KR20190004685A - Liquid crystal device and Liquid crystal display device - Google Patents

Abstract

The present invention relates to a liquid crystal device, and more particularly, to a liquid crystal device including an optically active substance (chiral agent) in a liquid crystal layer, and a liquid crystal display device using the liquid crystal device. The present invention includes: a first substrate and a second substrate which are subjected to alignment treatment on one surface thereof and arranged in opposition to to each other; and a liquid crystal layer provided between one surface of the first substrate and one surface of the second substrate. In the first substrate and the second substrate, the direction of the alignment treatment is set such that liquid crystal molecules of the liquid crystal layer are aligned in a first alignment state in which the liquid crystal molecules are tilted in the first direction. Further, a pretilt angle, which is given to the liquid crystal molecules of the liquid crystal layer at the interface with the liquid crystal layer, is 35° or more. The liquid crystal layer contains a chiral agent capable of causing a second alignment state in which the liquid crystal molecules are tilted in a second direction opposite to the first direction. The chiral agent is added such that the ratio (d/p) of the chiral pitch (p) to the layer thickness (d) of the liquid crystal layer is in the range of 0.25 to 0.75. The liquid crystal device of the present invention performs excellent or various display.

Description

[0001] The present invention relates to a liquid crystal device and a liquid crystal display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal element, particularly a liquid crystal element including an optically active substance (chiral agent) in a liquid crystal layer, and a liquid crystal display device using the liquid crystal element.

(The first turning direction) of the liquid crystal molecules determined by the combination of the alignment treatment direction of the pair of alignment films and the pre-tilt angle and the torsional direction of the liquid crystal molecules caused by the chiral agent For example, by applying a physical action, for example, a voltage equal to or higher than the saturation voltage of the electro-optical characteristic to the liquid crystal layer, the liquid crystal molecules are tilted in each direction in the first turning direction A liquid crystal display element in which a reverse twist arrangement state with respect to a first swirling direction and a spray twist arrangement state with respect to a second swirling direction are realized in a reversible manner is called a reverse twisted nematic (RTN) I call it. The first swirling direction is a swirling direction in which liquid crystal molecules twist when a chiral agent is not added to the liquid crystal layer.

For example, Patent Document 1 describes a reverse twisted nematic liquid crystal display device. In the reverse twisted nematic liquid crystal display element described in Patent Document 1, the alignment state in which the liquid crystal molecules twist in the first turning direction is unstable. It is possible to obtain an arrangement state in which the liquid crystal molecules twist in the first swinging direction by application of a high voltage, but the liquid crystal molecules transit to the arrangement state in which the liquid crystal molecules twist in the second swinging direction with the passage of time.

The tilt in the liquid crystal layer is increased by arranging the liquid crystal molecules in the first swirling direction by a combination of the alignment directions of the substrates while adding a chiral agent for turning the liquid crystal molecules in the second swirling direction, Patent Document 2 discloses an invention of a reverse twisted nematic liquid crystal device capable of suppressing a reduction in luminance. However, in the invention described in Patent Document 2, after the application of the voltage to be shifted from the arrangement state of twisting in the second swinging direction to the arrangement state of twisting in the first swinging direction is stopped, (I.e., an arrangement state in which the liquid crystal element is twisted in the second swirling direction). Therefore, there is a problem that a high driving voltage is required in driving the liquid crystal element in the arrangement state in which it is twisted in the second swinging direction.

In the case of a reverse twisted nematic liquid crystal display element, in general, liquid crystal molecules are arranged in an arrangement state (reverse twist arrangement state) in which the liquid crystal molecules twist in the first rotation direction and an arrangement state (spray twist arrangement state) in which the liquid crystal molecules twist in the second rotation direction There is no great difference in the apparent display state, and even when the bistability (the nature in which the reverse twist arrangement state and the spray twist arrangement state are almost the same in energy, and the voltage is unattached and stably stuck, respectively) is given, a high contrast ratio Difference) is difficult to obtain.

An alignment treatment is performed so that the angle formed by the rubbing direction between the upper and lower substrates is greater than 90 degrees and less than 120 degrees and a chiral agent having a property of twisting so as to be in the same direction as the angle formed by the rubbing direction is added to the liquid crystal layer And the reverse twisted nematic liquid crystal display element is characterized in that the liquid crystal display element is a reverse twisted nematic liquid crystal display element. The reverse twisted nematic liquid crystal display element described in Patent Document 3 is superior in sharpness to any temperature in comparison with a conventional twisted nematic liquid crystal display element. In addition, due to a good sharpness, especially in a simple matrix driving liquid crystal display device, high-duty driving is possible or the contrast is high when driving with the same duty. In addition, a simple matrix-driven liquid crystal display element in which the response to a low temperature is faster than that of a normal twisted nematic liquid crystal display element and the transmittance is not lowered at an off voltage even in a high temperature environment, , And liquid crystal display devices using thin film transistors (TFT).

In the liquid crystal display element described in Patent Document 3, the reverse twist arrangement state is very stable, and the electro-optical characteristic in this state is superior to that of a normal twisted nematic liquid crystal display element. However, it is not an invention that positively utilizes the bistability of the reverse twist arrangement state and the spray twist arrangement state.

Patent Document 4 discloses an invention of a liquid crystal element that performs display using a transition between a reverse twist array state and a spray twist array state. In the liquid crystal device described in Patent Document 4, the respective arrangement states can be switched to each other. However, the display by the arrangement state is optional, and gray display (halftone display) can not be performed even if black display or white display is possible, for example.

An invention of a liquid crystal display panel of an FFS mode (fringe field switching mode) using a TFT is described in Patent Document 5. According to the invention described in Patent Document 5, the actual aperture ratio of the liquid crystal display panel can be improved, brightness and contrast of display can be improved, and display quality can be improved. The structure shown in Patent Document 5 can be applied to a liquid crystal device having a parallel alignment liquid crystal layer not containing a chiral agent. However, for example, two stable alignment states described in Patent Document 4 are switched and displayed It is not suitable for a reverse twisted nematic liquid crystal display device. In Patent Document 5, there is no description about the half-tone display.

In the case of driving in the FFS mode, it is general that the liquid crystal layer is in parallel orientation. In many cases, a comb-shaped electrode connected to a TFT as a pixel electrode is often used, and a common electrode is generally provided with a beta electrode under the Gulch electrode. In this case, electrodes are often not formed on the counter substrate.

Patent Document 6 discloses an invention of a reverse twisted nematic liquid crystal display device having a comparatively low pretilt angle of 20 DEG or more and 45 DEG or less, which is made by the inventors of the present invention. In this liquid crystal display element, when the chiral pitch is p and the thickness of the liquid crystal layer is d, for example, a chiral agent is added so that d / p is more than 0.04 and less than 0.25. The liquid crystal display element described in Patent Document 6 is a reverse twisted nematic liquid crystal display element capable of bistable display in a reverse twist arrangement state and a spray twist arrangement state, and has high memory characteristics, a relatively high contrast ratio, and is capable of electrical switching.

The liquid crystal display element described in Patent Document 6 is a liquid crystal display element in which a high contrast ratio is realized and a display quality is high. However, the contrast at the time of frontal observation can not be high. This is relatively preferable when used as a reflective display, but is not preferable when used as a transmissive display.

Further, although the memory property at room temperature is high, for example, display at the temperature different from room temperature can not be observed due to the reverse twist arrangement state, and it is difficult to keep the display at a high temperature of 60 DEG C or more . Therefore, depending on the application, for example, in the case of being used as a liquid crystal display device for on-vehicle use, an aircraft use, or an outdoor use, the memory property of display may become insufficient.

Japanese Patent No. 2510150 Japanese Patent Application Laid-Open No. 2007-293278 Japanese Patent Application Laid-Open No. 2010-186045 Japanese Patent Laid-Open Publication No. 2011-107376 Japanese Patent No. 4238877 Japanese Patent Application Laid-Open No. 2011-203547

An object of the present invention is to provide a liquid crystal device capable of performing good or various display, and a driving method thereof.

According to an aspect of the present invention, there is provided a semiconductor device comprising: a first substrate; a second substrate disposed opposite to the first substrate; and a second substrate disposed between the first substrate and the second substrate, The present invention provides a liquid crystal device having a liquid crystal layer in which two different liquid crystal molecule alignment states are realized in a convertible manner.

According to the present invention, it is possible to provide a liquid crystal device capable of performing good or various displays, and a driving method thereof.

1 is a schematic cross-sectional view showing a liquid crystal display element according to a first embodiment.
2 is a schematic plan view showing a photomask used for etching an ITO film.
3A to 3E are schematic cross-sectional views showing the direction of an electric field at the time of voltage application.
4A to 4C are external views of the liquid crystal display element according to the first embodiment.
5A to 5C are graphs showing optical characteristics of the liquid crystal display element according to the first embodiment.
6A to 6C are photographs of a liquid crystal display element in which a longitudinal electric field is added to a part of the liquid crystal layer.
Fig. 7 is a schematic cross-sectional view showing another example (modified example) of the formation mode of the first and second collective electrodes 12c and 12d.
8A is a schematic diagram showing a liquid crystal display device according to the second embodiment, and Fig. 8B is a schematic plan view showing an electrode structure of the pixel portion 34. Fig.
9A and 9B are a schematic sectional view and a plan view showing a liquid crystal display element according to a third embodiment, respectively.
10A to 10G are schematic sectional views showing a method of manufacturing a liquid crystal display element according to the third embodiment.
11A to 11D are schematic cross-sectional views showing a method of manufacturing the liquid crystal display element according to the third embodiment.
12A is a photograph showing the pixel area after completion of the liquid crystal display element according to the third embodiment (initial state), and Fig. 12B is a graph showing the voltage difference between the common electrode 12a and the lower beta electrode 12b And the pixel area after adding the electric field system to the liquid crystal layer 15.
13A and 13B are a schematic sectional view and a plan view showing a liquid crystal display element according to a fourth embodiment, respectively.
14A to 14G are schematic sectional views showing a method of manufacturing a liquid crystal display element according to the fourth embodiment.
Figs. 15A to 15E are schematic sectional views showing a method for manufacturing a liquid crystal display element according to the fourth embodiment.
Fig. 16 is a table showing the results of examining the retention of display when a liquid crystal layer is arranged in a reverse twist with respect to a plurality of temperatures. Fig.
17 is a graph showing the temperature dependency of the pitch length of the chiral agent.
18 is a table showing the result of more detailed examination of the temperature dependence of the display pit (memory property) by the reverse twist arrangement state.
19A to 19D are photographs showing the results of an experiment on the memory stability of a liquid crystal display element to which 2 wt% of an ultraviolet curable material is added.
Fig. 20 is a microscope photograph showing a liquid crystal display element (liquid crystal display element after heat treatment at 90 占 폚 for 30 minutes) showing an external view in Fig. 19c.
21A to 21D are photographs showing the results of an experiment on the memory stability of a liquid crystal display element to which an ultraviolet curable material is added in other addition amounts (1 wt%, 2 wt%, and 5 wt%).
22 is a diagram showing an observation image (image) of a liquid crystal device in a typical manufacturing condition and a display state.
23 is a diagram showing the results of evaluation of the contrast and the display holding performance in a liquid crystal device having a pretilt angle of about 46 deg. And a twist angle of 70 deg.
24 shows the evaluation results of the temperature characteristics of the display holding performance in the liquid crystal device (the liquid crystal device in which the value of d / p is 0.444 to 0.500) having the pitch p of 8.0 占 퐉 to 9.0 占 퐉 among the conditions shown in Fig. Fig.
25 is a view showing an observation image of a liquid crystal element used for the evaluation shown in Fig.
Fig. 26 is a diagram showing an observation image of a liquid crystal device in which the pitch condition is set to 9 占 퐉 (short pitch condition) and 12 占 퐉 (long pitch condition).
27 is a diagram showing the optical characteristics of each liquid crystal element corresponding to the manufacturing conditions shown in Fig.
28 is a diagram showing optical characteristics of each liquid crystal element corresponding to the manufacturing conditions shown in Fig.
29 is a diagram showing the optical characteristics of each liquid crystal element corresponding to the manufacturing conditions shown in Fig.
30 is a diagram showing the optical characteristics of each liquid crystal element corresponding to the manufacturing conditions shown in Fig.
31 is a diagram showing the optical characteristics of each liquid crystal element corresponding to the manufacturing conditions shown in Fig.
Fig. 32 is a diagram showing a state in which voltage is applied to each electrode of the liquid crystal element according to the sixth embodiment and switching is performed. Fig.
33 is a flow chart showing a method for manufacturing a liquid crystal display element according to the seventh embodiment.
Figs. 34A and 34B are photographs showing polarization microscope observation results of a plurality of manufactured liquid crystal display elements in a display state, and Fig. 34C is a diagram showing an outline of a liquid crystal molecule arrangement in a focal conic orientation .
35A and 35B are diagrams for explaining the case where a liquid crystal display element (liquid crystal display element having a display state shown in Fig. 34B) manufactured at a pretilt angle of about 45 deg. And a d / p of 0.8, FIG. 35C is a graph showing the transmittance time dependency of the 180 degree azimuth (left and right direction) and the backlight contrast curve, and FIG. 35C is a graph showing the time- Fig.
36 is a graph showing conditions capable of realizing a reverse twist arrangement state and a bistable state in a focal-conic arrangement state.
37 is a schematic plan view showing a pattern of an ITO film formed on the upper transparent substrate 11a.
38 is a schematic plan view showing a pattern of the ITO film formed on the lower transparent substrate 11b.
39 is a schematic plan view showing a photomask used for etching an ITO film.
Fig. 40 is a schematic plan view showing a part of the formation area of the lower alignment film 14b formed on the lower substrate 10b.
41 is a schematic plan view showing the structure of a liquid crystal display element according to the seventh embodiment
42A to 42C are external views of the liquid crystal display element according to the seventh embodiment.

1 is a schematic cross-sectional view showing a liquid crystal display element according to a first embodiment.

First, a method for manufacturing a liquid crystal display element according to the first embodiment will be described.

Two transparent substrates (an upper transparent substrate 11a and a lower transparent substrate 11b) having a transparent conductive film, for example, a transparent substrate on which an ITO film is formed, for example, a glass substrate were prepared and cleaned.

The ITO film on the upper transparent substrate 11a was patterned using a photolithography process to form the upper side beta electrode 12a on the upper transparent substrate 11a. The patterning was performed so that the ITO film remained on the portion corresponding to the extraction electrode portion (terminal portion) and the pixel on the display. Etching of the ITO film was carried out by wet etching using ferric chloride. It is also possible to perform patterning by irradiating a laser beam and removing the ITO film at the irradiation position.

The ITO film on the lower transparent substrate 11b was patterned using a photolithography process and the lower side beta electrode 12b was formed on the lower transparent substrate 11b. The forming method is the same as the method of forming the upper side beta electrode 12a of the upper transparent substrate 11a.

After formation of the lower side beta electrode 12b, an insulating film 13 was formed on the lower side transparent substrate 11b including the lower side beta electrode 12b. The insulating film 13 is not formed on the extraction electrode portion of the lower side beta electrode 12b, for example. The insulating film 13 may be formed by a method of forming a resistor in the extraction electrode portion of the lower side beta electrode 12b and removing the lift off resistor after forming the insulating film 13, Or the like. The insulating film 13 may be an organic insulating film or an inorganic insulating film such as SiO ₂ or SiN _x . Or may be formed of a combination thereof. In the embodiment, a laminated film of an acrylic organic insulating film and SiO ₂ is used as the insulating film 13.

In the embodiment, a heat resistant film (polyimide tape) is attached to the extraction electrode portion of the lower side beta electrode 12b, and the organic insulating film is spin-coated in this state. And spinning at 2000 rpm for 30 seconds to obtain an organic insulating film with a thickness of 1 m.

Next, the lower transparent substrate (11b) formed in the organic insulating film, in a clean oven at 220 ℃ calcinated for 1 hour, then heated to the lower transparent substrate (11b) angle and attaching the heat-resistant film at a 80 ℃, SiO ₂ film's (AC discharge) to form a film with a thickness of 1000 ANGSTROM. The SiO ₂ film may be formed by a vacuum deposition method, an ion beam method, a CVD (chemical vapor deposition) method, or the like.

When the heat resistant film was peeled off, the organic insulating film and the SiO ₂ film could be removed from the adhesive portion of the heat resistant film. Subsequently, in order to improve the insulating property and transparency of the SiO ₂ film, the lower transparent substrate 11b was subjected to a lawsuit in a clean oven at 220 ° C for one hour.

The formation of the SiO ₂ film is not essential, but the insulating property of the insulating film 13 can be improved by forming the SiO ₂ film. In addition, it is possible to improve the adhesion and the patterning property of the first and second collecting electrodes 12c and 12d formed on the insulating film 13.

The insulating film 13 may be formed of only the SiO ₂ film without forming the organic insulating film. Since the SiO ₂ film tends to become porous, in this case, the thickness of the SiO ₂ film is preferably 4000 Å to 8000 Å. Or an inorganic insulating film 13 made of a laminated film of an SiO ₂ film and an SiN _x film.

An ITO film was formed on the insulating film 13. The ITO film was formed on the entire surface of the substrate by heating the lower transparent substrate 11b at 100 占 폚 and applying a sputtering method (alternating current discharge). The film thickness was set to about 1200 angstroms. The ITO film was patterned by a photolithography process to form electrodes for extraction of the first, second and third joyful electrodes 12c, 12d and their respective glowing electrodes 12c, 12d.

2 is a schematic plan view showing a photomask used for etching an ITO film. The photomask includes a portion corresponding to the first joyful electrode 12c, a portion corresponding to the second joyful electrode 12d, a portion corresponding to the extraction electrode of the first joyful electrode 12c, and a portion corresponding to the extraction electrode of the second joyful electrode 12d ≪ / RTI > At the time of etching, an electrode is formed with an ITO film covered with each corresponding portion. The inventors of the present invention have also found that when the electrode widths of the joyful electrode portions of the joyful electrode are 20 占 퐉 and 30 占 퐉 and the joyful portions of the two joyful electrodes are arranged alternately, The first and second juliet electrodes 12c and 12d were fabricated by using the electrode pattern.

Through the above process, the upper transparent substrate 11a on which the upper side beta electrode 12a is formed, and the lower side beta electrode 12b and the insulating film 13 above the first side and the second side of the first and second common electrodes 12c And 12d are formed on the lower transparent substrate 11b. Then, the two transparent substrates 11a and 11b with electrodes were cleaned and dried. The cleaning is performed, for example, by rinsing, for example, pure water cleaning with or without a detergent. Brush cleaning, spray cleaning, and the like. After dehydration, UV cleaning and IR drying are performed.

An alignment film material is coated on the transparent substrates 11a and 11b with electrodes to cover the electrodes 12a, 12c, and 12d. The application of the alignment film material was carried out using a spin coat. It may be done using Furekiso printing or inkjet printing. In the examples, the side chain density of the polyimide alignment film material, which is usually used for forming the vertical alignment film, was controlled and used as an alignment film material. The control of the side chain density is intended to enable the application of an appropriate pretilt angle. The alignment film material was applied so that the thickness of the alignment film was 500 ANGSTROM to 800 ANGSTROM.

The substrates 11a and 11b coated with the alignment film material were fired in a clean oven at a firing temperature of 200 DEG C for one hour. The upper alignment film 14a covering the upper side beta electrode 12a and the lower alignment film 14b covering the first and second Gulchi electrodes 12c and 12d were formed.

Next, rubbing treatment (orientation treatment) was carried out. The rubbing treatment was carried out with the indentation amount of 0.8 mm (strong rubbing condition). The rubbing treatment was carried out so that the twist angle of the liquid crystal display element was 70 DEG or 90 DEG.

Thus, the upper substrate 10a and the lower substrate 10b were fabricated. The upper substrate 10a is provided with an upper transparent substrate 11a, an upper side beta electrode 12a formed on the upper side transparent substrate 11a and an upper side orientation film 14a formed so as to cover the upper side beta electrode 12a. The lower substrate 10b includes a lower transparent substrate 11b, a lower side beta electrode 12b formed on the lower side transparent substrate 11b, an insulating film 13 formed on the lower side beta electrode 12b, The first and second collective electrodes 12c and 12d disposed in the interdigital portion and the lower orientation film 14b formed so as to cover the first and second collective electrodes 12c and 12d.

Subsequently, in order to keep the thickness of the liquid crystal cell constant, a gap control material is spread on one surface of the substrates 10a and 10b by, for example, a dry scattering method. A plastic ball having a particle diameter of 4 탆 was used for the gap control material so that the thickness of the liquid crystal cell was 4 탆.

A sealing material was printed on the other side of the substrates 10a and 10b to form a main seal pattern. For example, a thermosetting sealing material containing glass fibers having a particle diameter of 4 탆 is printed by a screen printing method. The sealant can also be applied using a dispenser. It is also possible to use a photo-curable sealant, not a thermosetting agent, and a curing-type sealant for light and heat.

The substrates 10a and 10b were stacked. The substrates 10a and 10b were laminated at predetermined positions to form a cell, and heat treatment was performed in a pressed state to cure the sealant. For example, the seal material is thermally cured using a hot press method. Thus, an empty cell is fabricated.

For example, a nematic liquid crystal material, for example, ZLI-2293 manufactured by MELCK Co., Ltd., was injected into the open cell by a vacuum injection method. A chiral agent was added to the liquid crystal material. We used CB15 of Melchor Co., Ltd. The chiral agent was added so that d / p was 0.5 (d = 4 탆, p = 8 탆) when the chiral pitch was p and the thickness (cell thickness) d of the liquid crystal layer was d.

The liquid crystal injection port is sealed with an end sealing material of, for example, an ultraviolet curing type, and the cell is heated above the phase transition temperature of the liquid crystal in order to align the liquid crystal molecules.

Thereafter, breakage was carried out along the damage to the transparent substrates 11a and 11b with a scraper device, and small division into individual cells was carried out.

Chambers and rinsing were performed on the cells divided into small pieces.

Finally, the polarizers 16a and 16b are attached to the surfaces of the two transparent substrates 11a and 11b opposite to the liquid crystal layer 15, respectively. The two polarizing plates 16a and 16b were arranged in a cross nicol, and the directions of the transmission axis and the rubbing direction were parallel to each other. It may be arranged to be orthogonal. A power source 20 is connected between the electrodes 12a, 12b, 12c, and 12d.

Thus, a liquid crystal display element according to the first embodiment was produced.

The liquid crystal display element according to the first embodiment has an upper substrate 10a, a lower substrate 10b and a twisted nematic liquid crystal layer 15 sandwiched between both substrates 10a and 10b, .

The upper substrate 10a includes an upper transparent substrate 11a, an upper beta electrode 12a formed on the upper transparent substrate 11a and an upper alignment film 14a formed on the upper beta electrode 12a. The lower substrate 10b includes a lower transparent substrate 11b, a lower side beta electrode 12b formed on the lower side transparent substrate 11b, an insulating film 13 formed on the lower side beta electrode 12b, And a lower alignment film 14b formed on the insulating film 13 so as to cover the first and second collective electrodes 12c and 12d formed and the first and second collective electrodes 12c and 12d.

The upper and lower transparent substrates 11a and 11b are formed of, for example, glass. The upper and lower beta electrodes 12a and 12b and the first and second collective electrodes 12c and 12d are formed of a transparent conductive material such as ITO. The first and second collective electrodes 12c and 12d are comb-shaped electrodes each having a plurality of merge portions. The merge portions of the first and second collective electrodes 12c and 12d are staggered along the left-right direction in Fig.

The liquid crystal layer 15 is disposed between the upper alignment film 14a of the upper substrate 10a and the lower alignment film 14b of the lower substrate 10b.

The upper and lower alignment films 14a and 14b are subjected to alignment treatment by rubbing. The alignment treatment directions of the upper alignment film 14a and the lower alignment film 14b are, for example, 70 ° or 90 ° when viewed in the normal direction of the upper and lower substrates 10a and 10b. When the rubbing direction of the upper alignment film 14a is the first direction and the rubbing direction of the lower alignment film 14b is the second direction, the second direction is the first direction, as viewed in the normal direction of the upper substrate 10a, In the direction of the right turning direction. The alignment state of the liquid crystal molecules in the liquid crystal layer 15 defined by the combination of the alignment treatment direction of the upper and lower substrates 10a and 10b and the pretilt angle is a reverse twist arrangement state in which the liquid crystal molecules twist in the first rotation direction.

A chiral agent is added to the liquid crystal material forming the liquid crystal layer 15. The alignment state of the liquid crystal molecules generated under the influence of the chiral agent is a spray twist arrangement twisted in a second rotation direction opposite to the first rotation direction.

The power source 20 is electrically connected to the upper and lower beta electrodes 12a and 12b and the first and second Gulch electrodes 12c and 12d. It is possible to apply a voltage (give a potential difference) to the electrodes 12a to 12d by the power supply 20.

3A to 3E are schematic cross-sectional views showing the direction of an electric field at the time of voltage application.

Please refer to FIG. For example, by applying an AC voltage between the upper and lower beta electrodes 12a and 12b, the liquid crystal layer 15 (pixel region) (the upper side and the lower side of the liquid crystal layer (The electric field in the thickness direction of the liquid crystal layer 15) can be added to the liquid crystal layer 15.

3B. (For example, between the lower side beta electrode 12b and the first side 6b and between the lower side beta electrode 12b and the first and second juliet electrodes 12c and 12d (Between the liquid crystal layer 15 (the pixel region) (the liquid crystal layer 15 above the lower beta electrode 12b, the first and second juliette electrodes 12c and 12c) by applying an alternating voltage to the liquid crystal layer 15 (The liquid crystal layer 15 above the region between the liquid crystal layer 15 and the first and second common electrodes 12c and 12d) and the electric field , The electric field in the in-plane directions of the substrates 10a and 10b} can be generated. By applying a voltage between the electrode 12b and the electrodes 12c and 12d, a drive mode for driving the liquid crystal display element by causing a transverse electric field in the liquid crystal layer 15 is referred to as an FFS mode (fringe field switching mode) . The transverse electric field generated in the liquid crystal layer 15 in the FFS mode of the mode shown in Fig. 3B is an electric field along the left-right direction in Fig.

3C. By applying an alternating voltage between the upper side beta electrode 12a and the first and second Joule electrodes 12c and 12d, a part of the liquid crystal layer 15 (pixel region), for example, A vertical electric field can be added to the liquid crystal layer 15 above the two-gulled electrodes 12c and 12d.

See FIG. A portion of the liquid crystal layer 15 (pixel region), for example, a part of the first joyful electrode 12c and the second joyful electrode 12d can be formed by applying an alternating voltage between the first and second joyful electrodes 12c and 12d. A horizontal electric field can be added to the liquid crystal layer 15 between the two-gulled electrodes 12d. By applying a voltage between the first and second collective electrodes 12c and 12d, a horizontal electric field is generated in a part of the liquid crystal layer (pixel region), and a driving mode for driving the liquid crystal display element is called an in- plane switching mode.

See FIG. 3E. A portion of the liquid crystal layer 15 (pixel region), for example, a part of the joyful portion 12c of the first joyful electrode 12c, may be formed by applying an alternating voltage between the lower-side beta electrode 12b and the first joyful electrode 12c. And a lateral electric field can be added to the liquid crystal layer 15 located in the vicinity of the liquid crystal layer 15. Likewise, by applying an alternating voltage between the lower-side beta electrode 12b and the second juxtacode 12d, the liquid crystal layer 15 in the vicinity of the juxtaposed portion of the second juliette electrode 12d, Can be added.

4A to 4C are external views of the liquid crystal display element according to the first embodiment. 4A to 4C show that when the electrode width of the fun portion of the first and second collective electrodes 12c and 12d is 20 mu m and the fun portion of the both of the collective electrodes 12c and 12d are arranged alternately, 12C are external views of the liquid crystal display element in which the intervals are 20 mu m and in which the shared electrodes 12c and 12d are formed.

Fig. 4A shows an external view of a state (initial state) in which the liquid crystal display element according to the first embodiment is completed. In the initial state, the liquid crystal molecules are in a spray twist arrangement state. A bright white display is obtained.

In this state, as shown in Fig. 3A, an AC voltage equal to or higher than the threshold voltage, that is, the minimum physical quantity voltage causing the reaction, was applied between the upper and lower beta electrodes 12a and 12b. By applying a voltage between the electrodes 12a and 12b, a subfield is generated in the entire liquid crystal layer 15 (pixel region).

FIG. 4B is a photograph of the appearance after voltage is applied between the electrodes 12a and 12b. Even in the frontal view, clear black display is obtained. It can be seen that the entire transition has shifted from the spray twist arrangement state to the reverse twist arrangement state. On the other hand, it is confirmed that a vertical electric field is generated in the entire liquid crystal layer 15 (pixel region) by application of a voltage between the electrodes 12a and 12b.

5A to 5C are graphs showing optical characteristics of the liquid crystal display element according to the first embodiment. 5A to 5C show the optical characteristics of the liquid crystal display device manufactured by setting the angle between the rubbing direction of the upper substrate 10a and the lower substrate 10b to 70 deg.

5A. 5A shows the azimuth and polar angle dependence of the contrast ratio (the transmittance to the spray twist arrangement state / the transmittance to the reverse twist arrangement state). R _U in the figure indicates a direction of rubbing treatment is performed for the upper substrate (10a), R _{L represents} it on the lower substrate (10b). Represents the transmission axis direction of the upper polarizing plate 16a in the direction parallel to the arrow direction of A and indicates the transmission axis direction of the lower polarizing plate 16b in the direction parallel to the arrow direction of P. The direction parallel to the direction of the thick arrow (90 ° -270 ° azimuth) is set at the center in the thickness direction of the liquid crystal layer 15 when the alignment state of the liquid crystal molecules in the liquid crystal layer 15 is the reverse twist alignment state Indicates the alignment direction of the liquid crystal molecules positioned. Here, the 0 占 180 占 azimuth corresponds to the left and right directions in Fig. That is, in the alignment direction of the liquid crystal molecules located at the center in the thickness direction of the liquid crystal layer 15 and the FFS mode of the mode shown in Fig. 3B when the alignment state of the liquid crystal molecules in the liquid crystal layer 15 is in the reverse twist alignment state And the direction of the generated transverse electric field are directions perpendicular to each other. This also applies to a liquid crystal display element manufactured by setting the angle between the rubbing direction of the upper substrate 10a and the lower substrate 10b to 90 deg.

Fig. 5B shows the polarized dependence of the transmittance on the 90 DEG-270 DEG orientation. The angle of inclination at which the substrate 10a or 10b tilts in the normal direction (the front view direction of the liquid crystal display element) is 0 ° and the angle at which the substrate 10a or 10b is inclined is expressed as a positive polar angle, The tilt angle is shown as a negative polar angle. In the graph of Fig. 5B, the horizontal axis represents the polar angle and the vertical axis represents the transmittance in units "% ". The curved line connecting the black rhombus (denoted by " St ") represents the polar angle dependence of the transmittance when the liquid crystal molecules are arranged in the twisted state of the spray, and the curve connecting the black squares It shows that when the reverse twist array is in the state.

The transmittance is about 12.6% when viewed in front of the spray twist arrangement and about 0.02% when it is in the reverse twist arrangement.

5C shows the polar angle dependence of the contrast ratio with respect to the 90 DEG-270 DEG orientation. The horizontal axis of the graph of FIG. 5C is the same as that of FIG. 5B. The vertical axis represents the contrast ratio. With respect to the liquid crystal display element according to the first embodiment, the contrast ratio becomes maximum (maximum value 566) at the time of frontal observation.

The same results were obtained for the liquid crystal display device manufactured by setting the angle between the rubbing direction of the upper and lower substrates 10a and 10b to 90 degrees. As described above, the liquid crystal display element according to the first embodiment is a liquid crystal display element having excellent optical characteristics capable of displaying, for example, a bright white display or a clear black display.

4C. The present inventors then apply an AC voltage equal to or higher than the minimum physical quantity voltage that causes a reaction between the lower side beta electrode 12b and the first and second juliette electrodes 12c and 12d as shown in Fig. (Electric field along the left direction in Figs. 1 and 3B} is generated in the entire liquid crystal layer 15 (pixel region) in the direction parallel to the liquid crystal layer 15 (the first and second splay electrodes 12c and 12d are staggered).

Fig. 4C is an external view of the liquid crystal display element in the state shown in Fig. 4B after the lateral electric field shown in Fig. 3B is added. It can be seen that the front surface is rejoining the spray twist array state indicating the white display state as in the initial state.

The liquid crystal molecules located at the center in the thickness direction of the liquid crystal layer 15 are inclined in the longitudinal direction (vertical direction) from the lateral direction (horizontal direction) by the addition of the vertical electric field, Quot; state ". The liquid crystal molecules located at the center in the thickness direction of the liquid crystal layer 15 are aligned in the transverse direction from the longitudinal direction by the addition of the transverse electric field (a twist of the liquid crystal molecules located at the center in the thickness direction of the liquid crystal layer 15 Direction of the director in the arrangement state}, the switching from the reverse twist arrangement state to the spray twist arrangement state can be considered.

When a longitudinal electric field is added to the liquid crystal layer 15 in the reverse twist arrangement state, the reverse twist arrangement state is maintained, and when a horizontal electric field is added to the liquid crystal layer 15 in the spray twist arrangement state, State is maintained.

Subsequently, as shown in Fig. 3C, an AC voltage equal to or higher than the minimum physical quantity voltage causing the reaction is applied between the upper side beta electrode 12a and the first and second Joulichi electrodes 12c and 12d. The voltage applied between the electrode 12a and the electrodes 12c and 12d is applied to part of the liquid crystal layer 15 (the liquid crystal layer 15 above the first and second collective electrodes 12c and 12d) An electric field is generated. Therefore, the liquid crystal molecules above the first and second collective electrodes 12c and 12d transit from the spray twist arrangement state to the reverse twist arrangement state. The spray twist arrangement state is maintained above the region between the both-sided electrodes 12c and 12d.

6A to 6C are photographs of a liquid crystal display element in which a longitudinal electric field is added to a part of the liquid crystal layer. 6A is an overall photograph, FIG. 6B is an enlarged photograph, and FIG. 6C is a microscopic photograph. 6A to 6C show that when the electrode width of the joyful portion of the first and second joyful electrodes 12c and 12d is 20 μm and the joyful portions of the both Joyce electrodes 12c and 12d are arranged alternately, And a gap of 20 mu m. For example, each character of "S", "T", "A", "N", "L", "E", "Y", "L", "C", "D" (Electrode width of the first and second juliet electrodes 12c and 12d) / space (the distance between the juxtaposed portions of the first and second juliet electrodes 12c and 12d shifted) (Arrangement region of the juxtaposed portions of the first and second juxtiple electrodes 12c and 12d).

Referring to FIGS. 6A and 6B, "S", "T", "A", "N", "L", "E", "Y", "L", "C" s "are displayed in an intermediate hue (brightness), that is, gray, between white (display by the spray twist array state) and black (display by the reverse twist array state).

FIG. 6C is a micrograph of an area including a gray display (halftone display). In the gray display portion, microscopically, a black display portion (a reverse twist array state portion) and a white display portion (a spray twist array state portion) are arranged in a stripe shape. The reason why the voltage is applied between the electrode 12a and the electrodes 12c and 12d to make a transition to the black display (reverse twist arrangement state) is that the first and second joyful electrodes 12c and 12d It is a region slightly wider than the width of the merge part arrangement area or the merge portion. In the remaining areas, a white display (spray twist arrangement state) was maintained. According to the microscopic observation, although the black display portion and the white display portion are arranged in a stripe shape, black and white stripes are not observed from the naked eye, and a natural gray display is obtained. It can be considered that the stripe shape distribution of the black display portion and the white display portion has a fineness higher than that of human eyes.

In the examples shown in the photographs of Figs. 6A to 6C, the line / space was 20 mu m / 20 mu m, but when the size is 50 mu m to 100 mu m / 50 mu m to 100 mu m or less, a natural gray display is observed with the naked eye.

The inventors of the present invention have found that the black display by the reverse twist arrangement state, the white display by the spray twist arrangement state, and the gray display (the area which becomes the reverse twist arrangement state and the area which becomes the spray twist arrangement state coexist in one pixel, (Display by mixing them) was held (memorized) in a state as it was unless a separate voltage was applied.

The liquid crystal display element according to the first embodiment is a liquid crystal display element having a bistable alignment state in which alignment states of liquid crystal molecules are stable in both the reverse twist alignment state and the spray twist alignment state, Which can display a variety of information.

The inventors of the present invention fabricated a liquid crystal display device according to a reference example having a line / space of 20 mu m / 20 mu m and a cell thickness of 10 mu m for an embodiment having a line / space of 20 mu m / 20 mu m and a cell thickness of 4 mu m, did. A voltage was applied between the upper side beta electrode of the liquid crystal display element and the first and second juliet electrodes according to the reference example, but gray display could not be obtained unlike the first embodiment. It was confirmed that not only the liquid crystal molecules above the first and second Juliet electrodes but also the liquid crystal molecules above the region between both Jolt electrodes transited to the reverse twist arrangement state.

From the experiment of the reference example, it can be considered that a gray display (halftone display) is realized when the size of the line / space and the cell thickness satisfy the conditions. As a result of the in-depth study, the inventors of the present invention have found that the realization conditions of the halftone display do not depend on the line size (the electrode width of the juxtaposed portions of the first and second juliet electrodes 12c and 12d) (The distance between the juxtaposed portions of the first and second juxtaposed electrodes) and the cell thickness is important for the realization of halftone display. When the cell thickness d is less than 10 占 퐉, the half-tone display can be obtained, so that the space size s of the jig (comb)

s > 2 x d (1)

, It can be said that halftone display is possible.

In the first embodiment, a voltage is applied between the upper-side beta electrode 12a and the first and second juliette electrodes 12c and 12d, The liquid crystal molecules at that position are transited to the reverse twist arrangement state by applying a seedling electric field to the layer 15 and only between the upper side beta electrode 12a and the first juxtiple electrode 12c or the upper side beta electrode 12a, Intermediate display can be realized even if an AC voltage equal to or higher than the minimum physical quantity voltage causing the reaction is applied only between the first and second second and third juxtiption electrodes 12a and 12b.

When a voltage is applied between the upper side beta electrode 12a and the first juxtative electrode 12c, a longitudinal electric field is added to the liquid crystal layer 15 above the first Juggern electrode 12c, Transition from the twisted array state to the reverse twisted array state. When a voltage is applied between the upper side beta electrode 12a and the second side electrode 12d, a longitudinal electric field is added to the liquid crystal layer 15 above the second splay electrode 12d, and liquid crystal molecules Transition from the spray twist arrangement state to the reverse twist arrangement state.

In addition, in the embodiment, in order to have a line / space of 20 μm / 20 μm (line: space = 1: 1), for example, the transmittance at white display (all liquid crystal molecules in the pixel region in the spray twist arrangement state) When the transmittance at the time of black display (all the liquid crystal molecules in the pixel region is in a reverse twist arrangement state) is 0%, a gray display having a transmittance of about 50% can be obtained. However, by adjusting the ratio of the lines / It is also possible to change the hue (brightness) level of the halftone display. The sizes of the lines and spaces can be arbitrarily selected under the condition of the expression (1).

Fig. 7 shows another example (modified example) of the formation of the first and second collecting electrodes 12c and 12d. In this figure, the line size of the first joyful electrode 12c (the electrode width of the joyful portion) is 20 m, the size of the second joyful electrode 12d thereof is 40 m, and the space size of the positive electrodes 12c and 12d is 10 m The first and second merge electrodes 12c and 12d are shown. That is, the line size of the electrode 12c: the line size of the electrode 12d: the space size = 2: 4: 1.

When a voltage equal to or greater than the minimum physical quantity voltage is applied between the upper side beta electrode 12a and the first juliette electrode 12c in the case where the first and second collective electrodes 12c and 12d are formed as described above, A vertical electric field is generated in the liquid crystal layer 15 above the liquid crystal layer 12c, and the liquid crystal molecules at that position transition from the spray twist arrangement state to the reverse twist arrangement state. Therefore, in this voltage applying mode, a halftone display with a transmittance of about 25% is realized.

When a voltage equal to or higher than the minimum physical quantity voltage causing a reaction is applied between the upper side beta electrode 12a and the second side electrode 12d, a sub field is generated in the liquid crystal layer 15 above the second sphere electrode 12d And a halftone display with a transmittance of about 50% for shifting the liquid crystal molecules at that position from the spray twist arrangement state to the reverse twist arrangement state is realized.

When a voltage equal to or greater than the minimum physical quantity voltage causing the reaction is applied between the upper side beta electrode 12a and the first and second Joule's electrodes 12c and 12d, And a liquid crystal molecule at the position shifts from the spray twist arrangement state to the reverse twist arrangement state to realize halftone display with a transmittance of about 75%.

The white display when the liquid crystal molecules in the entire liquid crystal layer 15 (pixel region) is arranged in the twisted array state and the liquid crystal molecules in the liquid crystal layer 15 (pixel region) are arranged in the reverse twist arrangement state (Gradation) display in which the transmittance is changed at an equal ratio (proportionally) can be realized in the liquid crystal display element according to the modified example in addition to the black display at the time when the transmissivity is changed.

The liquid crystal display element according to the modification is characterized in that the line sizes of the first and second collective electrodes 12c and 12d are different from each other. It is also characterized in that a line size and a space size of each of the electrodes 12c and 12d are designed so that the transmittance can be changed at an equal ratio. According to the liquid crystal display element according to the modified example, it is possible to perform a wider variety of display than the liquid crystal display element according to the first embodiment.

In the description up to this point, the intermediate gray level display is performed by generating a vertical electric field in a part of the liquid crystal layer 15 (pixel region) in the spray twist arrangement state. However, for example, in the liquid crystal display according to the first embodiment and the modification It is also possible to cause a transverse electric field to occur in a part of the liquid crystal layer 15 (pixel region) in the IPS mode described with reference to Fig. 3D and perform halftone display on the display element. For example, when the liquid crystal molecules in the liquid crystal layer 15 (pixel region) are arranged in the reverse twist arrangement state, when an alternating voltage is applied between the first and second juxtiple electrodes 12c and 12d, A transverse electric field is generated in a region between the portions of the electrodes 12c and 12d and above the liquid crystal molecules in the liquid crystal layer 15 at that position, and the liquid crystal molecules in the position transits to the spray twist arrangement state to perform halftone display.

For example, a transverse electric field is applied in the IPS mode to the liquid crystal display element according to the first embodiment in which the liquid crystal molecules of the liquid crystal layer 15 are in a reverse twist arrangement state (between the first and second juxtiple electrodes 12c and 12d) (Brightness) of a halftone display that can be obtained when an AC voltage is applied is obtained by adding a vertical electric field to a part of the liquid crystal layer 15 (pixel region) in the spray twist arrangement state (the upper side beta electrode 12a, The transmittance at the time of black display is set to 0%, the transmittance at the time of white display is set to 100%, and the transmittance at the time of black display is set at 0% , The transmittance becomes about 50%.

It is also possible to apply a half tone display by shifting a part of the liquid crystal layer 15 (pixel region) in the reverse twist arrangement state to the spray twist arrangement state by adding the electric field described with reference to Fig. 3E. In the case shown in Fig. 3E, the liquid crystal molecules of the liquid crystal layer 15 in the vicinity of the jig -type portion forming region of the first glowing electrode 12c and the liquid crystal layer 15 in the vicinity thereof are transited to the spray twist arrangement state to realize halftone display.

According to the method in which a transverse electric field is generated in a part of the liquid crystal layer 15 (pixel region) and the liquid crystal molecules in the liquid crystal layer 15 are transited from the reverse twist arrangement state to the spray twist arrangement state, the relationship of the electric equation (1) , It is possible to obtain a halftone display. Therefore, a driving method for generating a transverse electric field in a part of the liquid crystal layer 15 (pixel region) and transiting the liquid crystal molecules in the region from the reverse twist arrangement state to the spray twist arrangement state is a liquid crystal layer 15 (A display conversion method) than a driving method in which a longitudinal electric field is generated in a part of the liquid crystal molecules in the liquid crystal molecules and the liquid crystal molecules in the liquid crystal molecules are transited from the spray twist arrangement state to the reverse twist arrangement state. However, in the case of the electric variation using the filament electric field, the 5-gradation display can be performed, but in the case of using the transverse electric field, for example, only the 3-gradation display can be performed.

As described above, the liquid crystal display element according to the embodiment is a liquid crystal display element in which the alignment state of the liquid crystal molecules is stable in both the reverse twist alignment state and the spray twist alignment state, and has a memory property. It can be applied to a display using bistability, and in this case, it is possible to drive using memory property. For example, in the case of performing dot matrices display, rewriting of the display may be performed for each line. A horizontal electric field is added to the pixel to be white-colored, and a vertical electric field is added to the pixel to be black- do. Further, a subpixel electric field or a transverse electric field is added to a part of the liquid crystal layer (pixel region) for a pixel for which halftone display is desired. Various driving methods can be considered. Hereinafter, a liquid crystal display device which performs matrix display using an XY electrode as a second embodiment will be described.

8A is a schematic diagram showing a liquid crystal display device according to the second embodiment, and Fig. 8B is a schematic plan view showing an electrode structure of the pixel portion 34. Fig.

The liquid crystal display device according to the second embodiment is a simple matrix type liquid crystal display device in which a plurality of pixel portions 34 are arranged in a matrix, A pixel structure similar to that of a liquid crystal display element is used. Specifically, the liquid crystal display device according to the second embodiment includes m control lines B1 to Bm extending in the X direction, a driver 31 for giving control signals to the control lines B1 to Bm, N control lines A1 to An intersecting the lines B1 to Bm and extending in the Y direction, a driver 32 for giving control signals to the control lines A1 to An, and a driver 32 for intersecting the control lines B1 to Bm, A driver 33 for giving control signals to the control lines C1 to Cn and D1 to Dn, n control lines C1 to Cn and D1 to Dn extending from the control lines B1 to Bm and control lines A1 to An And a pixel portion 34 defined in the intersection region.

Each of the control lines B1 to Bm, A1 to An, C1 to Cn and D1 to Dn is made of a transparent conductive film such as ITO formed in a stripe shape, for example. A portion where the control lines B1 to Bm intersect with A1 to An functions as an upper side beta electrode 12a and a lower side beta electrode 12b (see Fig. 8B). The control lines C1 to Cn are connected to the merge portion of the first merge electrode 12c provided in the region corresponding to each pixel portion 34. [ Likewise, the control lines D1 to Dn are connected to the merge portion of the second julqi electrode 12d provided in the region corresponding to each pixel portion 34. [

As a method of driving the liquid crystal display according to the second embodiment, a method of performing display swapping for each line with the control lines B1, B2, B3, ... (line sequential driving method) will be described. In this case, for example, a horizontal electric field is applied to the pixel portion 34 which is desired to be a relatively bright display (a display near the white display), and a pixel portion 34 to which a relatively dark display (34).

For example, when a black display or a white display is performed, a square wave voltage (for example, about 1.5 V at 150 Hz) not to cause the transition of the alignment state is applied to the control line B1, and the control lines A1- Cn and D1 to Dn have a square wave voltage (for example, about 1.5 V at 150 Hz) of a voltage of about the minimum physical quantity causing synchronization, or a half-period shift, a threshold value, .

Specifically, among the control lines A1 to An, a square wave voltage that is half the period of the rectangular wave voltage applied to the control line B1 is applied to the control line corresponding to the pixel portion 34 to be displayed in black. At this time, no voltage is applied to the control lines C1 to Cn and D1 to Dn. As a result, a voltage of about 3.0 V is effectively applied to the pixel portion 34 to add a vertical electric field. If this voltage is equal to or higher than the saturation voltage, it is possible to change the light transmittance of the pixel portion 34 by causing a transition of the alignment state (transition to the reverse twist arrangement state) in the liquid crystal layer 15.

On the other hand, among the control lines A1 to An, a square wave voltage synchronized with the rectangular wave voltage applied to the control line B1 is applied to the control line corresponding to the pixel portion 34 which does not need to change the display. At this time, no voltage is applied to the control lines C1 to Cn and D1 to Dn. Thereby, the voltage is not effectively applied to the pixel portion 34. [ Therefore, the liquid crystal layer 15 does not undergo transition in the alignment state, and the light transmittance does not change.

Among the control lines C1 to Cn and D1 to Dn, the control line corresponding to the pixel portion 34 to be displayed in white is applied with a square wave voltage which is half the period of the square wave voltage applied to the control line B1. At this time, no voltage is applied to the control lines A1 to An. As a result, a voltage of about 3.0 V is effectively applied to the pixel portion 34 to add a transverse electric field. If this voltage is equal to or higher than the saturation voltage, it is possible to change the light transmittance of the pixel portion 34 by causing transition in the liquid crystal layer 15 in the alignment state (transition to the spray twist arrangement state).

On the other hand, among the control lines C1 to Cn and D1 to Dn, a square wave voltage synchronized with the square wave voltage applied to the control line B1 is applied to the control line corresponding to the pixel portion 34 which does not need to change the display. At this time, no voltage is applied to the control lines A1 to An. Thereby, the voltage is not effectively applied to the pixel portion 34. [ Therefore, the liquid crystal layer 15 does not undergo transition in the alignment state, and the light transmittance does not change.

In the case of performing gray display (halftone display), the control line B1 is set to a degree at which no transition of the alignment state occurs to the pixel portion 34 in which black display is performed (in a reverse twist arrangement state) (For example, about 150 V at about 1.5 V) is applied to the control lines C 1 to Cn and a square wave voltage (for example, about 1.5 V at about 150 V) of about the threshold voltage that causes a half- .

Specifically, among the control lines C1 to Cn, a square wave voltage that is half the period of the rectangular wave voltage applied to the control line B1 is applied to the control line corresponding to the pixel portion 34 to be gray displayed. At this time, no voltage is applied to the control lines A1 to An and D1 to Dn. As a result, a voltage of about 3.0 V is effectively applied to the liquid crystal molecules in the vicinity of the jig portion of the first JE-ZUCH electrode 12c and the vicinity thereof in the pixel portion 34 to add a transverse electric field. If this voltage is equal to or higher than the saturation voltage, transition of the alignment state (transition to the spray twist arrangement state) is caused in the liquid crystal molecules in the corresponding region to change the light transmittance of the region (approximately half the region of the pixel portion 34) .

On the other hand, among the control lines C1 to Cn, a square wave voltage synchronized with the square wave voltage applied to the control line B1 is applied to the control line corresponding to the pixel portion 34 which does not need to change the display. At this time, no voltage is applied to the control lines A1 to An and D1 to Dn. Thereby, the voltage is not effectively applied to the pixel portion 34. [ Therefore, the liquid crystal layer 15 does not undergo transition in the alignment state, and the light transmittance does not change.

Although an example in which the control line B1 and the control lines C1 to Cn are synchronized with each other or a voltage which is shifted by half a period is applied, the voltage may be applied to the control line B1 and the control lines D1 to Dn synchronously or half a period.

The above-described driving is sequentially performed with the control lines B2, B3, ... so that dot matrix display becomes possible. The display state that is rewritten by such driving can be semi-permanently viewed. To change the display, the above-mentioned control may be executed again from the control line B1.

Further, by changing the electrode widths of C1 to Cn or D1 to Dn and the period of the voltage to be applied, more detailed halftone display is possible.

Although the case where the electrode width of the Gulch electrode is uniform is described here, the electrode width may be different depending on the place. In the case where the electrode width is uniform, a Moire pattern can be seen due to a gray-scale pattern of intermediate gray levels that can be obtained, but it can be reduced.

Here, an example of a so-called simple matrix type liquid crystal display device is shown, but an active matrix type liquid crystal display device using a TFT or the like can also be used. In the case of the active matrix type liquid crystal display device, it is not necessary to change the line for each control line B1 and the like, thereby reducing the replacement time. In addition, since the voltage can be applied twice or more, for example, to the threshold value, it is possible to switch at a higher speed.

Hereinafter, the liquid crystal display element using TFTs as the third and fourth embodiments will be described.

9A and 9B are a schematic sectional view and a plan view showing a liquid crystal display element according to a third embodiment, respectively. Fig. 9A is a cross-sectional view taken along line 9A-9A in Fig. 9B. Fig. FIG. 9B shows approximately one pixel, and many of the same pixels are formed in the X direction and the Y direction.

The liquid crystal display element according to the third embodiment has an upper substrate 10a, a lower substrate 10b and a twisted nematic liquid crystal layer 15 sandwiched between both substrates 10a and 10b, .

The upper substrate 10a includes an upper transparent substrate 11a, a common electrode (upper beta electrode) 12a formed on the upper transparent substrate 11a and an upper alignment film 14a formed on the common electrode 12a do. The lower substrate 10b includes a lower transparent substrate 11b, a lower beta electrode 12b formed on the lower transparent substrate 11b, a common line 22, a scanning line 23, a lower transparent substrate 11b (Pixel electrode) 21 formed on the insulating film 13, the semiconductor film 24, the source electrode 25, the drain electrode 26, and the insulating film 13 formed on the insulating film 13 And a lower alignment film 14b formed on the insulating film 13.

The upper and lower transparent substrates 11a and 11b are, for example, transparent glass substrates which are arranged to face each other. It may be a transparent plastic substrate. A plurality of spacers are dispersed and arranged (for example, not shown) between the upper and lower orientation films 14a and 14b, and the spacing between the substrates 11a and 11b / RTI >

The lower-side beta electrodes 12b are provided on one surface of the lower transparent substrate 11b. As shown in Fig. 9B, the lower beta electrode 12b is formed in a substantially rectangular shape, and a part of the lower beta electrode 12b is electrically connected to a common line 22, for example. The lower beta electrode 12b can be obtained by patterning a transparent conductive film such as ITO.

The common line 22 is provided on one surface of the lower transparent substrate 11b and extends in one direction (Y direction in Fig. 9B). The common line 22 is connected to the lower side beta electrode 12b and a predetermined potential is given to the lower side beta electrode 12b from the voltage supply means not shown through the common line 22. [ The common line 22 is formed of a metal film such as a laminated film of aluminum and molybdenum, for example.

The scanning lines 23 are provided on one surface of the lower transparent substrate 11b and extend in one direction (Y direction in Fig. 9B). As shown in Fig. 9B, the scanning line 23 of this embodiment is disposed with the lower-side beta electrode 12b sandwiched between the scanning line 23 and the common line 22. Fig. The scanning line 23 is formed of a metal film such as a laminated film of aluminum and molybdenum, for example.

The insulating film 13 is provided on one surface of the lower transparent substrate 11b so as to cover the lower side common electrode 12b, the common line 22 and the scanning line 23. [ As the insulating film 13, for example, a silicon nitride film, a silicon oxide film, or a laminated film thereof is used.

The semiconductor film 24 is provided on the insulating film 13 at a predetermined position overlapping with the scanning line 23. The semiconductor film 24 is patterned in an island shape as shown in Fig. 9B. As the semiconductor film 24, for example, an amorphous silicon film can be used. A portion of the scanning line 23 overlapping with the semiconductor film 24 functions as a gate electrode of the TFT. The portion of the insulating film 13 overlapping with the semiconductor film 24 functions as a gate insulating film of the TFT.

The source electrode 25 is provided at a predetermined position on the insulating film 13, and a part of the source electrode 25 is connected to the semiconductor film 24. The source electrode 25 of this embodiment is formed integrally with the signal line 27 as shown in Fig. 9B. The source electrode 25 and the signal line 27 are formed of a metal film such as a laminated film of, for example, aluminum and molybdenum.

The drain electrode 26 is provided at a predetermined position on the insulating film 13, and a part of the drain electrode 26 is connected to the semiconductor film 24. The drain electrode 26 is formed of, for example, a metal film such as a laminated film of aluminum and molybdenum.

The slit electrode 21 is provided at a predetermined position on the insulating film 13 so that at least a part of the slit electrode 21 overlaps the lower side beta electrode 12b. The slit electrode 21 has, for example, a plurality of spherical slits (openings) 21a as shown in Fig. 9B. The slit electrode 21 can be obtained by patterning a transparent conductive film such as ITO. In the third embodiment, the size of the slit electrode 21 is set such that the width of the straight portion (electrode width, length in the X direction in Fig. 9B) existing between the slits 21a is 20 mu m, (The length in the X direction in Fig. 9B) was set to 20 mu m. And the size is not limited to this. For example, when the width of the slit 21a is s, it is possible to set to satisfy the above-mentioned expression (1). The slit electrode 21 is connected to the drain electrode 26. A horizontal electric field can be given to the liquid crystal layer 15 by applying a voltage between the slit electrode 21 and the lower beta electrode 12b.

The lower alignment film 14b is formed by laminating the semiconductor film 24, the source electrode 25, the drain electrode 26 and the slit electrode 21 on the insulating film 13 on one surface of the lower transparent substrate 11b Respectively.

Likewise, the upper alignment film 14a is provided so as to cover the common electrode 12a on one side of the upper transparent substrate 11a. For each of the upper and lower alignment films 14a and 14b, uniaxial alignment treatment is performed, for example, by rubbing. As the orientation films 14a and 14b, it is used to develop a relatively high pretilt angle (about 20 DEG or more, preferably about 35 DEG +/- 10 DEG). The direction R _U of the alignment process of the upper alignment film 14a and the alignment direction R _L of the alignment process of the lower alignment film 14b are the same as those of the alignment process of the liquid crystal layer The direction D of alignment of the liquid crystal molecules located at the center in the thickness direction of the slit electrodes 21 and 21 in the direction of the transverse electric field E (slit 21a) generated when a voltage is applied between the lower beta electrode 12b and the slit electrode 21 Direction parallel to the array direction} (see Fig. 9B).

The common electrode 12a is provided on one surface of the upper transparent substrate 11a. At least a part of the common electrode 12a is formed so as to overlap with the lower-side beta electrode 12b and the slit electrode 21. [ The common electrode 12a can be obtained by patterning a transparent conductive film such as ITO. By applying a voltage between the common electrode 12a and the lower-side beta electrode 12b, it is possible to give a uniform electric field to the liquid crystal layer 15 (pixel region). By applying a voltage between the common electrode 12a and the slit electrode 21, a part of the liquid crystal layer 15 (the pixel region) (the upper side of the slit electrode 21 except the upper side of the slit 21a) The liquid crystal layer 15).

The liquid crystal layer 15 is disposed between the upper substrate 10a and the lower substrate 10b and is formed using a nematic liquid crystal material having a positive dielectric anisotropy Δε, for example. The thick line in the liquid crystal layer 15 in Fig. 9A schematically shows the liquid crystal molecules in the liquid crystal layer 15. Fig. The liquid crystal molecules in the voltage uninfluenced state have a predetermined pretilt angle with respect to the respective substrate surfaces of the upper substrate 10a and the lower substrate 10b. The angle formed by the directions R _U and R _L (refer to FIG. 9B) of the alignment process of the upper alignment film 14a and the lower alignment film 14b is set to, for example, about 90 degrees. The liquid crystal molecules in the liquid crystal layer 15 of the liquid crystal layer 15 are aligned in the azimuthal direction between the upper substrate 10a and the lower substrate 10b. A chiral agent is added to the liquid crystal layer 15.

The signal line 27 is provided on one side of the insulating film 13 and extends in one direction (X direction in FIG. 9B) substantially perpendicular to the direction in which the common line 22 and the scanning line 23 extend.

The upper polarizer 16a is disposed outside the upper substrate 10a. The lower polarizer 16b is disposed outside the lower substrate 10b. The display of the liquid crystal display element according to the third embodiment is viewed by the user from the side of the upper polarizer 16a. The upper and lower polarizers 16a and 16b are arranged, for example, in Cross Nicol.

The liquid crystal display element according to the third embodiment is also a reverse twisted nematic liquid crystal display element. The arrangement state of the liquid crystal molecules in the liquid crystal layer 15 defined by the orientation treatment direction of the upper and lower substrates 10a and 10b and the combination of the pretilt angle is also the same as in the first embodiment, It is a reverse twisted array. The alignment state of the liquid crystal molecules generated under the influence of the chiral agent is a spray twist arrangement twisted in a second rotation direction opposite to the first rotation direction. By adding a seedling electric field to the liquid crystal layer 15, liquid crystal molecules in the liquid crystal layer 15 in the added region can be transited from the spray twist array state to the reverse twist array state. Further, by adding a transverse electric field to the liquid crystal layer 15, liquid crystal molecules in the liquid crystal layer 15 in the added region can be transited from the reverse twist arrangement state to the spray twist arrangement state.

Figs. 10A to 10G and Figs. 11A to 11D are schematic sectional views showing a method of manufacturing a liquid crystal display element according to the third embodiment.

A glass substrate used as the upper transparent substrate 11a and the lower transparent substrate 11b is prepared. For example, a glass substrate made of alkali-free glass having a thickness of 0.7 mm can be used.

10A. The common line 22 and the scanning line 23 are formed on one surface of the glass substrate for the lower transparent substrate 11b. An aluminum film is formed on the lower transparent substrate 11b by a film forming method such as a sputtering method, and a molybdenum film is formed thereon. Thereafter, a laminated film of an aluminum film and a molybdenum film is patterned by a dry etching method or the like.

10B. And the lower side beta electrode 12b is formed at a predetermined position on one surface side of the lower transparent substrate 11b. Specifically, an ITO film is formed on the lower transparent substrate 11b by a film forming method such as a sputtering method, and the ITO film is patterned by a wet etching method or the like.

10C. The insulating film 13 is formed so as to cover the lower side common electrode 12b, the common line 22 and the scanning line 23 on one side of the lower side transparent substrate 11b. For example, a silicon nitride film is formed by a film forming method such as a sputtering method or a plasma CVD method.

10D. A semiconductor film (24) is formed at a predetermined position on the insulating film (13). An amorphous silicon film is formed on the insulating film 13 by a film forming method such as a plasma CVD method and the amorphous silicon film is patterned into an island shape by a dry etching method or the like.

See FIG. 10E. A source electrode 25, a drain electrode 26, and a signal line 27 are formed at predetermined positions on the insulating film 13. For example, a lamination film of a molybdenum film / aluminum film / molybdenum film is formed on the insulating film 13 and the semiconductor film 24 by a film forming method such as a sputtering method, and this laminated film is patterned by a dry etching method or the like do.

10F. A slit electrode (21) is formed at a predetermined position on the insulating film (13). An ITO film is formed on the insulating film 13 by a film forming method such as a sputtering method and the ITO film is patterned by a wet etching method or the like. Further, a passivation film may be provided on the insulating film 13.

See FIG. 10g. On the other hand, a common electrode 12a is formed on a glass substrate for the upper transparent substrate 11a. Specifically, an ITO film is formed over the entire one surface of the upper transparent substrate 11a by a film forming method such as a sputtering method. With respect to the actual manufacturing process, when the common electrode 12a is present on the entire surface of the substrate, there is a possibility of causing a shot by the main seal portion, film peeling or the like during braking from scribing, It is preferable to shield the outer periphery.

Hereinafter, the liquid crystal display element according to the third embodiment can be manufactured by the same method as the method for manufacturing the liquid crystal display element according to the first embodiment. However, it is preferable to use a material suitable for TFT driving for the liquid crystal material, the alignment film material and the like.

11A. A lower alignment film 14b is formed on the insulating film 13 on the lower transparent substrate 11b.

As shown in Fig. 11B, an upper alignment film 14a is formed on the common electrode 12a on the upper transparent substrate 11a.

The upper and lower transparent substrates 11a and 11b on which electrodes are formed are cleaned. The cleaning is carried out, for example, by rinsing, for example, pure water rinsing. It is preferable not to use detergent. Brush cleaning, spray cleaning, and the like. After dewatering, UV cleaning and IR drying are performed. The atmospheric pressure plasma cleaning may be performed.

In the formation of the alignment films 14a and 14b, an alignment film having a high voltage holding ratio was selected, and specifically, a polyimide film having a lowered side chain density of a material normally used as a vertical alignment film was used. The alignment film material is formed on the upper and lower transparent substrates 11a and 11b with appropriate thicknesses, for example, about 500 Å to about 800 Å, by a suitable method such as Fresco print, inkjet printing, (For example, baking at 160 ° C to 180 ° C for 1 hour in a clean oven). Thereafter, the upper and lower alignment films 14a and 14b were each subjected to an alignment treatment, for example, a rubbing treatment at an indentation amount of 0.8 mm. The rubbing direction is set so that the twist angle of the liquid crystal molecules on each of the substrates 11a and 11b becomes, for example, an abbreviation of 90 degrees when the upper transparent substrate 11a and the lower transparent substrate 11b are overlapped.

After the rubbing treatment, the substrates 11a and 11b may be cleaned, but they are not performed here.

Thus, the upper substrate 10a and the lower substrate 10b were fabricated.

11C. Subsequently, in order to keep the thickness of the liquid crystal cell constant, a gap control material is spread on one side of the substrates 10a and 10b by, for example, a dry scattering method (scattering method). A plastic ball having a particle diameter of 4 mu m was used as the gap control material so that the thickness of the liquid crystal cell was 4 mu m. The gap control may be such that the gap control material is scattered on the substrate surface, and the rib pattern may be formed on the upper substrate 10a, for example, so that the predetermined cell thickness may be maintained.

A sealing material was printed on one side of the substrates 10a and 10b to form a main seal pattern. For example, a thermosetting sealing material containing glass fibers having a particle diameter of 4 탆 is printed by a screen printing method. The sealant can also be applied using a dispenser. It is also possible to use a photo-curable sealant, not a thermosetting agent, and a curing-type sealant for light and heat.

The substrates 10a and 10b were superimposed. The substrates 10a and 10b were made to overlap each other at a predetermined position to form a cell, and heat treatment was performed in a pressed state to cure the sealing material. For example, the seal material is thermally cured using a hot press method. Thus, an empty cell was fabricated.

11D. For example, a liquid crystal material is injected into a blank cell by a vacuum injection method. You can also use the ODF method. Here, the vacuum injection method was used. The liquid crystal material is preferably a nematic type material having a positive dielectric anisotropy and a high voltage holding ratio. For example, there is no particular restriction as long as it is a liquid crystal material generally used for a twisted nematic liquid crystal display device driven by a TFT.

A chiral agent was added to the liquid crystal material. As the chiral agent, R-811 of Melco Co., Ltd. was used as an example and d / p of 0.16 was added.

After liquid crystal injection, an end seal treatment was performed while pressing. The cell was heat-treated at a high temperature (temperature equal to or higher than the phase transition temperature of liquid crystal), and the alignment state of the liquid crystal molecules was summarized.

Finally, polarizers 16a and 16b are attached to the opposite side of the two transparent substrates 11a and 11b from the liquid crystal layer 15. The two polarizing plates 16a and 16b were arranged in a crossed Nicols state so that the direction of the transmission axis and the rubbing direction were parallel. It may be arranged to be orthogonal.

Thus, a liquid crystal display element according to the third embodiment was manufactured.

The inventors of the present invention have confirmed the display of the liquid crystal display element according to the third embodiment.

12A is a photograph showing a pixel region after completion of the liquid crystal display element (initial state) according to the third embodiment. The entire surface is in a spray twist arrangement state, and a bright white display is obtained.

12B is a photograph showing a pixel region after a voltage is applied between the common electrode 12a and the lower side beta electrode 12b and a longitudinal electric field is added to the liquid crystal layer 15. Fig. Here, an AC voltage (square wave) of 10 V and 100 Hz was applied for about 1 second. The entire surface is transited from the spray twist arrangement state to the reverse twist arrangement state, and a dark black display is obtained.

9B, since the voltage can not be controlled so as to be shifted from the spray twist arrangement state to the reverse twist arrangement state for each pixel, the conversion from the white display to the black display is performed at least for the scanning line 22 It should be done line by line. It would normally be preferable to convert the entire line (whole surface).

Next, a voltage was applied to the individual pixels (TFT), and a transverse electric field was generated in the liquid crystal layer 15. Specifically, a voltage is applied to the scanning line 23 (gate line) and the signal line 27 (source line) to give a potential difference with the lower-side beta electrode 12b, . A pulse voltage of 10V as a gate voltage, and a voltage obtained by inverting each frame by ± 10V as a source voltage were added. As a result, it was confirmed that a white display as shown in the photograph shown in Fig. 12A could be obtained. By the addition of the transverse electric field, the liquid crystal molecules transit from the reverse twist arrangement state to the spray twist arrangement state. The time from the black display to the white display is about one second. Immediately after the application of the voltage was stopped, the black display state (reverse twist arrangement state) remained in the form of a dot on the slit electrode 21. However, after 3 seconds to 4 seconds, The display state (spray twist array state) has been reached.

The conversion from the black display to the white display is performed by selecting the scanning line 23 and the signal line 27 to which a voltage is applied and is controllable for each pixel, so that various displays can be realized by the waveform applied to the TFT.

Gray display (halftone display) was continued. A voltage was applied between the drain electrode 26 and the common electrode 12a through the TFT in the state in which the liquid crystal molecules of the liquid crystal layer 15 were arranged in a twisted array. In this case, an alternating voltage (square wave) of 10 V and 100 Hz was applied to the signal line 27 (source line) having the pixel to be gray-displayed, and the gate voltage was applied in synchronism therewith. As a result, a vertical electric field is added to a part of the liquid crystal layer 15 (the liquid crystal layer 15 above the slit electrode 21 except the upper side of the slit 21a), and the liquid crystal molecules at that position are arranged in the reverse twist arrangement state . Thereafter, 0 V was applied to any signal line 27 (source line) of the pixel partially in the reverse twist arrangement state, and the gate voltage was applied in synchronization with the signal line 27 (source line). Thus, gray display is realized.

13A and 13B are a schematic sectional view and a plan view showing a liquid crystal display element according to a fourth embodiment, respectively. 13A is a cross-sectional view taken along line 13A-13A in Fig. 13B. 13B shows approximately one pixel, and a large number of pixels are formed in the X direction and the Y direction.

The third embodiment shown in Figs. 9A and 9B is different from the third embodiment shown in Figs. 9A and 9B in that the common line 22a is formed on the insulating film 28 so as to be electrically connected to the slit electrode 21 instead of the lower- Point and drain electrodes 26a are connected to the lower-side beta electrodes 12b instead of the slit electrodes 21. [

Hereinafter, the same reference numerals are used for components common to those of the third embodiment, and a detailed description thereof will be omitted.

The liquid crystal display element according to the fourth embodiment has an upper substrate 10a, a lower substrate 10b and a twisted nematic liquid crystal layer 15 sandwiched between both substrates 10a and 10b, .

The upper substrate 10a includes an upper transparent substrate 11a, a common electrode (upper beta electrode) 12a formed on the upper transparent substrate 11a and an upper alignment film 14a formed on the common electrode 12a do. The lower substrate 10b includes a lower transparent substrate 11b, a lower side beta electrode 12b formed on the lower side transparent substrate 11b, a scanning line 23, an insulating film (not shown) formed on the lower side transparent substrate 11b A semiconductor film 24 formed on the insulating film 13, a source electrode 25 and a drain electrode 26a, an insulating film 28 formed on the insulating film 13 to cover them, (Pixel electrode) 21, a common line 22a, and a lower alignment film 14b formed on the insulating film 28 so as to cover them. Here, the drain electrode 26a is formed to penetrate the insulating film 13 and to be electrically connected to the lower-side beta electrode 12b.

The common line 22a is provided on the insulating film 28 on one side of the lower transparent substrate 11b and extends in one direction (Y direction in Fig. 13B). The common line 22a is connected to the slit electrode 21 as shown in Fig. 13B and is connected to the slit electrode 21 via a common line 22a, Is given. The common line 22a is formed of a metal film such as a laminated film of aluminum and molybdenum, for example.

The drain electrode 26a is provided at a predetermined position on the insulating film 28 and a part of the drain electrode 26a is connected to the lower side beta electrode 12b through the insulating film 13. [ The drain electrode 26a is formed of, for example, a metal film such as a laminated film of aluminum and molybdenum.

The insulating film 28 is provided so as to cover the semiconductor film 24, the source electrode 25, and the drain electrode 26a on the insulating film 13 on one side of the lower transparent substrate 11b. As the insulating film 28, for example, a silicon nitride film, a silicon oxide film, or a laminated film thereof is used.

The slit electrode 21 is provided at a predetermined position on the insulating film 28 so that at least a part of the slit electrode 21 overlaps the lower side beta electrode 12b. The slit electrode 21 has a plurality of slits (openings) 21a and is connected to the common line 22a as shown in Fig. 13 (b). In the fourth embodiment, the slit electrode 21 and the common wire 22a are integrally formed. The slit electrode 21 can be obtained by patterning a transparent conductive film such as ITO. A horizontal electric field can be applied to the liquid crystal layer 15 by applying a voltage between the slit electrode 21 and the lower beta electrode 12b.

The lower alignment film 14b is provided so as to cover the common line 22a and the slit electrode 21 on the insulating film 28 on one side of the lower transparent substrate 11b.

The liquid crystal display element according to the fourth embodiment is also a reverse twisted nematic liquid crystal display element. The arrangement state of the liquid crystal molecules of the liquid crystal layer 15 defined by the alignment treatment direction of the upper and lower substrates 10a and 10b and the combination of the pretilt angles is not limited to the twisted state in the first turning direction And the alignment state of the liquid crystal molecules generated under the influence of the chiral agent is a spray twist arrangement twisted in a second rotation direction opposite to the first rotation direction. By adding a seedling electric field to the liquid crystal layer 15, liquid crystal molecules in the liquid crystal layer 15 in the added region can be transited from the spray twist array state to the reverse twist array state. Further, by adding a transverse electric field to the liquid crystal layer 15, liquid crystal molecules in the liquid crystal layer 15 in the added region can be transited from the reverse twist arrangement state to the spray twist arrangement state.

Figs. 14A to 14G and Figs. 15A to 15E are schematic sectional views showing a method for manufacturing a liquid crystal display element according to the fourth embodiment. Hereinafter, in the description of the manufacturing method, a detailed description of the same components as those of the third embodiment will be omitted.

As shown in Fig. 14A, a scanning line 23 made of a predetermined metal film is formed on one surface of the lower transparent substrate 11b.

As shown in Fig. 14B, a lower side beta electrode 12b made of, for example, ITO is formed at a predetermined position on one side of the lower transparent substrate 11b.

The insulating film 13 is formed so as to cover the lower side beta electrode 12b and the scanning line 23 on one side of the lower side transparent substrate 11b as shown in Fig.

The semiconductor film 24 is formed at a predetermined position on the insulating film 13, as shown in Fig.

The source electrode 25, the drain electrode 26a, and the signal line 27 are formed as shown in Fig. 14E. For the drain electrode 26a, an opening for exposing a part of the lower-side beta electrode 12b is provided at a predetermined position of the insulating film 13 in advance, and then a metal film is formed by a sputtering method or the like, This is possible.

An insulating film 28 covering the semiconductor film 24, the source electrode 25, the drain electrode 26a and the signal line 27 is formed on the insulating film 13 as shown in Fig.

The common line 22a and the slit electrode 21 are formed at predetermined positions on the insulating film 28 as shown in Fig. Further, a passivation film may be provided on the insulating film 28.

On the other hand, as shown in Fig. 15A, the common electrode 12a is formed on one surface of the upper transparent substrate 11a.

15B, the lower alignment film 14b is formed on the insulating film 28 above the lower transparent substrate 11b.

Further, as shown in Fig. 15C, an upper alignment film 14a is formed on the common electrode 12a on the upper transparent substrate 11a.

The alignment process is performed on the upper and lower alignment films 14a and 14b and the steps similar to those of the third embodiment such as the substrate polymerization process and the liquid crystal layer 15 formation process shown in Figs. 15D and 15E are performed, A liquid crystal display element according to the embodiment is manufactured.

The liquid crystal display element according to the fourth embodiment also has a structure in which effective longitudinal electric fields are added to a part of the liquid crystal layer 15 (pixel region), and in the same manner as in the other embodiments, coexistence of the reverse twist arrangement state and the spray twist arrangement state, To form a halftone display, and to perform halftone display.

In the liquid crystal display elements according to the third and fourth embodiments, one TFT is formed in each pixel, but a plurality of TFTs may be formed. In this case, multi-gradation display can be further realized by dividing the pixel electrode, for example. It is also possible to perform image display such as photographing. Here, the pixel electrodes need not be divided into the same area.

The third and fourth embodiments are transmissive liquid crystal display elements. For example, the lower-side beta electrode 12b may be a reflective electrode and may be a reflective liquid crystal display element. In this case, it is desirable to set the twist angle to approximately 70 degrees.

The liquid crystal display elements according to the first to fourth embodiments and modifications are liquid crystal display elements that can easily realize a white display state with high contrast, a black display state, and stable display in a halftone display state. A glue electrode or a slit electrode is used as the electrode constituting the pixel. According to the liquid crystal display elements according to the first to fourth embodiments, the longitudinal electric field or the transverse electric field is generated partially in the liquid crystal layer of the pixel region, and the distribution of the transmittance is given in the pixel That is, for example, when viewing from the direction of the substrate normal, the liquid crystal molecules of the liquid crystal layer form a region in a reverse twist arrangement state and a region in a spray twist arrangement state). As shown in a modified example of the first embodiment, for example, a five-step multi-step gradation display is possible by considering the electrode size (width, area, etc.). The liquid crystal layer of the pixel region may have a reverse twist arrangement and some of the liquid crystal layers may be arranged in a spray twist arrangement. For example, the arrangement may not be the same when viewed along the substrate normal direction. In the liquid crystal display elements according to the first to fourth embodiments and the modified examples, an electrode capable of causing an electric field in which a part of the liquid crystal layer in the pixel area becomes a reverse twist arrangement state and another part is in a spray twist arrangement state It is equipped.

In addition, the liquid crystal display elements according to the first to fourth embodiments can be manufactured at low cost. The manufacturing method is substantially the same as that of a general twisted nematic liquid crystal display device except for the alignment film material, the rubbing condition (control of the amount of indentation), the firing conditions of the alignment film, In comparison, the cost increase factor is small.

In the liquid crystal display elements according to the first to fourth embodiments, the reverse twist arrangement state, the spray twist arrangement state, and the mixed state thereof of the liquid crystal layer 15 are stably maintained. For this reason, in any of the white display, the black display, and the gray display, the display state is observed while the display is changed and the voltage remains unchanged. No power is consumed other than when the display is switched. Therefore, it is possible to drive very low power consumption with extremely low power consumption. Especially when applied to a reflective display, the merit is large. The display can be semi-permanently held (held), and is compatible with the high contrast ratio.

As shown in the second embodiment, a driving method using memory characteristics such as a line sequential driving method can be applied as a driving method. Therefore, in this case, a large-capacity dot matrix display can be performed by simple matrix display without using an expensive TFT or the like. That is, it is possible to perform a large-capacity display at a low cost.

When a switching element such as a TFT is used, display switching of a large capacity can be performed at a high speed. In the case of using a liquid crystal display element using a TFT, for example, a TFT substrate widely used for IPS liquid crystal can be used as it is. For example, a transparent electrode needs to be formed on the counter substrate, but since the counter electrode can be easily formed by using a mask spatter or the like, the factor of cost rise is small. The counter substrate is provided with an electrode, which is advantageous in that it is less likely to be adversely affected by static electricity at the time of rubbing.

Further, according to the liquid crystal display elements according to the first to fourth embodiments and modified examples, it is possible to realize a display which is very suitable for both transmissive display, transmissive display and reflective display.

Next, the liquid crystal display element according to the fifth embodiment will be described in comparison with the comparative example.

First, the inventors of the present invention produced a plurality of reverse twisted nematic liquid crystal display devices according to Comparative Examples, and their display characteristics were examined.

Two transparent substrates having transparent electrodes, for example, indium tin oxide (ITO) electrodes, are prepared. In this example, two transparent substrates were cleaned and dried using a test cell having parallel plate type electrodes.

An alignment film material is coated on the transparent substrate so as to cover the ITO electrode. Application of the alignment film material was carried out using a spin coat. It may be done using Furekiso printing or inkjet printing. In this example, as the vertical alignment film material used for forming the vertical alignment film, the side chain density of the polyimide alignment film material having a low side chain density was controlled and used as an alignment film material. This is because control of the side chain density makes it possible to give an appropriate pretilt angle. The alignment film material was applied so that the thickness of the alignment film was 500 ANGSTROM to 800 ANGSTROM.

(?) Firing and main firing are performed on the transparent substrate coated with the alignment film material. The firing was carried out at different firing temperatures between 160 ° C and 260 ° C. Thus, an alignment film covering the ITO electrode was formed.

Next, a rubbing treatment (alignment treatment) is performed. The rubbing process is, for example, a process of rotating a cylindrical roll having a cloth wound thereon at a high speed to rub the alignment film, thereby causing the liquid crystal molecules contacting the substrate to be aligned (oriented) in one direction. The rubbing treatment was carried out under the conditions of 0.4 mm, 0.8 mm, and 1.2 mm in the indentations. The rubbing treatment was carried out so that the twist angle of the liquid crystal display element was 70 DEG or 90 DEG.

Subsequently, in order to keep the thickness of the liquid crystal cell (the distance between the substrates) constant, a gap control material was spread on the surface of one of the transparent substrates, for example, by a dry scattering method. A plastic ball having a particle diameter of 4 占 퐉 was used as the gap control material so that the thickness of the liquid crystal cell was 4 占 퐉.

A sealing material was printed on one surface of the transparent substrate to form a main seal pattern. For example, a thermosetting sealing material containing glass fibers having a particle diameter of 4 탆 is printed by a screen printing method. The sealant can also be applied using a dispenser. It is also possible to use a photo-curable sealant, not a thermosetting agent, and a curing-type sealant for light and heat.

The transparent substrate was superimposed. Two transparent substrates were polymerized at a predetermined position to form a cell, and heat treatment was performed in a pressed state to cure the sealing material. For example, the seal material is thermally cured using a hot press method. Thus, an empty cell is fabricated.

For example, a nematic liquid crystal is injected into a vacant cell by a vacuum injection method. A chiral agent was added to the liquid crystal. Chiral Zero used CB15 or R-811 from Melco Corporation. The chiral agent was added at a plurality of addition amounts such that the chiral pitch p and the cell thickness d were d / p of 0.33 to 0.53, for example.

The liquid crystal injection hole is sealed with an end sealing material of, for example, an ultraviolet curing type, and the cell is heated to a temperature not lower than the phase transition temperature of the liquid crystal in order to arrange the orientation of the liquid crystal molecules. In the case of the reverse twisted nematic liquid crystal display element, for example, when the liquid crystal material is injected or heated to a temperature not lower than the phase transition temperature of the liquid crystal, the twisted state is twisted in a direction in which a twisting force corresponding to the chiral agent is generated .

Thereafter, breakage was carried out along the damage to the transparent substrate with the scribe apparatus, and the cells were divided into individual cells.

Chambers and rinsing were performed on the cells divided into small pieces.

Finally, a polarizing plate was attached to the surface of the two transparent substrates opposite to the liquid crystal layer. The two polarizing plates were arranged in such a way that the direction of the transmission axis and the rubbing direction were parallel to each other. It may be arranged to be orthogonal. A power source was connected between the ITO electrodes of both transparent substrates.

Thus, a liquid crystal display element according to a comparative example was produced. In the liquid crystal display element according to the comparative example, the liquid crystal molecules of the liquid crystal layer exhibit a spray twist arrangement state with respect to the initial state, and the spray twist arrangement state can be changed to the reverse twist arrangement state by application of the longitudinal electric field, And is a reverse twisted nematic liquid crystal display element capable of transitioning the reverse twist arrangement state to the spray twist arrangement state by application of an electric field.

The inventors of the present invention conducted various investigations on the display of the reverse twisted nematic liquid crystal display device according to the comparative example.

At first, visual observation of display was carried out. The liquid crystal display element according to the comparative example was displayed at a high contrast ratio even when observed from the front. In addition, even after being left at room temperature for 3 months, the indication was seen.

Next, the purity of the display when the liquid crystal layer was in the reverse twist arrangement state was examined for a plurality of temperatures.

16 is a table showing the results of the investigation. 16, one liquid crystal display element (comparative example) is left at each temperature of -40 DEG C, 40 DEG C, and 50 DEG C for 24 hours for each type of chiral agent to be added and its addition amount (chiral pitch) It was observed whether or not the indication due to the reverse twist array state was observed and the result of the judgment was shown. O display indicates that the liquid crystal layer has been kept in a satisfactory state (the reverse twist array state has been almost maintained in the liquid crystal layer), the X display indicates that the liquid crystal layer has not been observed (almost shifted to the spray twist array state) (A state in which a reverse twist array state is partially maintained and a state in which a part thereof is transited to a spray twist array state).

When CB15 was used as the chiral agent and the addition amount was adjusted so that the chiral pitch was 8.0 占 퐉, the display in the reverse twist arrangement state was satisfactorily observed at any temperature of -40 占 폚, 40 占 폚, and 50 占 폚 . As described above, the liquid crystal display element having high memory performance over a wide temperature range can also be obtained by selecting the material and the addition amount of the chiral agent for the comparative example. However, in a liquid crystal display element in which R-811 is added so that the chiral pitch is 8.0 μm, 8.5 μm, and 9.0 μm and a liquid crystal display element in which CB15 is added so as to have a chiral pitch of 9.0 μm, It can be understood that the temperature range in which the display by the arrangement state is stably observed is not wide. It can be considered that the pitch length of the chiral agent changes due to the temperature.

17 is a graph showing the temperature dependency of the pitch length of the chiral agent. The horizontal axis of the graph represents the temperature in units of " C " and the vertical axis represents the pitch length in units of " Pm ". The broken line a indicates the temperature dependency of the pitch length with respect to CB15, and the broken line b indicates that with respect to R-811. It can be seen that the amount of change in pitch with respect to temperature varies depending on the chiral material, but changes little even when the material is selected.

The inventors of the present invention investigated in detail the temperature dependence of the display pit (memory property) according to the reverse twist arrangement state.

18 is a table showing the results of the investigation. 18 shows four liquid crystal display elements (comparative examples) for each of the types of chiral agents to be added and their addition amounts (chiral pitch p) at 40 占 폚, 50 占 폚, 60 占 폚, 70 占 폚, 80 占 폚 and 90 占 폚 After heat treatment for 30 minutes at each temperature, it was observed whether or not a display due to the reverse twist arrangement state was observed or not, and the results were judged. The numbers in the table indicate the number of liquid crystal display elements whose display was well observed. For example, the notation " 3/4 " indicates that 3 out of the four liquid crystal display elements were favorably displaying the display. The X display means that there is no liquid crystal display element that has been properly displaying the display.

When the heat treatment temperature is 50 DEG C or lower, a relatively large number of liquid crystal display elements maintain display in accordance with the reverse twist arrangement state. However, when the temperature is 60 DEG C or higher, the memory property disappears and the state transitions to the spray twist arrangement state

As described above, the reverse twisted nematic liquid crystal display device according to the comparative example has a high memory property at room temperature, for example. However, at a temperature different from the room temperature, display according to the reverse twist alignment state can not be observed. It is difficult to keep it at a high temperature.

Next, the liquid crystal display element according to the fifth embodiment will be described. A schematic sectional view of the liquid crystal display element according to the fifth embodiment is almost the same as in Fig. The manufacturing method of the liquid crystal display element according to the fifth embodiment is almost the same as that of the first embodiment. In the fifth embodiment, the main firing was performed at different firing temperatures between 160 ° C and 260 ° C. The rubbing treatment was carried out under the conditions of the indentation amounts of 0.4 mm, 0.8 mm and 1.2 mm. The rubbing treatment was carried out so that the liquid crystal display element had a twist angle of 70 ° or 90 °.

Next, as a chiral agent to be added to the liquid crystal material, CB15 or R-811 of a meltblowing agent (trade name) was used. The chiral agent was added in a plurality of addition amounts such that the ratio d / p was, for example, 0.33 to 0.53 when the chiral pitch was p and the thickness d of the liquid crystal layer was d.

(UV curable material having liquid crystallinity) as an example, and UCL-001 (manufactured by Dainippon Ink) as a fifth example in a liquid crystal material, for example, a material capable of being polymerized by light or heat Was added. The material is not limited to this. From the viewpoint of memory stability to be described later, it is preferable that the material is an ultraviolet curable material. Although a material having no liquid crystalline property can exhibit the same effect as the effect described later, it is preferable to use an ultraviolet ray-curable material having liquid crystallinity in consideration of orientation.

The inventors of the present invention have found that the addition amount of the monomer material having ultraviolet curing property is 1 wt% to the total mass of the material (liquid crystal material, chiral agent, and ultraviolet curable monomer material) for injecting the monomer material into the liquid crystal layer 15, 2 wt%, and 5 wt%, respectively.

In the fifth embodiment, ultraviolet rays are irradiated after the injection of a liquid crystal material containing a chiral agent and a UV curable liquid crystal to initiate a polymerization reaction of UV curable liquid crystal, and a polymer (polymer ) Was synthesized (polymerization treatment). For the purpose of the experiment, ultraviolet irradiation was carried out both when the liquid crystal molecules of the liquid crystal layer 15 were arranged in the reverse twist array and when the liquid crystal molecules in the liquid crystal layer 15 were arranged in the spray twist array. The ultraviolet rays were irradiated under the condition that the dose was 18 mW / cm ² and the integrated dose was 1 J / cm ² , but the ultraviolet irradiation conditions are not limited thereto.

In the fifth embodiment, the liquid crystal layer 15 contains a polymer (polymer) synthesized by irradiating ultraviolet rays to a polymerizable material, in the embodiment, UV curable liquid crystal. The polymerizable material is added in a range of 5% or less with respect to the mass of the liquid crystal layer 15 (the total mass of the liquid crystal material, the chiral agent, and the polymerizable material).

The inventors of the present invention conducted various investigations on the display of the liquid crystal display element according to the fifth embodiment.

19A to 19D are photographs showing the results of an experiment on the memory stability of a liquid crystal display element to which 2 wt% of an ultraviolet curable material is added.

Fig. 19A is an external view showing a liquid crystal display element obtained by irradiating ultraviolet rays of 1 J / cm < ² > to cause a polymerization reaction and synthesizing a polymer (polymer) in the liquid crystal layer 15. Fig. The photograph on the left side shows the appearance of the liquid crystal display element irradiated with ultraviolet rays in the spray twist arrangement state and the photograph on the right side shows the appearance of the liquid crystal display element irradiated with ultraviolet rays in the reverse twist arrangement state. This point is common to all of Figs. 19A to 19D.

In the liquid crystal display element according to the fifth embodiment, white display is performed in the spray twist arrangement state, and black display is performed in the reverse twist arrangement state. The liquid crystal display element which was in the spray twist arrangement state upon irradiation with ultraviolet light maintained the spray twist arrangement state even after the ultraviolet ray irradiation and the reverse twist arrangement state was maintained even after the ultraviolet ray irradiation in the liquid crystal display element which was in the reverse twist arrangement state upon irradiation with ultraviolet light .

Fig. 19B is an external view showing a liquid crystal display element after applying a voltage equal to or higher than a threshold voltage to the upper and lower beta electrodes 12a and 12b and adding a longitudinal electric field to the liquid crystal layer 15. Fig.

It can be seen that the liquid crystal display element shown in the photograph on the left transitions from the spray twist arrangement state to the reverse twist arrangement state. In the liquid crystal display element shown in the right photograph, a reverse twist arrangement state is maintained.

Fig. 19C is an external view of the liquid crystal display element after heat treatment at 90 deg. C for 30 minutes. It can be seen that the reverse twist arrangement state is stably held even after the heat treatment at a high temperature of 90 占 폚.

19D shows a state in which a voltage equal to or higher than a threshold voltage for causing a reaction is applied to the lower side common electrode 12b and the first and second collective electrodes 12c and 12d and a liquid crystal display Is an appearance photograph showing a device.

Even in the photograph on the left side (the liquid crystal display element in which the ultraviolet rays are irradiated in the arrangement state of the spray twist), in the picture on the right side (the liquid crystal display element irradiated with the ultraviolet rays in the reverse twist arrangement state), the spray twist arrangement Quot; state ". < / RTI >

19A to 19D, the liquid crystal display element according to the fifth embodiment has the switching characteristics (switchability between the reverse twist arrangement state and the spray twist arrangement state) of the display due to the addition of an electric field, (Thermal stability) of the liquid crystal display device.

20 is a photomicrograph showing a liquid crystal display element (liquid crystal display element after heat treatment at 90 占 폚 for 30 minutes) showing an external view in Fig. 19c. The left side shows a micrograph of a liquid crystal display element irradiated with ultraviolet rays in a reverse twist arrangement state and the right side shows a microscope photograph of a liquid crystal display element irradiated with ultraviolet rays in a spray twist array state. A photograph of the corners of the display area is shown on the left and right, and a photograph of the edge of the display area is shown below. According to the microscopic observation, it is found that although there is fluctuation of several tens of micrometers at the boundary between the display region (reverse twist arrangement state) and the non-display region (spray twist arrangement state), the reverse twist arrangement state is stably observed in the display region have. In addition, no significant difference was found between the liquid crystal display element (photo on the left) irradiated with ultraviolet rays in the reverse twist arrangement state and the liquid crystal display element (photo on the right) irradiated with ultraviolet light in the spray twist arrangement state, It can be seen that the reverse twist array state is being stably observed.

Next, the inventors of the present invention conducted experiments on the relationship between the concentration of the ultraviolet-curable material and the memory property.

21A to 21D are photographs showing the results of an experiment on the memory stability of a liquid crystal display element to which an ultraviolet curable material is added at different addition amounts (1 wt%, 2 wt%, and 5 wt%). Similarly to the photographs shown in Figs. 19A to 19D, the photographs of the left column also show the appearance of the liquid crystal display element irradiated with ultraviolet rays in the spray twist arrangement state, and the photographs of the superior row show the reverse twist arrangement state Shows the appearance of a liquid crystal display element irradiated with ultraviolet rays. 21A to 21D, a top view is a photograph of the appearance of a liquid crystal display element produced with an addition amount of an ultraviolet curable material of 1 wt%, and a discontinuous image of a liquid crystal display element manufactured with an addition amount of an ultraviolet curable material of 2 wt% And the lower end shows an external view of the liquid crystal display element manufactured by adding 5 wt% of the ultraviolet curable material. In addition, the liquid crystal display device produced with the added amount of 1 wt% and 5 wt% had cell thickness unevenness.

21A is an external view showing a liquid crystal display element obtained by irradiating ultraviolet rays of 1 J / cm < ² > to cause a polymerization reaction and synthesizing a polymer (polymer) in the liquid crystal layer 15. Fig.

The liquid crystal display element which was in the spray twist arrangement state at the time of ultraviolet ray irradiation maintained the spray twist arrangement state even after the ultraviolet ray irradiation, and the liquid crystal display element which had the reverse twist arrangement state at the time of ultraviolet ray irradiation, It can be said that the reverse twist arrangement state of the display element is maintained even after ultraviolet irradiation.

21B is an external view showing a liquid crystal display element after applying a voltage equal to or higher than a threshold voltage to the upper and lower beta electrodes 12a and 12b and adding a longitudinal electric field to the liquid crystal layer 15. Fig.

It can be seen that the liquid crystal display elements shown in the photographs of the left column are transited from the spray twist arrangement state to the reverse twist arrangement state. In the liquid crystal display element shown in the photograph of the top row, the reverse twist arrangement state is maintained.

21C is an external view of the liquid crystal display element after heat treatment at 90 DEG C for 30 minutes. It can be seen that even after the heat treatment at a high temperature of 90 占 폚, the reverse twist arrangement state is stably kept regardless of the addition amount (1 wt%, 2 wt%, or 5 wt%) of the ultraviolet curable material.

21D is a schematic diagram showing a state in which a liquid crystal display is formed by applying a voltage equal to or greater than a minute physical quantity voltage to the lower side beta electrode 12b and the first and second collective electrodes 12c and 12d and applying a lateral electric field to the liquid crystal layer 15 Is an appearance photograph showing a device.

In the case of the photos of the left column (the liquid crystal display element in which the ultraviolet rays were irradiated in the arrangement state of the spray twist), the addition of the transverse electric field in any of the addition amounts of 1 wt%, 2 wt% and 5 wt% (Transition) to the arrangement state.

Referring to the photograph of the superior row (a liquid crystal display element in which ultraviolet rays are irradiated in a reverse twist arrangement state), with respect to the liquid crystal display element in which the addition amount of the ultraviolet curable material is 1 wt% and 2 wt%, the spray twist arrangement State. However, it can be seen that, even when a transverse electric field is applied to the liquid crystal display element of 5 wt%, the reverse twist arrangement state (transition to the spray twist arrangement state) does not occur.

From the results shown in Figs. 21A to 21D, the liquid crystal display element according to the embodiment in which the polymerizable material is added to the liquid crystal layer, the polymerizable material is polymerized, and the polymer (polymer) is synthesized in the liquid crystal layer, It can be said that it is a liquid crystal display device which is equipped with switching property (switching property between the reverse twist arrangement state and the spray twist arrangement state) and high memory property (thermal stability). However, in the case of the addition amount of 5 wt%, the liquid crystal display element irradiated with ultraviolet rays in the reverse twist arrangement state could not be transited from the reverse twist arrangement state to the spray twist arrangement state after the heat treatment, The addition amount of the material is preferably 5 wt% or less.

Further, the liquid crystal display element according to the fifth embodiment displays images with a high contrast ratio even when observed from the front as in the liquid crystal display element according to the comparative example.

The liquid crystal display element according to the fifth embodiment has a high display memory property (thermal stability) and can display display semi-permanently regardless of the temperature. Even in a high temperature environment of, for example, about 90 DEG C, The display in each arrangement state (reverse twist arrangement state, or spray twist arrangement state) can be stably viewed. Therefore, the present invention can be applied to a liquid crystal display device requiring high reliability, such as a vehicle, an aircraft, or an outdoor unit. In addition, it can be compatible with display with a high contrast ratio. Thus, the liquid crystal display element according to the fifth embodiment is a liquid crystal display element having a high display quality.

In addition, it is not necessary to irradiate ultraviolet rays with a voltage applied to the liquid crystal display element. The ultraviolet rays may be irradiated in any of two stable arrangement states (a reverse twist arrangement state or a spray twist arrangement state).

The liquid crystal display element according to the fifth embodiment is capable of driving with extremely low power consumption which can be driven by a driving method using memory property and is particularly advantageous when applied to a reflective display, In the production thereof, the same effects as those of the first embodiment can be obtained in that the cost increase factors are smaller than those of a general twisted nematic liquid crystal display device.

Next, the liquid crystal device according to the sixth embodiment will be described.

A schematic sectional view of the liquid crystal element according to the sixth embodiment is the same as Fig. The manufacturing method of the liquid crystal device according to the sixth embodiment is substantially the same as that of the first embodiment. In the sixth embodiment, the amount of indentation at the time of rubbing is set to 0.4 mm to 1.2 mm. As a result, the upper and lower alignment films 14a and 14b can exhibit a pretilt angle of about 35 DEG to 60 DEG with respect to the liquid crystal molecules. The chiral agent was added under the condition that d / p was 0.25 to 0.75.

The inventors of the present invention fabricated several liquid crystal devices with different manufacturing conditions in order to find suitable alignment conditions of the liquid crystal device. A polyimide material having a low side chain density of a material used as a vertical alignment film as an alignment film material was generally used and the firing temperature at the time of forming the alignment film and the amount of indentation at the time of rubbing were used as variable parameters. Concretely, several temperatures were set in the range of 160 ° C to 260 ° C for the firing temperature. The amount of indentation at the time of rubbing was 0.4 mm, 0.8 mm, and 1.2 mm. The film thickness of the alignment film was set to 500 Å to 800 Å. The twist angle of the liquid crystal molecules in the liquid crystal layer was set to 90 degrees or 70 degrees. The term " twist angle " as used herein refers to a conceivable angle in the spray twist state, and the actual twist angle in the reverse twist state is (180 DEG -φ). This also applies to other embodiments. The thickness of the liquid crystal layer was 4 mu m. A chiral agent was added to the liquid crystal material constituting the liquid crystal layer, and the added amount thereof was d / p of 0.167 to 0.800. The upper polarizing plate 16a and the lower polarizing plate 16b are arranged such that when the twist angle? Is 90 占, the transmission axes thereof are substantially parallel to the rubbing direction, and both are arranged in a crossed Nicol arrangement, and the twist angle? In the case of this angle of 70 °, each of the transmission axes was set at a position deviated by 10 ° from the rubbing direction, so that both were arranged in a crossed Nicol arrangement.

Fig. 22 is a view showing an observation image of a liquid crystal device in a typical manufacturing condition and a display state. Specifically, FIG. 22A is an observation image of a liquid crystal device immediately after a liquid crystal layer is partly changed from a spray twist alignment state to a reverse twist alignment state by a voltage application, and FIG. 22B is a view . As shown in Fig. 22A, it can be seen that the liquid crystal element of this example exhibits a high contrast ratio when viewed from the front. Also, as shown in Fig. 22B, it can be seen that most of the display is kept even after three months have elapsed.

23 is a diagram showing the results of evaluation of the contrast and the display holding performance in a liquid crystal device having a pretilt angle of about 46 deg. And a twist angle of 70 deg. In Fig. 23, the result of evaluating both the positive and negative sides of the front contrast and the state retention time for each liquid crystal element manufactured by setting the value of d / p of the liquid crystal layer within a range of 0.167 to 0.800 under a plurality of conditions have. Further, the firing temperature of the alignment film of each liquid crystal element was set to 200 占 폚, CB15 was used as the chiral agent, and a liquid crystal material having a relatively small value of the refractive index anisotropy? N was used. With respect to the front contrast, the liquid crystal layer was changed from the spray twist alignment state to the reverse twist alignment state by voltage application, and a change with time in the holding performance in the reverse twist alignment state was observed. As a result, it was found that the value of d / p was good in the front contrast between 0.333 and 0.500, and particularly, higher than 0.385 in contrast. When the value of d / p is in the range of 0.167 to 0.286, the transmitted light becomes dark (when dark), and when d / p is in the range of 0.615 to 0.800, the transmitted light becomes bright (display). With respect to the state retention time, d / p was 0.444 and d / p was 1.44 or more for each liquid crystal device having d / p of 0.385 and d / p of 0.421 in a liquid crystal device with d / = 0.500, the state retention time for one week or more was obtained.

24 shows the evaluation results of the temperature characteristics of the display holding performance in the liquid crystal device (the liquid crystal device in which the value of d / p is 0.444 to 0.500) having the pitch p of 8.0 占 퐉 to 9.0 占 퐉 among the conditions shown in Fig. Fig. Here, two types (R-8111 and CB15) are also used for the chiral agent. Here, the evaluation was made as to whether or not the display in the reverse twist alignment state was observed after the liquid crystal device was left under the respective temperature conditions for 24 hours. In the case of the temperature condition of 40 占 폚, all of the liquid crystal devices other than the liquid crystal device in which the chiral agent was CB15 and the pitch was 9.0 占 퐉 exhibited high display retention performance. However, in the case of the temperature condition of 50 캜, the display holding performance was lowered in some liquid crystal devices. In the case of the temperature condition of -40 ° C, the display retention performance of the liquid crystal device with a pitch of 8.0 μm was changed to R-811. It can be considered that this result is due to the change of the pitch of the chiral agent depending on the temperature condition. However, it can be seen that a high display holding performance can be obtained in a wide temperature range by selecting the type of chiral agent and the addition amount thereof have.

25 is a view showing an observation image of a liquid crystal element used for the evaluation shown in Fig. Specifically, FIG. 25A is an observation view of a liquid crystal device with a chiral R-811 and a pitch of 8.0 μm, FIG. 25B is an observation view of a liquid crystal device with a chiral R-811 and a pitch of 8.5 μm, 25D is an observation view of a liquid crystal element made of chiral agent CB15 and a pitch of 8.0 mu m, and Fig. 25E is a view of a liquid crystal element made of chiral agent CB15, pitch 9.0 lt; RTI ID = 0.0 > m. < / RTI > The pretilt angle of each liquid crystal element is about 46 degrees. It can be seen that any liquid crystal element has a high front contrast and excellent display retention performance.

Fig. 26 is a diagram showing an observation image of a liquid crystal device in which the pitch condition is set to 9 占 퐉 (short pitch condition) and 12 占 퐉 (long pitch condition). Specifically, FIG. 26A is an observation image before applying a voltage to a liquid crystal element under a short pitch condition, FIG. 26B is an observation image immediately after voltage application of a liquid crystal element under a short pitch condition, and FIG. Fig. 26D is an observation image before voltage application of the device, and Fig. 26D is an observation image immediately after the voltage application of the liquid crystal device under the long pitch condition. 26E shows the relationship between the rubbing direction and the alignment state in each liquid crystal element. The pretilt angle of each liquid crystal element is about 46 占 and the manufacturing conditions are the same as described above. As shown in Figs. 26A and 26B, the liquid crystal device under the short pitch condition has a high front contrast, and the boundaries of the electrodes are clearly shown. On the other hand, as shown in Fig. 26C and Fig. 26D, the liquid crystal device under the long pitch condition has a slightly lower front contrast, the boundaries of the electrodes appear indistinctly even though the voltage is immediately applied, have. It can be seen that the long pitch condition (d / p = 0.333) shown here is a less preferable condition when the pretilt angle is high (about 46 deg.). From these results, it can be said that it is necessary to satisfy both conditions of relatively high pretilt angle and short pitch in order to obtain stable display holding performance.

Figs. 27 to 31 are diagrams showing the optical characteristics of each liquid crystal element corresponding to the manufacturing conditions shown in Fig. 24. Fig. Specifically, FIG. 27A, FIG. 28A, FIG. 29A, FIG. 30A and FIG. 31A show visual characteristics, and FIGS. 27B, 28B, 29B, 30B and 31B show the arrangement of the rubbing direction and the transmission axis of the polarizing plate 27D, FIG. 28D, FIG. 29D, FIG. 30D, and FIG. 31D show the transmittance characteristics (T _St ) of the spray twisted state and FIGS. And the transmittance characteristic (T _ut ) in the reverse twisted state. The optical characteristics shown in Fig. 27 are those of chiral R-811 and a liquid crystal device having a pitch of 8.0 m, the optical characteristics shown in Fig. 28 are those of chiral R-811 and a liquid crystal device having a pitch of 8.5 m, The optical characteristics shown in Fig. 29 are those of chiral R-811 and a liquid crystal device with a pitch of 9.0 mu m, the optical characteristics shown in Fig. 30 are those of chiral CB15 and a liquid crystal device with a pitch of 8.0 mu m, The optical characteristics of the liquid crystal device are chiral CB15 and a pitch of 9.0 mu m. In any liquid crystal device, the firing temperature of the alignment film is 200 占 폚 (pretilt angle is about 35 占 to about 60 占) and the twist angle is 70 占. In the case of any liquid crystal device, the contrast ratio of the front surface is high (CR = 141 to 677), and in particular, the liquid crystal device having the CBL15 and pitch of 8.0 占 퐉 has high visibility without any display reversal at any viewing angle (See FIG. 30). When the pretilt angle in this condition is measured, it is found that the pretilt angle of 35 ° to 60 ° (there is a deviation in the measurement result by the measuring method) is shown.

The reason why such characteristics are exhibited is not completely understood, but it is generally considered that, in the reverse twist alignment state, a large distortion occurs in the liquid crystal layer depending on the relationship of the pretilt angle at the interface and the non-torsional force due to chiral . The liquid crystal molecules in the vicinity of the center in the layer thickness direction of the liquid crystal layer become tilted with respect to the plane of the substrate even in the voltage off state. Generally, in the reverse twist orientation state, the inclination angle at the bulk is higher than the pretilt angle at the interface. This has also been confirmed in the liquid crystal molecule orientation simulation based on the continuum theory. Each of the liquid crystal devices of the embodiment can make the tilt angle of the liquid crystal molecules to be very high near the center in the layer thickness direction of the liquid crystal layer by making the pretilt angle very high and the liquid crystal molecules stand up to a state close to the vertical alignment I guess it is not. Thus, it can be considered that a comparatively dark black display can be obtained even in the voltage direction in the front direction.

Next, for the liquid crystal element (liquid crystal element according to the sixth embodiment) manufactured under conditions which can be regarded as suitable within the above-described verification range, the manufacturing conditions and the switching state of the display state will be described. Regarding the specific production conditions, the alignment film was fired at 200 캜 for 1 hour and the film thickness was set to 500 Å to 800 Å. The amount of indentation at the rubbing treatment was set at 0.8 mm. The twist angle? Of the liquid crystal layer was 90 占 or 70 占 and the layer thickness was 4 占 퐉. As the liquid crystal material, ZLI-2293 (manufactured by Melk Co.) was used, and CB15 was used as the chiral zero. The amount of the chiral agent added was d / p = 0.5 (pitch: 8 mu m). The polarizing plate is arranged so that its transmission axis is parallel or orthogonal to the rubbing direction, and the transmission axes of the polarizing plates are substantially orthogonal to each other. In this case, the polarizing plate is disposed such that each of the transmission axes is in parallel with the rubbing direction of the alignment film of the substrate adjacent thereto.

Fig. 32 is a view showing a state in which voltage is applied to each electrode of the liquid crystal device according to the sixth embodiment and switching is performed. Fig. 32B is a view of the liquid crystal device in the initial state, and FIG. 32C is a view of the liquid crystal device after the application of the longitudinal electric field. FIG. 32A is a view showing the arrangement of the electrode pattern, And Fig. 32D is an observation view of the liquid crystal device after application of the transverse electric field. In this liquid crystal element, the electrode width of the comb-like electrode (first and second juxtative electrodes 12c and 12d) is 20 mu m and the electrode interval is 20 mu m. "Ru" in FIG. 32A indicates the rubbing direction of the upper substrate, "Rb" indicates the rubbing direction of the lower substrate, and "P" and "A" indicate the transmission axis direction of each polarizing plate.

As shown in Fig. 32B, in the state after completion of the liquid crystal element, the liquid crystal layer is in the twist alignment state of spray, and the transmitted light is in a bright state (i.e., white display). Then, as shown in Fig. 32C, after applying the longitudinal electric field to the liquid crystal layer, the liquid crystal layer shifts to the reverse twist alignment state, and the transmitted light becomes dark (i.e., black display). 32D, after applying a transverse electric field to the liquid crystal layer using the Gulch electrodes 12c and 12d, the liquid crystal layer again transitions to the twisted state of the spray, and when the transmitted light is bright as in the initial state (White display). The reason why such switching is possible can be considered as follows. In the spray twist alignment state, the liquid crystal molecules in the substantially central portion of the liquid crystal layer in the layer thickness direction are aligned in the horizontal direction, but in the reverse twist alignment state due to application of the longitudinal electric field, The liquid crystal molecules are aligned in the vertical direction. Thereafter, a transverse electric field is applied to the liquid crystal molecules at substantially the center in the thickness direction of the liquid crystal layer in the reverse twisted state by the application of the transverse electric field, whereby the liquid crystal molecules again align in the horizontal direction. This alignment direction can be considered to be a transition of the liquid crystal layer into the spray twist state since the liquid crystal molecules in the liquid crystal layer in the spray twist alignment state are in the alignment direction in which the liquid crystal molecules should exist at approximately the center in the layer thickness direction.

When the addition amount of the chiral agent of the liquid crystal device was reduced (d / p < 0.25) as a comparative example, the bulk of the liquid crystal layer in the initial state (spray twist alignment state) And it is difficult to switch between the light and dark states. It has also been found that it is difficult to obtain a light-dark state between the spray twist state and the reverse twist state even if the chirality is adjusted in response to this, in the case where the pretilt angle is made to be as high as 70 degrees or more. From this, it can be said that it is necessary to set the relationship between the addition amount of chiral agent and the pretilt angle to the above-mentioned condition in order to make both black black display and biaxial stability compatible. Here, although the pretilt angle is set to 46 deg., As is generally known, the pretilt angle in such a region is very difficult to measure and there is a margin of error in the numerical value. There is a possibility that a deviation of about ± 15 ° to 30 ° exists due to the difference in the measurement method and the problem of the degree of measurement.

According to the liquid crystal device according to the sixth embodiment, it is possible to easily realize a bright display state in which the contrast is high and a bistable display in the dark (dark) display state. In particular, the transmittance of the dark display is low, and a reliable display can be realized even when viewed from the front.

The liquid crystal display element according to the sixth embodiment is capable of driving with ultra low power consumption which can be driven by a drive method using memory property and is particularly advantageous when applied to a reflective display, Can be performed. The same effects as those of the first embodiment can be obtained in view of the fact that the cost increase factors are smaller in comparison with a general twisted nematic liquid crystal display device.

33 is a flow chart showing a method for manufacturing a liquid crystal display element according to the seventh embodiment. The inventors of the present invention have preliminarily examined conditions under which a plurality of liquid crystal display elements are fabricated in accordance with a flow chart shown in the drawing and a good display is realized.

Two transparent substrates on which transparent electrodes, for example, ITO electrodes are formed, are prepared (step S101). In this example, two test substrates each having a parallel plate type electrode were used, and two transparent substrates were cleaned and dried (step S102).

An alignment film material is coated on the transparent substrate so as to cover the ITO electrode (step S103). Application of the alignment film material was carried out using a spin coat. It may be done using Furekiso printing or inkjet printing. In this example, the side chain density of the polyimide alignment film material used for forming the vertical alignment film is usually lowered and used as the alignment film material. The control of the side chain density is intended to enable the impartation of an appropriate pretilt angle. The alignment film material was applied so that the thickness of the alignment film was 500 ANGSTROM to 800 ANGSTROM.

(Step S104), and main baking (step S105) of the transparent substrate on which the alignment film material is applied. The firing was carried out by changing the firing temperature between 160 ° C and 200 ° C. In this way, an alignment film covering the ITO electrode was formed (steps S103 to S105).

Next, a rubbing treatment (alignment treatment) is performed (step S106). The rubbing process is, for example, a process of rotating a cylindrical roll having a cloth wound thereon at a high speed to rub the alignment film, whereby the liquid crystal molecules contacting the substrate are aligned (oriented) in one direction. The rubbing treatment was carried out under the conditions of the indentation amounts of 0.4 mm, 0.8 mm and 1.2 mm. The rubbing treatment was carried out so that the twist angle of the liquid crystal display element was 70 DEG or 90 DEG.

Subsequently, in order to keep the thickness of the liquid crystal cell constant, a gap control material is dispersed on the surface of one of the transparent substrates by, for example, a dry scattering method (step S107). A plastic ball having a particle diameter of 4 [ And the thickness of the liquid crystal cell was set to 4 m.

A sealing material is printed on the other surface of the transparent substrate to form a main seal pattern (step S108). For example, a thermosetting sealing material containing glass fibers having a particle diameter of 4 탆 is printed by a screen printing method. The sealant may be applied using a dispenser. It is also possible to use a photo-curable sealant, not a thermosetting agent, and a curing-type sealant for light and heat.

The transparent substrate is polymerized (step S109). Two transparent substrates are polymerized at a predetermined position to form a cell, and heat treatment is performed in a pressed state to cure the sealing material. For example, the seal material is thermally cured using a hot press method. In this way, a public cell is produced.

For example, a nematic liquid crystal is injected into the vacant cell by a vacuum injection method (step S110). A chiral agent was added to the liquid crystal. Chiral Zero used CB15 or S-811 from Melco Corporation. The addition amount of the chiral agent was adjusted so that d / p was, for example, 0.5 to 1.2 when the chiral pitch was p and the cell thickness was d.

The liquid crystal injection hole is sealed with an end sealing material of, for example, an ultraviolet curing type (step S111). In order to arrange the orientation of the liquid crystal molecules, the cell is heated to a temperature not lower than the phase transition temperature of the liquid crystal (step S112). Thereafter, the scraper device breaks along the damage to the transparent substrate and breaks it into individual cells.

A chamfer (step S113) and cleaning (step S114) are performed on the cells that are divided in small size.

Finally, a polarizing plate is attached to the surface of the two transparent substrates opposite to the liquid crystal layer (step S115). The two polarizing plates were arranged in such a way that the direction of the transmission axis and the rubbing direction were parallel to each other. It may be arranged to be orthogonal. A power source was connected between the ITO electrodes of both transparent substrates.

Figs. 34A and 34B are photographs showing polarization microscope observation results of the display state of a plurality of manufactured liquid crystal display elements. Fig. 34A shows the display state at the time of frontal view of the liquid crystal display device manufactured under the condition that the pretilt angle is about 35 DEG and the d / p is 0.57, and the photograph of FIG. 34B shows the display state at about 45 Of the liquid crystal display element manufactured under the condition that the d / p is 0.8 and the d / p is 0.8.

In Fig. 34A, the portion that appears black (black display) is a region where a voltage is applied between the electrodes of both transparent substrates, and the portion that appears whitish (white) is a region without voltage application. The same also applies to Fig. 34B. FIG. 34B also shows an enlarged view of a whitened portion.

The whitened portion looks like a uniform white mark on the naked eye, but when viewed under a microscope, a fine-grained orientation is recognized. This can be thought of as a focal conic orientation.

Fig. 34C shows an outline of the arrangement of liquid crystal molecules in the focal conic orientation. The focal-conic orientation refers to a state in which the liquid crystal molecules take a spiral structure in the liquid crystal layer so that the axis of the spiral is parallel to the plane of the substrate (upper substrate and lower substrate).

On the other hand, in the portions shown in black in the photographs of Figs. 34A and 34B, the liquid crystal molecules repel the twisting force applied in accordance with the chiral agent, and the reverse twisted in the easy tilt direction from the relationship of the pre- It can be considered that the twist array state is indicated. The liquid crystal molecules located at the center in the thickness direction of the liquid crystal layer stand up to some extent in the vertical direction, so that the black display is obtained. In the manufacturing conditions of the liquid crystal cell shown in the photograph of FIG. 34A and the manufacturing conditions of the liquid crystal cell shown in the photograph of FIG. 34B, since the amount of the chiral agent added is relatively large, the distortion (distortion) inside the liquid crystal layer is large, It is assumed that the central molecule in the thickness direction of the layer is standing up vertically.

The produced liquid crystal display element is in the focal-conic arrangement state in the initial state. When a voltage equal to or greater than the saturation voltage value of the electro-optical characteristic is applied between the ITO electrodes of the both transparent substrates (causing a zenith electric field having an intensity equal to or higher than the threshold value voltage), a transition is made to the reverse twist arrangement state. From the photographs shown in Figs. 34A and 34B, it can be seen that in the manufactured liquid crystal display element, display is performed at a high contrast ratio even when observed from the front.

The memory characteristics of white display (focal-conic arrangement state) and black display (reverse twist arrangement state) were very stable, and microscopic arrangement of liquid crystal molecules was observed by a microscope. However, did.

35A is a diagram showing a liquid crystal display element (a liquid crystal display element showing a state shown in FIG. 34B) manufactured with a pretilt angle of about 45 degrees and a d / p of 0.8, ) ≪ / RTI > The abscissa axis of the graph represents the viewing angle when the front direction (substrate normal direction) is 0 deg. In units of degrees. The right angle of upward observation is indicated by a positive angle, and the angle of upward observation of leftward angle is indicated by a negative angle. The vertical axis of the graph indicates the transmittance in units of "%". The curved line (denoted by S-t) after the rhombic pattern shows the visual dependency of the transmittance in the focal-conic arrangement state. The curved line (denoted by U-t) after the square represents it in the reverse twist array state.

Fig. 35B shows an iso (or equal) contrast curve of a liquid crystal display element (liquid crystal display element showing a state shown in Fig. 34B) produced under the condition that the pretilt angle is about 45 deg. And d / p is 0.8.

As can be seen from Fig. 35B, for the manufactured liquid crystal display element, an iso-contrast curve that is almost symmetrical with respect to all directions is obtained. As shown in Fig. 35A, the transmittance time dependency, which is almost symmetrical to the left and right, is obtained even in the reverse twist arrangement state (black display) in the focal-conic arrangement state (white display) Can be clearly seen to have a symmetrical contrast characteristic. Thus produced liquid crystal display elements are liquid crystal display elements having excellent visual characteristics.

For comparison, FIG. 35C shows the visual contrast characteristics of the liquid crystal display element according to the embodiment of the invention disclosed in Patent Document 6. FIG. This drawing is the same as the one described in the drawing (FIG. 13 (A)) of Patent Document 6. As can be seen from Fig. 35C, in the liquid crystal display element described in Patent Document 6, the contrast ratio is asymmetrical. The liquid crystal display element preliminarily manufactured according to the flow chart (Fig. 33) showing the manufacturing method of the liquid crystal display element according to the seventh embodiment achieves the symmetry of the contrast ratio in comparison with the above invention It is excellent in visual characteristics. 35C, in the embodiment of the invention described in Patent Document 6, the contrast ratio at the time of frontal observation is slightly larger than 3, and in the graph shown in FIG. 35A, in accordance with the flow chart shown in FIG. 33 The contrast ratio in the frontal view of the manufactured liquid crystal display device is calculated to be slightly smaller than 4. In this way, when viewed from the front, the visual characteristics are excellent even in that display can be performed with a high contrast ratio. These features (height of display quality) are also equipped with a liquid crystal display element (described later) according to the seventh embodiment.

The present inventors have studied, for example, a condition in which a reversed twist arrangement state and a focal-conic alignment state are realized by physically giving a physical action to a liquid crystal layer, so that the arrangement states of the liquid crystal molecules become stable together.

Fig. 36 is a graph showing the conditions for enabling the reverse twist arrangement state and the bistable state in the focal-conic arrangement state to be realized. The horizontal axis of the graph represents the pretilt angle in units of 占 and the vertical axis represents the addition amount of the chiral agent by d / p.

In the figure, in the combination of the pretilt angle and the d / p in the range below the curve obtained by the rhombus, the focal-conic arrangement state does not appear. That is, when the addition amount of the chiral agent is too small, the spray twist arrangement state is displayed instead of the focal conic arrangement state.

Also, in the combination of the pretilt angle and the d / p in the range above the curve following the square, the focal-conic arrangement is always maintained. That is, if the added amount of the chiral agent is too large, the phase transition from the focal-conic arrangement state to the reverse twist arrangement state can not be made.

The curve moves somewhat up and down according to the anchoring strength of the interface and the elastic constant of the liquid crystal. However, in the combination of the pretilt angle and the d / p in the range between the curves, the reverse twist arrangement state and the A bistable state is realized. The reverse twist arrangement state and the bistable state in the focal-conic arrangement state are special states that appear when the chirality of the chirality is controlled within a certain range.

34A and 34B show the display state, and FIGS. 35A and 35B show the pretilt angle (about 45 DEG) and the d / p (0.8) of the liquid crystal display element showing the visual characteristics.

From the results shown in this drawing, it can be seen that the closer the pretilt angle is to the vertical, the more likely the focal-conic arrangement state is obtained even if the value of d / p is low. According to the experiment repeatedly conducted by the inventors of the present invention, even if the pretilt angle is low, when the orientation of the liquid crystal molecules is made close to vertical by the voltage, the state of the focal conic arrangement is observed. If the value is relatively high, the focal-conic arrangement state does not appear.

The reason why the reverse twist arrangement state and the focal-conic arrangement state of the bistable state are realized is that alignment treatment is performed in which both the upper and lower substrates sandwiching the liquid crystal layer express a pretilt angle of 20 DEG or more and 85 DEG or less, It can be said that the chiral agent is added to the liquid crystal layer in a range where d / p is 0.5 or more and 2 or less. When alignment treatment is performed so that a pretilt angle of not less than 35 DEG and not more than 55 DEG is generated in both of the upper and lower substrates, when a chiral agent is added in a range in which d / p is not less than 0.5 and not more than 1.2, It can be said that a bistable state in a reverse twist arrangement state and a focal-conic arrangement state is feasible.

The inventors of the present invention produced a liquid crystal display element according to the seventh embodiment based on the above preliminary consideration.

A schematic sectional view in one pixel of the liquid crystal display element according to the seventh embodiment is the same as in Fig.

A chiral agent is added to the liquid crystal material forming the liquid crystal layer 15. The alignment state of the liquid crystal molecules in the liquid crystal cell completion state (initial state) was a focal-conic arrangement. The arrangement state of the liquid crystal molecules can be shifted from the focal conic arrangement to the reverse twist arrangement by applying an AC voltage equal to or higher than the threshold voltage between the two beta electrodes 12a and 12b by the power source 20 .

The configuration and manufacturing method of the liquid crystal display element according to the seventh embodiment will be described in detail with reference to Figs. 37 to 41. Fig.

37 is a schematic plan view showing a pattern of an ITO film formed on the upper transparent substrate 11a. For example, a pixel electrode (an electrode for forming the upper-side beta electrode 12a for each pixel) and an extraction electrode for the pixel electrode are formed with the ITO film shown in the figure.

The ITO film pattern is formed, for example, in such a manner that the ITO film extends in a stripe shape in the left and right direction in the drawing. For this figure, 12A are shown attached to the sign of the ₁ ~ 12A ₁₀ to the ITO film constituting the pixel electrode.

The patterning of the ITO film was performed by using a photolithography process after cleaning the ITO glass substrate. Etching of ITO was carried out by wet etching using ferric chloride. It is also possible to perform patterning by irradiating a laser beam and removing the ITO film.

38 is a schematic plan view showing a pattern of the ITO film formed on the lower transparent substrate 11b. As the ITO film shown in the figure, for example, pixel electrodes (electrodes for forming the lower-side beta electrodes 12b for each pixel) and extraction electrodes for the pixel electrodes are formed.

The ITO film pattern is formed, for example, in such a manner that the ITO film extends in a stripe shape in the vertical direction of the drawing. In this drawing, a part of the ITO film constituting the pixel electrode is indicated by 12B ₁ to 12B ₉ . The vertical direction in the drawing and the horizontal direction in Fig. 37 are directions perpendicular to each other.

The patterning of the ITO film can be performed by the same method as the method of forming the ITO film pattern described with reference to Fig.

After the ITO film is patterned, an insulating film 13 is formed on the lower transparent substrate 11b including the ITO film. The insulating film 13 is not formed, for example, in the extraction electrodes 12BT ₁ to 12BT ₉ (terminal portions). In this drawing, hatched lines are shown in regions where the insulating film 13 is not formed. The insulating film 13 can be formed by a method in which a resistor is formed on a lead-out electrode portion or the like, a lift-off resistor is removed after forming an insulating film, or a method in which a sputtering is performed while covering a lead- Do. In addition, the insulating film 13 may be an inorganic insulating film such as an organic insulating film or SiO₂, SiN _x. Or a combination thereof. In this case, a laminated film of an acrylic organic insulating film and SiO2 was used as the insulating film 13.

In the seventh embodiment, a heat resistant film (polyimide tape) was attached to the extraction electrode portion and the organic insulating film was spin-coated (spinning at 2000 rpm for 30 seconds) to a film thickness of 1 m. Subsequently, the lower transparent substrate 11b having the organic insulating film spin-coated was baked at 220 DEG C for 1 hour at a high temperature in a clean oven, and then the lower transparent substrate 11b was heated to 80 DEG C with the heat resistant film adhered thereon, A SiO 2 film was formed to have a thickness of 1000 ANGSTROM by a sputtering method (AC discharge). The SiO 2 film may be formed by a vacuum deposition method, an ion beam method, a CVD method, or the like.

When the heat-resistant film was peeled off, the organic insulating film and the SiO 2 film could be removed from the adhesive portion of the heat-resistant film. Subsequently, in order to improve the insulating property and transparency of the SiO2 film, the lower transparent substrate 11b was baked at 220 DEG C for 1 hour at a high temperature in a clean oven.

The formation of the SiO 2 film is not essential, but the insulating property of the insulating film 13 can be improved by forming the SiO 2 film. In addition, it is possible to improve the adhesion and the patterning property of the first and second collecting electrodes 12c and 12d formed on the insulating film 13.

The insulating film 13 may be formed of only the SiO ₂ film without forming the organic insulating film. Since the SiO ₂ film tends to become porous, in this case, the thickness of the SiO ₂ film is preferably 4000 Å to 8000 Å. Or an inorganic insulating film 13 composed of a lamination of an SiO ₂ film and an SiN _x film.

An ITO film was formed on the insulating film 13. The ITO film was formed on the entire surface of the substrate by heating the lower transparent substrate 11b at 100 占 폚 and applying a sputtering method (alternating-current discharge). The film thickness was set to about 1200 ANGSTROM. The ITO film may be formed using a vacuum deposition method, an ion beam method, a CVD method, or the like. The ITO film was patterned by a photolithography process to form a first joyful electrode 12c, a second joyful electrode 12d, and extraction electrodes for these electrodes 12c and 12d.

39 is a schematic plan view showing a photomask used for etching an ITO film. The photomask includes a portion corresponding to the first joyful electrode 12c, a portion corresponding to the second joyful electrode 12d, a portion corresponding to the extraction electrode of the first joyful electrode 12c, a portion corresponding to the extraction electrode of the second joyful electrode 12d, And a portion corresponding to the extraction electrode of the lower side beta electrode 12b. At the time of etching, an electrode is formed from an ITO film covered at each corresponding portion. The inventors of the present invention have found that when the electrode widths of the comb tooth-shaped electrode comb tooth portions are 20 mu m and 30 mu m, and when the comb tooth portions of the two comb tooth-shaped electrodes are alternately arranged, a plurality of electrode intervals of 20 mu m, 30 mu m, 50 mu m, 100 mu m, The first and second juliet electrodes 12c and 12d were fabricated by using the electrode pattern of FIG.

After the above-described steps, two electrode-attached substrates were prepared (step S101 in FIG. 33). The two electrode-adhered substrates are cleaned and dried (step S102). In the case of washing, pure water rinse is performed. It may be done with detergent. Brush cleaning, or spray cleaning. Thereafter, it is dewatered and dried. It is possible to carry out UV cleaning and IR drying as a method other than washing with water.

An alignment film material was coated on the two electrode-coated substrates so as to cover the ITO electrodes (step S103). Application of the alignment film material was carried out using a spin coat. It may be done using Furekiso printing or inkjet printing. In general, the polyimide alignment film material used for forming the vertical alignment film has a lower side chain density and is used as an alignment film material. This is the same material as the alignment film material used for the liquid crystal display device manufactured for the preliminary consideration. The alignment film material was applied so that the thickness of the alignment film was 500 ANGSTROM to 800 ANGSTROM. (Step S104) and main baking (step S105) of an electrode-attached substrate on which an alignment film material was applied were performed. The firing was carried out in a clean oven at 180 ° C for 1 hour. And may be carried out at a temperature of 160 ° C or higher and 180 ° C or lower. Thus, an alignment film covering the ITO electrode was formed (steps S103 to S105).

Fig. 40 is a schematic plan view showing a part of the formation area of the lower alignment film 14b formed on the lower substrate 10b. The lower alignment film 14b is formed, for example, in the region where the first and second juliec electrodes 12c and 12d are arranged and the pixel is fixed. In this drawing, only the upper left portion is shown as the formation region of the lower side orientation film 14b, but the same applies to the other arrangement regions of the glowing electrodes 12c and 12d.

Next, a rubbing treatment (alignment treatment) was performed (step S106). The rubbing treatment is carried out in such a manner that the amount of indentation is set to 0.8 mm and both the upper alignment film 14a and the lower alignment film 14b are stretched by 20 ° or more and 85 ° or less such as 35 ° or more and 55 ° or less, Angles. Further, the twist angle of the liquid crystal display element was set to 90 degrees.

The pretilt angle in this region is very difficult to measure, and the numerical value of 45 占 may possibly include a small error. There is a possibility that a deviation of about ± 15 ° to ± 30 ° exists due to a difference in measurement method or a problem of measurement accuracy.

In order to make the cell thickness 4 mu m, a gap control material having a particle diameter of 4 mu m was scattered on one substrate surface (step S107). It is also possible to disperse a gap control material having a particle diameter of 3 占 퐉 or more and 5 占 퐉 or less in order to make the cell thickness from 3 占 퐉 to 5 占 퐉. A sealing material was printed on one substrate surface to form a main seal pattern (step S108). The two substrates were polymerized at a predetermined position (step S109), and the seal material was cured.

The polymerization of the two substrates is carried out in such a manner that when the rubbing direction of the upper alignment film 14a is the first direction and the rubbing direction of the lower alignment film 14b is the second direction, (The upper side), the direction of 90 degrees in the right turn direction with respect to the first direction.

A nematic liquid crystal was injected by a vacuum injection method (step S110). As the liquid crystal material, a low refractive index anisotropic material having a refractive index anisotropy? N of 0.067 was used. A chiral agent was added to the liquid crystal. We used CB15 of Melchor Co., Ltd. The addition amount of the chiral agent was adjusted so that d / p was 0.8 (p = 5 m) when the chiral pitch was p and the cell thickness was d. When the alignment treatment is performed so that a pretilt angle of not less than 20 DEG and not more than 85 DEG is formed on the upper and lower alignment films 14a and 14b according to the pretilt angle, d / p is not less than 0.5 but not more than 2, And may be 0.5 or more and 1.2 or less when orientation treatment is performed so that a pretilt angle of 55 DEG or less is expressed.

The liquid crystal injection port is sealed with an ultraviolet curing type end seal material (step S111), and the cell is heated to a temperature equal to or higher than the phase transition temperature of the liquid crystal (step S112). Thereafter, breakage was carried out along the damage to the transparent substrate with the scribe apparatus, and the cells were divided into individual cells. A chamfer (step S113) and cleaning (step S114) were performed on the cells divided in small size.

Finally, a polarizing plate was attached to the surface of the two substrates opposite to the liquid crystal layer (step S115). The two polarizing plates were arranged in such a way that the direction of the transmission axis and the rubbing direction were parallel to each other. It may be arranged to be orthogonal. Power was connected to the ITO electrodes (upper and lower side electrodes 12a and 12b, and first and second collective electrodes 12c and 12d) on both substrates.

41 is a schematic plan view showing the structure of a liquid crystal display element according to the seventh embodiment. In Fig. 41, the structures shown in Figs. 37 to 40 are all polymerized. One pixel is defined by transverse electrodes extending in the lateral direction and vertical electrodes extending in the vertical direction. For this figure, indicates the sign of the paste 12A ₁ ~ 12A ₁₀ to the longitudinal electrodes, are shown attached to the sign of the 12B ₁ ~ 12B ₉ in a part of the longitudinal electrode. What is indicated by an arrow is a pixel which is defined in a region in which the transverse electrode 12A ₉ and the longitudinal electrode 12B ₈ overlap in the substrate normal direction. The transverse electrode 12A ₉ in this pixel corresponds to the upper side beta electrode 12a in Fig. 1 and the longitudinal electrode 12B ₈ corresponds to the lower side beta electrode 12b.

42A to 42C are external views of the liquid crystal display element according to the seventh embodiment. 42A to 42C illustrate the case where the electrode width of the fun portion of the first and second collective electrodes 12c and 12d is 20 mu m and the collective portions of the both of the collective electrodes 12c and 12d are alternately arranged. And the area of the liquid crystal display element in which the glowing electrodes 12c and 12d are formed with a gap of 20 mu m.

Fig. 42A shows an external view of a state in which the liquid crystal display element is completed (initial state). As to the initial state, the liquid crystal molecules are in the focal-conic arrangement state. A uniform white display was obtained with the naked eye.

In this state, a voltage was applied between the upper and lower beta electrodes 12a and 12b. By application of a voltage to both the electrodes 12a and 12b, a longitudinal electric field is generated in the liquid crystal layer 15. [

FIG. 42B is a photograph of the appearance after voltage is applied to the electrodes 12a and 12b. The entire transition from the focal-conic array state to the reverse twist array state can be seen. Also, it can be seen that black display is obtained from the front view. On the contrary, it is confirmed that a vertical electric field is generated in the liquid crystal layer 15 by application of a voltage to both the electrodes 12a and 12b.

Next, a transverse electric field was generated in the liquid crystal layer 15 in the FFS mode.

FIG. 42C is an external view of the liquid crystal display element in the state shown in FIG. 42B after it is driven in the FFS mode. It can be seen that the front is re-entering the initial state (the focal-conic arrangement state).

The liquid crystal display element according to the seventh embodiment is a liquid crystal display element capable of switching between a focal-conic arrangement state and a reverse twist arrangement state. The electrons can be transited to the latter by application of the seed electron field. Further, the latter can be changed to electrons by application of a transverse electric field. As a method of transiting the reverse twist array state into the focal-conic array state, driving in the IPS mode can be adopted in addition to driving in the FFS mode.

When a longitudinal electric field is added to the liquid crystal layer in a focal-criconic alignment state in which the liquid crystal molecules spiral in the in-plane direction, the liquid crystal molecules positioned at the center in the thickness direction of the liquid crystal layer are aligned in the vertical direction . Thus, it can be considered that switching from the focal-conic arrangement state to the reverse twist arrangement state is performed. It can be considered that switching from the reverse twist arrangement state to the focal-conic arrangement state is performed by dispersing the liquid crystal molecular alignment at the interface in the reverse twist arrangement state by the addition of the transverse electric field.

The liquid crystal display element according to the seventh embodiment is a liquid crystal display element in which the focal-conic arrangement state and the reverse twist arrangement state transit with each other and the state is stably observed according to the direction of the electric field to be added. The white display state in which the contrast is high and the bistable display in the black display state can be easily realized. Particularly, it is possible to realize a display in which the black display is dark and clearly viewed even when viewed from the front. Therefore, the present invention can be suitably applied to any of a transmissive display, a transmissive display, and a reflective display. The liquid crystal display element according to the seventh embodiment is a liquid crystal display element having a contrast ratio that is symmetrical to the left and right.

In the liquid crystal display element according to the seventh embodiment, display using, for example, memory characteristics is possible. Pixels for which white is to be displayed are arranged in a focal-conic arrangement, and pixels for displaying black are arranged in a reverse twist arrangement. At least the subpixel electric field is added to the pixel to be changed from the white display to the black display. It is also possible to apply a subfield to the pixel for which the black display is desired to be maintained. Conversely, a lateral electric field is added to at least a pixel to be changed from a black display to a white display. It is also possible to apply a transverse electric field to a pixel which wants to maintain a white display.

The liquid crystal display element according to the seventh embodiment can be driven as in the second embodiment. The display can be semi-permanently viewed and compatible with the high contrast ratio.

The liquid crystal display element according to the seventh embodiment is capable of driving with ultra low power consumption which can be driven by a drive method using memory property and is particularly advantageous when applied to a reflective display, In the production thereof, the same effects as those of the first embodiment can be obtained in that the cost increase factors are smaller than those of a general twisted nematic liquid crystal display device.

The present invention has been described above based on the examples and the like, but the present invention is not limited to these examples.

For example, in the first embodiment or the like, the polarizing plate is arranged in cross-Nicol arrangement so as to form a liquid crystal display element of non-married white display. Alternatively, the polarizing plate may be arranged in parallel Nicol and may be a liquid crystal display element of no-marie black display. It is easy to realize a display with a high contrast ratio only in non-mariable white. In the case of the normally white display, the angle formed by the transmission axis direction of the upper and lower polarizers 16a and 16b is preferably near 90 deg. In order to obtain a good black display.

In the embodiments, the alignment treatment is performed by rubbing. However, the alignment treatment can be performed by using other alignment treatment methods such as the photo alignment method and the oblique direction deposition method.

In the embodiment, electrodes for causing a transverse electric field are formed on all or part of the liquid crystal layer 15 (pixel region) only in the lower substrate 10b. However, not only the lower substrate 10b, but also the upper substrate 10a, Can also be formed. The electrode causing the transverse electric field may be formed on at least one of the upper substrate 10a and the lower substrate 10b.

In the fifth embodiment, a polymerizable material was added under the condition that the mass of the liquid crystal layer 15 was 1 wt%, 2 wt%, and 5 wt%. The effect is not limited to the range of 1 wt% to 5 wt%, and even if the addition amount of the polymerizable material is in the range of 0.5 wt% to 5 wt%, the same effect can be obtained.

It will be apparent to those skilled in the art that various changes, improvements, combinations, and the like are possible.

The present invention can be used in all areas of liquid crystal devices, for example, in general liquid crystal display devices that perform simple matrix driving. It is also applicable to a liquid crystal display device which requires low power consumption, wide viewing angle characteristics, and low cost.

It is preferably applicable to reflective, transmissive, and projection displays such as display surfaces of information devices (personal computers, portable information terminals, and the like) that do not require frequent rewriting due to power saving Do. It can also be used for information display surfaces of magnetic recording or electrically recorded cards, children's toys, electronic papers, and the like.

It can also be used for displays to maintain display even during power outages caused by disasters.

10a upper substrate
10b Lower substrate
11a upper transparent substrate
11b lower transparent substrate
12a upper beta electrode
12b lower beta electrode
12c < / RTI >
12d < / RTI >
13 insulating film
14a upper alignment film
14b lower alignment film
15 liquid crystal layer
16a upper polarizer
16b lower polarizer
20 Power
21 Slit electrode
21a slit
22, 22a common line
23 scanning lines
24 semiconductor film
25 source electrode
26, 26a drain electrode
27 signal line
28 insulating film
31 to 33 driver
34 pixel portion

Claims (5)

The first substrate and the second substrate which are subjected to alignment treatment on their respective surfaces,
And the liquid crystal layer provided between one surface of the first substrate and one surface of the second substrate,
Wherein the first substrate and the second substrate set the direction of the alignment treatment so that the liquid crystal molecules of the liquid crystal layer cause a first alignment state in which the liquid crystal molecules are twisted in the first direction, , The pretilt angle given to the liquid crystal molecules of the liquid crystal layer is 35 DEG or more,
Wherein the liquid crystal layer contains a chiral agent capable of causing a second alignment state in which the liquid crystal molecules are twisted in a second direction opposite to the first direction,
Wherein the chiral agent is added so that the ratio d / p of the chiral pitch to the layer thickness d of the liquid crystal layer is 0.25 or more and 0.75 or less. The liquid crystal element according to claim 1, wherein the liquid crystal layer has a twist angle in a range from 70 DEG to 90 DEG in the second alignment state. Further comprising electric field applying means for applying an electric field to the liquid crystal layer,
An electric field is applied to each of the first substrate and the second substrate in a direction substantially perpendicular to the liquid crystal layer so that the liquid crystal layer transits to the first alignment state by the electric field applying means, 3. The liquid crystal element according to claim 1 or 2, wherein an electric field is applied in a direction substantially parallel to the substrate and the one surface of the second substrate to cause the liquid crystal layer to transition to the second alignment state. The liquid crystal device according to claim 1, wherein the pretilt angle is smaller than 70 deg.. A liquid crystal display device comprising a plurality of pixel portions, each of the plurality of pixel portions comprising the liquid crystal device according to any one of Claims 1 to 4.

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