, and the result was that extremely good bistability was obtained, seizure, progress of monostability, etc. were sufficiently suppressed, and high reliability was obtained. There was also a sufficient margin for the drive voltage. At the same time, the breakdown voltage between the upper and lower substrate electrodes was 30 V or more.

(Experimental Example 6) The following constituent members were prepared in order to manufacture a sample of the liquid crystal element (sample, element constitution shown in FIG. 1) according to the present invention.

A single-sided or double-sided soda-lime glass (soda glass) substrate on which an ITO (700Å or 1500Å) film as a transparent electrode was formed was prepared.

A shown below as an alignment film on the above-mentioned substrate,
B was spin-coated with a single substance or a mixture, and baked at 200 ° C. to form a polyimide film having a film thickness of 50 Å, and subjected to rubbing treatment.

Thus, a substrate having uniaxial orientation characteristics was manufactured.

S1: Polyamic acid Toray LP6
4 (trade name) S2: Polyamic acid LP64 with an alkyl chain introduced into the main chain.

Next, a substrate having non-uniaxial orientation characteristics was prepared.

The coating film (see reference numeral 6) has the following S3 and S4.
Or a mixture thereof was spin-coated and baked at 200 ° C. to form a film having a thickness of 1500 Å (no rubbing or further surface treatment was performed).

S3: Antimony-doped SnO ₂ ultrafine particles were used as a polysiloxane matrix GR651L (Te
chneglas Inc. Distributed in the product name).

S4: Antimony-doped SnO ₂ ultrafine particles dispersed in a silica matrix.

Isotropic phase from high temperature side to low temperature side → Sm
A ferroelectric chiral smectic C liquid crystal having a spontaneous polarization of 30 nC / cm ² (at a temperature of about 30 ° C.) and a tilt angle of about 24 degrees having a phase transition sequence of A → Sm ^* C → crystal layer was prepared.

Of the above film forming materials, S3 and S4 are mixed with the ultrafine particles in order to impart conductivity and adjust the polarity, and the mixed materials of S3 and S4 are both measured in the film thickness direction. The volume resistance is about 10 ⁵ Ω · c
It was m.

Sample N was obtained by combining the above-mentioned components.
o. 1-5 were produced. The reference sample (No. 1) was prepared by using an upper substrate on which an alignment film was formed by 100% polyamic acid B and rubbed, and a material S4 in which ultrafine particles of SnO ₂ doped with antimony were dispersed in a silica base material, which was 100%. It was coated on the substrate and not rubbed. The above-mentioned liquid crystal was injected between these upper and lower substrates to obtain a liquid crystal element expressing a smectic C phase.

In the sample (No. 2), the upper substrate was No. 2 above.
1 and the lower substrate is the above antimony-doped S
It is a non-rubbed substrate having a coating having a volume resistance of the order of 10 ⁵ Ωcm, which is a mixture of the material S3 in which nO ₂ ultrafine particles are dispersed in GR651L of polysiloxane base material and the above material S4 in a ratio of 50:50. The other configurations are the same as those of the reference sample.

Sample No. 3 is the material S1 and the material S2 5
A combination of an upper substrate obtained by rubbing a film obtained by mixing at a ratio of 0:50 and a lower substrate obtained by mixing the material S3 and the material S4 at a ratio of 65:35 without rubbing. is there. Similarly, sample No. Sample No. 4 is the upper substrate. Three
Same as above, the lower substrate is sample No. It is the same as 2.

Sample No. 5, the upper substrate is made of the material S1 10
The film obtained by using 0% was rubbed, and the lower substrate had a film obtained by mixing the material S3 and the material S4 in a ratio of 10:90 and which was not rubbed.

The liquid crystal molecules of the liquid crystal element are set to the first stable state U1.
Threshold value V when switching from the second stable state to
_1, the city limits value when switching from U2 to U1 and V _2, and the difference between the threshold when the | V ₁ -V ₂ | performed multiple times repeatedly in succession under a predetermined environmental condition that The threshold difference was measured.

Reference sample No. The threshold difference of 1 is 1.0, and the reference sample No. Similarly, for other sample No. 2-5 were standardized. Then, the threshold difference is 0.9 or more, □ is 0.6 to 0.9, ◯ is 0.4 to 0.6, and ◎ is 0.4 or less.

The results are shown in Table 3.

[0207]

[Table 3]

(Experimental example 7) The sample No. 5
By changing the mixing ratio of the material S3 and the material S4 when forming the non-uniaxially oriented coating film, the surface potential of the coating film is increased to +100 mV to -180 mV. A substrate was produced. Other than that, the sample No. 5
Is the same as

As a result, the surface potential of the non-uniaxially oriented coating film has a small difference from the surface potential (-220 mV) of the other uniaxially oriented substrate, preferably 50 mV or less in absolute value, and / or the same polarity. In the case of, better results were obtained.

(Experimental Example 8) Sample No. of the above-mentioned Experimental Example 6 Two
In the manufacturing method of (1), the surface potential is +100 mV by changing the mixing ratio of the material S3 and the material S4 of the non-uniaxially oriented coating film.
A liquid crystal device having a plurality of coated substrates in the range of -180 mV was prepared.

For other configurations, the sample No. Same as 2. As a result, the surface potential of the non-uniaxially oriented coating has a small difference from the surface potential (+50 mV) of the other uniaxially oriented substrate, and preferably has an absolute value of 50 mV and / or has the same switching characteristics. Good results were obtained in.

According to Experimental Examples 6 to 8, the surface potential characteristics were finely controlled by using the coating film prepared by the simple process of mixing the materials when manufacturing the substrate having the non-uniaxial orientation characteristics. It can be seen that it is possible to provide a liquid crystal element that exhibits good switching characteristics even when continuously driven.

Example 9 (Experimental Example 9-1) A liquid crystal cell having the structure shown in FIG. 1 was produced as follows. (Production of Samples 1 to 5) The thickness of the glass substrate (two sheets used) was 1.1 mm, and an ITO film having a thickness of about 150 nm was formed as a transparent electrode.

On the side subjected to the uniaxial orientation treatment, nylon 6.6: polypyridinethiophene (PYP) having the following structure was used.
y) is 100: 0, 90:10, 75:25, 50: 5
A film having a thickness of 5 nm was formed by mixing and forming a film having a weight ratio of 0: 0: 100. The surface potential of the substrate subjected to the uniaxial orientation treatment was measured and found to be +270 mV and -50 m, respectively.
V, -190 mV, -210 mV, and -350 mV.

Structural formula of nylon 6.6 (repeating unit)
Is

[0216]

[Outside 1] The structural formula (repeating unit) of polypyridinethiophene is

[0219]

[Outside 2] Is.

The uniaxial orientation treatment was performed by rubbing with a roller. The condition is that a nylon cloth is wrapped around a roller with a diameter of 80 mm, and the rotation speed of this roller is 1000 r.
pm, the pressing amount of the cloth into the substrate was 0.4 mm, and the substrate feed rate and the number of times were 5 mm / s and 3 times.

A 0.5 wt% ethanol solution of a silane coupling agent ("ODS-E" manufactured by Chisso Co., Ltd.) was applied to a substrate having non-uniaxial orientation characteristics under a spin condition of 2000 rpm x 20 seconds, and 180 ° C. And dried for 1 hour. O
The surface potential on DS-E was -110 mV.

The uniaxially treated substrate treated as described above and the substrate having non-uniaxial orientation characteristics were bonded together via a 2.0 μm bead spacer to form five cells. In these cells, from the high temperature side to the low temperature side, the liquid phase → SmA
→ SmC * → Spontaneous polarization having a phase transition sequence that becomes a crystalline phase 30 C / cm ² (in temperature of about 30 ° C.), tilt angle of about 24
The sample was prepared by heating the ferroelectric liquid crystal to a liquid phase under reduced pressure and injecting it by capillary action, returning to normal pressure, and then lowering the temperature at 2 ° C./min. These samples are sample N
o. It was set to 11, 12, 13, 14, and 15.

(Experimental Example 9-2) Another liquid crystal cell having the structure shown in FIG. 1 was prepared as follows. (Production of Samples 16 to 18) The thickness of the glass substrate (two sheets used) was 1.1 mm, and an ITO film having a thickness of about 150 nm was formed as a transparent electrode.

Then, on the side to which the uniaxial orientation treatment is applied,
LP64 (PI-A) and LP64 manufactured by Toray Co., Ltd. having the following structure
75: 2 is a polyimide (PI-B) having a structure in which an alkyl moiety is further added to the imide ring of the main chain structure of
A film composed of 5:50:50 and 10:90 by weight was formed to a thickness of 5 nm. The thin film was uniaxially processed. The rubbing condition is that a nylon cloth is wrapped around a roller with a diameter of 80 mm, and the rotation speed of this roller is 1000 rp.
m, the pressing amount of the cloth into the substrate was 0.3 mm, and the substrate feeding speed and the number of times were 10 mm / s and 4 times. The surface potential of the substrate subjected to the uniaxial alignment treatment was measured, and the results were -160 mV, -120 mV, and -30 mV, respectively. A 0.5 wt% ethanol solution of a silane coupling agent (ODS-E) was applied to the substrate side having the non-uniaxial orientation property under a spin condition of 2000 rpm × 20 seconds, and
It was dried at 0 ° C. for 1 hour. The surface potential on ODS-E is -1
It was 10 mV.

A substrate having a uniaxial orientation property and a substrate having a non-uniaxial orientation property with respect to the liquid crystal molecules treated as described above are bonded together via a 2.8 μm bead spacer.
I created two cells. In each of these cells, the liquid crystal composition was heated to a liquid phase under reduced pressure, injected in the current state of a capillary, returned to normal pressure, and then cooled at 2 ° C./min to prepare three samples. These three samples are No. 16, 17, 18
And

(Experimental Example 9-3) A liquid crystal cell was prepared as follows. (Production of Sample 19) The thickness of the glass substrate (two sheets used) was 1.1 mm, and an ITO film having a thickness of about 150 nm was formed as a transparent electrode.

Nylon 6.6 having a thickness of 5 nm was formed on the side subjected to the uniaxial orientation treatment. The thin film was uniaxially processed. The rubbing condition is that a nylon cloth is wrapped around a roller with a diameter of 80 mm, and the rotation speed of this roller is 1000.
rpm, the pressing amount of the cloth into the substrate was 0.4 mm, and the substrate feeding speed and the number of times were 5 mm / s and 3 times. The result of measuring the surface potential of the substrate subjected to this uniaxial orientation treatment +27
It was 0 mV.

Polysiloxane was coated to a thickness of 5 nm on the side of the substrate having non-uniaxial orientation characteristics. The surface potential of the polysiloxane coating film surface was +50 mV. 2.0 μm of uniaxially oriented substrate and non-uniaxially treated substrate treated as described above
An attachment was created via the bead spacers. Samples were prepared by heating the above liquid crystal composition into a liquid phase under reduced pressure, injecting the liquid into these cells under the current capillary conditions, returning to normal pressure, and then lowering the temperature at 2 ° C./min. This sample is It was set to 19.

The samples 11 to 19 were evaluated as follows. First, sample No. By applying a bipolar voltage to cell No. 11, the threshold voltage when the liquid crystal molecule switches from the first state to the second state among the two stable states, and conversely to the second state From the threshold voltage at the time of switching to the first state, and the difference between them was obtained. Same sample No. Similarly, the difference of the threshold voltage was obtained by changing the measurement temperature environment of No. 1 and the average value thereof was obtained.

Similarly, for other sample Nos. The same measurement was performed for 12 to 19.

In order to compare the values thus obtained, the sample No. The value of 1 was standardized as 1.0. If such a value is used as the degree of improvement, the value should be low.
Therefore, by comparing this value with the values of other samples, those with a standardized value of 0.9 or more are □ = 0.6 to 0.8 are Δ, and 0.3 to 0.5 are Was rated as 0.2 or less.

According to this experiment, the sample Nos. 12,
13, 14, 16, 17, and 18 have been improved by about 50% or more. In particular, in Samples 16 and 17 in which the absolute value of the surface potential difference is set to be small on both substrates, extremely good characteristics are imparted to the switching threshold symmetry.

[0231]

[Table 4]

According to Experimental Examples 9-1 to 9-3 described above, the alignment film obtained by the simple process of mixing the organic polymer material is used as the uniaxial alignment film of the liquid crystal element subjected to the asymmetric alignment treatment. Thus, it can be seen that a liquid crystal element that exhibits good switching characteristics under all environmental conditions and has a large driving machine can be obtained.

[0233]

As described in detail above, according to the present invention,
It exhibits a good liquid crystal alignment state, reduces the asymmetry of switching characteristics, secures the stability of the two states of liquid crystal, especially ferroelectric liquid crystal and anti-ferroelectric liquid crystal, and further suppresses the change over time of the switching threshold. The liquid crystal device is provided.

Further, according to the present invention, the alignment film obtained by a simple process of mixing the organic polymer material is used as the uniaxial alignment film of the liquid crystal element subjected to the asymmetric alignment treatment,
Shows good switching characteristics under all environmental conditions,
A liquid crystal device having a large driving machine is provided.

Furthermore, according to the present invention, by using the coating film prepared by the simple process of mixing the materials when preparing the substrate having the non-uniaxial orientation property, it is possible to continuously drive the film. A liquid crystal element exhibiting switching characteristics can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structure of a liquid crystal element as an example of the present invention.

FIG. 2 is an explanatory diagram showing an outline of an example of a surface potential measuring system adopted in the present invention.

FIG. 3 is a schematic diagram illustrating the concept of internal potential in the liquid crystal element of the present invention.

FIGS. 4A to 4D are schematic diagrams illustrating an example of a state of internal potential in the liquid crystal element of the present invention.

FIG. 5 is a sectional view schematically showing an alignment state of liquid crystal molecules in an example of the liquid crystal element of the present invention.

6 (a) and 6 (b) are explanatory views showing the operational effects of the liquid crystal element of the present invention.

FIG. 7 is a diagram showing an equivalent circuit of the liquid crystal element of the present invention.

FIG. 8 is a diagram showing an equivalent circuit of a conventional liquid crystal element.

FIG. 9 is an explanatory diagram showing a volume resistance measuring system in a film thickness direction of a coating film or a passivation film in a liquid crystal element of an example of the present invention.

FIG. 10 is an explanatory view showing a volume resistance measuring system in a sheet direction of a coating film in a liquid crystal element of an example of the present invention.

FIG. 11 is a diagram showing a relationship between a measured value of a surface potential in a non-uniaxially treated layer and a switching threshold in each liquid crystal element manufactured in Experimental Example 1 of the present invention.

FIG. 12 is a diagram showing a relationship between a measured value of a surface potential in a non-uniaxially treated layer and a switching threshold in each liquid crystal element manufactured in Experimental Example 2 of the present invention.

FIG. 13 is a cross-sectional view showing the structure of a liquid crystal element and its surface potential measuring system in an experimental example of the present invention.

FIG. 14 is a diagram showing hysteresis and switching asymmetry evaluated for a liquid crystal element of an experimental example of the present invention.

[Explanation of symbols]

 1,91 Substrate 2,92 Substrate 3,93 Electrode 4,94 Alignment control layer 5,95 Electrode 6,96 Layer for imparting non-uniaxial alignment property 7,97 Treatment part 8 Liquid crystal 21 Surface potential measurement sample 22 Electrode 23 Substrate 24 Surface potential measurement probe 25 Sensor electrode 26 Vibrator 27 Surface potential measurement control device 28 Liquid crystal 29 Heat evaporation container 30 Sample heating table 31 Temperature control device 32 Vacuum exhaust system 33 Gas introduction system 34 Biaxial distance transfer device 35 Vacuum chamber 41 Electrode substrate 42 Electrode substrate 43 Layer having uniaxial orientation property 44 Layer having non-uniaxial property 45 Surface potential 46 Surface potential 47 Internal potential difference 71 Membrane to be measured 72 Electrode 73 Electrode 74 Membrane to be measured 75 Electrode 76 Electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (31) Priority claim number Japanese Patent Application No. 7-8188 (32) Priority date Hei 7 (1995) January 23 (33) Country of priority claim Japan (JP) (31) Priority Claim number Japanese patent application No. 7-8955 (32) Priority date Hei 7 (1995) January 24 (33) Priority claiming country Japan (JP) (72) Inventor Ihachiro Gofuku 3-30 Shimomaruko, Ota-ku, Tokyo No. 2 within Canon Inc. (72) Inventor Shuzo Kaneko 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Canon Inc.

Claims (58)

[Claims] 1. A liquid crystal is sandwiched between a pair of opposing substrates,
One of the substrates has a uniaxial alignment property for liquid crystal molecules, and the other substrate is a liquid crystal element having a non-uniaxial alignment property, and a surface potential detected on the surface of the substrate having the uniaxial alignment property. A liquid crystal element having an absolute value of a difference from a surface potential detected on the surface of the substrate on the side having the non-uniaxial orientation property that is smaller than 50 mV. 2. The absolute value of the difference between the surface potential detected on the surface of the substrate having the uniaxial orientation property and the surface potential detected on the surface of the substrate having the non-uniaxial orientation property is 30 mV. The liquid crystal element according to claim 1, which is smaller than the above. 3. The surface potential detected on the surface of the substrate having the uniaxial orientation property and the 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 1, which is characterized in that. 4. The liquid crystal device according to claim 1, wherein the substrate having a non-uniaxial orientation property with respect to the liquid crystal molecules has a film for adjusting the surface potential of the substrate surface. 5. The substrate having a non-uniaxial alignment characteristic with respect to the liquid crystal molecules, the volume resistivity is 10 ⁴ Ωcm~10 ⁸ Ωcm
2. The liquid crystal element according to claim 1, wherein a film in the range of 1 is formed. 6. The liquid crystal device according to claim 4, wherein a coating film having ultrafine particles dispersed in a base material is formed on the side of the substrate having a non-uniaxial orientation property with respect to the liquid crystal molecules. . 7. The liquid crystal device according to claim 6, wherein the ultrafine particles have a particle size of 30Å to 150Å. 8. The liquid crystal device according to claim 6, wherein the ultrafine particles are an oxide to which a conductivity control impurity is added. 9. The liquid crystal device according to claim 6, wherein the ultrafine particles are SnO _x doped with antimony. 10. The liquid crystal device according to claim 1, wherein an alignment control film formed by subjecting a polymer film to a uniaxial alignment process is provided on the substrate side having uniaxial alignment characteristics with respect to the liquid crystal molecules. 11. The surface potential polarity detected on the surface of the substrate having the non-uniaxial orientation property is the same polarity as the surface potential polarity detected on the surface of the substrate having the uniaxial orientation property. Liquid crystal element. 12. The surface energy at the liquid crystal interface on the substrate side having the non-uniaxial orientation property is 30 dyne / cm.
The liquid crystal element according to claim 1, wherein: 13. The liquid crystal device according to claim 1, wherein the surface energy at the liquid crystal interface on the substrate side having the non-uniaxial alignment property is larger than the surface energy at the liquid crystal interface on the substrate side having the uniaxial alignment property. . 14. The surface energy at the liquid crystal interface on the substrate side having the non-uniaxial orientation property is 40 dyne / cm.
The liquid crystal element according to claim 1, which is as described above. 15. The liquid crystal element according to claim 4, wherein the film provided on the substrate side having the non-uniaxial orientation property is a laminated film composed of a plurality of films. 16. The single layer film forming the laminated film has different surface potentials from each other, and the surface potential of the laminated film is an intermediate value of the surface potentials of the single layer film. Item 15. A liquid crystal device according to item 15. 17. The layer located closest to the substrate in the laminated film is a film made of a polycrystalline metal oxide doped with a conductivity control impurity or a polycrystalline semiconductor doped with a conductivity control impurity. The liquid crystal device according to claim 15, wherein the liquid crystal device is a liquid crystal device. 18. The film made of the polycrystalline metal oxide or polycrystalline semiconductor has a volume resistance of 1 in the film thickness direction.
The liquid crystal device according to claim 17, wherein the liquid crystal device has a volume resistance in the range of 0 ⁴ Ωcm to 10 ⁸ Ωcm and a volume resistance in the film surface direction of 10 ⁶ Ωcm to 10 ⁹ Ωcm. 19. The layer closest to the substrate in the laminated film,
The liquid crystal element according to claim 15, wherein the liquid crystal element is a film formed by dispersing ultrafine particles added with a conductivity control impurity in a base material. 20. The liquid crystal device according to claim 19, wherein the volume resistance of the film obtained by dispersing the ultrafine particles in the matrix is in the range of 10 ⁴ Ωcm to 10 ⁸ Ωcm. 21. The liquid crystal device according to claim 4, wherein the film provided on the substrate side having the non-uniaxial orientation property is made of a mixture of a plurality of different materials. 22. The coating has a volume resistance of 10 ⁴ Ωcm.
22. The liquid crystal device according to claim 21, wherein the liquid crystal device is a film in the range of 10 < ⁸ > [Omega] cm. 23. The liquid crystal device according to claim 21, wherein the coating film is a coating film in which ultrafine particles having a particle diameter of 30Å or 300Å are dispersed in a base material. 24. The ultrafine particles have a particle size of 30Å to 150Å
24. The liquid crystal element according to claim 23. 25. The liquid crystal device according to claim 23, wherein the base material is silica or a siloxane polymer. 26. The coating has a thickness of 300Å to 5000.
22. The liquid crystal device according to claim 21, wherein the liquid crystal device is Å. 27. The one substrate is provided with an alignment film subjected to a uniaxial alignment treatment, and the alignment film is made of a material obtained by mixing a plurality of organic polymer materials. The liquid crystal device according to item 1. 28. An alignment film for providing the uniaxial orientation characteristic is provided on the substrate side having the uniaxial orientation characteristic,
2. The liquid crystal element according to claim 1, wherein the alignment film is made of a mixture of a plurality of organic polymer materials that can be used as alignment films exhibiting uniaxial alignment characteristics when used alone. 29. The liquid crystal device according to claim 1, wherein the liquid crystal is a liquid crystal exhibiting a chiral smectic phase. 30. The liquid crystal device according to claim 29, wherein the liquid crystal does not exhibit a cholesteric phase. 31. A liquid crystal composition comprising at least one fluorine-containing compound having a smectic phase or a latent smectic phase having a structure in which a fluorocarbon end portion and a hydrocarbon end portion are bonded to a central nucleus. The liquid crystal element described. 32. The liquid crystal device according to claim 1, wherein the liquid crystal is a ferroelectric liquid crystal. 33. The liquid crystal device according to claim 1, wherein the liquid crystal is an antiferroelectric liquid crystal. 34. The liquid crystal device according to claim 1, wherein the switching threshold difference is ± 1.0 V or less. 35. The liquid crystal device according to claim 1, wherein the absolute values of the surface potentials of the layers of both substrates are 100 mV or less. 36. A liquid crystal device in which a liquid crystal is sandwiched between a pair of opposed substrates, one substrate having uniaxial alignment characteristics with respect to liquid crystal molecules, and the other substrate having non-uniaxial alignment characteristics with respect to liquid crystal molecules. Wherein the surface potential polarity detected on the surface of the substrate having the non-uniaxial orientation characteristic is the same polarity as the surface potential polarity detected on the surface of the substrate having the uniaxial orientation characteristic. . 37. The liquid crystal device according to claim 36, wherein a film for adjusting the surface potential polarity on the substrate side is provided on the substrate side having the non-uniaxial orientation property. 38. The film provided on the substrate side having the non-uniaxial orientation property has a volume resistance of 10 ⁴ Ωcm to 10 ⁸ Ωc.
37. The liquid crystal element according to claim 36, which is a film in the range of m. 39. The liquid crystal device according to claim 36, wherein the film provided on the substrate side having the non-uniaxial orientation property is a coating film in which ultrafine particles are dispersed in a base material. 40. The liquid crystal device according to claim 37, wherein the film provided on the substrate side having the non-uniaxial orientation property is a laminated film composed of a plurality of films. 41. The single layer film constituting the laminated film has different surface potentials from each other, and the surface potential of the laminated film is an intermediate value of the surface potentials of the single layer film. Item 40. A liquid crystal device according to item 40. 42. The phase closest to the substrate in the laminated film is a film made of a polycrystalline metal oxide doped with a conductivity control impurity or a polycrystalline semiconductor doped with a conductivity control impurity. 41. The liquid crystal device according to claim 40, wherein 43. The liquid crystal device according to claim 36, wherein the liquid crystal is a liquid crystal exhibiting a chiral smectic phase. 44. The liquid crystal device according to claim 43, wherein the liquid crystal undergoes a phase transition in the order of an isotropic phase, a smectic phase, and a chiral smectic C phase at a lowered temperature. 45. The liquid crystal device according to claim 36, wherein an alignment control film formed by uniaxially aligning a polymer film is provided on the substrate side having the uniaxial alignment property. 46. The absolute value of the difference between the surface potential detected on the surface having the uniaxial orientation characteristic and the surface potential detected on the substrate surface having the uniaxial orientation characteristic is 100.
37. The liquid crystal element according to claim 36, which has a voltage of mV or less. 47. The liquid crystal element according to claim 36, wherein the absolute values of the surface potentials of the both substrates are 100 mV or less, respectively. 48. The absolute value of the switching threshold difference is 1.0.
37. The liquid crystal element according to claim 36, which is V or less. 49. A liquid crystal device in which liquid crystal is sandwiched between a pair of opposed substrates, one substrate having uniaxial alignment characteristics with respect to liquid crystal molecules and the other substrate having non-uniaxial alignment characteristics with respect to liquid crystal molecules. A liquid crystal element in which a film having a volume resistance in the range of 10 ⁴ Ωcm to 10 ⁸ Ωcm is provided on at least the substrate side having non-uniaxial orientation characteristics. 50. The volume resistance is 10 ⁴ Ωcm to 10 ⁸
The surface energy measured by the droplet contact angle at the liquid crystal interface on the substrate side having the non-uniaxial orientation property provided with the film in the range of Ωcm is determined by the droplet contact angle at the liquid crystal interface on the substrate side having the uniaxial orientation property. The liquid crystal element according to claim 49, which has a measured surface energy or more. 51. The liquid crystal device according to claim 49, wherein the film having a volume resistance in the range of 10 ⁴ Ωcm to 10 ⁸ Ωcm provided on the substrate having the non-uniaxial orientation property is a coating film. 52. The liquid crystal element according to claim 51, wherein the coating film has irregularities of 200 Å or more. 53. The coating film has a particle size of 30 to 30 in the base material.
52. The liquid crystal device according to claim 51, wherein 0Å conductive fine particles are dispersed. 54. The liquid crystal device according to claim 53, wherein the base material in which the conductive fine particles are dispersed is a siloxane polymer. 55. The volume resistance is at least 10 ⁴ Ωcm to 10 ⁸ Ωcm on the side of the substrate having at least non-uniaxial orientation characteristics.
50. The liquid crystal element according to claim 49, wherein an inorganic film having a volume resistance in the film thickness direction measurement of 10 ⁴ Ωcm to 10 ⁸ Ωcm is provided as a layer immediately below the film having the range of 5). 56. The liquid crystal element according to claim 49, wherein in the substrate having the uniaxial orientation property, an orientation control layer having a volume resistance in the range of 10 ⁴ Ωcm to 10 ⁸ Ωcm is provided on the substrate. 57. The liquid crystal device according to claim 49, wherein the liquid crystal exhibits a chiral smectic phase. 58. The liquid crystal device according to claim 49, wherein the liquid crystal undergoes a phase transition in the order of an isotropic phase, a smectic A phase, and a chiral smectic phase when the temperature is lowered.