JP4034000B2 - Method for manufacturing liquid crystal electro-optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacture of the liquid crystal device which operates fast and has a high contrast ratio and high reliability. SOLUTION: This manufacturing method includes a process for injecting a mixture of a liquid crystal material and an unset resin material containing a >=60 wt.% monomer into between a couple of substrates, one of which has an alignment film, so that the liquid crystal material has a smectic phase and a process for setting the unset resin while it is oriented in the orientation direction of the oriented film.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a birefringence mode liquid crystal electro-optical device using a ferroelectric or antiferroelectric liquid crystal material.
[0002]
The present invention relates to a liquid crystal electro-optical device having a uniaxially oriented ferroelectric or antiferroelectric liquid crystal material and a cured resin material, and a method for manufacturing the same.
[0003]
The present invention relates to a liquid crystal electric material having a uniaxially oriented ferroelectric or antiferroelectric liquid crystal material and a cured resin material provided on a substrate sandwiching the liquid crystal material or an electrode or alignment film on the substrate. The present invention relates to an optical device and a manufacturing method thereof.
[0004]
The present invention relates to a method for manufacturing a liquid crystal electro-optical device in which a resin containing a reaction initiator is added to a ferroelectric or antiferroelectric liquid crystal material to cure the resin.
[0005]
The present invention relates to a liquid crystal electro-optical device using a ferroelectric or antiferroelectric liquid crystal material, in which the helical structure of the liquid crystal material exhibited in a bulk state is suppressed by a substrate interval, and does not involve generation of domains. The present invention relates to a liquid crystal electro-optical device that performs switching and a manufacturing method thereof.
[0006]
The present invention relates to a configuration and method for obtaining a halftone in a liquid crystal electro-optical device in which a ferroelectric or antiferroelectric liquid crystal material is used and a helical structure in which the liquid crystal material exhibits a bulk state is suppressed by a substrate interval. About.
[0007]
The present invention relates to a liquid crystal electro-optical device in which gradation is continuously changed using a ferroelectric or antiferroelectric liquid crystal material and a method for manufacturing the same.
[0008]
The present invention relates to an active matrix liquid crystal electro-optical device using a ferroelectric or antiferroelectric liquid crystal material.
[0009]
[Prior art]
Recently, liquid crystal display devices (LCD) have attracted attention. In particular, a twisted nematic (hereinafter referred to as TN) type using a nematic liquid crystal or a super twisted nematic (hereinafter referred to as STN) type is widely known and put into practical use.
An active matrix type using a nematic liquid crystal material and provided with a switching element such as a thin film transistor (TFT) in each pixel has been actively developed as a display capable of high-speed, high-contrast and multi-gradation display.
[0010]
A basic configuration of a TN type or STN type liquid crystal electro-optical device is described below. An alignment film is applied and baked on a substrate having an electrode, and is rubbed as an alignment treatment to obtain a first substrate. Similarly, an alignment film is applied to a substrate having electrodes, baked, and rubbed to form a second substrate. The first substrate and the second substrate are provided so that the electrodes face each other, and a liquid crystal is sandwiched between the substrates.
[0011]
At the contact surface between the two substrates and the liquid crystal layer, the liquid crystals are aligned in the rubbing direction according to the regulating force by rubbing. In the upper and lower substrates, the rubbing direction is shifted so as to be positioned at 90 ° for the TN type and 200 ° to 290 ° for the STN type. The liquid crystal molecules in the vicinity of the middle of the liquid crystal layer are arranged in a spiral between the liquid crystal molecules located at 90 ° to 290 ° so that the energy becomes the smallest.
[0012]
These liquid crystal molecules arranged in a spiral form a spiral structure by being applied in parallel or perpendicular to the direction of the electric field by applying a voltage between the two substrates and by the dielectric anisotropy of the liquid crystal molecules. As described above, when the liquid crystal molecules are perpendicular to the substrate surface, the amount of transmitted light is changed so as to indicate a bright state, and when the liquid crystal molecules are parallel, a dark state is indicated. In addition, since the state of such liquid crystal molecules continuously changes depending on the voltage applied between the substrates and the amount of transmitted light changes accordingly, the light (transmission) state and darkness can be controlled by appropriately controlling the applied voltage. The gradation between the (non-transparent) states, ie the intermediate floor, is obtained.
[0013]
The fact that a halftone can be obtained in this way is very effective especially for colorization, and if the response speed of the liquid crystal is sufficient, it can cope with full colorization.
[0014]
However, the nematic liquid crystal has a slow response speed of several hundred milliseconds, and does not have sufficient characteristics for displaying moving images or the like that require a high-speed response.
Since nematic liquid crystal has fluidity, when the device is stood and used, the liquid crystal accumulates in the lower part of the device and the lower part of the cell swells. In this case, since the cell thickness greatly changes in the apparatus, coloring or color unevenness occurs, or the response of the liquid crystal is not uniform even when the same voltage is applied.
[0015]
In recent years, since it is desired to increase the screen size and speed of the apparatus, the above-described problems of nematic liquid crystal are becoming more and more serious.
[0016]
On the other hand, LCDs using ferroelectric liquid crystals have also been developed. Ferroelectric liquid crystals have spontaneous polarization of liquid crystal molecules and can be switched at high speed in several tens of microseconds. An active matrix type LCD using this ferroelectric liquid crystal and capable of displaying at higher speed has been developed.
[0017]
Ferroelectric liquid crystal or anti-ferroelectric liquid crystal has spontaneous polarization and can operate at a high response speed of several to several hundreds of microseconds. It responds at about three orders of magnitude faster than nematic liquid crystal. To do.
[0018]
Further, in a liquid crystal electro-optical device using a ferroelectric liquid crystal or an anti-ferroelectric liquid crystal, the liquid crystal molecules are arranged on at least one substrate surface in accordance with the regulating force if the alignment treatment is performed. These liquid crystal molecules have a layered structure that is regularly stacked from one substrate surface to the other substrate surface. It also has a layer structure with respect to the parallel direction of the substrate.
[0019]
Because of this layer structure, ferroelectric liquid crystal or antiferroelectric liquid crystal has poor fluidity, and liquid crystal does not collect at the bottom of the device like nematic liquid crystal when the device is stood up. There is an advantage that the cell thickness is kept constant and uniform display is possible.
[0020]
SmC originally exhibited by ferroelectric liquid crystal materials ^* In the phase, the major axis of the liquid crystal molecule is tilted by a certain tilt angle with respect to the normal of the layer of the liquid crystal material (substantially parallel to the substrate), and in the bulk state, the liquid crystal molecules cross from layer to layer. As a result, the orientation of the orientation vector is twisted, and the spontaneous polarization of the liquid crystal molecules is canceled as a whole, so that the ferroelectricity cannot be expressed.
[0021]
Therefore, a so-called surface-stabilized liquid crystal electro-optical device that exhibits ferroelectricity by Clark or the like has been proposed. The basic structure is that a ferroelectric smectic liquid crystal material is sandwiched between a pair of substrates having electrodes, the liquid crystal molecules are aligned parallel and uniaxially to the substrate, and the layer having the liquid crystal material is perpendicular or inclined with respect to the substrate. It is to be formed. At this time, the spiral structure that the liquid crystal material takes in a bulk state is solved by setting the distance between the pair of substrates to about 1 μm. Further, as a result of solving the spiral structure, two stable alignment states in which the orientation vectors of the liquid crystal molecules take, that is, a bistable alignment state are obtained.
[0022]
With the above configuration, by reversing the polarity of the electric field applied to the pixel electrode, the torque generated by the product of the spontaneous polarization of the liquid crystal material and the electric field applied by the electrode is high-speed between the two states. Response is possible.
[0023]
The liquid crystal molecules change the direction of spontaneous polarization of the liquid crystal molecules themselves by 180 ° (hereinafter referred to as inversion) by applying a voltage between both substrates. The liquid crystal molecules have a direction changed by a certain angle from the uniaxial orientation direction, and the direction of the liquid crystal molecules is reversed by applying a voltage, and switching from the bright (transmission) state to the dark (non-transmission) state or from the dark state to the bright state. I do.
[0024]
Since these liquid crystal electro-optical devices using nematic, ferroelectric, or anti-ferroelectric liquid crystals utilize the optical anisotropy of liquid crystal molecules, they have polarizing plates outside both substrates, Electro-optical properties are obtained.
[0025]
When a ferroelectric or antiferroelectric liquid crystal material is used, the optical axis of one polarizing plate is aligned with one of two stable states in the direction indicating one alignment state, and the other polarizing plate is Make the optical axis vertical.
[0026]
As a method for uniaxially aligning the liquid crystal molecules, there is known a method of forming a means (hereinafter referred to as a uniaxial alignment means) for providing an alignment regulating force for uniaxially aligning the liquid crystal material on the surface of the substrate sandwiching the liquid crystal material in contact with the liquid crystal material. It has been. A rubbing method is typically known. In the rubbing method, an alignment film having a thickness of 100 to 500 mm, usually made of an organic polymer, is formed on the surface of the substrate having the electrodes, and the alignment film surface is rubbed in one direction with a cloth (rubbing process). Is applied, and the alignment film is provided with a uniaxial alignment regulating force for aligning liquid crystal molecules in one direction. The substrate surface or electrode surface may be directly rubbed. The rubbing method is widely used in TN type and STN type liquid crystal electro-optical devices using nematic liquid crystal, and is frequently used as an excellent alignment method that is simple and easy to increase in area even with a ferroelectric liquid crystal.
[0027]
In addition, since the ferroelectric liquid crystal has high order and has a layer structure, the alignment is not disturbed unless the layer structure is broken once it is aligned. Therefore, the alignment is not limited to the rubbing method, and liquid crystal molecules are sufficiently aligned even in an alignment method that does not use an alignment film, such as a shear stress method, a magnetic field alignment method, or a temperature gradient method, that is, only an initial alignment. Switching can be performed. However, these may be used experimentally, but it takes a long time to align the liquid crystal material, and is not practical for manufacturing a large-area device. Is not used much.
[0028]
In addition, there is an oblique vapor deposition method in which SiO or the like is vapor-deposited obliquely with respect to the substrate surface as another alignment method. However, there is a problem in mass productivity, and when performing on a large area substrate, There arises a problem that the difference in the vapor deposition angle and vapor deposition direction at each of the above points cannot be ignored. Therefore, the rubbing method is an alignment method widely used industrially in ferroelectric liquid crystal electro-optical devices.
[0029]
In addition, since the ferroelectric liquid crystal or the anti-ferroelectric liquid crystal can be switched about three orders of magnitude faster than the nematic liquid crystal, the so-called frame that controls ON and OFF for each display frame and performs gradation display according to the display time. Enables gradation display. By controlling the ON / OFF time with a digital value using a TFT, a multi-tone digital gradation display can be performed. Details are described in Japanese Patent Application No. 4-275413, which is the invention of the present applicant.
[0030]
In this case, an amorphous silicon TFT may be used as the TFT. However, in order to cope with high-speed switching of the ferroelectric liquid crystal and to achieve higher speed, multi-gradation, and high contrast ratio in this digital gradation display, The charge injection into the pixel needs to be performed more quickly. For this reason, a crystalline silicon TFT that operates at about four orders of magnitude faster than an amorphous silicon TFT and can flow a large current enough to sufficiently reverse spontaneous polarization is used.
[0031]
[Problems of the prior art]
When a cell was produced by forming a uniaxial alignment means on the surface of the substrate in contact with the liquid crystal material sandwiching the ferroelectric or antiferroelectric liquid crystal material, there was a problem in switching of liquid crystal molecules.
[0032]
For example, in the case of the rubbing method, in the process of gradually cooling after injecting the liquid crystal material into the cell, in the SmA phase, the rubbing direction and the alignment vector are parallel. ^* When the phase transitions, the liquid crystal molecules have a tilt tilt angle from the layer normal, so that SmC ^* In the phase, the alignment vector of the liquid crystal molecules is not parallel to the rubbing direction. This gives a bistable state, but since the rubbing direction is between one stable state and the other stable state of the liquid crystal molecules, the influence of the uniaxial alignment regulating force due to the rubbing of the liquid crystal molecules during the switching. The switching of liquid crystal molecules was hindered.
[0033]
On the other hand, the alignment method by physical means such as the shear stress method, the magnetic field alignment method, the temperature gradient method described above is not practical, but there is no one that emits uniaxial alignment regulating force after alignment of the liquid crystal material. There is nothing that hinders switching, and good switching characteristics can be obtained.
[0034]
Therefore, in a ferroelectric liquid crystal electro-optical device in which liquid crystal molecules are aligned by forming uniaxial alignment means on the surface in contact with the liquid crystal material, the liquid crystal electro-optical device is aligned by a shear stress method, a magnetic field alignment method, a temperature gradient method, etc. Compared to the above, there are problems such as a decrease in switching speed and insufficient switching.
[0035]
Therefore, the regulating force to align the liquid crystal material uniaxially works only when the liquid crystal material is injected between the substrates and then the liquid crystal material is initially aligned in the course of slow cooling. There has been a demand for a configuration that does not have an alignment regulating force.
[0036]
That is, after the liquid crystal molecules are uniaxially aligned, it is possible to substantially reduce or eliminate the alignment regulating force of the uniaxial alignment means, which is a ferroelectric liquid crystal electro-optic with excellent switching characteristics and industrial productivity. It was needed to realize the device.
[0037]
Further, in a liquid crystal electro-optical device using a ferroelectric liquid crystal or an antiferroelectric liquid crystal, a so-called surface-stabilized ferroelectric liquid crystal having a structure in which the substrate interval is set to several μm and the helical structure of liquid crystal molecules is suppressed. Since (SSFLC) has bistability, the obtained light transmission state is only two states, light and dark, and a halftone using nematic liquid crystal was not obtained. That is, the amount of transmitted light cannot be changed continuously due to the change in the state of the liquid crystal molecules.
[0038]
The surface-stabilized liquid crystal electro-optical device can switch between the first state and the second state by reversing the polarity of the electric field, and can be driven between the two states when driven with an electric field strength equal to or higher than the saturation voltage. It becomes switching. However, when the electric field strength is gradually changed, the amount of transmitted light of the entire liquid crystal material in the region to which the electric field is applied is not changed and switched, but usually the following switching is performed. For example, when switching from the first state to the second state, a region reversed to the second orientation state (hereinafter referred to as a domain) is generated in the region indicating the first state, and an electric field is further generated. As the strength increases, the area of the domain increases and the process moves to the second state.
[0039]
One of the methods for obtaining a halftone in a liquid crystal electro-optical device using a ferroelectric liquid crystal or an anti-ferroelectric liquid crystal utilizing such properties is an area gradation method.
[0040]
When the process of inversion of the liquid crystal molecules of a ferroelectric liquid crystal or antiferroelectric liquid crystal is observed under a polarizing microscope, applying a voltage causes a dark state in a bright state region in a specific region where the voltage is applied. A bright state region (hereinafter referred to as a domain) occurs in the region or the dark state region, and when the voltage is further applied, the area of each domain expands, and the bright state in the specific region as a whole becomes a dark state. Or the dark state becomes brighter.
[0041]
In the area gradation method, by utilizing the fact that the size of the domain slightly changes depending on the applied voltage, the area of the bright or dark domain in one pixel is controlled by controlling the applied voltage. In this way, a halftone is obtained.
[0042]
In addition, there is a pixel division method as another method for obtaining a halftone in a surface stable liquid crystal electro-optical device using a ferroelectric liquid crystal or an antiferroelectric liquid crystal. In this case, one pixel is formed by a plurality of small pixels, and a halftone is obtained by combining two states of light and dark by each small pixel.
[0043]
For example, when one pixel is composed of four small pixels, the darkest or brightest state makes all four small pixels dark or bright. When halftones are to be obtained, for example, one of the small pixels is set to the dark state and the remaining three are set to the bright state, so that one pixel has 75% of the brightest state. A halftone with a transmitted light quantity of 2 is obtained.
[0044]
As described above, when an intermediate tone is obtained with a liquid crystal electro-optical device using a ferroelectric liquid crystal or an anti-ferroelectric liquid crystal, an area gray scale method in which the domain size is controlled as described above, or a pseudo pixel is used. It must be based on a pixel division method or the like that expresses the target.
[0045]
However, in the area gradation method, the inversion of the ferroelectric or antiferroelectric liquid crystal is steep, and in particular, even if the applied voltage value slightly changes, the domain greatly expands, so that the area gradation can be realized. Since the voltage width is very narrow and there is hysteresis, it is difficult to control the domain area with an applied voltage of several mV. Further, when the applied voltage is lowered, the response speed becomes extremely slow, and uniform display cannot be performed. In addition, it is difficult to increase the display resolution, which is not practical.
[0046]
In addition, the pixel division method is inefficient in using a plurality of pixels per pixel, and there is a technical limit in reducing one pixel and increasing the number of pixels. It is also unsuitable for high resolution.
[0047]
Further, since the conventional surface-stable liquid crystal electro-optical device using the ferroelectric liquid crystal or the anti-ferroelectric liquid crystal has a high threshold voltage, it cannot be driven at a low voltage.
[0048]
In addition, in a conventional surface-stable liquid crystal electro-optical device, the alignment treatment applied to a pair of substrates is different for both substrates, thereby making the alignment stability of the liquid crystal material monostable and changing the electric field strength for gradation display. There was a device that could do. However, even with this method, inversion is accompanied by a domain at the time of switching, and the same difficulty as the above-mentioned bistable type is caused, so that it is not sufficient as a gradation display.
[0049]
Accordingly, there has been a demand for a configuration capable of performing good halftone display in a liquid crystal electro-optical device using a ferroelectric or antiferroelectric liquid crystal material.
[0050]
In addition, when the frame gray scale method is used in an active matrix ferroelectric liquid crystal electro-optical device, in order to perform high-speed and high-contrast display, the inversion of the liquid crystal molecules of the ferroelectric liquid crystal when a signal is applied is extremely short. It is necessary to perform inversion over time and to fully invert, and that the state of the liquid crystal molecules after the inversion does not change and is constant. The state of the liquid crystal molecules is mainly determined by the magnitude of the voltage applied to the electrodes on both substrates.
[0051]
However, it is well known that impurities having a charge from the liquid crystal or the alignment film are present in the device, or extra charge that generates a voltage in the opposite direction to the voltage when a voltage is applied. These charges move freely in the liquid crystal material sandwiched between the two substrates with the application of voltage. Most of these charges move and reach the surface of the alignment film. However, since the alignment film is inherently insulating, the charge does not move any further, and is between the alignment film and the liquid crystal layer (layer of liquid crystal material) (alignment film). It is accumulated in the liquid crystal interface).
[0052]
These charges cause a problem that is undesirable for a liquid crystal electro-optical device.
For example, an effect of canceling the voltage applied between the electrodes occurs, and the contrast is attenuated. For example, when a pulse voltage is applied by driving a TFT, transmission and non-transmission switching is not steep with respect to the pulse application, and a two-step response in which switching occurs after a short delay after switching, or attenuation occurs immediately after switching I did. In order to solve this, it was necessary to make the voltage to be applied larger than the voltage necessary to reverse the spontaneous polarization, but this was not a sufficient measure.
[0053]
In addition, when a voltage is applied between the electrodes, the amount of charge in the liquid crystal layer changes with time, so the state of the liquid crystal molecules is not stable. Furthermore, since the liquid crystal molecules that are electrically adsorbed by the charge accumulated at the alignment film-liquid crystal interface require a larger voltage than the non-adsorbed liquid crystal molecules inside the liquid crystal layer, the liquid crystal molecules in the liquid crystal layer However, there is a problem in that the state of light transmission does not change all at once, and the light transmission characteristic, which is the most important characteristic of the liquid crystal electro-optical device, is not stable.
[0054]
In the liquid crystal electro-optical device, the display becomes unstable, the response speed of the liquid crystal material cannot be fully utilized, and the display speed is inevitably lowered, and the contrast is lowered. In particular, when the frame gradation display is performed, the number of gradations is limited.
[0055]
In order to solve this problem, a method of aligning liquid crystal molecules by selecting an alignment film material that alleviates charge accumulation or obliquely depositing SiO or the like on an electrode instead of an alignment film that is an insulating film However, it requires a lot of preliminary experiments and is time consuming and expensive, and it cannot be said that the effect changes depending on the combination of materials. There is also a method of removing impurities by refining the liquid crystal, but this method is very unsuitable in view of mass productivity because there are very few liquid crystals that can be purified and used. In addition, a charge transfer complex or the like is used to adsorb or combine charges existing in the liquid crystal layer so that a plus or minus charge becomes a plus or minus 0 state (hereinafter referred to as cancellation or neutralization). Although there is a method, it is difficult to measure in the device a charge transfer complex that can completely cancel the charge, and the excess charge transfer complex moves in the liquid crystal layer in the same manner as the above-described charge.
[0056]
As described above, the charge that exists in the liquid crystal layer, which is a factor that causes a change in the voltage applied to the liquid crystal layer, that is, a factor that causes the state of the liquid crystal molecules to change over time and destabilizes the optical characteristics of the device, is canceled. Various methods have been proposed for this, but it is difficult to cancel easily and completely.
[0057]
[Problems to be solved by the invention]
The present invention has been a problem when an alignment method in which uniaxial alignment means is formed on the surface of a substrate sandwiching a ferroelectric liquid crystal material, particularly when a rubbing method having excellent practicality is used for a ferroelectric liquid crystal. ^* Liquid crystal electro-optical device that eliminates the inhibition of switching of liquid crystal molecules due to the difference between the direction of the uniaxial alignment regulating force in the phase and the directions of the two stable states indicated by the liquid crystal molecules, and does not hinder the switching of the liquid crystal molecules Another object of the present invention is to provide a manufacturing method thereof.
[0058]
The present invention also relates to a liquid crystal electro-optical device using a ferroelectric or antiferroelectric liquid crystal material, in which the helical structure of the liquid crystal material exhibited in a bulk state is suppressed by the substrate spacing, and the generation of domains is suppressed. Another object of the present invention is to provide a device that performs optical switching without accompanying the device and a manufacturing method thereof.
[0059]
In addition, the present invention uses a ferroelectric liquid crystal or an antiferroelectric liquid crystal which can easily increase the area and speed of the device, and, as in a nematic liquid crystal, continuously changes in gradation and halftone due to a change in applied voltage. It is another object of the present invention to provide a liquid crystal electro-optical device and a method for manufacturing the same.
[0060]
Further, the present invention provides a liquid crystal electro-optical device using an active matrix ferroelectric liquid crystal having a crystalline silicon TFT, which eliminates the influence of undesired charges in the liquid crystal layer and increases the speed and optical characteristics of the device. It is another object of the present invention to provide a high-performance liquid crystal electro-optical device that can achieve high-speed multi-gradation display and has a high contrast ratio.
[0061]
[Means for Solving the Problems]
The present invention solves the various problems described above.
The main configuration of the present invention is as follows.
A uniaxially oriented ferroelectric or antiferroelectric liquid crystal material sandwiched between a pair of opposing substrates;
A film made of a resin material or a plurality of convex portions provided on the inner surface of at least one of the pair of substrates;
A liquid crystal electro-optical device.
[0062]
In addition, other main configurations of the present invention are as follows:
A pair of opposing substrates;
A ferroelectric or antiferroelectric liquid crystal material sandwiched between the pair of substrates and having a spiral structure suppressed and uniaxially oriented;
Electrodes for applying a voltage to the ferroelectric or antiferroelectric liquid crystal material provided on the pair of substrates;
Uniaxial orientation means for uniaxially orienting the liquid crystal material provided on one or both of the pair of substrates;
A liquid crystal electro-optical device having
A film or a plurality of convex portions made of a resin material in contact with the ferroelectric or antiferroelectric liquid crystal material,
Having on the surface of the substrate or the electrode or the uniaxial orientation means
A liquid crystal electro-optical device.
[0063]
In addition, other main configurations of the present invention are as follows:
A pair of opposing substrates;
A ferroelectric or antiferroelectric liquid crystal material sandwiched between the pair of substrates and having a spiral structure suppressed and uniaxially oriented;
Electrodes for applying a voltage to the ferroelectric or antiferroelectric liquid crystal material provided on the pair of substrates;
Uniaxial orientation means for uniaxially orienting the liquid crystal material provided on one or both of the pair of substrates;
A liquid crystal electro-optical device having
Part or all of the surface in contact with the liquid crystal material is made of a film made of a resin material or a plurality of convex portions.
A liquid crystal electro-optical device.
[0064]
That is, the present invention relates to a uniaxially oriented ferroelectric or antiferroelectric liquid crystal material and a surface sandwiching the liquid crystal material, that is, a substrate sandwiching the liquid crystal material, or a surface such as an electrode or an alignment film on the substrate. Between these, a film or a plurality of convex portions are provided by a resin material.
In other words, a film or a convex portion made of a cured resin material is provided on a part or the whole of a surface sandwiching the liquid crystal material, that is, a substrate, an electrode on the substrate, an alignment film, or the like, in contact with the liquid crystal material that is uniaxially aligned It is characterized by this.
[0065]
With this configuration, switching can be speeded up, alignment defects can be reduced, and unwanted charges can be removed.
Furthermore, in the liquid crystal electro-optical device in which the helical structure in which the liquid crystal material is exhibited in the bulk state is suppressed by the substrate interval, switching without domain generation (domainless switching) becomes possible, and the liquid crystal electro-optical device using nematic liquid crystal In this way, it is possible to obtain a halftone in which the transmitted light intensity changes uniformly and continuously according to the electric field intensity, and further, it is possible to obtain various effects such as a reduction in driving voltage.
Hereinafter, the configuration of the present invention will be described in detail.
[0066]
[Resin film]
Other main components of the present invention are:
A ferroelectric or antiferroelectric liquid crystal material is sandwiched between a pair of substrates,
At least one of the inner surfaces of the pair of substrates is given an alignment regulating force for uniaxially aligning the ferroelectric or antiferroelectric liquid crystal material,
And means for suppressing the orientation regulating force is provided on the surface to which the orientation regulating force is applied.
A liquid crystal electro-optical device.
[0067]
In addition, other main configurations of the present invention are as follows:
A liquid crystal electro-optical device in which a ferroelectric or antiferroelectric liquid crystal material is sandwiched between a pair of substrates having electrodes inside,
Having uniaxial orientation means on the inner surface of either or both of the substrates,
On the uniaxial orientation means, there is means for suppressing the orientation regulating force of the uniaxial orientation means.
A liquid crystal electro-optical device.
[0068]
In addition, other main configurations of the present invention are as follows:
A liquid crystal electro-optical device in which a ferroelectric or antiferroelectric liquid crystal material is sandwiched between a pair of substrates having electrodes inside,
Having uniaxial orientation means on the inner surface of either or both of the substrates,
Having a resin film on at least the uniaxial orientation means
A liquid crystal electro-optical device.
[0069]
In addition, other main configurations of the present invention are as follows:
A liquid crystal electro-optical device in which a ferroelectric or antiferroelectric liquid crystal material is sandwiched between a pair of substrates having electrodes inside,
Having uniaxial orientation means on the inner surface of either or both of the substrates,
The liquid crystal material and the uniaxial alignment means are separated from each other.
A liquid crystal electro-optical device.
[0070]
In addition, other main configurations of the present invention are as follows:
A liquid crystal electro-optical device in which a ferroelectric or antiferroelectric liquid crystal material is sandwiched between a pair of substrates having electrodes inside,
Having uniaxial orientation means on the inner surface of either or both of the substrates,
Having an insulating film on at least the uniaxial orientation means;
A liquid crystal electro-optical device.
[0071]
According to another aspect of the invention, in the liquid crystal electro-optical device,
Uniaxial orientation means is an orientation film that has been rubbed
A liquid crystal electro-optical device.
[0072]
According to another aspect of the invention, in the liquid crystal electro-optical device,
A switching element connected to the pixel electrode on one of the pair of substrates;
Active matrix drive
A liquid crystal electro-optical device.
[0073]
In addition, other main configurations of the present invention are as follows:
Between a pair of substrates having electrodes on both inner surfaces and uniaxial orientation means on one or both,
Sandwiching a mixture of a ferroelectric or antiferroelectric liquid crystal material and an uncured resin,
After the liquid crystal material is uniaxially aligned according to the alignment regulating force of the alignment means,
Curing the uncured resin and curing the uncured resin in a film on the substrate surface
This is a method for manufacturing a liquid crystal electro-optical device.
[0074]
According to another aspect of the present invention, in the method for manufacturing the liquid crystal electro-optical device,
Uncured resin must be UV curable resin
This is a method for manufacturing a liquid crystal electro-optical device.
[0075]
In addition, the other main configuration of the present invention is
A ferroelectric or antiferroelectric liquid crystal material is sandwiched between a pair of substrates having electrodes on both inner surfaces and uniaxial orientation means on one or both;
On the uniaxial orientation means, there is means for suppressing the orientation regulating force of the uniaxial orientation means,
And in the liquid crystal electro-optical device in which the liquid crystal material is aligned according to the alignment regulating force of the uniaxial alignment means,
The temperature of the liquid crystal material is changed from room temperature to the SmA phase or N ^* Raise the temperature to show the phase,
Maintain the temperature for a certain time and then cool to room temperature
This is a method for manufacturing a liquid crystal electro-optical device.
[0076]
The present invention will be described with reference to FIG. FIG. 1 is a conceptual diagram of a simple matrix type liquid crystal electro-optical device using the above-described invention. In FIG. 1, 101 and 102 are translucent substrates, 103 and 104 are pixel electrodes, 105 is an alignment film that has been subjected to a rubbing process that is a uniaxial alignment means for aligning liquid crystal material and the like in a predetermined direction, Reference numeral 107 denotes a ferroelectric liquid crystal material. The liquid crystal material 107 is uniaxially aligned according to the alignment film 105. Between the alignment film 105 and the liquid crystal material 107, a resin film 106 that is a means for suppressing the alignment regulating force of the alignment film is formed. Further, polarizing plates 109 and 110 are provided on the outer surfaces of the translucent substrates 101 and 102.
[0077]
In order to fabricate this liquid crystal electro-optical device, the substrate is sandwiched between a pair of translucent substrates 101 and 102 having electrodes 103 and 104 and an alignment film 105 which is a uniaxial alignment means, the substrate interval being determined by a spacer 108. After the liquid crystal material is aligned according to the alignment film 105, a resin film that suppresses the alignment regulating force may be formed on the alignment film.
[0078]
Specifically, a mixture of a liquid crystal material and an uncured resin to which a reaction initiator is added is heated between a pair of translucent substrates having an electrode and an alignment film until it becomes isotropic phase, and is gradually injected. The liquid crystal material is cooled and uniaxially aligned by the alignment film. Thereafter, by applying means for curing the uncured resin mixed in the liquid crystal material, the uncured resin is cured as a film on the alignment means.
[0079]
At this time, since the resin is cured after the liquid crystal material is aligned according to the alignment means, the resin can be cured in a thin film on the alignment film while maintaining a good alignment state before curing. The cured resin does not adversely affect the alignment of the liquid crystal material.
[0080]
According to the present invention, switching can be speeded up, alignment defects can be prevented, and unwanted charges can be removed.
[0081]
In the present invention, the alignment film is formed on a substrate and an electrode by a rubbing process, as in the case of the conventional film, formed of a polyimide-based organic polymer resin or the like. The rubbing conditions may be the same as the conventional one.
[0082]
In addition, the present invention can be applied to any alignment means for uniaxially aligning the liquid crystal material depending on the surface characteristics of the surface in contact with the liquid crystal material. The same applies to the case where a uniaxial orientation regulating force is applied by directly rubbing the substrate or the electrode surface. It can also be applied to obliquely deposited films.
[0083]
A polymer resin or the like can be used as the resin film 106 as a means for suppressing the orientation regulating force.
[0084]
The material of the resin film 106 as a means for suppressing the alignment regulating force of the present invention is desirably a material mixed with the liquid crystal material at a high temperature and separated from the liquid crystal material when the temperature is lowered. Further, it is highly desirable that the uncured resin does not contain a solvent in order to cure the resin while being sandwiched between the two substrates. Furthermore, since the separation of the liquid crystal material and the resin and the formation of the alignment state of the liquid crystal material largely depend on the temperature, it is desirable that the resin be cured by a factor different from the temperature. Considering such matters, it is preferable to use, for example, an ultraviolet curable resin as an uncured resin and ultraviolet rays as a curing means.
[0085]
The concentration of the resin material in the mixture of the resin material and the liquid crystal material is arbitrary, but about 20% or less is appropriate.
[0086]
In the liquid crystal electro-optical device of the present invention shown in FIG. 1, the liquid crystal material 107 is separated from the alignment film 105 by the resin film 106 on the surface of the alignment film. Therefore, the alignment regulating force of the alignment film on the liquid crystal material is suppressed.
Alternatively, even if the resin film 106 is thin and the liquid crystal material 107 and the alignment film 105 are partially in contact with each other, the alignment regulating force is substantially suppressed by the presence of the resin film 106.
In the above-described manner, the present invention aligns the liquid crystal material with the alignment film which is a uniaxial alignment means, while substantially reducing or invalidating the alignment regulating force of the subsequent alignment film. Therefore, it is possible to prevent the alignment regulating force of the alignment film from hindering the switching of the liquid crystal molecules.
[0087]
Further, by increasing the concentration of the resin material added to the liquid crystal material in order to form the resin film 106, or by controlling the type of the alignment film, the curing method, etc., the resin is in a column shape between the two substrates. It may be formed in a (columnar) shape. However, since this columnar resin is also formed after the liquid crystal material is aligned, there is almost no influence on the alignment of the liquid crystal material. This columnar resin can be kept constant by preventing the interval between the substrates from being increased, for example, when the display device has a large area, and the collapse of the layer structure can be prevented.
[0088]
In addition, the liquid crystal electro-optical device of the present invention has fewer alignment defects than a conventional liquid crystal electro-optical device having no resin film. As a result, the contrast ratio as an apparatus can be improved.
[0089]
Further, when the resin material used for the resin film 106 has high insulating properties, it becomes an insulating film, so that it can have a function of a short-circuit preventing film for preventing a short circuit between the upper and lower electrodes.
[0090]
In a liquid crystal electro-optical device using a normal ferroelectric liquid crystal, when alignment failure occurs, the liquid crystal material is heated to a temperature at which it becomes an Iso (isotropic) phase, and then cooled to the liquid crystal phase. In the above-described present invention, since the alignment regulating force of the uniaxial alignment means is reduced by the resin film in the present invention, the alignment state is not sufficiently repaired even if this method is used.
[0091]
However, in the device of the present invention, the liquid crystal material is not Iso but SmA. ^* Phase or N ^* It was found that the alignment state was repaired by heating to a phase and maintaining the temperature for a certain period of time. Therefore, even if a poor alignment state occurs in the apparatus of the present invention, it can be repaired.
[0092]
That is, the liquid crystal electro-optical device is raised to the temperature shown below depending on the type of liquid crystal material, held at that temperature for a certain time, and then gradually cooled. First, as the temperature
(1) Iso-N ^* -SmA-SmC ^* In the case of liquid crystal material having a phase sequence of -Cry, N ^* Temperature showing phase or SmA phase.
(2) Iso-SmA-SmC ^* In the case of a liquid crystal material having a phase sequence of -Cry, the temperature indicating the SmA phase.
And
[0093]
Next, the apparatus is preferably maintained at the temperature shown above for several minutes or more, preferably for 10 to 60 minutes.
[0094]
By adopting the above method, the orientation of the device of the present invention in a state where the mixture of the liquid crystal material and the resin material is injected, slowly cooled, and then the resin is cured can be improved, and an orientation defect has occurred. In this case, good orientation can be obtained and the contrast ratio can be improved.
[0095]
In addition, when the resin film 106 is formed as in the present invention, undesired charges due to impurities in the liquid crystal material are substantially eliminated due to cleavage of the reaction initiator and curing of the resin material. Therefore, when a voltage is applied between the electrodes, a current flows only when the spontaneous polarization of the liquid crystal material is reversed, and no excess current flows at other times. Thereby, more stable and high-speed switching can be realized.
[0096]
The configuration of the present invention is effective not only in a simple matrix type liquid crystal electro-optical device but also in an active matrix type device in which a switching element is connected to each pixel.
[0097]
According to the present invention, after the alignment of the liquid crystal material, the uniaxial alignment regulating force with respect to the liquid crystal material disappears or decreases, and the inhibition of switching of the liquid crystal molecules can be prevented. As a result, switching speed could be increased. Moreover, orientation defects could be reduced. Moreover, the occurrence of a short circuit between the electrodes could be prevented.
[0098]
Further, even when the uniaxial orientation is suppressed, it is possible to improve the orientation of the liquid crystal material and repair the alignment disorder.
[0099]
[Domainless switching by resin film]
In addition, the other main configuration of the present invention is
Between a pair of substrates having electrodes inside,
When no electric field is applied, the spiral structure is solved,
And sandwiching a uniaxially oriented ferroelectric or antiferroelectric liquid crystal material,
The substrate surface has a resin film in contact with the liquid crystal material,
Switching of the liquid crystal material by an electric field applied to the electrode is performed without generating a domain.
A liquid crystal electro-optical device.
[0100]
In addition, the other main configuration of the present invention is
Between a pair of substrates having electrodes inside, a helical structure is unwound when no electric field is applied, and a uniaxially oriented ferroelectric or antiferroelectric liquid crystal material is sandwiched,
The substrate surface has a resin film in contact with the liquid crystal material,
The orientation vector orientation of liquid crystal molecules is continuously changed by the electric field applied to the electrode.
A liquid crystal electro-optical device.
[0101]
In addition, the other main configuration of the present invention is
Between a pair of substrates having electrodes inside, a helical structure is unwound when no electric field is applied, and a uniaxially oriented ferroelectric or antiferroelectric liquid crystal material is sandwiched,
At least one of the pair of substrates has an alignment film for uniaxially aligning the liquid crystal material,
The substrate surface and the alignment film surface have a resin film in contact with the liquid crystal material,
The orientation vector orientation of liquid crystal molecules is continuously changed by the electric field applied to the electrode.
A liquid crystal electro-optical device.
[0102]
In addition, the other main configuration of the present invention is
Between a pair of substrates having electrodes inside, a helical structure is unwound when no electric field is applied, and a uniaxially oriented ferroelectric or antiferroelectric liquid crystal material is sandwiched,
One of the substrates has a switching element connected to the pixel electrode,
At least one of the pair of substrates has an alignment film for uniaxially aligning the liquid crystal material,
The substrate surface and the alignment film surface have a resin film in contact with the liquid crystal material,
The orientation vector orientation of liquid crystal molecules is continuously changed by the electric field applied to the electrode.
A liquid crystal electro-optical device.
[0103]
In addition, the other main configuration of the present invention is
Between a pair of substrates having electrodes on both inner surfaces and uniaxial orientation means on one or both,
Sandwiching a mixture of an uncured resin having a monomer amount of 60% or more by weight in a ferroelectric or antiferroelectric liquid crystal material,
After the liquid crystal material is uniaxially aligned according to the alignment regulating force of the alignment means,
Curing the uncured resin and curing the uncured resin in a film on the substrate surface
This is a method for manufacturing a liquid crystal electro-optical device.
[0104]
According to another aspect of the present invention, in the method for manufacturing the liquid crystal electro-optical device,
Uncured resin must be UV curable resin
This is a method for manufacturing a liquid crystal electro-optical device.
[0105]
In the present invention, in a liquid crystal electro-optical device using a ferroelectric or anti-ferroelectric liquid crystal material, switching without domain generation (domainless switching) is performed.
The present invention will be described with reference to FIG. FIG. 9 shows an active matrix driving type liquid crystal electro-optical device according to the present invention. 9, 1101 and 1102 are translucent substrates, 1103 is a counter electrode, 1104 is a pixel electrode, 1105 is a thin film transistor (TFT) as a switching element, and 1106 is a liquid crystal material such as an alignment film arranged in a certain direction. 1107 is a resin film, and 1108 is a ferroelectric liquid crystal material. Here, the liquid crystal material 1108 is uniaxially aligned according to the alignment means 1106. Polarizing plates 1109 and 1110 are provided on the outer surfaces of the translucent substrates 1101 and 1102.
[0106]
As the uniaxial alignment treatment method used in the above configuration, it is possible to use a rubbing treatment of an alignment film made of an organic polymer or the like as in the conventional method. Also, the rubbing condition is rubbed in one direction on the alignment film by a roller wound with a cloth or the like as in the conventional case. Further, the alignment film may be formed on both substrates or only on one substrate. As other uniaxial alignment methods, various alignment methods such as a magnetic field alignment method, a shear stress method, a temperature gradient method, and an oblique deposition method can be used.
[0107]
In order to fabricate this liquid crystal electro-optical device, a liquid crystal material and a reaction initiator are added to a pair of translucent substrates 1101 and 1102 having electrodes 1103 and 1104 whose substrate spacing is determined by a spacer (not shown). The liquid crystal material is uniaxially aligned by sandwiching the mixture with the uncured resin. After that, by applying means for curing the uncured resin mixed in the liquid crystal material, the uncured resin is cured as a film on the surface of the alignment means or the electrode in contact with the liquid crystal material, and the resin film 1107. It becomes. Some resins cure in columns between substrates (not shown).
[0108]
At this time, since the resin is cured after the liquid crystal material is aligned according to the alignment means, the resin can be cured in a thin film on the alignment film while maintaining a good alignment state before curing. As a result, the cured resin does not adversely affect the alignment of the liquid crystal material, the occurrence of alignment defects can be prevented, and the decrease in contrast can be prevented.
[0109]
The resin material used in the above structure desirably has a mixed state with a liquid crystal material at a high temperature and is separated from the liquid crystal material when the temperature is lowered. Further, it is highly desirable that the uncured resin does not contain a solvent in order to cure the resin while being sandwiched between the two substrates. Furthermore, since the separation of the liquid crystal material and the resin and the formation of the alignment state of the liquid crystal material largely depend on the temperature, it is desirable that the resin be cured by a factor different from the temperature. Considering such matters, it is preferable to use, for example, an ultraviolet curable resin as an uncured resin and ultraviolet rays as a curing means. Further, it is desirable that the resin has high compatibility with the liquid crystal material so that it is difficult to separate during injection, and the amount of monomer in the resin is preferably 60% or more, and more preferably 80% or more.
[0110]
The present inventors provide a resin film in contact with a ferroelectric or antiferroelectric liquid crystal material on a substrate or an alignment film or electrode on the substrate, such as a device using a nematic liquid crystal material, It was discovered that a switching state (domainless switching) in which the gradation does not change evenly according to the electric field strength can be obtained without generating a domain.
[0111]
Originally, uniaxially oriented ferroelectric liquid crystal has SmC ^* In the phase, the liquid crystal molecules remain at the same angle with respect to the normal of the layer and remain at the same probability at any position on the side of the cone with the normal of the layer as the axis. The direction is free. This state is called goldstone mode. In the above-described surface stabilization type device, it is considered that the orientation of the orientation vector that the molecule can take in the goldstone mode is switching limited to two specific directions.
[0112]
If switching without this limitation can be realized, all the liquid crystal materials in the region to which the electric field is applied are uniformly generated without generating domains when an electric field is applied to the liquid crystal material continuously. In addition, it has been considered that switching in which the amount of transmitted light continuously changes according to the strength of the electric field becomes possible.
[0113]
In particular, the gradation display method using the electric field strength is a method already performed in the TN and STN type liquid crystal electro-optical devices, and therefore there is an advantage that this technique can be applied as it is.
[0114]
Even in cells that use ferroelectric liquid crystals, there have been reports of examples in which the amount of transmitted light in any region has been changed uniformly without domain generation, even though this is a limited range so far. However, it has been difficult to produce such a device with high productivity.
[0115]
According to the configuration of the present invention, the liquid crystal material in the entire region to which the electric field is applied can be switched in such a manner that the amount of transmitted light continuously changes uniformly according to the strength of the electric field without generation of domains. Also in the production, it can be produced in almost the same process as a conventional surface stable type apparatus, and has high productivity.
[0116]
The liquid crystal electro-optical device of the present invention is considered to be in a state in which the liquid crystal molecules can freely take the orientation vector, unlike the conventional surface stable type device. As a result, switching of a liquid crystal electro-optical device having a configuration in which a liquid crystal material using a ferroelectric or antiferroelectric liquid crystal material suppresses a helical structure that the liquid crystal material exhibits in a bulk state is performed without causing domain generation. Thus, the entire region to which the electric field is applied can be changed uniformly, and high-speed halftone display due to the electric field change can be easily performed. Therefore, gradation display by electric field strength can be performed at extremely high speed.
[0117]
In the present invention, the resin film is considered to have an action of relaxing anchoring of the alignment film and the electrode with respect to the liquid crystal material.
[0118]
In addition, the response of the liquid crystal molecules has been improved, and when the liquid crystal material is driven, the conventional bistable type has a two-stage inversion state between light and dark because of switching with domains, and only one stage is required. The steepness is greatly improved.
[0119]
In the device of the present invention, the liquid crystal material does not have bistability. Therefore, the configuration of the present invention is particularly suitable for an active matrix drive type device having a switching element in each pixel.
[0120]
Further, in the configuration of the present invention, the threshold value at the time of switching is lower than that of the conventional bistable type device. For this reason, it is possible to perform low-voltage driving as compared with the conventional bistable type device.
[0121]
In the above-described apparatus of the present invention, in addition to the case where the amount of transmitted light changes uniformly over the entire pixel part, depending on the production conditions such as the liquid crystal used, the resin material, the resin curing conditions, etc. There may be a case in which domain generation (reversal) in a minute region is mixed.
[0122]
Note that the resin may be formed in a column shape (columnar shape) between two substrates depending on the concentration of the resin material added to the liquid crystal material. This is a useful method when it is necessary to keep the substrate interval constant, for example, when the display device has a large area.
[0123]
In addition, N ^* The temperature is increased to the temperature shown in the phase or SmA phase, and is kept constant for 10 min or more, preferably 10 to 30 min at that temperature, and then gradually cooled to room temperature again. By this method, the alignment state of the liquid crystal material can be further improved.
[0124]
[Domainless switching and frame gradation]
In addition, the other main configuration of the present invention is
Between a pair of substrates having electrodes inside, a helical structure is unwound when no electric field is applied, and a uniaxially oriented ferroelectric or antiferroelectric liquid crystal material is sandwiched,
One of the substrates has a switching element connected to the pixel electrode,
At least one of the pair of substrates has an alignment film for uniaxially aligning the liquid crystal material,
The substrate surface and the alignment film surface have a resin film in contact with the liquid crystal material,
The direction of the orientation vector of the liquid crystal molecules is continuously changed by the electric field applied to the electrode,
Frame gradation display by controlling transmission and non-transmission of each pixel with multiple frames
A liquid crystal electro-optical device.
[0125]
In addition, the other main configuration of the present invention is
Between a pair of substrates having electrodes inside, a helical structure is unwound when no electric field is applied, and a uniaxially oriented ferroelectric or antiferroelectric liquid crystal material is sandwiched,
One of the substrates has a switching element connected to a pixel electrode, and at least one of the substrates has an alignment film for uniaxially aligning the liquid crystal material,
A resin film is provided on the substrate surface and the alignment film surface in contact with the liquid crystal material,
Controlling the amount of transmitted light by continuously changing the orientation vector orientation of the liquid crystal molecules by the electric field applied to the electrode,
In addition, frame gradation display is performed by controlling transmission and non-transmission of each pixel by a plurality of frames.
A liquid crystal electro-optical device.
[0126]
According to another aspect of the invention, in the liquid crystal electro-optical device,
One frame is divided into N (natural numbers of 2 or more) subframes having different durations,
T is the duration of the shortest subframe. ₀ And the duration of these subframes is T ₀ 2T ₀ 2 ² T ₀ ・ ・ ・ ・ ・ ・ 2 ^N T ₀ Driven by a display method that is either
A liquid crystal electro-optical device.
[0127]
In the active matrix driving type liquid crystal electro-optical device in which each pixel is provided with a switching element using a ferroelectric or anti-ferroelectric liquid crystal material, switching without domain generation (domainless switching) is provided. And frame gradation display.
[0128]
An example of the present invention will be described with reference to FIG. FIG. 17 shows an active matrix driving type liquid crystal electro-optical device according to the present invention. In FIG. 17, 2101 and 2102 are translucent substrates, 2103 is a counter electrode, 2104 is a pixel electrode, 2105 is a thin film transistor (TFT) as a switching element, and 2106 is a liquid crystal material such as an alignment film arranged in a certain direction. The uniaxial orientation means, 2107 is a resin film, and 2108 is a ferroelectric liquid crystal material. Here, the liquid crystal material 2108 is uniaxially aligned according to the alignment means 2106. Polarizing plates 2109 and 2110 are provided on the outer surfaces of the translucent substrates 2101 and 2102.
[0129]
As the uniaxial alignment treatment method used in the above configuration, it is possible to use a rubbing treatment of an alignment film made of an organic polymer or the like as in the conventional method. Also, the rubbing condition is rubbed in one direction on the alignment film by a roller wound with a cloth or the like as in the conventional case. Further, the alignment film may be formed on both substrates or only on one substrate. As other uniaxial alignment methods, various alignment methods such as a magnetic field alignment method, a shear stress method, a temperature gradient method, and an oblique deposition method can be used.
[0130]
In order to fabricate this liquid crystal electro-optical device, a liquid crystal material and a reaction initiator are added to a pair of translucent substrates 2101 and 2102 having electrodes 2103 and 2104, the distance between the substrates being determined by a spacer (not shown). The liquid crystal material is uniaxially aligned by sandwiching the mixture with the uncured resin. After that, by applying means for curing the uncured resin mixed in the liquid crystal material, the uncured resin is cured as a film on the surface of the alignment means or the electrode in contact with the liquid crystal material, and the resin film 2107. It becomes. Some resins cure in columns between substrates (not shown).
[0131]
At this time, since the resin is cured after the liquid crystal material is aligned according to the alignment means, the resin can be cured in a thin film on the alignment film while maintaining a good alignment state before curing. As a result, the cured resin does not adversely affect the alignment of the liquid crystal material, the occurrence of alignment defects can be prevented, and the decrease in contrast can be prevented.
[0132]
The resin material used in the above structure desirably has a mixed state with a liquid crystal material at a high temperature and is separated from the liquid crystal material when the temperature is lowered. Further, it is highly desirable that the uncured resin does not contain a solvent in order to cure the resin while being sandwiched between the two substrates. Furthermore, since the separation of the liquid crystal material and the resin and the formation of the alignment state of the liquid crystal material largely depend on the temperature, it is desirable that the resin be cured by a factor different from the temperature. Considering such matters, it is preferable to use, for example, an ultraviolet curable resin as an uncured resin and ultraviolet rays as a curing means. Further, it is desirable that the resin has high compatibility with the liquid crystal material so that it is difficult to separate during injection, and the amount of monomer in the resin is preferably 60% or more, and more preferably 80% or more.
[0133]
As described above, the present inventors provide a device using a nematic liquid crystal material by providing a resin film in contact with a ferroelectric or antiferroelectric liquid crystal material on a substrate or an alignment film or electrode on the substrate. It was found that a switching state (domainless switching) in which the gradation does not occur and the gradation changes uniformly according to the electric field strength can be obtained.
[0134]
According to the above-described configuration of the present invention, the liquid crystal material in the entire region to which the electric field is applied can be switched so that the amount of transmitted light continuously changes uniformly according to the strength of the electric field without generating the domain. Also in the production, it can be produced in almost the same process as a conventional surface stable type apparatus, and has high productivity.
[0135]
In addition, the response of the liquid crystal molecules has been improved, and when the liquid crystal material is driven, the conventional bistable type has a two-stage inversion state between light and dark because of switching with domains, and only one stage is required. The steepness is greatly improved.
[0136]
Further, in the configuration of the present invention, the threshold value at the time of switching is lower than that of the conventional bistable type device. For this reason, it is possible to perform low-voltage driving as compared with the conventional bistable type device.
[0137]
In addition, the present inventors undesirably destabilize the state of the liquid crystal present in the liquid crystal layer (material) by mixing an uncured resin in the liquid crystal material, injecting it between the substrates, and then curing it. It was discovered that the effects of various charges can be eliminated.
[0138]
As this action, the above-mentioned undesired charges are taken into the resin when the resin material is cured, or the reaction initiator generally mixed in the uncured resin is diffused into the liquid crystal material to cure the resin. It is conceivable that the electric charge is sometimes cleaved to generate an electric charge, and the undesired electric charge is adsorbed or bonded to the electric charge.
[0139]
According to the present invention, charge transfer and charge accumulation at the alignment film liquid crystal interface, which have been problems in the past, are eliminated. Therefore, when a voltage is applied between the electrodes, the spontaneous polarization is rapidly reversed and fully reversed. Moreover, the change with time of the display state after the inversion was also eliminated. In addition, since there are no liquid crystal molecules adsorbed on the substrate, the entire liquid crystal layer between the electrodes undergoes a state change at the same time as voltage is applied, and more stable optical characteristics can be obtained. Therefore, a display having a high speed and a high contrast ratio can be realized.
[0140]
In the configuration of the present invention, the liquid crystal material does not have bistability, but since the active matrix driving is performed, the bistability of the liquid crystal material itself is not necessary. In addition, gray scale display is possible by the electric field strength. Therefore, according to the present invention, high-speed and high-contrast gradation display can be realized both in halftone by frame gradation and halftone by electric field by domainless switching, and each can be used independently. By combining the two, a liquid crystal electro-optical device with very high speed and multi-gradation display and high image quality can be obtained.
[0141]
In the apparatus of the present invention, in addition to the case where the transmitted light amount changes uniformly over the entire pixel portion, depending on the manufacturing conditions such as the liquid crystal used, the resin material, and the resin curing conditions, the transmitted light amount varies with the uniform change. In some cases, domain generation (reversal) in a certain region is mixed.
[0142]
In addition, N ^* The temperature is increased to the temperature shown in the phase or SmA phase, and is kept constant for 10 min or more, preferably 10 to 30 min at that temperature, and then gradually cooled to room temperature again. By this method, the alignment state of the liquid crystal material can be further improved.
[0143]
Further, depending on the concentration of the resin material added to the liquid crystal material or the like, the resin may be deposited in a column shape (columnar shape) between the two substrates and may be scattered in the apparatus. This is a useful method when it is necessary to keep the substrate interval constant, for example, when the display device has a large area.
[0144]
This column-shaped resin prevents the expansion and reduction of the distance between the substrates, and improves the strength of the substrate to prevent the occurrence of distortion, suppresses the collapse of the liquid crystal layer structure and display unevenness, etc. Can also be used. Further, the alignment is not disturbed. Therefore, a liquid crystal electro-optical device using a large area ferroelectric liquid crystal can be realized.
[0145]
When the display portion of the device after separation and deposition of the resin is viewed from the substrate surface, sufficient performance as a liquid crystal electro-optical device can be obtained if the proportion of the area occupied by the column-cured resin is 0.1 to 20%. .
[0146]
With the above configuration, the present invention realizes a liquid crystal electro-optical device using a high-speed, high-contrast ferroelectric liquid crystal by removing undesired charges in the liquid crystal layer, and digital gradation using high-quality frame gradation Is possible.
[0147]
Further, gradation display by electric field strength can be easily performed, and excellent gradation display can be performed with a very high number of gradations in combination with the frame gradation.
[0148]
In addition, the liquid crystal electro-optical device of the present invention can greatly reduce the voltage at which the ferroelectric liquid crystal material switches at high speed compared to the conventional bistable device, and can reduce power consumption.
[0149]
Further, it is possible to realize a liquid crystal electro-optical device that prevents the increase in the area of the substrate by using a resin and does not break the layer structure of the liquid crystal material even when the area is increased.
[0150]
In addition, the function of removing the effect of unwanted charges was obtained by mixing only a reaction initiator usually added in a commercially available resin into the liquid crystal material and then cleaving with ultraviolet rays or the like. Even if the amount of the reaction initiator added to the resin is changed, the resin may be divided into a resin material (monomer or oligomer) and a reaction initiator and mixed separately.
[0151]
[Domainless switching with multiple protrusions]
In addition, the other main configuration of the present invention is
A pair of opposing substrates;
A ferroelectric or antiferroelectric liquid crystal material sandwiched between the pair of substrates and having a spiral structure suppressed and uniaxially oriented;
Electrodes for applying a voltage to the ferroelectric or antiferroelectric liquid crystal material provided on the pair of substrates;
A plurality of convex portions provided on a surface in contact with the ferroelectric or antiferroelectric liquid crystal material;
A liquid crystal electro-optical device.
[0152]
In addition, the other main configuration of the present invention is
A pair of opposing substrates;
A ferroelectric or antiferroelectric liquid crystal material sandwiched between the pair of substrates and having a spiral structure suppressed and uniaxially oriented;
Electrodes for applying a voltage to the ferroelectric or antiferroelectric liquid crystal material provided on the pair of substrates;
A plurality of convex portions made of a resin material provided on a surface in contact with the ferroelectric liquid crystal or the anti-ferroelectric liquid crystal;
A liquid crystal electro-optical device.
[0153]
In addition, the other main configuration of the present invention is
A pair of opposing substrates;
A ferroelectric or antiferroelectric liquid crystal material sandwiched between the pair of substrates and having a spiral structure suppressed and uniaxially oriented;
Electrodes for applying a voltage to the ferroelectric or antiferroelectric liquid crystal material provided on the pair of substrates;
A plurality of convex portions having a diameter of about 500 nm or less, made of a resin material, provided on a surface in contact with the ferroelectric or antiferroelectric liquid crystal material;
A liquid crystal electro-optical device.
[0154]
In addition, the other main configuration of the present invention is
A pair of translucent substrates facing each other;
A plurality of stripe-shaped electrodes provided on the inner surface of one of the pair of translucent substrates;
A plurality of stripe-shaped electrodes provided on an inner surface of the other light-transmissive substrate of the pair of light-transmissive substrates and orthogonal to the plurality of stripe-shaped electrodes;
A polarizing plate provided on the outer surface of the pair of translucent substrates;
A ferroelectric or antiferroelectric liquid crystal material sandwiched between the pair of translucent substrates and having a spiral structure suppressed and uniaxially oriented;
A plurality of convex portions made of a resin material provided on a surface in contact with the ferroelectric or antiferroelectric liquid crystal material;
A liquid crystal electro-optical device.
[0155]
In addition, the other main configuration of the present invention is
A pair of translucent substrates facing each other;
A plurality of switching elements and a pixel electrode connected to the switching elements provided on an inner surface of one of the pair of translucent substrates;
A counter electrode provided on the inner surface of the other translucent substrate of the pair of translucent substrates;
A polarizing plate provided on the outer surface of the pair of translucent substrates;
A ferroelectric or antiferroelectric liquid crystal material sandwiched between the pair of translucent substrates and having a spiral structure suppressed and uniaxially oriented;
A plurality of convex portions made of a resin material provided on a surface in contact with the ferroelectric or antiferroelectric liquid crystal material;
A liquid crystal electro-optical device.
[0156]
According to another aspect of the invention, in the liquid crystal electro-optical device,
The resin material must be UV curable
A liquid crystal electro-optical device.
[0157]
In addition, the other main configuration of the present invention is
Between a pair of translucent substrates having electrodes on the inner surface, a mixture of a ferroelectric or antiferroelectric liquid crystal material and an uncured resin material containing 40% by weight or more of the monomer is filled. Process,
Precipitating the uncured resin material from the mixture;
Aligning the liquid crystal material;
Curing the uncured resin material;
A method for manufacturing a liquid crystal electro-optical device.
[0158]
In addition, the other main configuration of the present invention is
Between a pair of translucent substrates having electrodes on the inner surface, a mixture of a ferroelectric or antiferroelectric liquid crystal material and an uncured resin material containing 60 to 90% by weight of monomer is contained. Filling process,
Precipitating the uncured resin material from the mixture;
Aligning the liquid crystal material;
Curing the uncured resin material;
A method for manufacturing a liquid crystal electro-optical device.
[0159]
In addition, the other main configuration of the present invention is
A monomer that is a mixture of a ferroelectric or antiferroelectric liquid crystal material and an uncured resin material between a pair of translucent substrates having electrodes on the inner surface, the monomer being contained in the uncured resin material Filling the amount of which is 2.0% by weight or more of the mixture;
Precipitating the uncured resin material from the mixture;
Aligning the liquid crystal material;
Curing the uncured resin material;
A method for manufacturing a liquid crystal electro-optical device.
[0160]
According to another aspect of the present invention, in the method for manufacturing the liquid crystal electro-optical device,
The uncured resin material is UV curable,
The process of curing the uncured resin material is UV irradiation
This is a method for manufacturing a liquid crystal electro-optical device.
[0161]
The basic configuration of the present invention will be described with reference to FIG.
Here, an example of a simple matrix liquid crystal electro-optical device is shown.
Here, alignment means 3114 and 3115 for uniaxially aligning liquid crystal molecules are formed on at least one substrate surface over a light-transmitting substrate 3111 and 3110 having electrodes 3112 and 3113.
The distance between the substrates is uniformly controlled by the spacer 3118. The substrate interval is narrow enough to suppress the helical structure of the liquid crystal molecules. Both substrates are fixed with a sealant 3119. A liquid crystal material 3116 is sandwiched between the substrates. The liquid crystal material 3116 is uniaxially aligned according to the alignment means 3114 and 3115.
[0162]
On the other hand, a plurality of fine protrusions 3117 are mainly formed on the alignment means 3114 and 3115 in contact with the surface of the liquid crystal material. The convex portion 3117 is made of resin. Further, polarizing plates 3120 and 3121 are provided on the outer surface of the translucent substrate.
When the alignment means is formed only on one of the substrates, the convex portion 3117 is formed, for example, on the alignment means 3114 and the translucent substrate 3111 or the electrode 3113 on this substrate. Further, when an insulating film or a ferroelectric thin film is provided on one or both substrates in contact with the liquid crystal material, a convex portion 3117 is formed thereon.
[0163]
As the uniaxial alignment method, various methods such as a magnetic field alignment method, a shear stress method, a temperature gradient method, and an oblique deposition method can be used in addition to the rubbing method using an alignment film.
[0164]
In order to fabricate the liquid crystal electro-optical device, an uncured resin is mixed with a ferroelectric liquid crystal or an anti-ferroelectric liquid crystal, heated to an isotropic phase and mixed well, and this mixture is injected between substrates. The liquid crystal is again SmC ^* Cool until showing phase (usually room temperature). In this process, the liquid crystal is aligned according to the alignment regulating force of the uniaxial alignment means, and a good extinction position can be confirmed under a polarizing microscope. The resin is separated and deposited from the mixture in the form of being discharged between liquid crystal molecules or between layers. When the resin is almost completely separated from the liquid crystal, it is cured and insoluble in the liquid crystal. Since these resins are discharged along with the alignment of the liquid crystal and are separated and deposited, naturally the alignment of the liquid crystal is not disturbed.
[0165]
When the liquid crystal material was evaporated on the substrate after the resin was cured and observed with a scanning electron microscope (SEM), the substrate was composed of a resin having a height of about several tens of nm, a diameter of several tens to several hundreds of nm, and about 500 nm or less. A large number of fine convex portions can be confirmed. In some cases, the convex portions are uniformly distributed on the surface as a whole, and a plurality of convex portions are partially connected.
[0166]
In this manner, a plurality of fine protrusions can be provided on the surface in contact with the liquid crystal material, that is, on the surface of the substrate, the translucent substrate, the alignment film, the insulating film, or the like.
[0167]
Further, with respect to the liquid crystal electro-optical device having such a configuration, the applied voltage is controlled, and the switching in which the amount of transmitted light is continuously changed without the occurrence of a domain is possible, so that a halftone can be obtained. Further, a substantially uniform gradation can be obtained in a region to which the same voltage is applied, for example, in one pixel. Even if the switching state is observed with a polarizing microscope, the presence of the domain is not confirmed at least visually.
[0168]
Various resins can be used as the resin used here. Considering that the liquid crystal undergoes layer deformation due to heat and that the liquid crystal and the resin must be separated, it is desirable to use a resin that is cured by a factor other than heat.
For example, an ultraviolet curable resin that is cured by ultraviolet irradiation is extremely preferable.
[0169]
In addition, in order to produce fine protrusions composed of resin, the resin used should be low viscosity and easy to follow the alignment of the liquid crystal, and contains a lot of low molecular resin (hereinafter referred to as monomer) depending on the molecular weight. It is better to be
[0170]
Usually, the resin is composed of a monomer, an oligomer (polymer resin), and a reaction initiator. This resin is mixed in the liquid crystal material by about 0.1 to 20%, preferably about 1 to 10%.
[0171]
It is desirable that the composition of the resin material is such that the amount of the monomer is 2% by weight or more based on the mixture of the liquid crystal material and the resin material, and mixed in the liquid crystal material.
Further, it is desirable that the composition of the resin material is constituted so that the amount of the monomer is 40% by weight or more, preferably 60 to 90% by weight of the resin material, and mixed in the liquid crystal material.
[0172]
When the amount of monomer is small, the number of convex portions to be formed is reduced, and switching in which the amount of transmitted light continuously changes without generation of domains and switching between light and dark two states in which domains occur, or Only the latter switching is likely to occur, and conversely, if the amount of monomer is large, switching causes the amount of transmitted light to change continuously without the occurrence of domains, but optical characteristics such as contrast ratio tend to decrease.
The monomer is preferably an acrylic monomer.
[0173]
By making the composition of the resin in this way, the produced liquid crystal electro-optical device has a height of several tens of nm, a diameter of several tens to several hundreds of nm, and about 500 nm on the substrate or the surface of the electrode, alignment film, etc. on the substrate. The following convex parts are formed.
[0174]
Further, the resin may be formed in a column shape (columnar shape) between the substrates. This has a function of bonding the two substrates to prevent the substrate interval from being increased, and is useful when the substrate interval needs to be kept constant, and facilitates an increase in the area of the substrate.
[0175]
Further, after curing the resin, N ^* When the temperature is raised to the temperature at which the layer or SmA layer is shown, and kept at that temperature for 10 minutes or more, desirably 10 to 30 minutes, and then cooled to room temperature again, the alignment state of the liquid crystal material may be improved.
[0176]
In the liquid crystal electro-optical device of the present invention, it is extremely effective to provide each pixel with an active matrix drive type configuration having switching elements such as thin film transistors and thin film diodes.
[0177]
By adopting the above-described configuration, in the liquid crystal electro-optical device using the ferroelectric liquid crystal or the anti-ferroelectric liquid crystal, the transmitted light amount can be continuously changed to obtain a halftone. The reason for this is the alignment described above. In addition to the decrease in the anchoring force of the film, the following can also be considered.
[0178]
When the state of switching in a conventional liquid crystal electro-optical device using a ferroelectric liquid crystal or an anti-ferroelectric liquid crystal is observed under a polarizing microscope, a dark domain is formed in a bright state by applying a gradually higher voltage. In addition, it can be seen that a bright domain appears in many places in a dark state, and each area gradually increases (hereinafter referred to as growth). That is, the switching of ferroelectric liquid crystal or antiferroelectric liquid crystal is a chain reaction in which the liquid crystal molecules present around the liquid crystal molecules are inverted one after another when a part of the liquid crystal molecules are inverted. Switching.
[0179]
On the other hand, when a plurality of fine protrusions are provided on a substrate as in the present invention, these exist in a size and shape that do not disturb the alignment of liquid crystal molecules between layers or adjacent liquid crystal molecules. . If there is such a convex portion as in the present invention, a part of the liquid crystal molecules are inverted, and adjacent liquid crystal molecules are inverted in a chain reaction, but the inversion chain is broken by the convex portion, I think that it will not induce further inversion of liquid crystal molecules.
[0180]
That is, the protrusions on these substrates prevent adjacent liquid crystal molecules from being inverted in a chain reaction, so that the liquid crystal molecules or extremely fine domains do not induce the inversion of the surrounding liquid crystal molecules, Each is considered to be independently inverted.
[0181]
Therefore, in a specific region, for example, in one pixel region, a very fine region that exhibits a bright state and a dark state appears at a specific ratio with respect to a specific applied voltage, and the amount of transmitted light is reduced by the applied voltage without generating a domain. It seems to change continuously and obtain a halftone.
[0182]
When the switching of the liquid crystal electro-optical device of the present invention is observed under a polarizing microscope, the entire region to which the voltage is applied is changed from the bright state to the dark state, or from the dark state to the bright state by changing the applied voltage value. It was confirmed that the amount of transmitted light changed uniformly and continuously without occurrence.
[0183]
In the liquid crystal electro-optical device of the present invention, the amount of transmitted light continuously and uniformly changes with the applied voltage value in the voltage application region, for example, in one pixel. Therefore, compared with the conventional area gradation method or pixel division method, the area required for obtaining gradation can be made extremely small, and a liquid crystal electro-optical device with high resolution and multiple gradations can be obtained.
[0184]
The liquid crystal electro-optical device of the present invention is characterized by its switching characteristics.
FIG. 22 shows optical characteristics when a conventional surface-stabilized liquid crystal electro-optical device is driven by a square wave of ± 1.5V.
[0185]
In FIG. 22, the optical characteristic with respect to the applied voltage at the time of switching from dark (Dark) to bright (Bright) or from bright to dark shows a two-stage response characteristic. That is, at the start of switching, first, the optical characteristics change very steeply, and then change gradually and the switching ends.
[0186]
On the other hand, FIG. 23 shows optical characteristics when the liquid crystal electro-optical device of the present invention is driven by a square wave of ± 1.5V.
In FIG. 23, the optical characteristics change sharply from the start to the end of switching, and do not have two stages as shown in FIG.
[0187]
Considering this difference, the two-step response in the conventional liquid crystal electro-optical device of FIG. 22 is that the first steep change in optical characteristics is caused by switching of liquid crystal molecules or micro domains at several locations. The gradual change in the optical characteristics in the second stage shows the state where the surrounding liquid crystal molecules are switched in a chain and the domain becomes larger according to the switching of the liquid crystal molecules or minute domains. It seems that there is.
[0188]
On the other hand, in the steep response in the liquid crystal electro-optical device of the present invention shown in FIG. 23, since the liquid crystal molecules or minute domains are switched in all regions, the optical characteristics change steeply from the start to the end of switching. I think that the.
[0189]
Further, as can be seen from the above, the liquid crystal electro-optical device of the present invention can perform high-speed and sufficient switching even at a low voltage as compared with the conventional one, so that the drive voltage can be lowered.
[0190]
As described above, according to the present invention, in a liquid crystal electro-optical device using a ferroelectric liquid crystal or an anti-ferroelectric liquid crystal, continuous gradation change and halftone due to a change in applied voltage, such as nematic liquid crystal, can be easily performed. It came to be obtained. Therefore, it is possible to realize a liquid crystal electro-optical device in which transmitted light or reflected light is switched at high speed and has multiple gradations and high resolution. Moreover, the enlargement is easy. Furthermore, the drive voltage can be lowered.
[0191]
[Action]
As described above, in the liquid crystal electro-optical device using a ferroelectric or antiferroelectric liquid crystal material, the present invention provides a resin or film on the surface of a substrate, electrode, alignment film, or the like that is in contact with the liquid crystal material. By providing it with a material or the like, problems such as switching and halftone display, which have been conventionally problematic, are solved.
[0192]
In the present invention, whether switching is accompanied by the generation of domains or changes continuously and continuously depends on the amount of monomer contained in the uncured resin material mixed in the liquid crystal material.
The uncured resin material is composed of a low molecular weight (molecular weight of about 1000 or less) monomer, a high molecular weight (molecular weight of about 1000 or more) oligomer, and a reaction initiator. Among these, when the amount of monomer is small, Switching is accompanied by the generation of domains, but as the amount of monomer is increased, the area in which each domain extends becomes smaller, while the number of areas in which the domain occurs increases. That is, in this state, it has bistability (memory property).
[0193]
As the amount of monomer is further increased, uniform and continuous switching is achieved without the occurrence of domains. In this state, no bistability (memory property) is observed.
In particular, when the amount of monomer in the resin material is 40% or more by weight, preferably 60% or more, and more preferably 80% or more, uniform and continuous switching without domain generation can be obtained. .
[0194]
Further, when the amount of oligomer contained in the resin material is increased, the amount of resin cured in a column shape increases. Conversely, when the amount of oligomer is decreased and the amount of monomer increases, the number of resins cured in a column shape decreases.
[0195]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the present invention are shown below.
[0196]
【Example】
[Example 1]
In this example, a simple matrix type liquid crystal electro-optical device shown in FIG. 1 was manufactured and each characteristic was evaluated. The substrates 101 and 102 of the liquid crystal cell are blue glass of 300 × 400 mm and a thickness of 1.1 mm, and pixel electrodes 103 and 104 are formed on the substrate by ITO (Indium Tin Oxide) to form a photoresist. It was fabricated by patterning.
[0197]
The alignment film material is a polyimide resin such as LQ-5200 (manufactured by Hitachi Chemical), LP-64 (manufactured by Toray), RN-305 (manufactured by Nissan Chemical Co., Ltd.), and LP-64 is used here. The alignment film was diluted with a solvent such as n-methyl-2-pyrrolidone and applied to both substrates by spin coating. The coated substrate was heated at 250 to 300 ° C., here, 280 ° C. for 2.5 hours to dry the solvent, and the coating film was imidized and cured. The film thickness after curing was 300 mm.
[0198]
Next, the alignment film is rubbed. The rubbing may be performed by a normal method, and rubbed in one direction at a rotational speed of 450 to 900 rpm, here 450 rpm, with a roller having a diameter of 130 mm around which a cloth such as rayon or cotton is wound. The roll indentation height was 0.1 mm, and the stage speed was 20 mm / sec. Thus, the alignment film 105 was formed.
[0199]
Next, in order to make the space between the cells constant, 1.5 μm diameter brass balls (catalyst conversion) were sprayed on one substrate as a spacer 108. On the other substrate, in order to fix the two substrates, a two-component epoxy adhesive is printed and applied around the substrate as a sealing agent by screen printing, and then the two substrates are bonded and fixed. did.
[0200]
A mixture of liquid crystal material 107 and uncured polymer resin is injected into the cell. As the liquid crystal material, a phenyl pyrimidine-based ferroelectric liquid crystal was used. This liquid crystal has the phase sequence Iso-SmA-SmC * -Cry. The phase transition temperature is 85 ° C for Iso-SmA, SmA-SmC ^* Was 79 ° C. In addition, various kinds of ferroelectric liquid crystal materials such as biphenyl type and phenylnaphthalene type can be used. As the polymer resin, a commercially available ultraviolet curable resin was used. The liquid crystal material and the uncured polymer resin are mixed at a weight ratio of 95: 5. The mixture was stirred at a temperature at which it was in an Iso (isotropic) phase so as to mix uniformly. The phase transition temperature of the mixture was 5 to 20 ° C. lower than that of the liquid crystal material alone.
[0201]
The mixture was injected under vacuum by setting the liquid crystal cell and the mixture to 100 ° C. After the injection, the liquid crystal cell was gradually cooled at a rate of 2 to 20 ° C./hr, here 3 ° C./hr.
[0202]
The alignment state of this liquid crystal cell was observed with a polarizing microscope under crossed Nicols. The extinction position at a certain rotation angle, that is, the light incident on one polarizing plate did not pass through the other polarizing plate, as if the light was blocked. The state was obtained. This indicates that the liquid crystal material has a uniform alignment.
[0203]
At this time, when the stage was turned by about 20 ° from the extinction state, light leakage due to birefringence did not occur in the field of view of the microscope, and black portions were scattered. Since the uncured resin does not exhibit birefringence, this black state portion is a columnar shape formed by separating the uncured resin from the liquid crystal material.
[0204]
Next, ultraviolet rays were irradiated to cure the polymer resin in the mixture injected into the cell. Ultraviolet rays were irradiated from both sides of the cell in a direction perpendicular to the substrate surface with substantially the same intensity. By doing in this way, the thickness of the resin film formed in both board | substrates can be equal compared with the case where an ultraviolet-ray is irradiated only from one side. This is because the alignment regulating force of the alignment film may not be sufficiently suppressed. Irradiation intensity is 3-30mW / cm ² Here, 10mW / cm ² The irradiation time was 0.5 to 5 min, and here 1 min.
[0205]
After the ultraviolet irradiation, the alignment state of the liquid crystal cell was observed under a polarizing microscope in the same manner as described above, but the alignment state hardly changed. There was no effect on the alignment state of UV irradiation.
[0206]
Next, the optical characteristics of the liquid crystal cell were measured. In the measuring method, in a polarizing microscope using a halogen lamp as a light source, a triangular wave of ± 30 V and 5 Hz is applied between the electrodes under crossed Nicols, and the transmitted light intensity of the cell is detected by a photomultiplier. The contrast ratio measured at that time was 100, which was sufficient as a liquid crystal electro-optical device. Here, the contrast ratio is a ratio of transmitted light intensity when 30V is applied to transmitted light intensity when -30V is applied. On the other hand, a liquid crystal electro-optical device composed of a liquid crystal material alone without mixing resin has a contrast ratio of 80 in the measurement under the same conditions.
[0207]
Next, the current-voltage characteristics were measured in the liquid crystal electro-optical device of this example. FIG. 2 shows a waveform obtained by applying a triangular wave of ± 30 V, 5 Hz to a pair of electrodes of the liquid crystal cell of the present invention and measuring the applied voltage and the current between the electrodes with an oscilloscope. The value of the current is obtained by measuring the voltage across a 100 kΩ resistor connected in series with one electrode. As shown in FIG. 3 schematically showing the waveform of FIG. 2, the current 202 flowing when the spontaneous polarization of the ferroelectric liquid crystal material reverses with the change in the polarity of the electric field changes sharply, and the response speed Is extremely fast. There was no current component other than the current component 202 and the capacitance component 201 between the pixel electrodes.
[0208]
FIG. 4 shows the result of measuring the current-voltage characteristics with an oscilloscope in the same manner in a liquid crystal cell having a conventional structure (same conditions except that no resin is used). As shown in FIG. 5 schematically showing the waveform of FIG. 4, the current component 204 when the spontaneous polarization is reversed is larger than that of the liquid crystal cell of the present invention of FIG. It can be seen that the response speed is slow. This is considered to suggest that the alignment regulating force of the alignment film prevents the reversal of spontaneous polarization. In addition, a current component 203 that appears slightly later than the switching of spontaneous polarization appears. Such an excess current flows, resulting in a decrease in response speed and cotton last ratio. This is thought to be due to the presence of extra charges due to impurities or the like in the liquid crystal material.
[0209]
Even if the entire cell is viewed with the naked eye, the presence of the resin is completely unknown.
[0210]
In order to see the state of the resin film on the alignment film in more detail, the substrate prepared by the above method was cleaned with alcohol and then observed with an atomic force microscope (AFM). The results are shown in FIG. For comparison, an observation image of the alignment film after rubbing before injecting the mixture of the resin material and the liquid crystal material is shown in FIG. According to this, it can be seen that the resin film 106 having a thickness of 10 to 30 nm is formed so as to cover almost the entire surface of the alignment film 105, and the resin is also covered with scratches caused by the rubbing treatment. Therefore, it is considered that the alignment regulating force of the alignment film is remarkably suppressed. Further, since this resin film was transparent and extremely thin, there was almost no attenuation of transmitted light.
[0211]
The phase transition temperature after curing the resin was about several degrees lower than that of the liquid crystal material alone. Here, the cell was raised to 80 ° C. at which the liquid crystal material exhibited the SmA phase, held at the temperature for 10 to 60 minutes, here 20 minutes, and then gradually cooled at a rate of 3 ° C./hr. Then, the alignment defects were further improved, and the contrast ratio of 120 was obtained when the optical characteristics were measured.
[0212]
However, when the cell after the resin curing was once heated to 86 ° C. showing an isotropic phase, and the cell was gradually cooled in the same manner as described above, the alignment of the liquid crystal material was partially disturbed. This also shows that the alignment regulating force that imparts uniaxial alignment to the liquid crystal material is suppressed by the resin film on the alignment film.
[0213]
Moreover, the short circuit between electrodes was hardly seen, and it was found that the resin film on the alignment film functions as a short-circuit prevention film. By increasing the amount of the resin material to be mixed and increasing the thickness of the formed resin film, it is possible to more reliably prevent a short circuit.
[0214]
Polarizing plates 109 and 110 are provided on the outer surfaces of the substrates 101 and 102.
[0215]
In this example, a commercially available UV curable resin is used as it is as a resin material. However, the amount of the oligomer with respect to the entire resin material is increased to change the compatibility between the liquid crystal material and the resin, or the type of the alignment film material and rubbing. By changing the conditions, it is possible to control the amount of adhesion of the resin film on the alignment film.
[0216]
In addition, the amount of the resin can be intentionally varied between the two substrates by changing the type of the alignment film and the rubbing density on both the substrates, or by irradiating ultraviolet rays only from one side.
[0217]
[Example 2]
In this embodiment, an example is shown in which the present invention is applied to an active matrix liquid crystal electro-optical device in which a crystalline silicon TFT (thin film transistor) is provided in each pixel as a switching element.
[0218]
Mobility 100 formed by crystallizing an amorphous silicon film on a silicon oxide film on a Corning 7059 glass plate (300 × 300 mm, thickness 1.1 mm) as a substrate by heating annealing at 600 ° C. for 48 hours in a hydrogen reducing atmosphere. (Cm ² / Vs), an N channel type crystalline silicon TFT, a pixel electrode made of ITO, a signal electrode and a scanning electrode made of a chrome / aluminum multilayer film, provided in a matrix of 640 × 480 pixels.
[0219]
Next, ITO was formed on the glass substrate as a counter substrate as a counter electrode, and then an alignment film was formed only on this substrate to form a so-called one-side alignment film. LP-64 (manufactured by Toray) was used as the alignment film material. The production method, production conditions, film thickness, and rubbing conditions are the same as in Example 1.
[0220]
Next, 1.5 μm-diameter true spheres (catalyst conversion) were dispersed as spacers on the substrate on which the alignment film was formed. Further, in order to fix both substrates on the other substrate, a two-component epoxy adhesive was printed and applied as a sealant around the substrate by screen printing, and then the two substrates were bonded and fixed.
[0221]
A mixture of a liquid crystal material and an uncured resin is injected into the cell. Liquid crystal materials take the phase sequence Iso-N * -SmA-SmC * -Cry. The phase transition temperature is Iso-N ^* Is 81 ° C, N ^* -SmA is 69 ° C, SmA-SmC ^* Was 54 ° C. The used resin and the mixing ratio of the resin and the liquid crystal material are the same as those in Example 1. The mixture was stirred at a temperature at which it was in an Iso (isotropic) phase so as to mix uniformly. The mixture had a phase transition temperature of 5 to 20 ° C. lower than that of the liquid crystal material alone.
[0222]
The mixture was injected under vacuum by setting the liquid crystal cell and the mixture to 100 ° C. After the injection, the liquid crystal cell was gradually cooled at a rate of 2 to 20 ° C./hr, here 3 ° C./hr.
[0223]
The alignment state of this liquid crystal cell was observed with a polarizing microscope under crossed Nicols. The extinction position at a certain rotation angle, that is, the light incident on one polarizing plate did not pass through the other polarizing plate, as if the light was blocked. A uniform orientation was obtained.
[0224]
At this time, when the stage was turned by about 20 ° from the extinction state, light leakage due to birefringence did not occur in the field of view of the microscope, and black portions were scattered. Since the uncured resin does not exhibit birefringence, this black state portion is a columnar shape formed by separating the uncured resin from the liquid crystal material.
[0225]
Next, in order to cure the polymer resin mixed in the liquid crystal material injected into the cell, ultraviolet rays were irradiated from the counter substrate side. Irradiation intensity is 3-30mW / cm ² Here, 10mW / cm ² The irradiation time was 0.5 to 5 min, and here 1 min.
[0226]
After the ultraviolet irradiation, the alignment state of the liquid crystal cell was observed under a polarizing microscope in the same manner as described above, but the alignment state hardly changed. There was no effect on the alignment state of UV irradiation.
[0227]
After the substrates were cleaned with alcohol, the surfaces of both substrates were observed with an atomic force microscope (AFM), and a resin film having a thickness of 10 to 30 nm was formed on both the substrate surfaces.
[0228]
Next, the optical characteristics of the liquid crystal cell were measured. FIG. 8 shows the interelectrode voltage and the optical response when measured. Drive voltage V _LC This waveform has a voltage of 14 V, a pulse width of 1 μs, and a frame width of 16 ms. The optical response is the light transmittance T shown in the figure. _LC The contrast ratio at this time was 100 at the end of the frame. On the other hand, a liquid crystal cell composed of a single liquid crystal material without mixing resin had a contrast ratio of 80 in the measurement under the same conditions.
[0229]
The phase transition temperature after curing the resin was about several degrees lower than that of the liquid crystal material alone. Here, the liquid crystal material of the cell according to the present invention is N ^* The temperature was raised to 70 ° C. showing the phase, held at the temperature for 10 to 60 minutes, here 20 minutes, and then gradually cooled to room temperature at a rate of 3 ° C./hr. Then, the alignment defects were further improved, and the contrast ratio of 120 was obtained when the optical characteristics were measured.
[0230]
Similarly, the cell of the present invention before the alignment improvement is raised to 55 ° C. where the liquid crystal material exhibits the SmA phase, held at the temperature for 20 minutes, and then gradually cooled to room temperature at a rate of 3 ° C./hr. But N mentioned above ^* Alignment defects were improved to the same extent as in the case where the temperature was maintained at a temperature showing a phase, and the contrast ratio was improved.
[0231]
However, when the cell after the resin curing was once heated to 83 ° C. which is an isotropic phase and the cell was gradually cooled in the same manner as described above, the alignment of the liquid crystal material was partially disturbed. This shows that after the resin is cured, a resin film is formed on the alignment film, and the liquid crystal material is not imparted with uniaxial orientation.
[0232]
A polarizing plate was provided on the outer surface of the substrate to complete the apparatus.
[0233]
Example 3
First, in this example, an experimental one-pixel cell shown in FIG. 10 was fabricated, and each characteristic was evaluated. The substrates 1111 and 1112 of the liquid crystal cell were blue plate glass having a thickness of 1.1 mm, and pixel electrodes 1113 and 1114 were formed on the substrate. The size of the pixel electrode was 5 mm □. An alignment film 1115 was formed on the surface on which the electrodes of both substrates were formed.
[0234]
A polyimide resin, here LP-64 (manufactured by Toray), was used as the alignment film material. The alignment film was diluted with a solvent such as n-methyl-2-pyrrolidone and applied by spin coating. The coated substrate was heated at 250 to 300 ° C., here 280 ° C. for 2.5 hours to dry the solvent, and the coating film was imidized and cured. The film thickness after curing was 300 mm.
[0235]
Next, in order to align the liquid crystal material uniaxially and align the liquid crystal material layer vertically or inclined with respect to the substrate, a uniaxial alignment regulating force was applied to the alignment film by a rubbing method. The rubbing was rubbed in one direction at a rotational speed of 450 to 900 rpm, here 450 rpm with a roller having a diameter of 130 mm around which a cloth such as rayon or cotton was wound in the same manner as in a normal method. The roll indentation height was 0.1 mm, and the stage speed was 20 mm / sec.
[0236]
Here, in order to make the space between the cells constant, 1.5 mm diameter true spheres (catalyst conversion) were sprayed on one substrate as a spacer 1118. On the other substrate, in order to fix the two substrates, a two-component epoxy adhesive is printed and applied as a sealant around the substrate by screen printing, and then the two substrates are bonded. Fixed.
[0237]
A mixture of liquid crystal material 1117 and uncured polymer resin was injected into the cell. A phenylpyrimidine-based ferroelectric liquid crystal was used as the liquid crystal material. The phase sequence was Iso-SmA-SmC * -Cry. As the polymer resin, a commercially available ultraviolet curable resin was used. For the purpose of preventing separation from the liquid crystal material when the mixture is injected, a polymer resin having a monomer amount of 90% by weight is used so as to increase compatibility with the liquid crystal material. . As the concentration of the uncured polymer resin in the liquid crystal material, if a large amount of resin is contained, a resin column is formed between the upper and lower substrates and the aperture ratio is lowered. The ratio was mixed. The mixture was stirred at a temperature at which it became the Iso phase so as to mix uniformly. In the mixture, the transition point from the Iso phase to the SmA phase was 5 ° C. lower than that of the liquid crystal material alone.
[0238]
The mixture was injected under vacuum by setting the liquid crystal cell and the mixture to 100 ° C. at which the mixture exhibited an Iso phase. After injection, the liquid crystal cell is SmC ^* Cool to phase, but rapidly cell ^* Since a large amount of alignment defects is generated when the phase is changed, the temperature is gradually cooled at a rate of 2 to 20 ° C./hr, here 3 ° C./hr.
[0239]
The cell was gradually cooled to room temperature by the above method, and the orientation state of the cell was observed with a polarizing microscope under crossed Nicols. When the stage was rotated, the extinction position at a certain rotation angle, that is, the light incident on one polarizing plate did not pass through the other polarizing plate, as if the light was blocked. This indicates that the liquid crystal material has a uniform alignment in which the alignment vectors of liquid crystal molecules are aligned in the same direction within the layer and from layer to layer.
[0240]
Further, when the stage was turned by about 20 ° from the extinction state, light leakage due to birefringence did not occur in the field of view of the microscope, and black portions were scattered. This portion indicates that the resin is separated and deposited in a column shape.
[0241]
Next, ultraviolet rays were irradiated to cure the polymer resin mixed in the liquid crystal material. The light source uses an Hg-Xe lamp rated at 150 W, and the irradiation intensity is 3 to 30 mW / cm. ² Here, 10mW / cm ² A cell was placed at a position where The irradiation time was 0.5 to 5 min, here 1 min.
[0242]
After the ultraviolet irradiation, the alignment state of the liquid crystal cell was observed under a polarizing microscope in the same manner as described above, but the alignment state hardly changed. There was no effect on the alignment state of UV irradiation.
[0243]
The contrast ratio in the orientation state was measured. In the measurement method, in a polarizing microscope using a halogen lamp as a light source, ± 30 V, 5 Hz triangular waves are applied between the electrodes of the cell under crossed Nicols, and the transmitted light intensity of the cell is detected by a photomultiplier. The contrast ratio was 120.
[0244]
Next, the switching process of the cell was observed with the same optical system as described above. A low-frequency triangular wave was applied to the cell. The light / dark switching is switching in which the total amount of transmitted light changes uniformly depending on the electric field strength, unlike the switching with domain generation found in the conventional ferroelectric liquid crystal electro-optical device.
[0245]
Therefore, contrast-voltage characteristics were measured. The measurement method shows the change in transmitted light intensity when the cell is first adjusted to the extinction position when DC 20V is applied, and then the voltage is increased to 20V with one end voltage set to 0V. The result is shown in FIG. The characteristic value of the cell of the present invention is shown by a square plot, but the threshold value was about 0.8V.
[0246]
In addition, the responsiveness of the liquid crystal material when the electric field direction was reversed was measured. FIG. 12 shows how the drive waveform and contrast change. At this time, the driving waveform was a rectangular wave of ± 3 V and 5 Hz. The response waveform 1401 of the apparatus of this example is a one-step response indicating a steep rise after the polarity inversion of the rectangular wave.
[0247]
Furthermore, the voltage dependence of the response of the liquid crystal material was investigated. The driving waveform was a rectangular wave of 5 Hz. The result is shown by the □ plot in FIG. The cell of the present invention exhibits a fast response speed of about 1 msec even in a low voltage region. Further, the voltage and response speed have a linear relationship in logarithmic coordinates. That is, the electric field strength and the response speed are always in a constant relationship. This suggests that the cell of this example is operating in goldstone mode.
[0248]
Next, current-voltage characteristics were measured. FIG. 14 shows the value of current flowing between the electrodes when a triangular wave of ± 30 V and 5 Hz is applied to the liquid crystal cell. As shown in the figure, there was no current component other than the current 1602 that flows when the capacitance component 1601 between the electrodes and the spontaneous polarization of the ferroelectric liquid crystal material are reversed due to the change in the polarity of the electric field.
[0249]
Next, the pulse memory property of the cell was examined. The drive waveform had a pulse width of 200 μm and a frame width of 20 ms. There was almost no pulse memory.
[0250]
FIG. 15 shows the interelectrode voltage and the optical response when this cell is used and an external driving circuit is connected and active driving is performed. The drive waveform has a voltage of 14 V, a pulse width of 1 μs, and a frame width of 16 ms. As shown in FIG. 15, the optical response was good, and the contrast ratio at this time was 120 at the end of the frame.
[0251]
Further, when the entire liquid crystal cell was observed with the naked eye, the presence of the resin was not known at all.
[0252]
After removing the substrate and washing and removing the liquid crystal with alcohol, the resin remaining on the substrate was observed with a scanning electron microscope, and the columnar resin on which both substrates were fixed could be observed. The hardened resin depends on the type of resin and liquid crystal material and the curing conditions, but in most cases, the shape seen from the side has a trapezoidal shape or a rectangle, and the cross section of the upper surface (the surface seen from the direction perpendicular to the substrate). ) Has a rounded square, rectangle, circle, or ellipse, and has a plateau as a whole. These resins have a top cross-sectional size (diameter in the case of a circular shape) of about several μm to several tens of μm, and the height is equal to the substrate interval. There are also dice-like ones whose height is about 1/10 of the thickness, and whose top cross-sectional size and height are almost equal.
[0253]
The shape of the resin also changes depending on the phase transition series of the liquid crystal material, the slow cooling rate, and the like. Some of them are indefinite and others have a long axis of resin in the uniaxial orientation direction. In addition, the interval between the resin cured in the column shape was about 10 to 100 μm.
[0254]
Furthermore, in order to see the state of the resin film on the surface in more detail, the substrate produced by the above method was washed with alcohol and then observed with an atomic force microscope (AFM). According to this, a polymer resin film was formed on the alignment film surface. The thickness of the film was about 10 to 30 nm depending on the production conditions, and had minute irregularities. There were some parts that seemed to have almost no resin film and parts that had a thickness of about 50 nm.
[0255]
For comparison, a cell having the same cell configuration and liquid crystal material was also subjected to the same measurement as described above except that no resin was contained. First, in the observation of the switching process using a triangular wave, switching was accompanied by the generation of a domain. Further, the voltage dependence of the transmitted light intensity had a threshold value of about 2 V as shown by the circle plot in FIG. Further, the response at the time of the electric field polarity reversal showed a two-step response in which the initial rise was abrupt as shown by 1402 in FIG. Further, when the voltage dependence of the response speed was examined, the response speed suddenly decreased when the voltage was 3 V or less as shown by the circle plot in FIG. 13, and the relationship between the electric field strength and the response speed was not linear.
[0256]
Further, when the current-voltage characteristics are measured, as shown in FIG. 16, in addition to the capacitance component 1801 between the electrodes and the current component 1802 generated when the spontaneous polarization is reversed as the electric field polarity changes, an extra current component is shown. A peak 1803 was observed. In addition, it can be seen that the peak value of the current component 1802 is lower and the width is wider than that of the device of the present invention, and the response speed is reduced. On the other hand, the pulse memory property was relatively good.
[0257]
Example 4
Here, an example of an active matrix driving type device in which a crystalline silicon TFT is provided in each pixel as a switching element is shown in correspondence with FIG.
[0258]
An amorphous silicon film is crystallized on a silicon oxide film (not shown) on a Corning 7059 glass plate (300 × 300 mm, thickness 1.1 mm) as a substrate 1102 by heat annealing at 600 ° C. for 48 hours in a hydrogen reducing atmosphere. Mobility (100 cm) ² / Vs) N-channel crystalline silicon TFT 1105, ITO (Indium Tin Oxide) pixel electrode 1104, chromium / aluminum multilayer film for signal electrode and scanning electrode, and a 640 × 480 pixel matrix. Provided.
[0259]
Next, a counter electrode was formed by forming a film of ITO on a soda-lime glass substrate as a counter substrate 1101 by a 1200 mm sputtering method. Other electrode materials include SnO ₂ (Tin oxide) can be used. As the substrate material, inorganic materials such as glass and quartz, and organic materials such as acrylic resin and polyethylene resin can be used.
[0260]
An alignment film 1106 is formed only on the substrate on which the counter electrode is formed, so as to achieve a so-called one-side alignment. As the alignment film material, a polyimide-based or polyamide-based resin, or a resin such as polyvinyl alcohol can be used. Examples of the polyimide resin include LQ-5200 (manufactured by Hitachi Chemical), LP-64 (manufactured by Toray), RN-305 (manufactured by Nissan Chemical Co., Ltd.), and LP-64 was used here. The alignment film was diluted with a solvent such as n-methyl-2-pyrrolidone and applied by spin coating. The coated substrate was heated at 250 to 300 ° C., here, 280 ° C. for 2.5 hours to dry the solvent, and the coating film was imidized and cured. The film thickness after curing was 300 mm.
[0261]
In order to align the liquid crystal material uniaxially and align the liquid crystal material layer perpendicularly or inclined to the substrate, a uniaxial alignment regulating force was applied to the alignment film by a rubbing method. The rubbing was rubbed in one direction at a rotational speed of 450 to 900 rpm, here 450 rpm with a roller having a diameter of 130 mm around which a cloth such as rayon or cotton was wound in the same manner as in a normal method. The roll indentation height was 0.1 mm, and the stage speed was 20 mm / sec.
[0262]
The substrate interval is 1 to 10 μm, and the spacer material is silica or alumina. Here, in order to make the space between the cells constant, 1.5 mm diameter brass (catalyst conversion) (not shown) was sprayed on the substrate on which the alignment film was applied as a spacer. On the other substrate, in order to fix the two substrates, a two-component epoxy adhesive is printed and applied as a sealant around the substrate by screen printing, and then the two substrates are bonded. Fixed.
[0263]
A mixture of liquid crystal material 1108 and uncured polymer resin was injected into the cell. A phenylpyrimidine-based ferroelectric liquid crystal was used as the liquid crystal material. The phase sequence was Iso-SmA-SmC * -Cry. As the polymer resin, a commercially available ultraviolet curable resin was used. For the purpose of preventing separation from the liquid crystal material when the mixture is injected, a polymer resin having a monomer amount of 90% by weight is used so as to increase compatibility with the liquid crystal material. . As the concentration of the uncured polymer resin in the liquid crystal material, if a large amount of resin is contained, a resin column is formed between the upper and lower substrates and the aperture ratio is lowered. The ratio was mixed. The mixture was stirred at a temperature at which it became the Iso phase so as to mix uniformly. In the mixture, the transition point from the Iso phase to the SmA phase was 5 ° C. lower than that of the liquid crystal material alone.
[0264]
The mixture was injected under vacuum by setting the liquid crystal cell and the mixture to 100 ° C. at which the mixture exhibited an Iso phase. After injection, the liquid crystal cell is SmC ^* Cool to phase, but rapidly cell ^* Since a large amount of alignment defects is generated when the phase is changed, the temperature is gradually cooled at a rate of 2 to 20 ° C./hr, here 3 ° C./hr.
[0265]
The cell was gradually cooled to room temperature by the above method, and the orientation state of the cell was observed with a polarizing microscope under crossed Nicols. When the stage was rotated, the extinction position at a certain rotation angle, that is, the light incident on one polarizing plate did not pass through the other polarizing plate, as if the light was blocked. This indicates that the liquid crystal material has a uniform alignment in which the alignment vectors of liquid crystal molecules are aligned in the same direction within the layer and from layer to layer.
[0266]
Further, when the stage was turned by about 20 ° from the extinction state, light leakage due to birefringence did not occur in the field of view of the microscope, and black portions were scattered. This portion indicates that the resin is separated and deposited in a column shape.
[0267]
Next, ultraviolet rays were irradiated to cure the polymer resin mixed in the liquid crystal material. The light source uses an Hg-Xe lamp rated at 150 W, and the irradiation intensity is 3 to 30 mW / cm. ² Here, 10mW / cm ² A cell was placed at a position where The irradiation time was 0.5 to 5 min, here 1 min.
[0268]
After the ultraviolet irradiation, the alignment state of the liquid crystal cell was observed under a polarizing microscope in the same manner as described above, but the alignment state hardly changed. There was no effect on the alignment state of UV irradiation. At this time, the column-shaped resin adheres the upper and lower substrates to prevent the distance between the substrates from increasing, and even if the area is increased, the layer structure of the liquid crystal material can be prevented from collapsing.
[0269]
The device thus fabricated had a contrast ratio of about 120. When a low-frequency triangular wave was applied between the electrodes and the switching state was observed with a polarizing microscope, the amount of transmitted light was uniformly changed in the electrode application region without domain generation.
[0270]
Polarizers 1109 and 1110 were attached to both substrates, and a drive circuit was connected to complete a liquid crystal electro-optical device. By rewriting one screen in 1/60 second and controlling the magnitude of the applied voltage, 256 gray scale display could be realized.
[0271]
After the substrate produced by the above method was washed with alcohol and observed with an atomic force microscope (AFM), a coating of a polymer resin was formed to a thickness of about 10 to 30 nm on both the alignment film surface and the pixel electrode surface.
[0272]
Note that in this embodiment, an N-channel thin film transistor is used as a switching element connected to a pixel. However, a P-channel thin film transistor or a complementary type using a P-channel thin film transistor and an N-channel thin film transistor is used. It may be configured. A configuration using a non-linear element such as an MIM diode may also be used.
[0273]
Example 5
In this embodiment, an example is shown in which an active matrix driving type device in which a crystalline silicon TFT is provided as a switching element in each pixel and frame gradation display is performed. The configuration corresponds to that in FIG.
[0274]
An amorphous silicon film is crystallized by heating annealing at 600 ° C. for 48 hours in a hydrogen reduction atmosphere on a silicon oxide film (not shown) on a Corning 7059 glass plate (300 × 300 mm, thickness 1.1 mm) as the substrate 2102. Mobility (100 cm) ² / Vs) N-channel crystalline silicon TFT 2105, ITO (indium tin oxide) pixel electrode 2104, chromium / aluminum multilayer film for signal electrode and scanning electrode, and a 640 × 480 pixel matrix. Provided.
[0275]
Next, a counter electrode was formed by forming a film of ITO on a soda-lime glass substrate as a counter substrate 2101 by a 1200 mm sputtering method. Other electrode materials include SnO ₂ (Tin oxide) can be used. As the substrate material, inorganic materials such as glass and quartz, and organic materials such as acrylic resin and polyethylene resin can be used.
[0276]
An alignment film 2106 is formed only on the substrate on which the counter electrode is formed, so as to achieve a so-called one-side alignment. As the alignment film material, a polyimide-based or polyamide-based resin, or a resin such as polyvinyl alcohol can be used. Examples of the polyimide resin include LQ-5200 (manufactured by Hitachi Chemical), LP-64 (manufactured by Toray), RN-305 (manufactured by Nissan Chemical Co., Ltd.), and LP-64 was used here. The alignment film was diluted with a solvent such as n-methyl-2-pyrrolidone and applied by spin coating. The coated substrate was heated at 250 to 300 ° C., here, 280 ° C. for 2.5 hours to dry the solvent, and the coating film was imidized and cured. The film thickness after curing was 300 mm.
[0277]
In order to align the liquid crystal material uniaxially and align the liquid crystal material layer perpendicularly or inclined to the substrate, a uniaxial alignment regulating force was applied to the alignment film by a rubbing method. The rubbing was rubbed in one direction at a rotational speed of 450 to 900 rpm, here 450 rpm with a roller having a diameter of 130 mm around which a cloth such as rayon or cotton was wound in the same manner as in a normal method. The roll indentation height was 0.1 mm, and the stage speed was 20 mm / sec.
[0278]
The substrate interval is 1 to 10 μm, and the spacer material is silica or alumina. Here, in order to make the space between the cells constant, 1.5 mm diameter brass (catalyst conversion) (not shown) was sprayed on the substrate on which the alignment film was applied as a spacer. On the other substrate, in order to fix the two substrates, a two-component epoxy adhesive is printed and applied as a sealant around the substrate by screen printing, and then the two substrates are bonded. Fixed.
[0279]
A mixture of liquid crystal material 2108 and uncured polymer resin was injected into the cell. A phenylpyrimidine-based ferroelectric liquid crystal was used as the liquid crystal material. The phase sequence was Iso-SmA-SmC * -Cry. As the polymer resin, a commercially available ultraviolet curable resin was used. For the purpose of preventing separation from the liquid crystal material when the mixture is injected, a polymer resin having a monomer amount of 90% by weight is used so as to increase compatibility with the liquid crystal material. . As the concentration of the uncured polymer resin in the liquid crystal material, if a large amount of resin is contained, a resin column is formed between the upper and lower substrates and the aperture ratio is lowered. The ratio was mixed. The mixture was stirred at a temperature at which it became the Iso phase so as to mix uniformly. In the mixture, the transition point from the Iso phase to the SmA phase was 5 ° C. lower than that of the liquid crystal material alone.
[0280]
The mixture was injected under vacuum by setting the liquid crystal cell and the mixture to 100 ° C. at which the mixture exhibited an Iso phase. After injection, the liquid crystal cell is SmC ^* Cool to phase, but rapidly cell ^* Since a large amount of alignment defects is generated when the phase is changed, the temperature is gradually cooled at a rate of 2 to 20 ° C./hr, here 3 ° C./hr.
[0281]
The cell was gradually cooled to room temperature by the above method, and the orientation state of the cell was observed with a polarizing microscope under crossed Nicols. When the stage was rotated, the extinction position at a certain rotation angle, that is, the light incident on one polarizing plate did not pass through the other polarizing plate, as if the light was blocked. This indicates that the liquid crystal material has a uniform alignment in which the alignment vectors of liquid crystal molecules are aligned in the same direction within the layer and from layer to layer.
[0282]
Further, when the stage was turned by about 20 ° from the extinction state, light leakage due to birefringence did not occur in the field of view of the microscope, and black portions were scattered. This portion indicates that the resin is separated and deposited in a column shape.
[0283]
Next, ultraviolet rays were irradiated to cure the polymer resin mixed in the liquid crystal material. The light source uses an Hg-Xe lamp rated at 150 W, and the irradiation intensity is 3 to 30 mW / cm. ² Here, 10mW / cm ² A cell was placed at a position where The irradiation time was 0.5 to 5 min, here 1 min.
[0284]
After the ultraviolet irradiation, the alignment state of the liquid crystal cell was observed under a polarizing microscope in the same manner as described above, but the alignment state hardly changed. There was no effect on the alignment state of UV irradiation. At this time, the column-shaped resin adheres the upper and lower substrates to prevent the distance between the substrates from increasing, and even if the area is increased, the layer structure of the liquid crystal material can be prevented from collapsing.
[0285]
The device thus fabricated had a contrast ratio of about 120. When a low-frequency triangular wave was applied between the electrodes and the switching state was observed with a polarizing microscope, the amount of transmitted light was uniformly changed in the electrode application region without domain generation.
[0286]
Further, when the electrode portion of the liquid crystal cell is viewed with the naked eye, the presence of the resin is not known at all. From these results, if the proportion of the area of the display portion occupied by the resin material is about 0.1 to 20%, it can be inferior to that of the conventional device.
[0287]
In this way, a cell having a uniform interelectrode distance could be produced. Even if the completed cell was made vertical, display irregularities could not be recognized at all. There was no deformation of the substrate and the layer structure of the ferroelectric liquid crystal used was not broken.
[0288]
When the substrate was washed with alcohol and then observed with an atomic force microscope (AFM), a polymer resin film was formed to a thickness of about 10 to 30 nm on both the alignment film surface and the pixel electrode surface.
[0289]
In this liquid crystal electro-optical device, polarizing plates 2109 and 2110 were attached to both substrates, and 32 gradation display was performed by digital gradation driving. FIG. 18 shows the gate voltage V focused on one pixel in the display method used here. _G , Drain voltage V _D , Pixel voltage V _LC , Pixel transmittance T _LC Shows changes. First, as shown in FIG. 18, one frame is composed of five subframes. The duration of each subframe is 0.5 msec for the first frame, 8 msec for the second subframe, 1 msec for the third subframe, 4 msec for the fourth subframe, and 2 msec for the fifth subframe (in FIG. 18, each subframe is 1 frame was set to 15.5 msec. That is, the duration of the first frame is set to the shortest duration T ₀ Then, the second subframe is 16T ₀ , 2T ₀ , 8T ₀ 4T ₀ Thus, 32 gradations can be displayed by combining the durations of these five subframes.
[0290]
In one subframe, first, the gate voltage V is applied to the scanning line. _G As a result, a rectangular pulse signal is applied to turn on the TFT gate electrode of one line (horizontal 640 pixels). On the other hand, on the signal line connected to the drain electrode of each TFT, a pulse train indicating either a positive or negative state has a drain voltage V _D As applied. This pulse train includes information of the total number of scans in this subframe interval, that is, 480 in this case, and each piece of information is synchronized with the scan of each line. All 480 lines are scanned to determine the ON or OFF state of all pixels, and one subframe is completed. As described above, the interval between the subframes is different, and each pixel has a pixel potential V _LC Despite being gradually approaching zero due to spontaneous discharge, the transmittance T _LC Is kept constant and remains ON or OFF. In this embodiment, the transmittance T during this period _LC Was extremely stable and did not change over time.
[0291]
In this way, when all subframes are completed, gradation display within one frame can be realized digitally. The pulse width of the scanning signal applied to the gate electrode of each TFT was 2 μsec, the pulse height was −15 V, and the data signal applied to the drain electrode was ± 10 V. With this apparatus, display unevenness, flicker, etc. did not appear at all, and a contrast ratio of 120 was obtained with 32 gradations.
[0292]
Here, even if the data signal applied to the drain electrode was set to ± 5 V, it operated without any problem.
[0293]
Further, when gradation display by the number of frames is not performed, rewriting of one screen is performed in 1/60 second, and electric field intensity is changed, that is, 32 gradation display is performed by controlling the magnitude of applied voltage. A clear gradation display was obtained.
[0294]
Further, it was possible to display 16 gradations according to the number of frames and 16 gradations according to the applied voltage, and to display 256 gradations.
[0295]
Note that in this embodiment, an N-channel thin film transistor is used as a switching element connected to a pixel. However, a P-channel thin film transistor or a complementary type using a P-channel thin film transistor and an N-channel thin film transistor is used. It may be configured. A configuration using a non-linear element such as an MIM diode may also be used.
[0296]
In this embodiment, one thin film transistor (TFT) as shown in FIG. 19 is used for one pixel, and a signal is applied to the scanning electrode to which the gate electrode of each TFT is connected to turn on one line of TFTs. A general driving method is used in which display is performed by applying a transmission or non-transmission signal or a gradation signal by a signal electrode to which a source or drain electrode is connected.
[0297]
In addition to this method, the present invention is also effective for a driving method in which, for example, as shown in FIG.
[0298]
Example 6
An indium tin oxide (which is abbreviated as ITO), which is an electrode material, is formed on a 10 cm square glass substrate to a thickness of 500 to 2000 mm by sputtering or vapor deposition, and 1000 mm in this embodiment. The electrode was patterned in a stripe shape. On this substrate, polyimide was applied by spin coating and baked at 280 ° C. As polyimide, RN-305 manufactured by Nissan Chemical Co., Ltd. and LP-64 manufactured by Toray were used. The polyimide film thickness was 100 to 800 mm, and 150 mm in this example. The substrate was rubbed and uniaxially aligned. Two of these substrates are produced. On one of the substrates, catalyst chemical-made spheres, which are silica particles, are dispersed as spacers, and an epoxy resin sealing material is formed on one of the substrates by screen printing. did. The two substrates were bonded to each other so that the distance between the electrodes was about 1.5 μm and the striped electrodes were orthogonal to each other to form a simple matrix type cell having 640 × 480 pixels.
[0299]
The liquid crystal material used in this example is a ferroelectric liquid crystal, CS1014, manufactured by Chisso Corporation. The Ps of this liquid crystal is 5.4 nC / cm ² And the phase sequence is I (isotropic phase) -N (nematic phase) -A (smectic A phase) -C ^* (Smectic C ^* Phase).
[0300]
The resin material used in this example was prepared by mixing a commercially available acrylic monomer having a molecular weight of about 150 to 200 and a urethane oligomer having a molecular weight of about 1500 to 3000 at a weight ratio of 90:10 to obtain a commercially available reaction initiator. About 3% by weight was mixed (hereinafter referred to as uncured resin material).
[0301]
The above liquid crystal material and uncured resin material 5% are mixed at a weight ratio of 95: 5, and heated and stirred until the liquid crystal shows an isotropic phase at 90 ° C. so that the mixed resin mixes better in the liquid crystal material. The resin was uniformly mixed in the liquid crystal material (hereinafter referred to as a liquid crystal mixture).
[0302]
The cell and the liquid crystal mixture were heated to 90 ° C., poured into the aforementioned cell, and gradually cooled to room temperature at 2 to 20 ° C./hr, in this example at 2 ° C./hr. When the orientation state at room temperature after slow cooling was observed under a polarizing microscope, the resin material scattered in the cell and having a columnar shape could be confirmed, but the resin shape on the substrate could not be confirmed. However, the alignment of the liquid crystal material was uniaxially aligned along the rubbing direction of the alignment film, as in the liquid crystal material to which no resin was added, and a good extinction position was obtained.
[0303]
Ultraviolet rays are applied to this cell with an intensity of 3 to 30 mW / cm. ² , Irradiation time 0.5 to 5 min, intensity 20 mW / cm in this example ² The resin was cured by irradiation for 1 min. Even after UV irradiation, the liquid crystal was uniaxially aligned along the rubbing direction of the alignment film, and a good extinction position was obtained.
[0304]
When the change in the amount of transmitted light accompanying the change in the applied voltage of the cell was observed, the gradation continuously changed from dark to bright and from bright to dark, and a light / dark halftone display was possible. The occurrence of the domain could not be confirmed visually.
[0305]
Both substrates of this cell were peeled and left in an oven at 200 ° C. for 5 hours to volatilize the liquid crystal. Thereafter, the substrate was observed under a polarizing microscope to confirm that the substrate was not polarized, and the resin shape on the substrate was observed with an SEM.
[0306]
24A and 24B show SEM photographs showing the fine patterns formed on the substrate in this way. FIG. 24B is an enlarged view of FIG. As shown in FIG. 24, a large number of fine convex portions made of a resin having a height of several tens of nm, a diameter of several tens to several hundreds of nm, and about 500 nm or less were observed. The convex portions were uniformly distributed on the surface as a whole, and some convex portions were partially connected.
[0307]
In this embodiment, the number of pixels may be 1920 × 480, and a color filter of three colors of red, blue, and green may be provided to display a full color display of 640 × 480. With 256 gradations, approximately 16.7 million colors can be displayed.
[0308]
Example 7
The configuration of the apparatus, the resin material, the manufacturing method, and the mixing ratio of the liquid crystal material and the uncured resin material in this example were the same as those in Example 6. However, the liquid crystal material in this example is biphenyl and Ps is 20.7 nC / cm. ² The phase sequence of I-A-C ^* Ferroelectric liquid crystal showing When the alignment state of the liquid crystal material of the formed cell was observed under a polarizing microscope, it was uniaxially aligned along the rubbing direction of the alignment film as in the case where the resin was not mixed, and a good extinction position was obtained.
[0309]
When the change in the amount of transmitted light accompanying the change in the applied voltage of the cell was observed, the gradation continuously changed from dark to bright and from bright to dark, and light and dark halftone display became possible. The occurrence of the domain could not be confirmed visually.
[0310]
Both substrates of this cell were peeled off and left in an oven at 280 ° C. for 5 hours to volatilize the liquid crystal. Thereafter, the substrate was observed under a polarizing microscope to confirm that the substrate was not polarized, and the resin shape on the substrate was observed with an SEM. Then, on average, a large number of fine convex portions made of a resin having a height of about 30 nm and a diameter of about 90 nm were observed.
[0311]
Example 8
The configuration of the apparatus, the liquid crystal material, the manufacturing method, and the mixing ratio of the liquid crystal material and the uncured resin material in this example were the same as those in Example 6. However, in this example, a commercially available acrylic monomer having a molecular weight of about 100 to 150 and a urethane oligomer having a molecular weight of about 1000 to 2000 are mixed at a weight ratio of 65:35, and a commercially available reaction initiator is about 3% by weight. What was mixed about% was used as an uncured resin material.
[0312]
When the alignment state of the liquid crystal material of the formed cell was observed under a polarizing microscope, it was uniaxially aligned along the rubbing direction of the alignment film as in the case where the resin was not mixed, and a good extinction position was obtained. .
[0313]
When the change in the amount of transmitted light accompanying the change in the applied voltage of the cell was observed, the gradation continuously changed from dark to bright and from bright to dark, and light and dark halftone display became possible. The occurrence of the domain could not be confirmed visually.
[0314]
Both substrates of this cell were peeled and left in an oven at 200 ° C. for 5 hours to volatilize the liquid crystal. Thereafter, the substrate was observed under a polarizing microscope to confirm that the substrate was not polarized, and the resin shape on the substrate was observed with an SEM. Then, on average, a large number of convex portions made of a resin having a height of about 30 nm and a diameter of about 90 nm were observed.
[0315]
Example 9
In this embodiment, an example of an active matrix driving type liquid crystal electro-optical device in which a crystalline silicon TFT (thin film transistor) is provided as a switching element in each pixel is shown.
[0316]
Mobility 100 formed by crystallizing an amorphous silicon film on a silicon oxide film on a Corning 7059 glass plate (300 × 300 mm, thickness 1.1 mm) as a substrate by heating annealing at 600 ° C. for 48 hours in a hydrogen reducing atmosphere. (Cm ² / Vs) N channel type crystalline silicon TFT, ITO (Indium Tin Oxide), pixel electrode, chromium / aluminum multilayer film or wiring with anodized aluminum on the surface, 640 × 480 pixels The matrix was constructed and provided.
[0317]
Next, a counter electrode was formed by forming a film of ITO on a blue glass substrate as a counter substrate by a 1200 mm sputtering method. Other electrode materials include SnO ₂ (Tin oxide) can be used. As the substrate material, inorganic materials such as glass and quartz, and organic materials such as acrylic resin and polyethylene resin can be used.
[0318]
An alignment film was formed only on the substrate on which the counter electrode was formed to achieve so-called one-side alignment. As the alignment film material, a polyimide-based or polyamide-based resin, or a resin such as polyvinyl alcohol can be used. Examples of the polyimide resin include LQ-5200 (manufactured by Hitachi Chemical), LP-64 (manufactured by Toray), RN-305 (manufactured by Nissan Chemical Co., Ltd.), and LP-64 was used here. The alignment film was diluted with a solvent such as n-methyl-2-pyrrolidone and applied by spin coating. The coated substrate was heated at 250 to 300 ° C., here, 280 ° C. for 2.5 hours to dry the solvent, and the coating film was imidized and cured. The film thickness after curing was 300 mm.
[0319]
In order to align the liquid crystal material uniaxially and align the liquid crystal material layer perpendicularly or inclined to the substrate, a uniaxial alignment regulating force was applied to the alignment film by a rubbing method. The rubbing was rubbed in one direction at a rotational speed of 450 to 900 rpm, here 450 rpm with a roller having a diameter of 130 mm around which a cloth such as rayon or cotton was wound in the same manner as in a normal method. The roll indentation height was 0.1 mm, and the stage speed was 20 mm / sec.
[0320]
The substrate interval is 1 to 10 μm, and the spacer material is silica or alumina. Here, in order to make the space between the cells constant, 1.5 μm diameter brass balls (manufactured by Catalysts and Chemicals) were sprayed on the substrate on which the alignment film was applied as a spacer. On the other substrate, in order to fix the two substrates, a two-component epoxy adhesive is printed and applied as a sealant around the substrate by screen printing, and then the two substrates are bonded. Fixed.
[0321]
A mixture of a liquid crystal material and an uncured resin material was injected into the cell. The liquid crystal material used in this example is a ferroelectric liquid crystal, CS1014, manufactured by Chisso Corporation. The Ps of this liquid crystal is 5.4 nC / cm ² And the phase sequence is I (isotropic phase) -N (nematic phase) -A (smectic A phase) -C ^* (Smectic C ^* Phase).
[0322]
The resin material used in this example was prepared by mixing a commercially available acrylic monomer having a molecular weight of about 150 to 200 and a urethane oligomer having a molecular weight of about 1500 to 3000 at a weight ratio of 90:10 to obtain a commercially available reaction initiator. About 3% by weight was mixed.
[0323]
The above liquid crystal material and uncured resin material are mixed at a weight ratio of 95: 5, and heated and stirred at 90 ° C. until the liquid crystal shows an isotropic phase so that the mixed resin mixes better in the liquid crystal material. The resin was uniformly mixed in the liquid crystal material to obtain a liquid crystal mixture.
[0324]
The cell and the liquid crystal mixture were heated to 90 ° C., poured into the aforementioned cell, and gradually cooled to room temperature at 2 to 20 ° C./hr, in this example at 2 ° C./hr. When the orientation state at room temperature after slow cooling was observed under a polarizing microscope, the resin material scattered in the cell and having a columnar shape could be confirmed, but the resin shape on the substrate could not be confirmed. However, the alignment of the liquid crystal material was uniaxially aligned along the rubbing direction of the alignment film, as in the liquid crystal material to which no resin was added, and a good extinction position was obtained.
[0325]
Further, when the stage was turned by about 20 ° from the extinction state, light leakage due to birefringence did not occur in the field of view of the microscope, and black portions were scattered. This portion indicates that the resin is separated and deposited in a column shape.
[0326]
Ultraviolet rays are applied to this cell with an intensity of 3 to 30 mW / cm. ² , Irradiation time 0.5 to 5 min, intensity 20 mW / cm in this example ² The resin was cured by irradiation for 1 min. Even after the ultraviolet irradiation, the liquid crystal was uniaxially aligned along the rubbing direction of the alignment film, and a good extinction position was obtained. At this time, the column-shaped resin adheres the upper and lower substrates to prevent the distance between the substrates from increasing, and even if the area is increased, the layer structure of the liquid crystal material can be prevented from collapsing.
[0327]
As a result of observing the switching state of the cell thus produced with a polarizing microscope, the amount of transmitted light continuously changed without generating a domain in each pixel. Further, the gradation is uniform within each pixel region.
[0328]
A polarizing plate was attached to both substrates, and a driving circuit was connected to complete a liquid crystal electro-optical device. By rewriting one screen in 1/60 second and controlling the magnitude of the applied voltage, 256 gray scale display could be realized.
[0329]
When the substrate produced by the above method was observed by SEM, many fine protrusions having a height of several tens of nm and a diameter of several tens to several hundreds of nm were confirmed on both the alignment film surface and the pixel electrode surface.
[0330]
Note that in this embodiment, an N-channel thin film transistor is used as a switching element connected to a pixel. However, a P-channel thin film transistor or a complementary type using a P-channel thin film transistor and an N-channel thin film transistor is used. It may be configured. Moreover, it is good also as a structure using thin film diodes, such as a MIM diode, and a non-linear element.
[0331]
In this embodiment, the number of pixels may be 1920 × 480, and a color filter of three colors of red, blue, and green may be provided to display a full color display of 640 × 480. With 256 gradations, approximately 16.7 million colors can be displayed.
[0332]
Comparative Example 1
This comparative example shows an example in which the uncured resin material was not mixed in the cell shown in Example 6.
[0333]
When the alignment state of the liquid crystal material of the formed cell was observed under a polarizing microscope, it was uniaxially aligned along the rubbing direction of the alignment film, and a good extinction position was obtained.
[0334]
When the change in the transmitted light amount accompanying the change in the applied voltage of the cell was observed, switching was performed only in the bright and dark two states in which the domain was generated, and the transmitted light amount did not change continuously.
[0335]
This cell has the same strength of 20 mW / cm as in Example 6. ² Then, after irradiating UV light for 1 min, the applied voltage was changed and the change in the amount of transmitted light was observed.
[0336]
"Comparative Example 2"
This comparative example shows an example in which the resin was not cured in the cell shown in Example 6.
A cell was prepared in the same manner as in Example 6, and a mixture of a liquid crystal material and an uncured resin was injected into the cell. When the alignment state of the liquid crystal material of the fabricated cell was observed under a polarizing microscope, it was uniaxially aligned along the rubbing direction of the alignment film, as in the case where no resin was mixed, and a good extinction position was obtained. .
[0337]
When this cell was not irradiated with ultraviolet light and the applied voltage was changed without curing the resin, the change in the transmitted light amount was observed. As a result, only the two bright and dark states in which the domain was generated were switched, and the transmitted light amount was continuous. Never changed.
[0338]
The substrate of this cell was observed by SEM in the same manner as in Example 6. However, no convex portion made of resin as in Example 6 was observed.
[0339]
Comparative Example 3
In this comparative example, an example is shown in which the mixing ratio of the monomer and oligomer of the resin material is varied in the cell shown in Example 6.
The resin material used in this comparative example was prepared by mixing a commercially available acrylic monomer having a molecular weight of about 150 to 200 and a urethane oligomer having a molecular weight of about 1500 to 3000 at a weight ratio of 10:90 to obtain a commercially available reaction initiator. About 3% by weight was mixed to obtain an uncured resin material.
When the alignment state of the liquid crystal material of the fabricated cell was observed under a polarizing microscope, it was uniaxially aligned along the rubbing direction of the alignment film, as in the case where no resin was mixed, and a good extinction position was obtained. .
[0340]
Ultraviolet rays are applied to this cell with an intensity of 3 to 30 mW / cm. ² , Irradiation time 0.5 to 5 min, intensity 20 mW / cm in this comparative example ² The resin was cured by irradiation for 1 min. Even after UV irradiation, the liquid crystal was uniaxially aligned along the rubbing direction of the alignment film, and a good extinction position was obtained.
[0341]
When the change in the transmitted light amount accompanying the change in the applied voltage of the cell was observed, switching was performed only in the bright and dark two states in which the domain was generated, and the transmitted light amount did not change continuously.
[0342]
The substrate of this cell was observed by SEM in the same manner as in Example 6. However, the convex shape as in Example 6 was hardly observed, and the surface state was very flat.
[0343]
【The invention's effect】
As described above, according to the present invention, it has been possible to prevent the inhibition of switching of liquid crystal molecules due to the alignment regulating force of the uniaxial alignment means, which has been a problem in the past. As a result, switching speed could be increased. Furthermore, alignment defects could be improved and insulation between electrodes could be improved to prevent short circuits. Therefore, the liquid crystal electro-optical device has a high contrast ratio and a high reliability at a high speed. A simple matrix type device can have a high definition with a high duty ratio, and an active matrix type device can also achieve high speed and stable display.
[0344]
In addition, since it can be manufactured by almost the same manufacturing process as conventional, it has high productivity. Moreover, even when an orientation failure occurs, it can be repaired.
[0345]
In addition, the amount of transmitted light could be controlled by the electric field strength without the occurrence of domains. Therefore, gradation display control by voltage can be easily realized while maintaining the high-speed response of the ferroelectric liquid crystal material. Further, since the threshold value is lowered, low voltage driving is possible. In addition, the response speed particularly in the low voltage region is extremely high. The liquid crystal electro-optical device of the present invention can realize high-speed and multi-gradation display, particularly by performing active matrix driving in which each pixel is provided with a switching element.
[0346]
In addition, undesired charge transfer and charge accumulation at the alignment film liquid crystal interface are eliminated, and sharp inversion of the liquid crystal molecules of the ferroelectric liquid crystal and stability of the molecular state after the inversion are obtained, resulting in faster and more stable optics. Characteristics are obtained. Therefore, a liquid crystal electro-optical device using a ferroelectric liquid crystal can realize a display having a high speed and a high contrast ratio.
[0347]
In particular, in an active matrix type liquid crystal electro-optical device using a crystalline silicon thin film transistor, the high speed response of the ferroelectric liquid crystal material and the crystalline silicon thin film transistor can be utilized to make a device having high speed and high contrast, It was possible to improve the number of gradations and contrast ratio of gradation display using frame gradations.
[0348]
Also, gradation display by electric field intensity can be easily performed, and excellent quality gradation display can be performed with a very high number of gradations in combination with the frame gradation.
[0349]
Compared with conventional bistable devices, the switching voltage of ferroelectric liquid crystal material can be greatly reduced, and power consumption can be reduced.
[0350]
In addition, the column-shaped resin prevents the expansion and reduction of the substrate interval without causing disorder of alignment, and improves the strength of the substrate to prevent the occurrence of distortion of the entire liquid crystal cell. It was possible to suppress the occurrence of collapse. Therefore, a liquid crystal electro-optical device using a large-area ferroelectric liquid crystal can be realized, and this device can be used upright.
[0351]
As described above, according to the present invention, in a liquid crystal electro-optical device using a ferroelectric liquid crystal or an anti-ferroelectric liquid crystal, it is possible to easily realize multi-gradation display and further full color with high resolution. I can do it now. Further, compared with a liquid crystal electro-optical device using nematic liquid crystal, it was possible to obtain a liquid crystal electro-optical device capable of multi-gradation display and full-color display that is extremely high speed and easy to increase in size.
[0352]
As described above, the liquid crystal electro-optical device of the present invention can be a high-speed, multi-gradation, high-resolution, low-voltage drive and large-area device, and can be easily manufactured. An extremely excellent liquid crystal electro-optic device suitable for a display device for displaying the image can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic view of a liquid crystal electro-optical device according to the present invention.
FIG. 2 is a photograph showing an oscilloscope waveform of current-voltage characteristics of a liquid crystal electro-optical device according to the invention in an example.
FIG. 3 is a schematic diagram of current-voltage characteristics of a liquid crystal electro-optical device according to the present invention in Examples.
FIG. 4 is a photograph showing an oscilloscope waveform of current-voltage characteristics of a conventional liquid crystal electro-optical device.
FIG. 5 is a schematic diagram of current-voltage characteristics of a conventional liquid crystal electro-optical device.
FIG. 6 is a photograph showing a thin film on a substrate surface of a liquid crystal electro-optical device according to an embodiment of the present invention, which is observed with an atomic force microscope.
FIG. 7 is a photograph showing a thin film on the surface of a substrate before injection of a liquid crystal material or the like of a liquid crystal electro-optical device according to an embodiment of the present invention, observed with an atomic force microscope.
FIG. 8 shows a voltage between pixel electrodes and an optical response of an active drive type liquid crystal electro-optical device according to an embodiment of the present invention.
FIG. 9 is a schematic view of a liquid crystal electro-optical device of the present invention.
FIG. 10 is a schematic view of a liquid crystal electro-optical device according to an embodiment of the present invention.
FIG. 11 shows transmitted light intensity-voltage characteristics in a liquid crystal electro-optical device according to an embodiment of the present invention.
FIG. 12 shows responsiveness of the liquid crystal electro-optical device according to the embodiment of the present invention when the electric field direction is reversed.
FIG. 13 shows response speed-voltage characteristics of a liquid crystal electro-optical device according to an embodiment of the invention.
FIG. 14 shows current-voltage characteristics of a liquid crystal electro-optical device according to an embodiment of the present invention.
FIG. 15 shows a pixel electrode voltage and an optical response when active driving is performed in a liquid crystal electro-optical device according to an embodiment of the present invention.
FIG. 16 shows current-voltage characteristics of a conventional liquid crystal electro-optical device.
FIG. 17 is a schematic view of a liquid crystal electro-optical device of the present invention.
FIG. 18 shows an applied signal, a pixel potential, and a pixel transmittance when performing digital gradation display in an example.
FIG. 19 shows a circuit used in an example of the present invention.
FIG. 20 shows an example of a circuit of the present invention.
FIG. 21 shows a basic configuration of a liquid crystal electro-optical device of the invention.
FIG. 22 shows optical characteristics when a conventional surface-stabilized liquid crystal electro-optical device is driven by a square wave of ± 1.5V.
FIG. 23 shows optical characteristics when the liquid crystal electro-optical device of the present invention is driven by a square wave of ± 1.5V.
FIG. 24 is a SEM photograph showing a fine pattern formed on a substrate.
[Explanation of symbols]
101, 102 substrate
103, 104 electrodes
105 Alignment film
106 Resin film
107 Liquid crystal materials
108 spacer
109, 110 Polarizing plate
201 Capacitance component of current flowing between pixel electrodes
202 Inversion current due to spontaneous polarization of liquid crystal material
203 Extra current component
204 Inversion current due to spontaneous polarization of liquid crystal material
1101 and 1102 substrates
1103 Counter electrode
1104 Pixel electrode
1105 switching element
1106 Alignment film
1107 Resin film
1108 Liquid crystal materials
1109, 1110 Polarizing plate
1111 and 1112 substrates
1113, 1114 electrode
1115 Alignment film
1116 Resin film
1117 Liquid crystal material
1118 Spacer
1401 Optical response waveform of the device of the present invention in the embodiment
1402 Optical Response Waveform of Conventional Device in Example
1601 Capacitance component of current flowing between pixel electrodes
1602 Inversion current due to spontaneous polarization of liquid crystal material
1801 Capacitance component of current flowing between pixel electrodes
1802 Inversion current due to spontaneous polarization of liquid crystal material
1803 Extra current component
2101 and 2102 substrates
2103 Counter electrode
2104 Pixel electrode
2105 Switching element
2106 Alignment film
2107 Resin film
2108 Liquid crystal materials
2109, 2110 Polarizing plate
3110, 3111 Translucent substrate
3112, 3113 electrodes
3114, 3115 orientation means
3116 Liquid crystal material
3117 Convex
3118 spacer
3119 sealant
3120 3121 Polarizing plate

Claims (7)

The alignment layer possess, between a pair of substrates which suppresses the substrate interval a helical structure of the ferroelectric liquid crystal was injected a ferroelectric liquid crystal, a mixture obtained by mixing the uncured UV-curable resin,
A method for producing a liquid crystal electro-optical device in which the ferroelectric liquid crystal is aligned according to the alignment direction of the alignment film, and then the uncured ultraviolet curable resin is cured by irradiating ultraviolet rays.
The method for producing a liquid crystal electro-optical device, wherein the uncured ultraviolet curable resin is contained in an amount of 20% by weight or less of the mixture. The alignment layer possess, between a pair of substrates which suppresses the substrate interval a helical structure of the ferroelectric liquid crystal, the injection a ferroelectric liquid crystal isotropic phase state, the mixture obtained by mixing uncured ultraviolet curing resin And
Cool until the ferroelectric liquid crystal exhibits an SmC ^* phase ,
A method for producing a liquid crystal electro-optical device in which the ferroelectric liquid crystal is aligned according to the alignment direction of the alignment film, and then the uncured ultraviolet curable resin is cured by irradiating ultraviolet rays.
The method for producing a liquid crystal electro-optical device, wherein the uncured ultraviolet curable resin is contained in an amount of 20% by weight or less of the mixture. 3. The method of manufacturing a liquid crystal electro-optical device according to claim 2 , wherein the uncured ultraviolet curable resin is precipitated from the mixture by the cooling. In any one of claims 1 to 3, the method for manufacturing a liquid crystal electro-optical device, wherein the uncured UV-curable resin containing a monomer 60% by weight or more. 5. The method for manufacturing a liquid crystal electro-optical device according to claim 4 , wherein the monomer includes an acrylic monomer. In any of claims 1 5, wherein the uncured UV-curable resin is a method for manufacturing a liquid crystal electro-optical device characterized in that it is cured into a film on the alignment film. In any of claims 1 5, wherein the uncured UV-curable resin is a method for manufacturing a liquid crystal electro-optical device characterized in that it is hardened with a plurality of protrusions on the alignment film.

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