KR20130084623A - Liquid crystal device and drive method thereof - Google Patents

Abstract

PURPOSE: A liquid crystal device and a driving method thereof are provided to made favorable or various indications by including a chiral agent in a liquid crystal layer. CONSTITUTION: A liquid crystal device comprises a first substrate (10a), second substrate (10b), and a liquid crystal layer (15). The second substrate faces the first substrate. The liquid crystal layer is arranged between the first substrate and the second substrate and comprises a chiral agent. The liquid crystal layer forms different two liquid crystal molecule arrangement. [Reference numerals] (10a) Upper substrate; (10b) Lower substrate; (11a) Upper transparent substrate; (11b) Lower transparent substrate; (12a) Upper beta electrode; (12b) Lower beta electrode; (12c,12d) First ctenidium electrode; (13) Second ctenidium electrode; (14a) Upper alignment layer; (14b) Lower alignment layer; (15) Liquid crystal layer; (16a) Upper polarizing plate; (16b) Lower polarizing plate; (20) Power supply

Description

Liquid crystal device and drive method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to liquid crystal devices, in particular liquid crystal devices comprising an optically active material (chiral agent) in the liquid crystal layer and a driving method thereof.

The twisting direction (first turning direction) of the liquid crystal molecules determined by the combination of the alignment treatment direction and the pre-tilt angle of the pair of alignment films, and the twisting direction of the liquid crystal molecules caused by the chiral agent (second turning) Direction) and the liquid crystal molecules are twisted in the respective directions (first turning direction) by applying a voltage above the saturation voltage of electro-optical properties, for example, to the liquid crystal layer by physical action, for example, to the liquid crystal layer. Is a reverse twisted nematic (RTN) type liquid crystal display device in which the reverse twisted arrangement state with respect to the second twist direction and the spray twist arrangement state with respect to the second turning direction are realized in a flexible manner. Call. The first turning direction is a turning direction in which liquid crystal molecules are twisted when no chiral agent is 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 device described in Patent Document 1, the arrangement state in which the liquid crystal molecules are twisted in the first turning direction is unstable. It is possible to obtain an array state that is twisted in the first turning direction by application of a high voltage, but as time passes, the liquid crystal molecules transition to an array state that is twisted in the second turning direction.

While adding a chiral agent that turns the liquid crystal molecules in the second turning direction, by arranging the liquid crystal molecules in the first turning direction by combination of the alignment directions of the substrates, the distortion in the liquid crystal layer is increased, and the driving voltage is greatly increased. Patent Literature 2 discloses an invention of a reverse twisted nematic liquid crystal device capable of a significant reduction. However, in the invention described in Patent Literature 2, the application of the voltage that causes the transition from the arrangement state twisted in the second turning direction to the arrangement state twisted in the first turning direction is stopped, and a few seconds later, the original arrangement state (first Since the liquid crystal element is re-translated in an array state twisted in two swing directions, when driving the liquid crystal element in an array state twisted in a second swing direction, there is a problem that a high driving voltage is required.

In the reverse twisted nematic liquid crystal display device, in general, the liquid crystal molecules are twisted in the first turning direction (reverse twist arrangement) and in the second twisting direction (spray twist arrangement). There is no big difference in the appearance of appearance, and high contrast ratio (transmittance ratio) even when given bistable stability (reverse twist arrangement state and spray twist arrangement state are almost the same in energy and stable in the case of no voltage applied) There is a problem that it is difficult to obtain the difference).

Orientation treatment is performed so that the angle formed by the rubbing direction is greater than 90 ° and less than 120 ° between the upper and lower substrates, 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. Patent Literature 3 discloses an invention of a reverse twisted nematic liquid crystal display device. The reverse twisted nematic liquid crystal display device of patent document 3 is excellent in sharpness with respect to any temperature compared with the normal twisted nematic liquid crystal display device. Further, due to the good sharpness, particularly in simple matrix drive liquid crystal display devices, high duty driving is possible or the contrast is high when driven at the same duty. In addition, a simple matrix driven liquid crystal display element is faster than a normal twisted nematic liquid crystal display element at low temperature, and transmittance is not lowered at off voltage even in a high temperature environment, and bright display can be realized. The LCD has advantages of both liquid crystal display devices using a thin film transistor (TFT).

The liquid crystal display device described in Patent Literature 3 is extremely stable in the reverse twist arrangement, and the electro-optical characteristics in that state are superior to the ordinary twisted nematic liquid crystal display device. However, the invention is not an invention that actively uses the bistable stability of the reverse twist arrangement and the spray twist arrangement.

Patent Document 4 discloses an invention of a liquid crystal device in which display is performed by using a transition between a reverse twist arrangement state and a spray twist arrangement state. In the liquid crystal element of patent document 4, each arrangement state can be switched with each other. However, the display by each arrangement state is optional. For example, black display and white display, although gray display (midtone display) cannot be performed.

Patent Document 5 describes the invention of a liquid crystal display panel in a FFS mode (fringe field switching mode) using a TFT. According to invention of patent document 5, the substantial aperture ratio of a liquid crystal display panel can be improved, the brightness and contrast of a display can be improved, and display quality can be improved. Although the structure shown in patent document 5 is applicable to the liquid crystal element which has a parallel alignment liquid crystal layer which does not contain a chiral agent, For example, it displays by switching two stable arrangement states of patent document 4, It is not suitable for the reverse twisted nematic liquid crystal display device. Patent Document 5 does not describe the halftone display.

When driving in FFS mode, it is common to make a liquid crystal layer into parallel orientation. In addition, it is common to use a blazing electrode connected to a TFT as a pixel electrode, and as a common electrode, a beta electrode is generally provided below the blazing electrode. In this case, many electrodes are not formed in a counter substrate.

Patent Document 6 discloses an invention of a reverse twisted nematic liquid crystal display device having a relatively low pretilt angle of 20 ° or more and 45 ° or less by the inventors of the present invention. When the chiral pitch is p and the thickness of the liquid crystal layer is d, for example, a relatively small chiral agent is added to the liquid crystal display so that d / p is greater than 0.04 and less than 0.25. The liquid crystal display device described in Patent Literature 6 is a reverse twisted nematic liquid crystal display device capable of bistable display in a reverse twisted arrangement state and a spray twisted arrangement state, high memory performance, relatively high contrast ratio, and electrical switching.

The liquid crystal display element of patent document 6 is a liquid crystal display element with high display quality in which high contrast ratio was implement | achieved. However, it cannot be said that the contrast at the time of frontal observation is high. This is relatively preferable when used as a reflective display, but is not necessarily desirable when used as a transmissive display.

In addition, for example, the memory at room temperature is high, but at a temperature different from room temperature, the display by the reverse twist arrangement may not be maintained, and in particular, it is difficult to hold it at a high temperature of 60 ° C or higher. . Therefore, depending on the application, when used as a liquid crystal display device for vehicle mounting, aircraft, or outdoors, for example, the memory performance of the display may be insufficient.

[Patent Document 1] Japanese Patent No. 2510150 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-293278 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-186045 [Patent Document 4] Japanese Patent Application Laid-Open No. 2011-107376 [Patent Document 5] Japanese Patent No. 4238877 [Patent Document 6] Japanese Patent Application Laid-Open No. 2011-203547

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

According to 1 aspect of this invention, it is arrange | positioned between a 1st board | substrate, a 2nd board | substrate arrange | positioned facing an electric 1st board | substrate, and an electric 1st board | substrate and an electric 2nd board | substrate, and are made of chiral In addition, a liquid crystal device having a liquid crystal layer that realizes two different liquid crystal molecule arrangement states in a flexible manner is provided.

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

1 is a schematic cross-sectional view showing a liquid crystal display device according to the first embodiment.
FIG. 2 is a schematic plan view showing a photomask used for etching an ITO film.
3A to 3E are schematic cross-sectional views showing electric field directions when voltage is applied.
4A to 4C are photographs of the external appearance of the liquid crystal display device according to the first embodiment.
5A to 5C are graphs showing optical characteristics of the liquid crystal display device according to the first embodiment.
6A to 6C are photographs of the liquid crystal display device in which a longitudinal electric field is added to part of the liquid crystal layer.
FIG. 7: is schematic sectional drawing which shows the other example (modification) of the formation aspect of 1st, 2nd blade electrode 12c, 12d.
FIG. 8A is a schematic diagram showing the liquid crystal display device according to the second embodiment, and FIG. 8B is a schematic plan view showing the electrode structure of the pixel portion 34.
9A and 9B are schematic sectional views and a plan view respectively showing a liquid crystal display device according to a third embodiment.
10A to 10G are schematic cross-sectional views showing the manufacturing method of the liquid crystal display device according to the third embodiment.
11A to 11D are schematic sectional views showing the manufacturing method of the liquid crystal display device according to the third embodiment.
FIG. 12A is a photograph showing a pixel region after completion (initial state) of the liquid crystal display device according to the third embodiment, and FIG. 12B shows a voltage between the common electrode 12a and the lower beta electrode 12b. It is a photograph which shows the pixel area after applying and adding the electric field to the liquid crystal layer 15. FIG.
13A and 13B are schematic sectional views and a plan view respectively showing a liquid crystal display device according to a fourth embodiment.
14A to 14G are schematic cross-sectional views showing the manufacturing method of the liquid crystal display device according to the fourth embodiment.
15A to 15E are schematic sectional views showing the manufacturing method of the liquid crystal display device according to the fourth embodiment.
FIG. 16: is a table | surface which shows the result of having investigated the holding property of the display when a liquid crystal layer is in a reverse twist arrangement state with respect to some temperature.
Fig. 17 is a graph showing the temperature dependence of the pitch length made of chiral.
Fig. 18 is a table showing the results of further investigation of the temperature dependence of the display holding (memory) according to the reverse twist arrangement.
19A to 19D are photographs showing the results of experiments on the memory stability of the liquid crystal display device in which 2 wt% of an ultraviolet curable material is added.
FIG. 20 is a micrograph showing the liquid crystal display device (the liquid crystal display device after performing a heat treatment for 30 minutes at 90 ° C.) showing an external photograph in FIG. 19C.
21A to 21D are photographs showing the results of experiments on the memory stability of the liquid crystal display device to which the ultraviolet curable material is added at different amounts (1 wt%, 2 wt%, 5 wt%).
Fig. 22 is a diagram showing an observation image of liquid crystal elements in typical production conditions and display states.
FIG. 23 is a diagram showing evaluation results of contrast and display holding performance in a liquid crystal element having a pretilt angle of about 46 degrees and a twist angle of 70 degrees.
FIG. 24 shows evaluation results of the temperature characteristics of display holding performance in a liquid crystal element (a liquid crystal element having a value of d / p of 0.444 to 0.500) having a pitch p of 8.0 μm to 9.0 μm among the conditions shown in FIG. 23. It is a figure which shows.
FIG. 25: is a figure which shows the observation image of the liquid crystal element used for evaluation shown in FIG.
Fig. 26 is a diagram showing an observation image of a liquid crystal element in which the pitch conditions are 9 μm (short pitch condition) and 12 μm (long pitch condition).
FIG. 27 is a diagram illustrating optical characteristics of each liquid crystal element corresponding to the fabrication conditions shown in FIG. 24.
FIG. 28 is a diagram showing optical characteristics of each liquid crystal element corresponding to the fabrication conditions shown in FIG.
FIG. 29 is a diagram showing the optical characteristics of each liquid crystal element corresponding to the fabrication conditions shown in FIG.
FIG. 30 is a diagram showing optical characteristics of each liquid crystal element corresponding to the fabrication conditions shown in FIG. 24.
FIG. 31 is a diagram showing optical characteristics of each liquid crystal element corresponding to the fabrication conditions shown in FIG. 24.
Fig. 32 is a diagram showing a state when a voltage is applied to each electrode and switched to the liquid crystal element according to the sixth embodiment.
FIG. 33 is a flow chart showing a manufacturing method of the liquid crystal display device according to the seventh embodiment.
34A and 34B are photographs showing polarization microscopic observation results in a display state of a plurality of produced liquid crystal display elements, and FIG. 34C is a diagram showing an outline of liquid crystal molecule arrangements in focal conic orientation. .
35A and 35B show the angle of 0 °-for a liquid crystal display device (liquid crystal display device shown in FIG. 34B) manufactured under the condition that the pretilt angle is about 45 ° and the d / p is 0.8. Fig. 35C is a graph showing the transmissivity visual dependence of the 180 ° azimuth (left-right orientation), and an equal contrast curve, and Fig. 35C is a time-contrast of the liquid crystal display device according to the embodiment of the invention described in Patent Document 6. Graph showing characteristics.
Fig. 36 is a graph showing conditions capable of realizing a reverse twisted arrangement state and a bistable state of a focal conic arrangement state.
FIG. 37 is a schematic plan view showing a pattern of the 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.
Fig. 39 is a schematic plan view showing a photomask used for etching an ITO film.
40 is a schematic plan view showing a part of the formation region of the lower alignment film 14b formed on the lower substrate 10b.
Fig. 41 is a schematic plan view showing the structure of the liquid crystal display device according to the seventh embodiment.
42A to 42C are external appearance photographs of the liquid crystal display device according to the seventh embodiment.

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

First, the manufacturing method of the liquid crystal display element by a 1st Example is demonstrated.

A transparent conductive film, for example, a transparent substrate on which an ITO film was formed, for example, a glass substrate (two upper transparent substrates 11a and a lower transparent substrate 11b) was prepared, and these were washed.

The ITO film on the upper transparent substrate 11a was patterned using the photolithography process, and the upper beta electrode 12a was formed on the upper transparent substrate 11a. Patterning was performed so that an ITO film remained in the extraction electrode part (terminal part) and the part corresponding to the pixel of a display. The etching of the ITO film was performed by wet etching using the second iron chloride. Moreover, you may pattern by irradiating a laser beam and removing the ITO film | membrane of an irradiation position.

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

After the lower beta electrode 12b was formed, the insulating film 13 was formed on the lower transparent substrate 11b including the lower beta electrode 12b. The insulating film 13 is not formed in, for example, the extraction electrode portion of the lower beta electrode 12b. The insulating film 13 is formed by forming a resistor in the extraction electrode portion of the lower beta electrode 12b, and removing the resistor by lift-off after the formation of the insulating film 13, in a state in which the extraction electrode portion is covered with a metal mask. Formation is possible by the method of forming by the. The insulating film 13 can be an organic insulating film or an inorganic insulating film such as SiO ₂ or SiN _x . You may form from these combinations. In the examples, a laminated film of an acrylic organic insulating film and SiO ₂ was used as the insulating film 13.

In the embodiment, first, a heat resistant film (polyimide tape) was attached to the extraction electrode portion of the lower beta electrode 12b, and the organic insulating film was spin coated in that state. An organic insulating film having a film thickness of 1 μm was obtained under the condition of spinning at 2000 rpm for 30 seconds.

Subsequently, the lower transparent substrate 11b having the organic insulating film formed thereon was baked at 220 ° C. for 1 hour in a clean oven. Then, the lower transparent substrate 11b was heated to 80 ° C. with the heat resistant film attached thereto, and then the SiO ₂ film was heated. The film was formed with a thickness of 1000 kPa by the factor method (alternating discharge). 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 here, the organic insulating film and the SiO ₂ film could be removed with respect to the adhesive point of the heat resistant film. Subsequently, in order to improve the insulation and transparency of the SiO ₂ film, the lower transparent substrate 11b was lit for 1 hour at 220 ° C. in a clean oven.

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

The insulating film 13 may be composed of only SiO ₂ film without forming an organic insulating film. Since SiO ₂ is likely to be a porous film, in this case, it is preferred that the SiO ₂ film with a thickness 4000Å ~ 8000Å. The inorganic insulating film 13 may be a laminate film of a SiO ₂ film and a SiN _x film.

An ITO film was formed on the insulating film 13. The ITO film | membrane heated the lower transparent board | substrate 11b to 100 degreeC, and formed into a film whole surface by the sputtering method (AC discharge). The film thickness was about 1200 mm. The ITO film was patterned by a photolithography process to form first pick-up electrodes 12c, second pick-up electrodes 12d, and extraction electrodes of the pick-up electrodes 12c and 12d.

2 is a schematic plan view showing a photomask used for etching an ITO film. The photomask corresponds to a portion corresponding to the first sac electrode 12c, a portion corresponding to the second sac electrode 12d, a portion corresponding to the extraction electrode of the first sac electrode 12c, and a portion of the extraction electrode corresponding to the second sac electrode 12d. Include the part. In etching, an electrode is formed of an ITO film covered with each corresponding portion. Furthermore, the inventors of the present invention have a plurality of electrode intervals of 20 μm, 30 μm, 50 μm, 100 μm, and 200 μm when the electrode width of the bladder electrode is 20 μm, 30 μm, and the bladder portions of two blach electrodes are alternately arranged. As the electrode pattern, a first sachet electrode 12c and a second sacrificial electrode 12d were produced.

Through the above steps, the first transparent substrate 11a on which the upper beta electrode 12a is formed, and the lower beta electrode 12b and the insulating film 13 through the upper portion thereof are interposed therebetween. , 12d) was formed on the lower transparent substrate 11b. The two transparent substrates 11a and 11b with electrodes were washed and dried. The washing is, for example, washing with water, for example, pure water washing with or without a detergent. Brush cleaning, spray cleaning, etc. can be performed. After dehydration, UV cleaning and IR drying are performed.

On the transparent substrates 11a and 11b with electrodes, an alignment film material is applied so as to cover the electrodes 12a, 12c and 12d. Application of the alignment film material was performed using a spin coat. You may carry out using a fureciso printing or inkjet printing. In the Example, the side chain density of the polyimide alignment film material normally used for formation of a vertical alignment film was controlled and used as an alignment film material. The control of the side chain density is for enabling provision of an appropriate pretilt angle. The alignment film material was applied so that the thickness of the alignment film was 500 kPa to 800 kPa.

About the board | substrate 11a, 11b which apply | coated the orientation film material, baking was performed for 1 hour by making baking temperature into 200 degreeC by the clean oven. Thus, the upper alignment film 14a covering the upper beta electrode 12a and the lower alignment film 14b covering the first and second sacrificial electrodes 12c and 12d were formed.

Next, rubbing treatment (orientation treatment) was performed. The rubbing treatment was performed with an indentation amount of 0.8 mm (strong rubbing conditions). Further, the rubbing treatment was performed such that the twist angle of the liquid crystal display element was 70 degrees or 90 degrees.

In this way, the upper substrate 10a and the lower substrate 10b were produced. 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 to cover the upper beta electrode 12a. The lower substrate 10b is formed on the lower transparent substrate 11b and the lower beta electrode 12b formed on the lower transparent substrate 11b and the insulating film 13 and the insulating film 13 formed on the lower beta electrode 12b. A sachet portion has first and second sachet electrodes 12c and 12d disposed on the interdigital substrate, and a lower alignment layer 14b formed to cover the first and second sachet electrodes 12c and 12d.

Subsequently, in order to keep the thickness of a liquid crystal cell constant, the gap control material was sprayed on the one surface of the board | substrate 10a, 10b by the dry-spray method, for example. As the gap control material, a plastic ball having a particle size of 4 μm was used so that the thickness of the liquid crystal cell was 4 μm.

The sealing material was printed on the other surface of the board | substrate 10a, 10b, and the main seal pattern was formed. For example, a thermosetting seal material containing glass fibers having a particle size of 4 µm is printed by screen printing. The sealant may also be applied using a dispenser. Moreover, you may use not only thermosetting but a photocurable sealing material and the hardening type sealing material for light and heat.

The substrates 10a and 10b were overlaid together. The board | substrate 10a, 10b was overlapped at predetermined position, it was cellized, heat-processed in the pressed state, and the sealing material was hardened. For example, the thermosetting of a sealing material is performed using the hot press method. In this way, an empty cell is produced.

For example, a nematic liquid crystal material, such as ZLI-2293 manufactured by Melk Co., Ltd., was injected into the empty cell by a vacuum injection method. Chiral agent was added to the liquid crystal material. As chiral agent, CB15 made from Melk Corporation was used. A chiral agent was added so that d / p might be 0.5 (d = 4 micrometer, p = 8 micrometer), for example, when letting chiral pitch p and the thickness (cell thickness) d of a liquid crystal layer be d.

The cell was heated above the phase transition temperature of the liquid crystal in order to seal the liquid crystal inlet with, for example, an end-curing member of an ultraviolet curing type and to prepare the alignment of the liquid crystal molecules.

Subsequently, breaking was performed along the damage applied to the transparent substrates 11a and 11b with a scribing device, and the cells were smallly divided into individual cells.

Chamfering and washing were performed for the cell divided small.

Finally, the polarizing plates 16a and 16b were attached to the surface opposite to the liquid crystal layer 15 of the two transparent substrates 11a and 11b. The two polarizing plates 16a and 16b were arranged in cross nicol and so that the direction of a transmission axis and a rubbing direction might become parallel. It can also be arranged to be orthogonal. The power supply 20 was connected between the electrodes 12a, 12b, 12c, and 12d.

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

In the liquid crystal display device according to the first embodiment, the twisted nematic liquid crystal layer 15 sandwiched between the upper substrate 10a, the lower substrate 10b, and the both substrates 10a and 10b disposed in parallel to each other. It is configured to include.

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 is formed on the lower transparent substrate 11b and the lower beta electrode 12b formed on the lower transparent substrate 11b and the insulating film 13 and the insulating film 13 formed on the lower beta electrode 12b. And the lower alignment layer 14b formed on the insulating film 13 to cover the formed first and second sacrificial electrodes 12c and 12d and the first and second sacrificial electrodes 12c and 12d.

The upper and lower transparent substrates 11a and 11b are made of glass, for example. The upper and lower beta electrodes 12a and 12b and the first and second bezel electrodes 12c and 12d are formed of a transparent conductive material such as ITO, for example. The first and second sacrificial electrodes 12c and 12d are comb-shaped electrodes each having a plurality of bladder portions. The bladder portions of the first and second sacrificial electrodes 12c and 12d are alternately arranged along the left and right directions in FIG. 1.

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 an alignment treatment by rubbing. The alignment direction of the upper alignment film 14a and the lower alignment film 14b is, for example, at an angle of 70 degrees or 90 degrees when viewed from the normal direction of the upper and lower substrates 10a and 10b. When the rubbing direction of the upper alignment layer 14a is the first direction and the rubbing direction of the lower alignment layer 14b is the second direction, the second direction is viewed from the normal direction of the upper substrate 10a, and thus, the first direction. Based on this, the direction to form a 70 ° or 90 ° in the right direction of rotation. The arrangement state of the liquid crystal molecules of the liquid crystal layer 15 defined by the combination of the orientation processing directions and the pretilt angles of the upper and lower substrates 10a and 10b is a reverse twist arrangement state that is twisted in the first turning direction.

A chiral agent is added to the liquid crystal material which forms the liquid crystal layer 15. The arrangement state of the liquid crystal molecules occurring under the influence of chiral agent is a spray twist arrangement twisted in the second turning direction opposite to the first turning direction.

The power supply 20 is electrically connected to the upper and lower beta electrodes 12a and 12b and the first and second sacrificial electrodes 12c and 12d. By the power supply 20, it is possible to apply a voltage (to give a potential difference) to the electrodes 12a to 12d.

3A to 3E are schematic cross-sectional views showing electric field directions when voltage is applied.

See FIG. 3A. For example, by applying an AC voltage between the upper and lower beta electrodes 12a and 12b, the entire liquid crystal layer 15 (pixel region) (the liquid crystal layer disposed between the upper and lower beta electrodes 12a and 12b) 15)}, an electric field (an electric field in the thickness direction of the liquid crystal layer 15) can be added.

See FIG. 3B. For example, between the lower beta electrode 12b and the first and second sachet electrodes 12c and 12d (between the lower beta electrode 12b and the first sac electrode 12c, and the lower beta electrode 12b and the first beta electrode 12b). By applying an alternating current voltage between two double electrodes 12d}, the entire liquid crystal layer 15 (pixel region) (the liquid crystal layer 15, first and second double electrodes 12c above the lower beta electrode 12b). 12d) and the lateral electric field (the electric field in the direction orthogonal to the thickness direction of the liquid crystal layer 15) in the liquid crystal layer 15 above the region between the first and second double electrode 12c, 12d. The electric field in the in-plane direction of the substrates 10a and 10b can be generated. By applying a voltage between the electrode 12b and the electrodes 12c and 12d, a lateral electric field is generated in the liquid crystal layer 15, and the driving mode for driving the liquid crystal display element is called a FFS mode (fringe field switching mode). It is called. In the FFS mode of the sun shown in FIG. 3B, the lateral electric field generated in the liquid crystal layer 15 is an electric field along the left and right directions in FIG. 1.

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

See FIG. 3D. By applying an alternating voltage between the first sacrificial electrode 12c and the second sacrificial electrode 12d, a part of the liquid crystal layer 15 (pixel region), for example, the first sacrificial electrode 12c and the first sacrificial electrode 12c, is formed. A transverse electric field can be added to the liquid crystal layer 15 between the two-blade electrodes 12d. The lateral electric field is generated in a part of the liquid crystal layer (pixel region) by the application of the voltage between the first and second sacrificial electrodes 12c and 12d, thereby driving the driving mode for driving the liquid crystal display element in the IPS mode (in- plane switching mode).

See FIG. 3E. By applying an alternating voltage between the lower beta electrode 12b and the first sacrificial electrode 12c, a part of the liquid crystal layer 15 (pixel region), for example, the sacchy portion of the first sacrificial electrode 12c And a lateral electric field can be added to the liquid crystal layer 15 in the vicinity thereof. Similarly, by applying an alternating voltage between the lower beta electrode 12b and the second sac electrode 12d, the transverse electric field is applied to the glacier portion of the second sac electrode 12d and the liquid crystal layer 15 near the top. It is also possible to add.

4A to 4C are external appearance photographs of the liquid crystal display device according to the first embodiment. 4A to 4C show an electrode width of 20 μm of the bladder portion of the first and second sacrificial electrodes 12c and 12d and alternately disposing the bladder portions of the both sacrificial electrodes 12c and 12d. This is a photograph of the appearance of the spot electrode 12c, 12d formation region of the liquid crystal display device having a spacing of 20 mu m.

4A, the external appearance photograph of the state (initial state) which the liquid crystal display element which concerns on 1st Example was completed is shown. In the initial state, the liquid crystal molecules are in a spray twist arrangement. A bright white display is obtained.

In this state, as shown in Fig. 3A, an alternating voltage above a threshold voltage, i.e., a minimum physical quantity voltage causing a reaction, was applied between the upper beta electrode 12a and the lower beta electrode 12b. By the application of a voltage between the positive electrodes 12a and 12b, a vertical electric field is generated in the entire liquid crystal layer 15 (pixel region).

4B is an external photograph after applying a voltage between the electrodes 12a and 12b. Also in frontal observation, clear black display is obtained. It can be seen that the whole has shifted from the spray twist arrangement to the reverse twist arrangement. On the contrary, 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 positive electrodes 12a and 12b.

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

See FIG. 5A. FIG. 5A shows the orientation and polar angle dependence of the contrast ratio (transmittance in the spray twist arrangement / transmission in the reverse twist arrangement). In the figure, R _U indicates the direction of the rubbing treatment performed on the upper substrate 10a, and R _{L indicates that on the} lower substrate 10b. The transmission axis direction of the upper polarizing plate 16a is shown in the direction parallel to the arrow direction of A, and the transmission axis direction of the lower polarizing plate 16b is shown in the direction parallel to the arrow direction of P. As shown in FIG. Further, the direction parallel to the thick arrow direction (90 ° -270 ° direction) is at the center of the thickness direction of the liquid crystal layer 15 when the liquid crystal molecules in the liquid crystal layer 15 are in the state of reverse twist arrangement. The orientation direction of the liquid crystal molecule located is shown. Here, the 0 ° -180 ° direction corresponds to the left and right direction in FIG. 1. In other words, when the arrangement state of the liquid crystal molecules of the liquid crystal layer 15 is in the reverse twist arrangement state, in the orientation direction of the liquid crystal molecules positioned in the center of the thickness direction of the liquid crystal layer 15 and in the FFS mode of the sun shown in FIG. 3B. The direction of the generated lateral electric field is a direction orthogonal to each other. This also applies to the liquid crystal display device manufactured by making the angle between the upper substrate 10a and the lower substrate 10b in the rubbing treatment direction at 90 °.

5B, the polar angle dependence of the transmittance | permeability with respect to a 90 degree-270 degree orientation is shown. The polar angle in the normal direction (the front viewing direction of the liquid crystal display element) of the substrates 10a and 10b is set to 0 °, and the tilt angle of tilting in the 270 ° direction is represented by the positive polar angle and tilted at 90 °. The angle of inclination was represented by the negative polar angle. In the graph of FIG. 5B, the horizontal axis represents the polar angle in units "°", and the vertical axis represents the transmittance in units "%". The curve connecting the black rhombus (denoted "St") shows the polar dependence of the transmittance when the liquid crystal molecules are in a spray twist arrangement, and the curve connecting the black square (denoted "Ut") represents the liquid crystal molecules. Represents when reverse twisted.

The transmittance is about 12.6% in the frontal view in the spray twist configuration, and about 0.02% in the reverse twist configuration.

In Fig. 5C, the polar angle dependence of the contrast ratio with respect to the 90 ° to 270 ° directions is shown. The horizontal axis of the graph of FIG. 5C is the same as that of FIG. 5B. The vertical axis represents the contrast ratio. For the liquid crystal display device according to the first embodiment, the contrast ratio becomes maximum (maximum value 566) at the time of frontal observation.

And the same result was obtained also about the liquid crystal display element produced by making the angle between the rubbing process directions of the upper board | substrate and lower board | substrate 10a, 10b 90 degrees. As described above, the liquid crystal display device according to the first embodiment is a liquid crystal display device having excellent optical characteristics, for example, capable of displaying in bright white display and clear black display.

4C. The inventors of the present invention next apply an AC voltage equal to or greater than the minimum physical quantity voltage that causes a reaction between the lower beta electrode 12b and the first and second sacrificial electrodes 12c and 12d, as shown in FIG. The transverse electric field {the direction in which the first and second sacrificial electrodes 12c and 12d are arranged alternately, the electric field along the left direction in Figs. 1 and 3B) was generated in the entire liquid crystal layer 15 (pixel region).

FIG. 4C is an external photograph after adding the lateral electric field of the sun shown in FIG. 3B to the liquid crystal display element of the state shown in FIG. 4B. It can be seen that the front surface is moving back to the spray twist arrangement state, which shows the same white display state as the initial state.

The liquid crystal molecules positioned in the center of the thickness direction of the liquid crystal layer 15 are tilted in the longitudinal direction (vertical direction) from the transverse direction (horizontal direction) by the addition of the longitudinal electric field, thereby reverse twisting the arrangement from the spray twist arrangement state. You can think of it as switching to a state. In addition, the liquid crystal molecules located in the center of the thickness direction of the liquid crystal layer 15 are spray twists of the liquid crystal molecules located in the center of the transverse direction (the thickness direction of the liquid crystal layer 15 from the longitudinal direction) by the addition of the transverse electric field. By tilting in the direction of the director in the arrangement state, it can be considered to switch from the reverse twist arrangement state to the spray twist arrangement state.

When the longitudinal electric field is added to the liquid crystal layer 15 in the reverse twisted arrangement state, the reverse twisted arrangement state is maintained, and when the lateral electric field is added to the liquid crystal layer 15 in the spray twisted arrangement state, the spray twist arrangement is performed. The state is maintained.

Subsequently, as shown in FIG. 3C, an alternating-current voltage equal to or higher than the minimum physical quantity voltage causing a reaction was applied between the upper beta electrode 12a and the first and second sacrificial electrodes 12c and 12d. By applying a voltage between the electrode 12a and the electrodes 12c and 12d, it is effective to a part of the liquid crystal layer 15 (the liquid crystal layer 15 above the first and second sacrificial electrodes 12c and 12d). There is a longitudinal electric field. For this reason, the liquid crystal molecules above the first and second sacrificial electrodes 12c and 12d transition from the spray twist arrangement state to the reverse twist arrangement state. The spray twist arrangement is maintained above the region between the two bladder electrodes 12c and 12d.

6A to 6C are photographs of the liquid crystal display device in which a vertical electric field is added to a part of the liquid crystal layer. 6A shows the whole picture, FIG. 6B shows the enlarged picture, and FIG. 6C shows the micrograph. 6A to 6C show an electrode width when the electrode width of the bladder portions of the first and second sacrificial electrodes 12c and 12d is 20 μm, and the bladder portions of both sacrificial electrodes 12c and 12d are alternately arranged. It is a photograph of the liquid crystal display element produced by making an interval 20 micrometers. For example, each character of "S", "T", "A", "N", "L", "E", "Y", "L", "C", "D", and "s" , 20 μm / 20 μm line {electrode width of the bladder portion of the first and second sacrificial electrodes 12c and 12d} / space {distance between the bladder portions of the first and second sacrificial electrodes 12c and 12d which are displaced } Is shown as a patterned portion (arrangement area of the bladder portion of the first and second sacrificial electrodes 12c and 12d).

6A and 6B, "S", "T", "A", "N", "L", "E", "Y", "L", "C", "D", " It is understood that each character of "s" is displayed in an intermediate hue (brightness) of white (displayed by the spray twist arrangement) and black (displayed by the reverse twist arrangement), that is, gray.

Fig. 6C is a micrograph of the area including the portion with gray display (midtone display). In the gray display portion, a black display portion (reverse twist arrangement state portion) and a white display portion (spray twist arrangement state portion) are arranged in a stripe shape microscopically. Transition to black display (reverse twist arrangement) by applying a voltage between the electrode 12a and the electrodes 12c and 12d is a planar view of the first and second sacrificial electrodes 12c and 12d. It was a slightly wider area than the width of the sapling area. In other areas, white marks (spray twist arrangement) were maintained. According to the microscopic observation, although the black display part and the white display part are arranged in a stripe shape, black and white stripe are not observed by the naked eye, and a natural gray display is obtained. This is considered to be because the stripe-shaped distribution of the black display portion and the white display portion has a finer resolution than that of the human eye.

In the example shown in the photographs of Figs. 6A to 6C, although the line / space was 20 µm / 20 µm, the gray display was observed with the naked eye when it was about 50 µm to 100 µm / 50 µm to 100 µm or less.

The inventors of the present invention provide a black display in a reverse twist arrangement, a white display in a spray twist arrangement, and a gray display (a region in which a reverse twist arrangement and a region in a spray twist arrangement coexist in one pixel, It was confirmed that display by mixing) was held (memory) as it is, unless voltage was separately applied.

The liquid crystal display device according to the first embodiment is a liquid crystal display device having bi-stability in an array state in which the arrangement state of the liquid crystal molecules is stable in both the reverse twist arrangement state and the spray twist arrangement state, and also halftone display. It is a liquid crystal display device capable of various displays.

The inventors of the present invention fabricated a liquid crystal display device according to a reference example having a line / space of 20 μm / 20 μm and a cell thickness of 20 μm / 20 μm and a cell thickness of 10 μm with respect to the embodiment having a line / space of 20 μm / 20 μm and performing the same experiment. did. A voltage was applied between the upper beta electrode and the first and second sacrificial electrodes of the liquid crystal display device according to the reference example. Unlike the first embodiment, gray display was not obtained. When observed under a microscope, it was confirmed that not only the liquid crystal molecules above the first and second sachet electrodes, but also the liquid crystal molecules above the region between the two sachet electrodes transitioned to the reverse twist arrangement.

From the experiment on the reference example, it can be considered that gray display (midtone display) is realized when the size of the line / space and the cell thickness satisfy certain conditions. The inventors of the present invention have found that, as a result of the in-depth study, the conditions for realizing halftone display do not basically depend on the line size (electrode width of the bladder portion of the first and second sacrificial electrodes 12c, 12d), and the space size. It has been found that the relationship between the distance between the bladder portions of the alternately arranged first and second bladder electrodes and the cell thickness is important for realizing halftone display. When the cell thickness d is less than 10 μm, halftone display can be obtained. Therefore, the space size s of the comb-shaped electrode is represented by the following formula (1).

s ＞ 2 × d · (1)

When it is satisfied, it can be said that halftone display is possible.

In the first embodiment, a voltage is applied between the upper beta electrode 12a and the first and second sacrificial electrodes 12c and 12d, and the liquid crystal above the first and second sacrificial electrodes 12c and 12d. A longitudinal electric field was added to the layer 15, and the liquid crystal molecules at the position were shifted in a reverse twisted arrangement, but only between the upper beta electrode 12a and the first bezel electrode 12c or the upper beta electrode 12a. The halftone display can be realized only by applying an alternating voltage equal to or greater than the minimum physical quantity voltage to cause a reaction only between the second electrode 12d and the second bladder electrode 12d.

When a voltage is applied between the upper beta electrode 12a and the first sac electrode 12c, a vertical electric field is added to the liquid crystal layer 15 above the first sac electrode 12c, and the liquid crystal molecules at that position are sprayed. Transition from the twist arrangement to the reverse twist arrangement. When a voltage is applied between the upper beta electrode 12a and the second sac electrode 12d, a vertical electric field is added to the liquid crystal layer 15 above the second sac electrode 12d, and the liquid crystal molecules at the position Transition from spray twist arrangement to reverse twist arrangement.

In the embodiment, since the line / space is 20 μm / 20 μm (line: space = 1: 1), for example, the transmittance at the time of white display (all liquid crystal molecules in the pixel region are in a spray twist arrangement) is 100%, When the transmittance at the time of black display (all liquid crystal molecules in the pixel region are in the reverse twist arrangement) is 0%, a gray display with a transmittance of about 50% can be obtained, but by adjusting the line / space ratio, It is also possible to change the hue (brightness) level of halftone display. The size of a line and a space can be selected arbitrarily on condition of Formula (1).

Fig. 7 shows another example (modification) of the embodiment in which the first and second sacrificial electrodes 12c and 12d are formed. In this figure, the line size (electrode width of the bladder portion) of the first bladder electrode 12c is formed to be 20 μm, that of the second bladder electrode 12d is 40 μm, and the space size of the positive electrodes 12c and 12d is 10 μm. First and second sacrificial electrodes 12c and 12d are shown. That is, the line size of the electrode 12c: the line size of the electrode 12d: space size = 2: 4: 1.

In the case where the first and second sacrificial electrodes 12c and 12d are formed in this manner, when the voltage above the minimum physical quantity voltage is applied between the upper beta electrode 12a and the first sacrificial electrode 12c, the first sacrificial electrode 12c and 12d is formed. (12c) A longitudinal electric field is generated in the upper liquid crystal layer 15, and the liquid crystal molecules at the position transition from the spray twist arrangement state to the reverse twist arrangement state. For this reason, in this voltage application mode, halftone display with a transmittance of about 25% is realized.

Further, when a voltage equal to or greater than the minimum physical quantity voltage causing a reaction is applied between the upper beta electrode 12a and the second sac electrode 12d, a seed field is generated in the liquid crystal layer 15 above the second sac electrode 12d. Thus, halftone display with a transmittance of about 50% is realized for the liquid crystal molecules at the position to transition from the spray twist arrangement to the reverse twist arrangement.

In addition, when a voltage equal to or greater than the minimum physical quantity voltage causing a reaction is applied between the upper beta electrode 12a and the first and second sacrificial electrodes 12c and 12d, the upper portion of the first and second sacrificial electrodes 12c and 12d is higher. A longitudinal electric field is generated in the liquid crystal layer 15 of the liquid crystal layer 15, and the liquid crystal molecules at the position transition from the spray twist arrangement state to the reverse twist arrangement state, so that halftone display with a transmittance of about 75% is realized.

Such halftone display, white display when the liquid crystal molecules of the entire liquid crystal layer 15 (pixel region) are in a spray twist arrangement state, and liquid crystal molecules of the whole liquid crystal layer 15 (pixel region) are reverse twisted arrangement state. In addition to the black display at this time, in the liquid crystal display device according to the modification, the display of five gradations in which the transmittance changes at a uniform ratio (proportionally) can be realized.

The liquid crystal display device according to the modification is characterized in that the line sizes of the first and second sacrificial electrodes 12c and 12d are different from each other. Moreover, it has the characteristic that the line size and space size of each electrode 12c, 12d are devised so that a transmittance | permeability can be changed in an equal ratio. According to the liquid crystal display device according to the modification, a variety of displays can be performed as compared with the liquid crystal display device according to the first embodiment.

In the above description, halftone display is performed by generating a longitudinal electric field in a part of the liquid crystal layer 15 (pixel region) in the spray twisted arrangement state, but for example, the liquid crystal according to the first embodiment and the modification. For the display element, it is also possible to cause a lateral 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 to perform halftone display. For example, in the case where the liquid crystal molecules of the entire liquid crystal layer 15 (pixel region) are in the reverse twisted arrangement state, when an AC voltage is applied between the first sacrificial electrode 12c and the second sacrificial electrode 12d, both A transverse electric field is generated in the area between the bladder portions of the electrodes 12c and 12d and above, and the liquid crystal molecules of the liquid crystal layer 15 at that position are transitioned to the spray twist arrangement to give halftone display.

For example, a lateral electric field is added in the IPS mode to the liquid crystal display device according to the first embodiment in which the liquid crystal molecules of the liquid crystal layer 15 are in a reverse twist arrangement (between the first and second sacrificial electrodes 12c and 12d). The color tone (brightness) of the halftone display obtained when an alternating current voltage is applied is obtained by adding a vertical electric field to a part of the liquid crystal layer 15 (pixel region) in a spray twist arrangement state (upper beta electrode 12a), It is approximately the same as that of halftone display performed by applying an alternating voltage between the first and second sacrificial electrodes 12c and 12d, the transmittance at the time of black display is 0%, and the transmittance at the time of white display is 100%. The transmittance | permeability when it is set to about 50%.

In addition, a part of the liquid crystal layer 15 (pixel region) in the reverse twisted arrangement state by adding the electric field of the embodiment described with reference to FIG. 3E can be transferred to the spray twisted arrangement state, and halftone display can be performed. In the case shown in FIG. 3E, the liquid crystal molecules of the glacial portion forming region of the first blazing electrode 12c and the liquid crystal layer 15 in the vicinity thereof are shifted to a spray twist arrangement state to realize halftone display.

According to the method of generating a lateral electric field in a part of the liquid crystal layer 15 (pixel region) and shifting the liquid crystal molecules in the region from the reverse twist arrangement to the spray twist arrangement, the relationship of the expression (1) is not satisfied. Even if it is not, it is possible to obtain a halftone display. For this reason, the drive method which generates a lateral electric field in a part of liquid crystal layer 15 (pixel area), and makes the liquid crystal molecules of the area | region transition from the reverse twist arrangement state to the spray twist arrangement state is liquid crystal layer 15 (pixel). It can also be said that the driving method (display conversion method) is more versatile than the driving method in which a vertical electric field is generated in a part of the area) and the liquid crystal molecules in the area are shifted from the spray twist arrangement state to the reverse twist arrangement state. However, in the case of the electric modification using the longitudinal electric field, five gradation display can be performed, but when using a lateral electric field, only three gradation display can be performed, for example.

As described above, the liquid crystal display element according to the embodiment is a liquid crystal display element having memory characteristics in which the arrangement state of the liquid crystal molecules is stable in both the reverse twist arrangement state and the spray twist arrangement state. It can be applied to a display using bistable stability, and in that case, driving using memory characteristics is possible. For example, when performing dot matrices display, the display may be rewritten for each line, a lateral electric field is added to pixels to be displayed in white, and a vertical electric field is added to pixels to be displayed in black. do. In addition, a vertical electric field or a lateral electric field is added to a part of the liquid crystal layer (pixel area) to pixels to which halftone display is to be performed. Various driving methods can be considered. Hereinafter, the liquid crystal display device which performs matrix display using XY electrodes as a 2nd Example is demonstrated.

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

The liquid crystal display device according to the second embodiment is a simple matrix liquid crystal display device configured by arranging a plurality of pixel portions 34 in a matrix form, and each pixel portion 34 is a liquid crystal display device according to the first embodiment. The same pixel configuration as the 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 which gives control signals to the control lines B1 to Bm, and each of which is controlled. N control lines A1 to An extending in the Y direction crossing the lines B1 to Bm, a driver 32 for giving control signals to the control lines A1 to An, and each of the control lines B1 to Bm crossing the Y direction. The driver 33 which gives a control signal to the n control lines C1 to Cn and D1 to Dn extending to the control lines C1 to Cn and D1 to Dn, and the angle between the control lines B1 to Bm and the control lines A1 to An. The pixel portion 34 is defined in the intersection region.

Each control line B1-Bm, A1-An, C1-Cn, and D1-Dn becomes from transparent conductive films, such as ITO formed in stripe shape, for example. The portion where the control lines B1 to Bm and A1 to An intersect serves as the upper beta electrode 12a and the lower beta electrode 12b (see Fig. 8B). The control lines C1 to Cn are connected to the blade portions of the first blade electrode 12c provided in the region corresponding to the pixel portions 34. Similarly, the control lines D1 to Dn are connected to the blade portions of the second blade electrodes 12d provided in the regions corresponding to the pixel portions 34.

As an example of the driving method of the liquid crystal display device according to the second embodiment, a control line B1, B2, B3, ... and a method of performing display rewriting for each line (line sequential driving method) will be described. In this case, for example, the pixel portion 34 that is to be made relatively bright (the display closer to the white display) is applied to the pixel portion 34, and the pixel portion is desired to be relatively dark display (the display closer to the black display). At 34, a longitudinal electric field is applied.

As an example, when black display or white display is performed, a square wave voltage (for example, 150 Hz at about 1.5 V) is applied to the control line B1, and control lines A1 to An and C1 to To Cn and D1 to Dn, a square wave voltage (e.g., 150 Hz at about 1.5 V) is applied to the threshold value, that is, the voltage of the minimum physical quantity that causes the reaction, which is synchronized with or half-cycle shifted.

In detail, among the control lines A1 to An, a square wave voltage shifted by half a period from a square 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, and a vertical electric field is added thereto. If the voltage is equal to or higher than the saturation voltage, the liquid crystal layer 15 can cause the transition of the alignment state (transition to the reverse twist arrangement) to change the light transmittance of the pixel portion 34.

On the other hand, the 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 among the control lines A1 to An. At this time, no voltage is applied to the control lines C1 to Cn and D1 to Dn. As a result, the pixel portion 34 is in a state in which no voltage is effectively applied. Therefore, the transition of the alignment state does not occur in the liquid crystal layer 15, and the light transmittance does not change.

In addition, among the control lines C1 to Cn and D1 to Dn, a square wave voltage shifted by half a period from a square wave voltage applied to the control line B1 is applied to the control line corresponding to the pixel portion 34 to be displayed in white. 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 lateral electric field. If the voltage is equal to or higher than the saturation voltage, the liquid crystal layer 15 can cause the transition of the alignment state (transition to the spray twist arrangement state) to change the light transmittance of the pixel portion 34.

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. As a result, the pixel portion 34 is in a state in which no voltage is effectively applied. Therefore, the transition of the alignment state does not occur in the liquid crystal layer 15, and the light transmittance does not change.

In the case where gray display (midtone display) is performed, the degree of transition of the alignment state does not occur in the control line B1 with respect to the pixel portion 34 which is performing black display as an example (in reverse twist arrangement). Apply a square wave voltage of 150 Hz at 1.5 V, and apply a square wave voltage (for example 1.5 Hz at 150 V) to the control lines C1 to Cn in synchronization with it or causing a half-cycle shift reaction. Is authorized.

In detail, among the control lines C1 to Cn, a square wave voltage shifted by half a period from a square wave voltage applied to the control line B1 is applied to the control line corresponding to the pixel portion 34 to be displayed in gray. 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 glacial portion of the first glazing electrode 12c and the liquid crystal molecules in the vicinity of the first glazing electrode 12c, thereby adding a lateral electric field. If the voltage is higher than the saturation voltage, the liquid crystal molecules in the corresponding region are caused to undergo an array transition (transition to the spray twist arrangement) to change the light transmittance of the region (about half of the pixel portion 34). Can be.

On the other hand, the 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 among the control lines C1 to Cn. At this time, no voltage is applied to the control lines A1 to An and D1 to Dn. As a result, the pixel portion 34 is in a state in which no voltage is effectively applied. Therefore, the transition of the alignment state does not occur in the liquid crystal layer 15, and the light transmittance does not change.

And although the example which applied the voltage which synchronized with the control line B1 and the control lines C1 to Cn, or shifted by half period was shown, you may apply the voltage which synchronizes with the control line B1 and the control lines D1 to Dn, or shifted by half period.

By performing the above-described driving in sequence with the control lines B2, B3, ..., the dot matrix display can be performed. The display state overwritten by such driving can be held semipermanently. To rewrite this display, the above control can be executed again from the control line B1.

By changing the electrode width of C1 to Cn or D1 to Dn and the period of the voltage to be applied, more delicate halftone display is possible.

In this case, the case where the electrode width of the bladder electrode is uniform has been described, but the electrode width may be different depending on the place. If the electrode width is uniform, the moire pattern may be seen by the light and shade pattern of the halftone display that can be obtained, but it is possible to reduce it.

Although an example of a so-called simple matrix liquid crystal display device is shown here, an active matrix liquid crystal display device using a TFT or the like can also be used. In the case of the active matrix liquid crystal display device, there is no need to rewrite each line such as the control line B1, so that the rewriting time can be shortened. In addition, since it is possible to apply, for example, a voltage twice or more with respect to the threshold value, it is possible to rewrite at a higher speed.

Hereinafter, the liquid crystal display element using TFT as a 3rd, 4th Example is demonstrated.

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

In the liquid crystal display device according to the third embodiment, the twisted nematic liquid crystal layer 15 sandwiched between the upper substrate 10a, the lower substrate 10b, and the both substrates 10a and 10b disposed in parallel to each other. It is configured to include.

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 layer 14a formed on the common electrode 12a. do. The lower substrate 10b has a lower beta electrode 12b, a common line 22, a scanning line 23, and a lower transparent substrate 11b formed on the lower transparent substrate 11b and the lower transparent substrate 11b. On the insulating film 13, the slit electrode (pixel electrode) 21 formed on the insulating film 13, the semiconductor film 24, the source electrode 25, the drain electrode 26, and so as to cover them 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 disposed to face each other. It may be a transparent plastic substrate. Between the upper and lower alignment layers 14a and 14b, for example, a large number of spacers are arranged in a dispersed manner (not shown), and the mutual spacing between the substrates 11a and 11b is provided by such spacers. Is maintained.

The lower beta electrode 12b is provided on one surface side of the lower transparent substrate 11b. The lower beta electrode 12b is formed in a substantially spherical shape, for example, as shown in FIG. 9B, and part of it is electrically connected to a common line 22. 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 side 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 beta electrode 12b, and a predetermined potential is given to the lower beta electrode 12b from a voltage supply means (not shown) via 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 line 23 is provided on one surface side of the lower transparent substrate 11b and extends in one direction (Y direction in FIG. 9B). As shown in FIG. 9B, the scanning line 23 of this embodiment is arranged with the lower beta electrode 12b interposed between the common line 22. As shown in 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 side of the lower transparent substrate 11b so as to cover the lower beta 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 the scan line 23. The semiconductor film 24 is patterned in an island shape, as shown in FIG. 9B. As the semiconductor film 24, an amorphous silicon film can be used, for example. The portion overlapping with the semiconductor film 24 of the scanning line 23 functions as a gate electrode of the TFT. The portion overlapping with the semiconductor film 24 of the insulating film 13 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 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 aluminum and molybdenum, for example.

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

The slit electrode 21 is provided at a predetermined position on the insulating film 13 at least partially overlapping the lower beta electrode 12b. As shown in FIG. 9B, the slit electrode 21 has a plurality of spherical slits (openings) 21a. The slit electrode 21 can be obtained by patterning transparent conductive films, such as ITO. In the third embodiment, the size of the slit electrode 21 is 20 μm in width (electrode width, length in the X direction of FIG. 9B) between the slits 21a, and each slit 21a. The width (length in the X direction of FIG. 9B) was set to be 20 μm. And the size is not limited to this. For example, when the width of the slit 21a is set to s, it is possible to set so as to satisfy the above expression (1). The slit electrode 21 is connected with the drain electrode 26. By applying a voltage between the slit electrode 21 and the lower beta electrode 12b, a transverse electric field can be applied to the liquid crystal layer 15.

The lower alignment layer 14b includes the semiconductor film 24, the source electrode 25, the drain electrode 26, and the slit electrode 21 on the insulating film 13 on one side of the lower transparent substrate 11b. It is installed to cover.

Similarly, the upper alignment film 14a is provided 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, for example, uniaxial alignment treatment is performed by rubbing. As the alignment films 14a and 14b, those which express relatively high pretilt angles (20 degrees or more, preferably about 35 degrees ± 10 degrees) are used. The direction R _U of the alignment treatment of the upper alignment film 14a and the direction R _L of the alignment treatment of the lower alignment film 14b are obtained when the arrangement state of the liquid crystal molecules of the liquid crystal layer 15 is in a reverse twisted arrangement state. The orientation direction D of the liquid crystal molecules located at the center of the thickness direction of 15) occurs when the voltage is applied between the lower beta electrode 12b and the slit electrode 21 in the transverse electric field direction E (slit 21a). It is set to be substantially orthogonal to the direction parallel to the arrangement direction} (see Fig. 9B).

The common electrode 12a is provided on one surface side of the upper transparent substrate 11a. At least a portion of the common electrode 12a is formed to overlap the lower 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 beta electrode 12b, a vertical electric field can be applied to the liquid crystal layer 15 (pixel region). In addition, by applying a voltage between the common electrode 12a and the slit electrode 21, a part of the liquid crystal layer 15 (pixel region) (except the upper side of the slit 21a), which is above the slit electrode 21 The seed electric field can be added to the liquid crystal layer 15}.

The liquid crystal layer 15 is disposed between the upper substrate 10a and the lower substrate 10b, and is composed of, for example, a nematic liquid crystal material having a positive dielectric anisotropy Δε. The thick line shown to the liquid crystal layer 15 of FIG. 9A shows the liquid crystal molecule in the liquid crystal layer 15 typically. When no voltage is applied, the liquid crystal molecules are aligned with a predetermined pretilt angle with respect to the substrate surfaces of the upper substrate 10a and the lower substrate 10b. Moreover, the angle which the direction _RU , _RL (refer FIG. 9B) of each orientation process of the upper orientation film 14a and the lower orientation film 14b sets is set before and after 90 degrees, for example, when voltage is not applied. The liquid crystal molecules of the liquid crystal layer 15 of the liquid crystal layer 15 are twisted and aligned in the azimuth direction between the upper substrate 10a and the lower substrate 10b. In addition, chiral agent is added to the liquid crystal layer 15.

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

The upper polarizing plate 16a is disposed outside the upper substrate 10a. In addition, the lower polarizing plate 16b is disposed outside the lower substrate 10b. The display of the liquid crystal display element according to the third embodiment is visually recognized by the user from the upper polarizing plate 16a side. The upper and lower polarizing plates 16a and 16b are arranged in cross nicol, for example.

The liquid crystal display device according to the third embodiment is also a reverse twisted nematic liquid crystal display device. Also in the third embodiment, the arrangement state of the liquid crystal molecules of the liquid crystal layer 15 defined by the combination of the alignment processing directions and the pretilt angles of the upper and lower substrates 10a and 10b is twisted in the first turning direction. Reverse twisted array. The arrangement state of the liquid crystal molecules under the influence of the chiral agent is a spray twist arrangement twisted in a second turning direction opposite to the first turning direction. By adding a seed electric field to the liquid crystal layer 15, the liquid crystal molecules of the liquid crystal layer 15 in the added region can be transferred from the spray twist arrangement state to the reverse twist arrangement state. In addition, by adding a lateral electric field to the liquid crystal layer 15, the liquid crystal molecules of the liquid crystal layer 15 in the added region can be transferred from the reverse twist arrangement to the spray twist arrangement.

10A to 10G and FIGS. 11A to 11D are schematic cross-sectional views showing a method for manufacturing a liquid crystal display device according to a 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 an 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. For example, 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, the laminated film of the aluminum film and the molybdenum film is patterned by a dry etching method or the like.

See FIG. 10B. The lower beta electrode 12b is formed at a predetermined position on one 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.

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

See FIG. 10D. The 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 deposition method such as 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. The source electrode 25, the drain electrode 26, and the signal line 27 are formed at predetermined positions on the insulating film 13. For example, a laminated film of 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 the laminated film is patterned by a dry etching method or the like. do.

See FIG. 10F. The slit electrode 21 is formed in 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, the common electrode 12a is formed on the glass substrate for the upper transparent substrate 11a. Specifically, an ITO film is formed over the entire surface of the upper transparent substrate 11a by a film forming method such as a sputtering method. In the actual manufacturing process, when the common electrode 12a is present on the entire surface of the substrate, there is a possibility of shorting due to the main seal portion, film peeling during breaking from scribing, etc. It is desirable to shield the outer periphery.

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

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

11B, the 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 and the like are formed are washed. The washing is, for example, washing with water, for example, pure water washing. It is preferable not to use a detergent. Brush cleaning, spray cleaning, etc. can be performed. After dehydration, UV cleaning and IR drying are performed. Atmospheric plasma cleaning may be performed.

In the formation of the alignment films 14a and 14b, an alignment film having a high voltage retention was selected, and specifically, a polyimide film in which the side chain density of the material used as the vertical alignment film was lowered was used. Appropriate methods such as Frekiso printing, inkjet printing, spin coating, and spin coating method, the alignment film material of the upper and lower transparent substrates (11a, 11b), respectively, a suitable film thickness, for example of about 500 ~ 800Å It applied in thickness and heat-processed (for example, baking for 1 hour at 160 degreeC-180 degreeC in clean oven). Thereafter, rubbing treatment was performed with respect to each of the upper and lower alignment films 14a and 14b with an orientation treatment, for example, a press-fit amount of 0.8 mm. The rubbing direction was set such that the twist angles of the liquid crystal molecules on the respective substrates 11a and 11b were abbreviated 90 ° when the upper transparent substrate 11a and the lower transparent substrate 11b were polymerized, for example.

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

In this way, the upper substrate 10a and the lower substrate 10b were produced.

See FIG. 11C. Subsequently, in order to keep the thickness of a liquid crystal cell constant, the gap control material was spread | dispersed on the one surface of the board | substrate 10a, 10b by the dry-spray method, for example. A plastic ball having a particle size of 4 μm was used for the gap control material, so that the thickness of the liquid crystal cell was 4 μm. In the gap control, the gap control material may be scattered on the substrate surface in this manner, or a rib pattern may be formed on the upper substrate 10a, for example, to maintain a predetermined cell thickness.

The sealing material was printed on one surface of the board | substrate 10a, 10b, and the main seal pattern was formed. For example, a thermosetting seal material containing glass fibers having a particle size of 4 µm is printed by screen printing. The sealant may also be applied using a dispenser. Moreover, you may use not only thermosetting but a photocurable sealing material and the hardening type sealing material for light and heat.

The board | substrates 10a and 10b were overlapped. The board | substrate 10a, 10b was overlapped in predetermined position, it was cellized, heat-processed in the pressed state, and the sealing material was hardened. For example, the thermosetting of a sealing material is performed using the hot press method. In this way, an empty cell was produced.

See FIG. 11D. For example, a liquid crystal material is injected into the empty cell by a vacuum injection method. You can also use the ODF method. The vacuum injection method was used here. As the liquid crystal material, a material having a high dielectric constant anisotropy and a high voltage retention is preferable. For example, there is no particular limitation as long as it is a liquid crystal material generally used for a twisted nematic liquid crystal display element driven by a TFT.

Chiral agent was added to the liquid crystal material. As an example, R-811 manufactured by Melk Co., Ltd. was used as the chiral agent so as to have a d / p of 0.16.

After liquid crystal injection, the end sealing process was performed, pressing. The cell was heat-treated at high temperature (temperature above the phase transition temperature of the liquid crystal) to arrange the alignment state of the liquid crystal molecules.

Finally, the polarizing plates 16a and 16b were attached to the surface opposite to the liquid crystal layer 15 of the two transparent substrates 11a and 11b. Two polarizing plates 16a and 16b were arrange | positioned so that the cross nicol and the direction of a transmission axis and a rubbing direction might become parallel. It can also be arranged to be orthogonal.

Thus, the liquid crystal display device according to the third embodiment was produced.

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

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

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

For example, in the configuration shown in Fig. 9B, since the voltage cannot be controlled to transition 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 by at least the scanning line 22. Do this line by line. Usually full line (full surface) conversion would be preferred.

Next, a voltage was applied to each pixel TFT to generate a lateral electric field in the liquid crystal layer 15. Specifically, a voltage is applied to the scan line 23 (gate line) and the signal line 27 (source line), and a potential difference is provided between the lower beta electrode 12b, so that the transverse electric field is applied to the liquid crystal layer 15. Added. The pulse wave of 10V as a gate voltage and the voltage which inverted +/- 10V as a source voltage for each frame were added. As a result, it was confirmed that a white display such as the photograph shown in FIG. 12A can be obtained. By the addition of the transverse electric field, the liquid crystal molecules transition from the reverse twist arrangement to the spray twist arrangement. In order to switch from black display to white display, the voltage application time is enough for about 1 second. Immediately after the application of the voltage was stopped, the black display state (reverse twist arrangement state) remained on the slit electrode 21 in the form of dots, but after 3 to 4 seconds, all of the slit electrode 21 was white. The display state (spray twist arrangement state) is entered.

The conversion from black display to white display is performed by selecting the scan line 23 and the signal line 27 to which voltage is applied, and can be controlled for each pixel. Therefore, various displays can be realized by waveforms applied to the TFTs.

Subsequently, gray display (midtone display) was performed. In the state where the liquid crystal molecules of the liquid crystal layer 15 were in a spray twisted arrangement, a voltage was applied between the drain electrode 26 and the common electrode 12a through the TFT. Here, an alternating voltage (square wave) of 10 V and 100 Hz was applied to the signal line 27 (source line) where the pixel to be displayed in gray was applied, and the gate voltage was applied in synchronization with it. 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 in the position are in a reverse twist arrangement state. Transitioned to. Thereafter, 0 V was applied to any signal line 27 (source line) of the pixel partially in the reverse twisted arrangement state, and the gate voltage was applied in synchronization with it. In this manner, gray display was realized.

13A and 13B are schematic sectional views and a plan view respectively showing a liquid crystal display device according to a fourth embodiment. FIG. 13A is a cross-sectional view taken along the line 13A-13A in FIG. 13B. Fig. 13B shows approximately one pixel, and many of the same pixels are formed along the X and Y directions.

9A and 9B, the common line 22a is formed on the insulating film 28 so that the common line 22a is electrically connected to the slit electrode 21 instead of the lower beta electrode 12b. The point and the drain electrode 26a are different in that they are connected to the lower beta electrode 12b instead of the slit electrode 21.

Hereinafter, the same code | symbol is used about the component which is common in 3rd Example, and these detailed description is abbreviate | omitted.

In the liquid crystal display device according to the fourth embodiment, the twisted nematic liquid crystal layer 15 sandwiched between the upper substrate 10a, the lower substrate 10b, and the two substrates 10a and 10b disposed in parallel to each other. It is configured to include.

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 layer 14a formed on the common electrode 12a. do. The lower substrate 10b is an insulating film formed on the lower transparent substrate 11b, the lower beta electrode 12b formed on the lower transparent substrate 11b, the scanning line 23, and the lower transparent substrate 11b so as to cover them. 13, on the semiconductor film 24 formed on the insulating film 13, the source electrode 25, the drain electrode 26a, on the insulating film 28 formed on the insulating film 13 so as to cover them, and on the insulating film 28 The formed slit electrode (pixel electrode) 21, the common line 22a, and the lower orientation film 14b formed on the insulating film 28 so that they may be covered. Here, the drain electrode 26a is formed so as to electrically connect with the lower beta electrode 12b through the insulating film 13.

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 with the slit electrode 21 as shown in FIG. 13B, and is predetermined potential with respect to the slit electrode 21 from the voltage supply means which is not shown in figure through the 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 thereof is connected to the lower beta electrode 12b through the insulating film 13. The drain electrode 26a is formed of a metal film such as a laminated film of aluminum and molybdenum, for example.

The insulating film 28 is provided on the insulating film 13 on one side of the lower transparent substrate 11b so as to cover the semiconductor film 24, the source electrode 25, and the drain electrode 26a. 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 at least partially overlapping the lower beta electrode 12b. As shown in FIG. 13B, the slit electrode 21 has a plurality of slits (opening portions) 21a and is connected to the common line 22a. In the fourth embodiment, the slit electrode 21 and the common line 22a are integrally formed. The slit electrode 21 can be obtained by patterning a transparent conductive film such as ITO. By applying a voltage between the slit electrode 21 and the lower beta electrode 12b, a transverse electric field can be applied to the liquid crystal layer 15.

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

The liquid crystal display device according to the fourth embodiment is also a reverse twisted nematic liquid crystal display device. Also in the fourth embodiment, the arrangement state of the liquid crystal molecules of the liquid crystal layer 15 defined by the combination of the orientation processing directions and the pretilt angles of the upper and lower substrates 10a and 10b is twisted in the first turning direction. The arrangement state of the liquid crystal molecules which is a reverse twist arrangement and which arises under the influence of a chiral agent is a spray twist arrangement which twists in a 2nd turning direction opposite to a 1st turning direction. By adding a seed electric field to the liquid crystal layer 15, the liquid crystal molecules of the liquid crystal layer 15 in the added region can be transferred from the spray twist arrangement state to the reverse twist arrangement state. In addition, by adding a lateral electric field to the liquid crystal layer 15, the liquid crystal molecules of the liquid crystal layer 15 in the added region can be transferred from the reverse twist arrangement to the spray twist arrangement.

14A to 14G and FIGS. 15A to 15E are schematic cross-sectional views showing a method for manufacturing a liquid crystal display device according to a fourth embodiment. Hereinafter, also in description of a manufacturing method, the detailed description is abbreviate | omitted about the content common to 3rd Example.

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

As shown in FIG. 14C, the insulating film 13 is formed on one surface of the lower transparent substrate 11b so as to cover the lower beta electrode 12b and the scanning line 23.

As shown in FIG. 14D, the semiconductor film 24 is formed at a predetermined position on the insulating film 13.

As shown in FIG. 14E, the source electrode 25, the drain electrode 26a, and the signal line 27 are formed. The drain electrode 26a is formed by forming an opening for exposing a part of the lower beta electrode 12b at a predetermined position of the insulating film 13 in advance, and then forming a metal film by patterning or the like and patterning it. This is possible.

As shown in FIG. 14F, 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. 14G, the common line 22a and the slit electrode 21 are formed at a predetermined position on the insulating film 28. As shown in FIG. In addition, a passivation film may be provided on the insulating film 28.

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

As shown in Fig. 15B, the lower alignment film 14b is formed on the insulating film 28 on the lower transparent substrate 11b.

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

A fourth treatment is performed on the upper and lower alignment films 14a and 14b through a process similar to that of the third embodiment, such as the substrate polymerization process and the liquid crystal layer 15 forming process shown in FIGS. 15D and 15E. A liquid crystal display device according to the embodiment is manufactured.

The liquid crystal display device according to the fourth embodiment also adds a valid electric field to a part of the liquid crystal layer 15 (pixel area), and like the other embodiments, coexistence and mixing of a reverse twist arrangement state and a spray twist arrangement state A liquid crystal display device capable of forming halftone display and performing halftone display.

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

Although the third and fourth embodiments are transmissive liquid crystal display elements, for example, the lower beta electrode 12b can be used as a reflective electrode and a reflective liquid crystal display element can be used. In that case, it is preferable to set the twist angle to approximately 70 degrees.

The liquid crystal display device according to the first to fourth embodiments and modifications is a liquid crystal display device which can easily realize stable display of a high contrast white display state, a black display state, and a halftone display state. As the electrode constituting the pixel, a blazing electrode or a slit electrode is used. According to the liquid crystal display elements according to the first to fourth embodiments, a partial electric field or a lateral electric field is partially generated in the liquid crystal layer of the pixel region, and the distribution of transmittances is added in the pixel (regions having different transmittances in the pixel, That is, for example, when viewed from the substrate normal direction, the liquid crystal molecules of the liquid crystal layer form a region in a reverse twist arrangement and a region in a spray twist arrangement), and various displays can be performed. As shown in the modification of the first embodiment, the electrode size (width, area, etc.) can be taken out, for example, five levels of multi-level gradation display are also possible. A part of the liquid crystal layer in the pixel region may be in a reverse twist arrangement, and another part may be in a spray twist arrangement. For example, the liquid crystal layer may not be in the same arrangement when viewed along the substrate normal direction. In the liquid crystal display device according to the first to fourth embodiments and modifications, an electrode capable of generating an electric field in which a part of the liquid crystal layer in the pixel region is in a reverse twist arrangement and another part is in a spray twist arrangement is formed. Equipped.

In addition, the liquid crystal display device according to the first to fourth embodiments can be manufactured at low cost. Since the manufacturing method is substantially the same as the manufacturing method of a general twisted nematic liquid crystal display element except for an alignment film material, rubbing conditions (control of indentation amount), firing conditions of the alignment film, and the like, a general twisted nematic liquid crystal display element In comparison, the cost increase 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 their mixed state of the liquid crystal layer 15 are stably maintained. Therefore, in either of the white display, the black display, and the gray display, after the display is rewritten, the display state is retained with no voltage applied. It does not consume power except when changing the display. This enables ultra low power consumption with extremely low power consumption. Especially when applied to reflective displays, the merit is large. The display can be held semi-permanently and compatible with high contrast ratios.

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

In the case of using a switching element such as a TFT, a large display switching can be performed at high speed. When using a liquid crystal display element using TFT, it is also possible to use the TFT board | substrate widely used for IPS liquid crystal as it is, for example. Although it is necessary to form a transparent electrode in the counter substrate, for example, since it can be formed easily using a mask-sputter etc., there are few factors of cost increase. There is also a merit that the counter substrate is provided with an electrode, and is hardly affected by static electricity during rubbing.

In addition, according to the liquid crystal display elements according to the first to fourth embodiments and modifications, a display that is very suitable for any of transmissive displays, transversal displays, and reflective displays can be realized.

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

The inventors of the present invention first produced a plurality of reverse twisted nematic liquid crystal display devices according to the comparative examples, and examined the display characteristics thereof.

Two transparent substrates, for example, an indium tin oxide (ITO) electrode, are prepared. Here, a test cell having a parallel plate type electrode was used, and two transparent substrates were washed and dried.

On the transparent substrate, an alignment film material is applied to cover the ITO electrode. Application | coating of the orientation film material was performed using the spin coat. You may carry out using a fureciso printing or inkjet printing. In this example, the side chain density of the polyimide oriented film material which has a low side chain density as a vertical alignment film material normally used for formation of a vertical alignment film was controlled and used as an alignment film material. This is because control of the side chain density enables provision of an appropriate pretilt angle. The alignment film material was applied so that the thickness of the alignment film was 500 kPa to 800 kPa.

The plastic substrate and the main firing of the transparent substrate coated with the alignment film material are carried out. This firing was carried out at different firing temperatures between 160 ° C and 260 ° C. In this way, an alignment film covering the ITO electrode was formed.

Next, a rubbing process (orientation process) is performed. A rubbing process is a process of rubbing an oriented film shape by rotating a cylindrical roll wound at high speed, for example, and arrange | positioning (orienting) the liquid crystal molecules which contact | connect a board | substrate in one direction by this. The rubbing treatment was performed under three conditions in which the indentation amount was 0.4 mm, 0.8 mm, and 1.2 mm. Further, the rubbing treatment was performed such that the twist angle of the liquid crystal display element was 70 degrees or 90 degrees.

Subsequently, in order to keep the thickness (distance between board | substrates) of a liquid crystal cell constant, the gap control material was spread | dispersed by the dry-spray method, for example on the transparent substrate surface. A plastic ball having a particle size of 4 μm was used for the gap control material, so that the thickness of the liquid crystal cell was 4 μm.

On the other hand, a seal material was printed on the surface of the transparent substrate to form a main seal pattern. For example, a thermosetting seal material containing glass fibers having a particle diameter of 4 µm is printed by screen printing. The sealant may also be applied using a dispenser. Moreover, you may use not only thermosetting but a photocurable sealing material and the hardening type sealing material for light and heat.

Transparent substrates were stacked together. Two transparent substrates were polymerized at predetermined positions to form a cell, and heat-treated in a pressed state to cure the seal member. For example, the thermosetting of a sealing material is performed using the hot press method. In this way, an empty cell is produced.

For example, the nematic liquid crystal is injected into the empty cell by the vacuum injection method. Chiral agent was added to the liquid crystal. As chiral agent, CB15 or R-811 made by Melk Corporation was used. When chiral pitch p and cell thickness d were used, chiral agent was added on condition of a some addition amount so that d / p may be 0.33-0.53, for example.

The cell was heated above the phase transition temperature of the liquid crystal in order to seal the liquid crystal inlet with, for example, an ultraviolet ray hardening type end seal, and to arrange the alignment of the liquid crystal molecules. For the reverse twisted nematic liquid crystal display device, for example, when the liquid crystal material is injected or heated above the phase transition temperature of the liquid crystal, the twisted nematic liquid crystal display device becomes a twisted twist arrangement in a direction in which a torsion force generated by the chiral agent is generated. .

Thereafter, the scribing device was broken along with the damage on the transparent substrate, and was divided into individual cells.

Chamfering and washing were performed for the cell divided small.

Finally, the polarizing plate was stuck to the surface on the opposite side to the liquid crystal layer of two transparent substrates. Two polarizing plates were arrange | positioned so that the direction of a transmission axis and a rubbing direction might be parallel in cross nicol. It may be arranged to be orthogonal. A power supply was connected between the ITO electrodes of both transparent substrates.

In this way, a liquid crystal display device according to a comparative example was manufactured. In the liquid crystal display device according to the comparative example, the liquid crystal molecules of the liquid crystal layer show the spray twist arrangement state with respect to the initial state, and by applying the electric field, the spray twist arrangement state can be shifted to the reverse twist arrangement state, and the horizontal It is a reverse twisted nematic liquid crystal display element which can transition a reverse twist arrangement state to a spray twist arrangement state by application of an electric field.

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

First, visual observation of the display was performed. The liquid crystal display device according to the comparative example was displayed with a high contrast ratio even when observed from the front side. Moreover, even after leaving for three months at room temperature, the display was retained.

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

16 is a table showing the results of the investigation. In FIG. 16, after leaving one liquid crystal display element (comparative example) for each kind of chiral agent added and its addition amount (chiral pitch) at -40 ° C, 40 ° C and 50 ° C for 24 hours, The result of observing and judging whether or not the display by the reverse twist arrangement state was observed was shown. The O mark indicates good retention (almost a reverse twist arrangement in the liquid crystal layer has been maintained), and the X mark indicates no visibility (transition to an almost spray twist arrangement), and the triangulation indicates its intermediate state. (Some of which maintain the reverse twist arrangement and some of the transition to the spray twist arrangement).

When using CB15 as a chiral agent and adjusting the addition amount so that a chiral pitch may be 8.0 micrometer, the display by a reverse twist arrangement | stack state will be hold | maintained well at any temperature of -40 degreeC, 40 degreeC, and 50 degreeC. I can see that it is. As described above, the chiral material and the addition amount are also selected for the comparative example, so that it is possible to obtain a liquid crystal display device having a high memory property in a wide temperature range. However, in the liquid crystal display element which added R-811 so that chiral pitch might be 8.0 micrometer, 8.5 micrometers, and 9.0 micrometer, and the liquid crystal display element which added CB15 so that chiral pitch might be 9.0 micrometer, reverse twist It can be seen that the temperature range in which the display by the arrangement state is stably held is not wide. This can be considered to be due to the change in the pitch length of the chiral agent depending on the temperature.

Fig. 17 is a graph showing the temperature dependence of the pitch length made of chiral. The horizontal axis of the graph shows the temperature in unit "° C", and the vertical axis shows the pitch length in the unit "μm". The broken line a shows the temperature dependence of the pitch length with respect to CB15, and the broken line b shows it with respect to R-811. Although the pitch change with respect to temperature changes with a chiral material, it turns out that it changes a lot even if material is selected.

The inventors of the present invention further investigated the temperature dependence of display retention (memory) according to the reverse twist arrangement.

18 is a table showing the irradiation results. 18 shows four liquid crystal display elements (comparative examples) for each kind of chiral agent added and the amount of chiral added (chiral pitch p), respectively, at 40 ° C, 50 ° C, 60 ° C, 70 ° C, 80 ° C, and 90 ° C. After heat-treatment at each temperature for 30 minutes, it observed and judged whether the display by the reverse twist arrangement state was hold | maintained, and the result was judged. The number in a table | surface shows the number of the liquid crystal display element for which display was hold | maintained favorably. For example, the notation "3/4" shows that three out of four liquid crystal display elements held the display satisfactorily. X mark means that there was no liquid crystal display element which held the display favorably.

When the heat treatment temperature is 50 ° C. or lower, the display according to the reverse twisted arrangement state is maintained in a relatively large number of liquid crystal display devices. However, when the heat treatment temperature is 60 ° C. or higher, the memory performance is lost and the transition to the spray twist arrangement state is observed.

As described above, the liquid crystal display device of the reverse twisted nematic type according to the comparative example has a high memory property at room temperature, but the display due to the reverse twist orientation can not be observed at a temperature different from the room temperature. In the above high temperature state, it is difficult to hold | maintain.

Next, the liquid crystal display device according to the fifth embodiment will be described. A schematic cross-sectional view of the liquid crystal display device according to the fifth embodiment is substantially the same as that of FIG. 1. In addition, the manufacturing method of the liquid crystal display device 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 three conditions in which the indentation amounts were 0.4 mm, 0.8 mm, and 1.2 mm. And the rubbing process was performed so that the twist angle of a liquid crystal display element might be set to 70 degrees or 90 degrees.

Next, CB15 or R-811 manufactured by Melk Co., Ltd. was used as a chiral agent to be added to the liquid crystal material. When the chiral agent was made into the chiral pitch p and the thickness d of the liquid crystal layer, it added on several addition amount conditions so that d / p might be 0.33-0.53, for example.

In the liquid crystal material, for example, a material which can be polymerized by light or heat, for example, an UV curable liquid crystal (ultraviolet curable material having liquid crystallinity), and in the fifth embodiment, UCL-001 made by Dainippon Ink, Inc. Was added. The material is not limited to this. It is preferable that it is an ultraviolet curable material from a viewpoint of memory stability mentioned later. Although the material which does not have liquid crystallinity can exhibit the same effect as the effect mentioned later, in consideration of orientation, it is preferable to use the ultraviolet curable material which has liquid crystallinity.

The inventors of the present invention, 1 wt%, based on the total mass of the material (liquid crystal material, chiral agent, and the ultraviolet curable monomer material) injecting the addition amount of the ultraviolet curable monomer material into the liquid crystal layer 15, A plurality of liquid crystal display elements were manufactured under three conditions of 2 wt% and 5 wt%.

In the fifth embodiment, after the injection of the liquid crystal material including the chiral agent and the UV curable liquid crystal, ultraviolet rays are irradiated to cause a polymerization reaction of the UV curable liquid crystal, and the polymer (polymer) in the liquid crystal layer 15 ) Was synthesized (polymerization treatment). For the experiment, ultraviolet irradiation was performed both when the liquid crystal molecules of the liquid crystal layer 15 were in the reverse twisted arrangement state and when the sprayed twisted arrangement was in the state. Although the ultraviolet-ray irradiated on the conditions which the irradiation amount of 18 mW / cm <^2> and the integrated exposure amount will be 1 J / cm <^2> , UV irradiation conditions are not limited to this.

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

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

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

19A is an external photograph showing a liquid crystal display device after irradiating 1J / cm ² ultraviolet rays to cause a polymerization reaction and synthesizing a polymer (polymer) in the liquid crystal layer 15. The photo on the left shows the external appearance of the liquid crystal display element irradiated with ultraviolet rays in the spray twisted arrangement state, and the photo on the right shows the appearance of the liquid crystal display element irradiated with ultraviolet rays in the reverse twisted arrangement state. This point is common to all of FIG. 19A-FIG. 19D.

The liquid crystal display device according to the fifth embodiment displays white color in the spray twisted arrangement state and black display in the reverse twisted arrangement state. The liquid crystal display device that was in the spray twist arrangement state at the time of ultraviolet irradiation maintained the spray twist arrangement state even after the ultraviolet irradiation, and the liquid crystal display element which was the reverse twist arrangement state at the time of ultraviolet irradiation maintained the reverse twist arrangement state even after the ultraviolet irradiation. .

19B is an external photograph showing the liquid crystal display device after applying a voltage equal to or higher than the threshold voltage to the upper beta electrode 12a and the lower beta electrode 12b and adding a vertical electric field to the liquid crystal layer 15.

It is understood that the liquid crystal display device shown in the photograph on the left is transitioning from the spray twist arrangement state to the reverse twist arrangement state. In the liquid crystal display device shown in the photograph on the right, the reverse twist arrangement is maintained.

19C is a photograph of appearance after heat-treating the liquid crystal display device at 90 ° C. for 30 minutes. It turns out that the reverse twist arrangement state is hold | maintained stably even after the heat processing at 90 degreeC high temperature.

FIG. 19D shows a liquid crystal display after applying a voltage equal to or greater than a threshold voltage causing a reaction to the lower beta electrode 12b and the first and second sacrificial electrodes 12c and 12d and adding a lateral electric field to the liquid crystal layer 15. It is an external photograph which shows an element.

Even in the left photograph (liquid crystal display element irradiated with ultraviolet rays in the spray twist arrangement), and also in the right photograph (liquid crystal element irradiated with ultraviolet rays in the reverse twist arrangement), the addition of the transverse electric field It can be seen that the state transitions.

From the results shown in Figs. 19A to 19D, the liquid crystal display device according to the fifth embodiment has high switching performance (switchability between the reverse twist arrangement state and the spray twist arrangement state) and high memory performance by the addition of an electric field. It can be seen that it is a liquid crystal display device having both (thermal stability).

FIG. 20 is a microscope picture showing the liquid crystal display device (the liquid crystal display device after the heat treatment for 30 minutes at 90 ° C.) shown in FIG. 19C in appearance. The left side shows the photomicrograph of the liquid crystal display element which irradiated the ultraviolet-ray in the reverse twist arrangement state, and the right side shows the micrograph of the liquid crystal display element which irradiated the ultraviolet-ray in the spray twist arrangement state. On the left and right sides, a photograph photographing the corner of the display area is shown above, and a photograph photographing the edge of the display area is shown below. Microscopic observation shows that the boundary between the display area (reverse twist arrangement state) and the non-display area (spray twist arrangement state) has several tens of micrometers of shaking, but is stable in the display area and the reverse twist arrangement state is held. have. In addition, a significant difference is not recognized between the liquid crystal display device (photo on the left) irradiated with ultraviolet rays in the reverse twisted arrangement and the liquid crystal display device (photo on the right) irradiated with ultraviolet rays in the spray twisted arrangement. It can be seen that the reverse twist arrangement is stably held.

Next, the inventors of the present invention conducted an experiment on the relationship between the addition concentration of the ultraviolet curable material and the memory property.

21A to 21D are photographs showing the results of experiments on the memory stability of the liquid crystal display device to which the ultraviolet curable material is added at different amounts (1 wt%, 2 wt%, 5 wt%). Similarly to the photographs shown in FIGS. 19A to 19D, the photographs in 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 in the right column show the reverse twist arrangement state. The external appearance of the liquid crystal display element which irradiated ultraviolet-ray at the time is shown. 21A to 21D, the upper part is an external photograph of the liquid crystal display device manufactured by adding 1 wt% of the ultraviolet curable material, and the middle part of the liquid crystal display device manufactured by adding 2 wt% of the ultraviolet curable material to the middle. The external photograph and the lower image show an external photograph of the liquid crystal display device fabricated by adding 5 wt% of the ultraviolet curable material. In addition, there were cell thickness stains in the liquid crystal display device fabricated with the added amounts of 1 wt% and 5 wt%.

FIG. 21A is an external photograph showing a liquid crystal display device after irradiating 1J / cm ² ultraviolet light to cause a polymerization reaction and synthesizing a polymer (polymer) in the liquid crystal layer 15.

In the case where the addition amount was 1 wt%, 2 wt%, or 5 wt%, the liquid crystal display device in the spray twist arrangement state at the time of ultraviolet irradiation, the spray twist arrangement state was maintained even after the ultraviolet irradiation, and the liquid crystal in the reverse twist arrangement at the time of ultraviolet irradiation. It can be said that the display element maintains the reverse twist arrangement even after ultraviolet irradiation.

FIG. 21B is an external photograph showing a liquid crystal display device after applying a voltage equal to or greater than a threshold voltage to the upper beta electrode 12a and the lower beta electrode 12b and adding a vertical electric field to the liquid crystal layer 15.

It is understood that the liquid crystal display device shown in the photograph in the left column is transitioning from the spray twist arrangement state to the reverse twist arrangement state. In the liquid crystal display device shown in the photograph of the right column, the reverse twist arrangement is maintained.

Fig. 21C is a photograph of the appearance after heat-treating the liquid crystal display for 30 minutes at 90 占 폚. Even after the heat treatment at a high temperature of 90 ° C., it can be seen that the reverse twist arrangement is stably held regardless of the addition amount (1 wt%, 2 wt%, 5 wt%) of the ultraviolet curable material.

FIG. 21D also shows the liquid crystal display after applying a voltage equal to or greater than the minimum physical quantity voltage to the lower beta electrodes 12b and the first and second sacrificial electrodes 12c and 12d and adding a transverse electric field to the liquid crystal layer 15. It is an external photograph showing an element.

In the left column photo (liquid crystal display element irradiated with ultraviolet rays in the spray twist arrangement), the amount of addition of the ultraviolet curable material is 1 wt%, 2 wt%, 5 wt% in any case, whereby the spray twist is caused by the addition of the transverse electric field. It is transitioning to an array state.

Referring to the photograph of the right picture (the liquid crystal display device irradiated with ultraviolet rays in the state of reverse twist arrangement), for the liquid crystal display device of 1 wt% and 2 wt% of the ultraviolet curable material, the spray twist arrangement is caused by the addition of the transverse electric field. Although it is transitioning to a state, it turns out that for a 5 wt% liquid crystal display element, even if a lateral electric field is added, it remains in a reverse twist arrangement state (it does not transition to a spray twist arrangement state).

From the results shown in FIGS. 21A to 21D, a liquid crystal display device according to an embodiment in which a polymerizable material is added to a liquid crystal layer, polymerized, and a polymer (polymer) is synthesized in the liquid crystal layer is used for the display according to the addition of an electric field. It can be said to be a liquid crystal display device having both switching property (switching between reverse twist arrangement and spray twist arrangement) and high memory performance (thermal stability). However, in the case where the addition amount is 5wt%, in the liquid crystal display device irradiated with ultraviolet rays in the reverse twisted arrangement state, polymerization is possible because the transverse electric field after the heat treatment could not transition from the reverse twisted arrangement state to the spray twist arrangement state. It is preferable that the addition amount of the material is 5 wt% or less.

In addition, the liquid crystal display device according to the fifth embodiment was displayed with a high contrast ratio even when observed from the front side, similarly to the liquid crystal display device according to the comparative example.

The liquid crystal display device according to the fifth embodiment has a high memory performance (thermal stability) of the display and can retain the display semi-permanently regardless of the temperature, even in a high temperature environment of, for example, about 90 ° C. The display in each arrangement state (reverse twist arrangement state or spray twist arrangement state) can be held stably. For this reason, it can be used also for liquid crystal display elements which require high reliability, such as vehicle mounting, aircraft, and outdoor use. Moreover, it is compatible with the display by a high contrast ratio. As described above, the liquid crystal display device according to the fifth embodiment is a liquid crystal display device having high display quality.

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

The liquid crystal display device according to the fifth embodiment is capable of ultra-low power consumption, which can be driven by a driving method using memory characteristics, and especially when applied to a reflective display, the merit is large, and large-capacity display at low cost. In the manufacture thereof, the same effect as in the first embodiment can be obtained in that the cost increase factor compared with the general twisted nematic liquid crystal display element is small.

Subsequently, the liquid crystal element according to the sixth embodiment will be described.

A schematic cross-sectional view of the liquid crystal device according to the sixth embodiment is the same as that in FIG. The liquid crystal element manufacturing method according to the sixth embodiment is substantially the same as that of the first embodiment. In the sixth embodiment, the indentation amount at the time of rubbing was set to 0.4 mm to 1.2 mm. As a result, the upper and lower alignment layers 14a and 14b can express a pretilt angle of about 35 ° to 60 ° with respect to the liquid crystal molecules. Moreover, chiral agent was added on condition that d / p may be 0.25-0.75.

The inventors of the present invention have produced several liquid crystal elements having different manufacturing conditions in order to find appropriate alignment conditions of the liquid crystal elements. As an alignment film material, the polyimide material which lowered the side chain density of the material used normally as a vertical alignment film was used, The baking temperature at the time of alignment film formation, and the amount of indentation at the time of rubbing were made into variable parameters. Specifically, the baking temperature set some temperature in the range of 160 degreeC-260 degreeC. In addition, the pushing amount 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 kPa to 800 kPa. About the twist angle of the liquid crystal molecule of a liquid crystal layer, it set to 90 degrees or 70 degrees. The "twist angle" here means the conceivable angle in a spray twist state, and a substantial twist angle in a reverse twist state is (180 degrees-phi). This point also applies to other embodiments. The liquid crystal layer thickness was 4 micrometers. The chiral agent was added to the liquid crystal material which comprises a liquid crystal layer, and the addition amount made it the value of d / p to be 0.167-0.800. The upper polarizing plate 16a and the lower polarizing plate 16b are arranged so that their transmission axes are substantially parallel to the rubbing direction when the twist angle φ is 90 °, and both are arranged in a cross nicol arrangement, and the twist angle φ is In the case of this 70 degree | times, each transmission axis was set to the position 10 degree away from a rubbing direction, and both were made to be cross nicol arrangement | positioning.

22 is a diagram showing an observation image of a liquid crystal element in typical production conditions and a display state. In detail, FIG. 22A is an observation image of the liquid crystal element immediately after the liquid crystal layer is partially changed from the spray twist alignment state to the reverse twist alignment state by the voltage value, and FIG. 22B shows the liquid crystal element after 3 months have elapsed. Is observed. As shown in Fig. 22A, it can be seen that the liquid crystal element of this example shows a high contrast ratio even when viewed from the front. As shown in Fig. 22B, it can be seen that most of the displays are retained even after three months.

Fig. 23 shows evaluation results of contrast and display holding performance in a liquid crystal element having a pretilt angle of about 46 degrees and a twist angle of 70 degrees. In FIG. 23, the result of evaluating the front contrast and the state holding time of each liquid crystal element produced by setting the value of d / p of the liquid crystal layer under a plurality of conditions between 0.167 and 0.800 is shown. have. Moreover, the baking temperature of the orientation film of each liquid crystal element was set to 200 degreeC, CB15 was used as a chiral agent, and the thing with comparatively small value of refractive index anisotropy (DELTA) n was used as a liquid crystal material. Moreover, about front contrast, the liquid crystal layer was made to transition from the spray twist orientation state to the reverse twist orientation state by voltage application, and the change with the retention performance of the reverse twist orientation state with time was observed. As a result, about front contrast, the value of d / p was good between 0.333-0.500, and high contrast was obtained especially above 0.385. The transmitted light became dark (dark display) between d / p of 0.167-0.286, and the transmitted light became bright (bright display) between d15 and 0.615-0.800, and both had low contrast. The state holding time is 1 hour or more in the liquid crystal element of d / p = 0.333, 1 or more days in each of the liquid crystal elements of d / p = 0.385 and d / p = 0.421, d / p = 0.444, d / p. In each liquid crystal device of = 0.500, state holding time was obtained for at least one week.

FIG. 24 shows evaluation results of the temperature characteristics of display retention performance in a liquid crystal element (a liquid crystal element having a value of d / p of 0.444 to 0.500) having a pitch p of 8.0 μm to 9.0 μm among the conditions shown in FIG. 23. It is a figure which shows. Here, two types (R-8111, CB15) are used also for a chiral agent. Evaluation here observes whether the display in a reverse twist orientation state is hold | maintained after leaving a liquid crystal element for 24 hours under each temperature condition. In the case of the temperature condition of 40 degreeC, in all liquid crystal elements other than the liquid crystal element in which the chiral agent was set to CB15 and the pitch was 9.0 micrometers, all showed the high display holding performance. However, in the case of temperature conditions of 50 degreeC, display holding performance fell in some liquid crystal elements. In the case of the temperature condition of -40 degreeC, display holding performance fell in the liquid crystal element which made the chiral agent R-811 and the pitch 8.0 micrometers. These results can be thought to be due to the change in the pitch of the chiral agent by the temperature conditions, but it can be seen that the high display retention performance can be obtained over a wide temperature range by selecting the type and amount of chiral agent. have.

FIG. 25: is a figure which shows the observation image of the liquid crystal element used for evaluation shown in FIG. Specifically, Fig. 25A is an observation image of a liquid crystal element with chiral R-811 and a pitch of 8.0 μm, and Fig. 25B is an observation image of a liquid crystal element with chiral R-811 and a pitch of 8.5 μm, and Fig. 25C. Is an observation image of a liquid crystal element with chiral R-811 and a pitch of 9.0 µm, and FIG. 25D is an observation image of a liquid crystal element with chiral CB15 and a pitch of 8.0 µm, and FIG. 25E is a chiral CB15 and a pitch of 9.0 µm. It is the observation image of the liquid crystal element made into micrometer. The pretilt angle of each liquid crystal element is about 46 degrees. It turns out that any liquid crystal element has high front contrast and excellent display and holding performance.

Fig. 26 is a diagram showing an observation image of a liquid crystal element in which the pitch conditions are 9 μm (short pitch condition) and 12 μm (long pitch condition). Specifically, FIG. 26A is an observation image before applying the voltage of the liquid crystal element under short pitch condition, FIG. 26B is an observation image immediately after applying the voltage of the liquid crystal element under short pitch condition, and FIG. 26C is a liquid crystal under long pitch condition. It is an observation image before voltage application of an element, and FIG. 26D is an observation image immediately after voltage application of the liquid crystal element under a long pitch condition. Fig. 26E shows the relationship between the rubbing direction and the alignment state in each liquid crystal element. In addition, the pretilt angle of each liquid crystal element is about 46 degrees, and manufacturing conditions are as above. As shown in Figs. 26A and 26B, the liquid crystal element with the short pitch condition has high front contrast and the boundary of the electrode is clearly shown. On the other hand, as shown in Figs. 26C and 26D, the liquid crystal element in the long pitch condition has a slightly lower front contrast, the boundary of the electrode is indistinctly apparent even after the voltage is applied, and the rubbing curve is remarkable. have. It can be seen that the long pitch condition (d / p = 0.333) shown here is a very unfavorable condition when the pretilt angle is high (about 46 degrees). 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 and hold performance.

27 to 31 are diagrams showing optical characteristics of each liquid crystal element corresponding to the fabrication conditions shown in FIG. Specifically, FIGS. 27A, 28A, 29A, 30A, and 31A show visual characteristics, respectively, and FIGS. 27B, 28B, 29B, 30B, and 31B respectively show arrangements of the rubbing direction and the transmission axis of the polarizing plate, respectively. 27C, 28C, 29C, 30C, and 31C show contrast characteristics, respectively, and FIGS. 27D, 28D, 29D, 30D, and 31D show transmittance characteristics T _St and spray twist states, respectively. The transmittance | permeability characteristic T _Ut of a reverse twisted state is shown. The optical characteristics shown in FIG. 27 are those of chiral R-811 and a liquid crystal element having a pitch of 8.0 μm, and the optical characteristics shown in FIG. 28 are those of a chiral R-811 and a liquid crystal element having a pitch of 8.5 μm. The optical characteristics shown in FIG. 29 are those of the chiral R-811 and a liquid crystal element having a pitch of 9.0 µm, and the optical characteristics shown in FIG. 30 are those of the chiral CB15 and a liquid crystal element having a pitch of 8.0 µm. Optical characteristics are that of a chiral CB15 and a liquid crystal element having a pitch of 9.0 m. Also in any liquid crystal element, the baking temperature of an oriented film is 200 degreeC (pretilt angle 35 degree-about 60 degree), and the twist angle is 70 degree. In the case of any liquid crystal element, the contrast ratio on the front is high (CR = 141 to 677), and in particular, the chiral CB15 and the liquid crystal element having a pitch of 8.0 μm do not show display inversion at any time and high visibility can be obtained. It can be seen that there is (see Fig. 30). When the pretilt angle under these conditions was measured, it was found that the pretilt angle of about 35 ° to 60 ° (the measurement result was varied) was shown.

The reason why such a characteristic is exhibited is not fully explained, but in general, in the reverse twisted alignment state, it may be considered that a large distortion occurs due to the relationship between the pretilt angle of the interface and the twisting force due to the chiral agent in the liquid crystal layer. Can be. By this distortion, even in the voltage-off state, the liquid crystal molecules near the center in the layer thickness direction of the liquid crystal layer are inclined with respect to the substrate plane. In general, in the reverse twist orientation, the inclination angle in bulk is higher than the pretilt angle of the interface. This has also been confirmed in liquid crystal molecular orientation simulation based on continuum theory. Each liquid crystal element of the embodiment can make the inclination angle of the liquid crystal molecules near the middle of the layer thickness direction of the liquid crystal layer very high by making the pretilt angle very high, so that the liquid crystal molecules rise up to a state close to the vertical alignment. I guess it is. Thus, it can be considered that a relatively dark black display can be obtained even in the voltage-off state even in the front direction.

Next, the manufacturing conditions and the state of the switching of the display state will be described with respect to the liquid crystal element (liquid crystal element according to the sixth embodiment) manufactured under conditions that can be considered to be suitable within the above-described verification range. About specific manufacturing conditions, the orientation film set the baking conditions at 200 degreeC for 1 hour, and made the film thickness into 500 kPa-800 kPa. In addition, the amount of indentation during the rubbing treatment was 0.8 mm. The twist angle phi of the liquid crystal layer was 90 degrees or 70 degrees, and the layer thickness was 4 micrometers. ZLI-2293 (made by Melk Co., Ltd.) was used as a liquid crystal material, and CB15 was used as chiral agent. The addition amount of a chiral agent was made to be d / p = 0.5 (pitch 8 micrometers). The polarizing plates were arranged such that their transmission axes were parallel or orthogonal to the rubbing direction, and their transmission axes were substantially orthogonal to each other. Here, the polarizing plate was arrange | positioned so that each transmission axis might become parallel with the rubbing direction of the orientation film of the board | substrate which adjoins, respectively.

Fig. 32 is a diagram showing a state when a voltage is applied to each electrode and switched to the liquid crystal element according to the sixth embodiment. In detail, FIG. 32A is a view showing the arrangement of the electrode pattern, the rubbing direction, and the polarizing plate, FIG. 32B is an observation image of the liquid crystal element in the initial state, and FIG. 32C is an observation of the liquid crystal element after application of the electric field. 32D is an observation image of the liquid crystal element after the lateral electric field is applied. In the liquid crystal element herein, the electrode width of the comb-shaped electrodes (the first bladder electrode 12c and the second bladder electrode 12d) is 20 µm and the electrode spacing is 20 µm. In addition, "Ru" shown in FIG. 32A shows the rubbing direction of the upper substrate, "Rb" shows the rubbing direction of the lower substrate, and "P" and "A" show the transmission axis directions 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 a spray twist alignment state, and the transmitted light is in a bright state (namely, white display). Then, as shown in Fig. 32C, after applying the longitudinal electric field to the liquid crystal layer, the liquid crystal layer transitions to the reverse twist alignment state, and the transmitted light is in a dark state (ie, black display). Then, as shown in Fig. 32D, after the transverse electric field is applied to the liquid crystal layer using the blazing electrodes 12c and 12d, the liquid crystal layer transitions back to the spray twist state, and the transmitted light is bright as the initial state. (White display). It is thought as follows that such a switching was possible. In the spray twist alignment state, the liquid crystal molecules in the center of the layer thickness direction of the liquid crystal layer are aligned in the horizontal direction. However, the application of the electric field results in a reverse twist alignment state, and the liquid crystal molecules in the center of the layer thickness direction of the liquid crystal layer Liquid crystal molecules are oriented in the vertical direction. Thereafter, the horizontal electric field is applied to the liquid crystal molecules at approximately the center of the layer thickness direction of the liquid crystal layer in the reverse twisted state by the application of the horizontal electric field, and the liquid crystal molecules are oriented in the horizontal direction again. Since this orientation direction is an orientation direction in which the liquid crystal molecule should exist in the substantially center of the layer thickness direction of the liquid crystal layer of a spray twist orientation state, it can be considered that a liquid crystal layer has transitioned to the spray twist state.

In addition, when the amount of chiral agent added to 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) was almost vertically aligned. It turned out that it was difficult to switch the contrast state. Moreover, when it made it high about 70 degrees or more with respect to a pretilt angle, even if the chiral agent was adjusted correspondingly, it turned out that it is difficult to obtain a contrast state between a spray twist state and a reverse twist state. From this, it can be said that it is necessary to set the relationship between the amount of chiral agent added and the pretilt angle to the above conditions in order to achieve both relatively black display and bistable stability. Here, although the pretilt angle was 46 degrees, as is generally known, the pretilt angle in such an area is very difficult to measure, and there exists an error width in the numerical value. There may be a deviation of ± 15 ° to 30 ° due to differences in measurement methods or problems in measurement accuracy.

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

The liquid crystal display device according to the sixth embodiment is capable of ultra-low power consumption, which can be driven by a driving method using memory characteristics, and in particular, when applied to a reflective display, the merit is large, and a large-capacity display at low cost is achieved. It is possible to carry out. In manufacturing, the cost increase factor compared with the general twisted nematic type liquid crystal display element is small, and the effect similar to 1st Example can be exhibited.

FIG. 33 is a flow chart showing a manufacturing method of the liquid crystal display device according to the seventh embodiment. The inventors of the present invention produced a plurality of liquid crystal display elements according to the flowchart shown in this drawing, and preliminarily considered conditions under which good display is realized.

Two transparent substrates on which a transparent electrode, for example, an ITO electrode is formed, are prepared (step S101). Here, two transparent substrates were washed and dried using a test cell having a parallel plate type electrode (step S102).

On the transparent substrate, an alignment film material is applied so as to cover the ITO electrode (step S103). Application of the alignment film material was performed using a spin coat. You may carry out using a fureciso printing or inkjet printing. In this example, the side chain density of the polyimide alignment film material used for formation of a vertical alignment film was usually made low, and was used as an alignment film material. The control of the side chain density is for enabling provision of an appropriate pretilt angle. The alignment film material was applied so that the thickness of the alignment film was 500 kPa to 800 kPa.

Temporary firing (step S104) and main firing (step S105) of the transparent substrate coated with the alignment film material are performed. This firing was performed by changing the firing temperature between 160 ° C and 200 ° C. In this way, the alignment film which covers an ITO electrode was formed (step S103-S105).

Next, a rubbing process (orientation process) is performed (step S106). A rubbing process is a process of rubbing the oriented film shape by rotating a cylindrical roll wound by cloth at high speed, for example, and arrange | positioning (orienting) the liquid crystal molecules contacting a board | substrate in one direction. The rubbing treatment was performed under three conditions in which the indentation amounts were 0.4 mm, 0.8 mm, and 1.2 mm. Further, the rubbing treatment was performed such that the twist angle of the liquid crystal display element was 70 degrees or 90 degrees.

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

The sealing material is printed on the other transparent substrate surface to form a main seal pattern (step S108). For example, a thermosetting seal material containing glass fibers having a particle size of 4 µm is printed by screen printing. A seal material can also be apply | coated using a dispenser. Moreover, you may use not only thermosetting but a photocurable sealing material and the hardening type sealing material for light and heat.

The transparent substrate is polymerized (step S109). Two transparent substrates are polymerized at predetermined positions to form a cell, and heat-treated in a pressed state to cure the seal member. For example, the thermosetting of a sealing material is performed using the hot press method. In this way, a blank cell is produced.

For example, the nematic liquid crystal is injected into the empty cell by the vacuum injection method (step S110). Chiral agent was added to the liquid crystal. As chiral agent, CB15 or S-811 made by Melk Corporation was used. The addition amount of a chiral agent was adjusted so that d / p might be 0.51.2, for example, when letting chiral pitch p and cell thickness d be.

The liquid crystal injection port is sealed with, for example, an ultraviolet curing type end seal material (step S111), and the cell is heated above the phase transition temperature of the liquid crystal in order to arrange the alignment of the liquid crystal molecules (step S112). Thereafter, the scribing device breaks along the damage engraved on the transparent substrate, and divides it into small cells.

A chamfer (step S113) and washing | cleaning (step S114) are performed about the cell divided | segmented small.

Finally, the polarizing plate is stuck to the surface on the opposite side to the liquid crystal layer of the two transparent substrates (step S115). Two polarizing plates were arrange | positioned so that the direction of a transmission axis and a rubbing direction might be parallel in cross nicol. It may be arranged to be orthogonal. A power supply was connected between the ITO electrodes of both transparent substrates.

34A and 34B are photographs showing polarization microscope observation results in a display state of a plurality of produced liquid crystal display elements. The photograph of FIG. 34A shows the display state at the time of the front observation of the liquid crystal display element manufactured on the conditions which made the pretilt angle about 35 degrees, and d / p 0.57, The photograph of FIG. 34B shows the pretilt angle about 45 degrees. It shows that of the liquid crystal display element manufactured on the conditions which made ° and d / p 0.8.

In FIG. 34A, the black part (black display) is a region where voltage is applied between the electrodes of both transparent substrates, and the white part (white display) is a region where no voltage is applied. The same applies to FIG. 34B. 34B, the enlarged photograph of the part which looks white is also shown.

Although the part which looks white is seen with a uniform white display visually, when it is magnified and observed with a microscope, the pattern of delicate orientation is recognized. This can be thought of as a focal conic orientation.

34C, the outline of the liquid crystal molecule array of focalconic orientation is shown. The focalconic alignment refers to an arrangement 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 surface of the substrate (upper substrate and lower substrate).

On the other hand, in the part which appears black in the photograph of FIG. 34A and 34B, the liquid crystal molecule responds to the torsional force provided by the chiral agent, and reverses to twist in the direction which is easy to twist from the relationship of the pretilt angle of an upper and lower board. You can think of it as showing a twisted array. Since the liquid crystal molecules located at the center of the thickness direction of the liquid crystal layer stand in the vertical direction to some extent, black display will be obtained. In the manufacturing conditions of the liquid crystal cell shown in the photograph of FIG. 34A, and the production conditions of the liquid crystal cell shown in the photograph of FIG. 34B, since the addition amount of chiral agent is comparatively large, distortion (distortion) inside a liquid crystal layer is large, and a liquid crystal It is guessed that the center molecular direction of the thickness direction of a layer is in the state standing up near vertical.

The produced liquid crystal display element is in a focal conical arrangement state in an initial state. When a voltage equal to or higher than the saturation voltage value of the electro-optical characteristic is applied between the ITO electrodes of both transparent substrates (which causes a longitudinal electric field of intensity equal to or higher than the threshold voltage), the state transitions to the reverse twist arrangement. It is understood from the photographs shown in FIGS. 34A and 34B that the produced liquid crystal display device displays at a high contrast ratio even when observed from the front.

The memory of the white display (the focal conic arrangement) and the black display (reverse twist arrangement) are very stable, and microscopic changes in the arrangement of the liquid crystal molecules have been observed under a microscope. did.

Fig. 35A shows a 0 ° to 180 ° azimuth (left and right orientation) with respect to a liquid crystal display device (the liquid crystal display device showing the display state in Fig. 34B) manufactured with a pretilt angle of about 45 ° and d / p 0.8. ) Is a graph showing the transmittance visual dependence. The horizontal axis of the graph shows the observation angle when the front direction (substrate normal direction) is 0 ° in units of "°". The observation angle tilted to the upper right is shown as a positive angle, and the observation angle tilted to the left is shown as a negative angle. The vertical axis of the graph represents the transmittance in units "%". The curve followed by the rhombus (denoted S-t) indicates the visual dependence of the transmittance in the focal conic arrangement. The squared curve (denoted U-t) represents that in reverse twisted configuration.

35B shows an equal contrast curve of the liquid crystal display device (the liquid crystal display device showing the display state in FIG. 34B) manufactured under the condition that the pretilt angle is about 45 ° and the d / p is 0.8.

As can be seen from FIG. 35B, almost symmetric isocontrast curves are obtained with respect to the entire orientation of the produced liquid crystal display device. Also, as shown in Fig. 35A, the liquid crystal display device fabricated from the fact that even in the focal conic arrangement state (white display) and in the reverse twist arrangement state (black display), the transmittance visual dependence which is almost symmetric is obtained. It can be clearly seen that has a contrast characteristic of symmetry. Thus, the produced liquid crystal display element is a liquid crystal display element excellent in visual characteristic.

For comparison, FIG. 35C shows the visual contrast characteristics of the liquid crystal display device according to the embodiment of the invention described in Patent Document 6. As shown in FIG. This figure is a figure same as what was described in the figure (FIG. 13 (A)) of patent document 6. As shown in FIG. As can be seen from FIG. 35C, in the liquid crystal display device described in Patent Document 6, the contrast ratio is asymmetric. The liquid crystal display device preliminarily manufactured according to the flowchart (FIG. 33) showing the manufacturing method of the liquid crystal display device according to the seventh embodiment realizes the symmetry of the contrast ratio in comparison with the above invention. In view of this, the visual characteristics are excellent. In addition, in the Example of invention described in patent document 6 from FIG. 35C, the contrast ratio at the time of front observation is a little larger than 3, and in the graph shown to FIG. 35A, according to the flowchart shown in FIG. In contrast, the contrast ratio of the fabricated liquid crystal display device is slightly smaller than four. In this way, when viewed from the front, the visual characteristics are excellent in that the display can be performed at a high contrast ratio. These features (height of display quality) also include a liquid crystal display element (described later) according to the seventh embodiment.

The present inventors earnestly studied the conditions under which, for example, by giving a physical action to the liquid crystal layer, the reverse twisted arrangement state and the focalconic arrangement state are realized in an interchangeable manner, and the respective arrangement states of the liquid crystal molecules become stable together.

Fig. 36 is a graph showing a condition for realizing the reverse twisted arrangement state and the bistable state of the focal conic arrangement state. The horizontal axis of the graph shows the pretilt angle in unit "°", and the vertical axis shows the addition amount of a chiral agent using d / p.

In this figure, in the combination of the pretilt angle and d / p which are in the range below the rhombic curve, the focalconic arrangement state is not expressed. In other words, if the amount of chiral agent added is too small, the spray twist arrangement is shown, not the pocal conic arrangement.

Moreover, in the combination of the pretilt angle and d / p which are in the range above the square curve, it will always be in a focal conic arrangement state. In other words, if the amount of chiral agent added is too large, the phase transition from the focal conic arrangement to the reverse twist arrangement cannot be achieved.

The curve moves slightly up and down depending on the anchoring strength of the interface and the elastic constant of the liquid crystal, but in the combination of the pretilt angle and d / p in the range between the two curves, the reverse twist arrangement state and the focal conic arrangement state A bistable state is realized. The bistable state of the reverse twist arrangement state and the focal conic arrangement state is a special state which appears when the chirality chirality is controlled within a certain range.

The circled display shows the display state in FIG. 34B, and shows the pretilt angle (about 45 degrees) and d / p (0.8) of the liquid crystal display device showing visual characteristics in FIGS. 35A and 35B.

From the results shown in this figure, it can be seen that the closer the pretilt angle is to the vertical, the easier it becomes to the focalonic arrangement state even if the value of d / p is low. According to experiments conducted by the inventors of the present invention, even when the pretilt angle is low, when the liquid crystal molecular orientation is close to the vertical by the voltage, the focalconic arrangement state is observed. If the value is not relatively high, no focalconic arrangement was expressed.

The bi-stable state of the reverse twist arrangement state and the focal conic arrangement state is realized in both of the upper and lower substrates sandwiching the liquid crystal layer, and an orientation treatment is performed in which a pretilt angle of 20 ° or more and 85 ° or less is expressed. It may be said that the chiral agent is added to a liquid crystal layer in the range which becomes d / p 0.5 or more and 2 or less. In addition, when the chiral agent is added in the range which d / p becomes 0.5 or more and 1.2 or less, when the orientation process is performed so that the pretilt angle of 35 degrees or more and 55 degrees or less may express on both of upper and lower boards, It can be said that the bistable state of the reverse twisted array state and the focal conic array state is feasible.

The inventors of the present invention produced the liquid crystal display device according to the seventh embodiment based on the above preliminary considerations.

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

A chiral agent is added to the liquid crystal material which forms the liquid crystal layer 15. The arrangement state of the liquid crystal molecules in the liquid crystal cell completion state (initial state) was a focal conic arrangement. For example, by applying an alternating voltage of at least a threshold voltage between the beta electrodes 12a and 12b by the power supply 20, the arrangement state of the liquid crystal molecules can be transferred from the focalconic array to the reverse twisted array. .

37-41, the structure and manufacturing method of the liquid crystal display element by 7th Example are demonstrated in detail.

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

The ITO film pattern is formed by, for example, the ITO film extending in a stripe shape in the left and right directions 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.

Patterning of the ITO film | membrane was performed using the photolithography process after wash | cleaning an ITO glass substrate. The etching of ITO was performed by wet etching using iron chloride. You may pattern by irradiating a laser beam and removing an ITO film | membrane.

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

For example, the ITO film pattern is formed by extending the ITO film in a stripe shape in the vertical direction of the drawing. In this figure, parts of the ITO film constituting the pixel electrode are denoted by symbols 12B ₁ to 12B ₉ . The up-down direction of this figure and the left-right direction of FIG. 37 are directions orthogonal to each other.

The patterning of the ITO film can be performed by the same method as the method for forming the ITO film pattern described with reference to FIG. 37.

After patterning the ITO film, the insulating film 13 is formed on the lower transparent substrate 11b including the ITO film. The insulating film 13 is not formed in, for example, the extraction electrodes 12BT ₁ to 12BT ₉ portions (terminal portions). In this figure, diagonal lines are shown in regions where the insulating film 13 is not formed. The insulating film 13 can be formed by forming a resistor in a take-out electrode portion or the like, removing the resistor by lift-off after forming the insulating film, or by forming a sputter while covering the take-out electrode portion with a metal mask. Do. The insulating film 13 can be an organic insulating film or an inorganic insulating film such as SiO 2 or SiN _x . You may form by a combination of these. Here, a laminated film of an acrylic organic insulating film and SiO 2 was used as the insulating film 13.

In the seventh embodiment, first, a heat resistant film (polyimide tape) was attached to the extraction electrode portion, and the organic insulating film was spin-coated (spinned at 2000 rpm for 30 seconds) at a film thickness of 1 m. Next, the lower transparent substrate 11b spin-coated with the organic insulating film was baked at a high temperature at 220 ° C. for 1 hour in a clean oven, and then the lower transparent substrate 11b was heated to 80 ° C. with the heat resistant film attached thereto. A SiO2 film was formed into a film with a thickness of 1000 mW by the sputtering method (AC discharge). The SiO2 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 here, the organic insulating film and the SiO2 film could be removed with respect to the adhesive point of the heat resistant film. Subsequently, in order to improve the insulation and transparency of the SiO 2 film, the lower transparent substrate 11b was baked at a high temperature at 220 ° C. for 1 hour in a clean oven.

Although the formation of the SiO2 film is not essential, the insulation of the insulating film 13 can be improved by forming the SiO2 film. In addition, it is possible to improve the adhesion and patterning properties of the first and second sacrificial electrodes 12c and 12d formed on the insulating film 13.

The insulating film 13 may be composed of only SiO ₂ film without forming an organic insulating film. Since SiO ₂ is likely to be a porous film, in this case, it is preferred that the SiO ₂ film with a thickness 4000Å ~ 8000Å. The inorganic insulating film 13 may be a laminate of an SiO ₂ film and a SiN _x film.

An ITO film was formed on the insulating film 13. The ITO film heated the lower transparent substrate 11b to 100 degreeC, and formed into a film whole surface by the sputtering method (AC discharge). The film thickness was about 1200 mm. The ITO film can also be formed using a vacuum vapor deposition method, an ion beam method, a CVD method, or the like. The ITO film was patterned by a photolithography process to form first and second electrodes 12c, 12d and extraction electrodes of these electrodes 12c and 12d.

Fig. 39 is a schematic plan view showing a photomask used for etching an ITO film. The photomask includes a portion corresponding to the first sachet electrode 12c, a portion corresponding to the second sac electrode 12d, a corresponding portion of the extraction electrode of the first sac electrode 12c, a portion corresponding to the extraction electrode of the second sac electrode 12d, And an extraction electrode corresponding portion of the lower beta electrode 12b. At the time of etching, an electrode is formed with an ITO film covered at each corresponding portion. The inventors of the present invention have a plurality of electrode intervals of 20 μm, 30 μm, 50 μm, 100 μm, 200 μm when the electrode width of the bladder portion of the comb-shaped electrode is alternately arranged with 20 μm, 30 μm and the bladder portion of two comb-shaped electrodes. As the electrode pattern of, the first sachet electrode 12c and the second sacrificial electrode 12d were produced.

Through the above process, two electrode attachment substrates were prepared (step S101 of FIG. 33). Two substrates with electrodes are washed and dried (step S102). In the case of water washing, pure water washing is performed. You may use detergent. You may wash with either brush washing or spray washing. It is then dehydrated and dried. As a method other than washing with water, UV washing and IR drying can be performed.

The alignment film material was apply | coated so that an ITO electrode might be covered on two board | substrates with electrodes (step S103). Application of the alignment film material was performed using a spin coat. You may carry out using a fureciso printing or inkjet printing. Usually, the side chain density of the polyimide oriented film material used for formation of a vertical alignment film was made low, and was used as an oriented film material. This material is the same as the alignment film material used for the liquid crystal display element produced for the preliminary consideration. The alignment film material was applied so that the thickness of the alignment film was 500 kPa to 800 kPa. The temporary baking (step S104) and the main baking (step S105) of the board | substrate with an electrode which apply | coated the orientation film material were performed. This firing was carried out in a clean oven at 180 ° C. for 1 hour. You may perform it at the temperature of 160 degreeC or more and 180 degrees C or less. In this way, the alignment film which covers an ITO electrode was formed (step S103-S105).

40 is a schematic plan view showing a part of the formation region of the lower alignment film 14b formed on the lower substrate 10b. The lower alignment film 14b is formed in a region where, for example, the first and second sacrificial electrodes 12c and 12d are arranged and the pixels are determined. In this figure, only the upper left portion is shown as the formation region of the lower alignment film 14b, but the same applies to the other placement regions 12c and 12d.

Next, the rubbing process (orientation process) was performed (step S106). In the rubbing treatment, the indentation amount is 0.8 mm, and the upper alignment film 14a and the lower alignment film 14b are both 20 ° to 85 °, for example, 35 ° to 55 °, for example, 45 ° pretilt. Angle was performed to express. Moreover, it implemented so that the twist angle of a liquid crystal display element might be 90 degrees.

And the pretilt angle of this area | region is very difficult to measure, and the numerical value of 45 degrees may include a few errors. Due to differences in measurement methods or problems in measurement accuracy, there may be a deviation of about ± 15 ° to ± 30 °.

In order to make the cell thickness 4 micrometers, the gap control material of particle size 4 micrometers was spread | dispersed on one board | substrate surface (step S107). In order to make the cell thickness 3 micrometers or more and 5 micrometers or less, it is also possible to distribute the gap control material of particle size 3 micrometers or more and 5 micrometers or less. The sealing material was printed on one board | substrate surface, and the main seal pattern was formed (step S108). Two board | substrates were superposed | polymerized in predetermined position (step S109), and the sealing material was hardened.

In the polymerization of the two substrates, 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 upper substrate 10a. From the normal direction (upper side), it performed so that it might become 90 degrees to a right rotation direction with respect to a 1st direction.

The nematic liquid crystal was injected by the vacuum injection method (step S110). As the liquid crystal material, a low refractive index anisotropic material having a refractive index anisotropy Δn of 0.067 was used. Chiral agent was added to the liquid crystal. As chiral agent, CB15 made from Melk Corporation was used. The addition amount of a chiral agent was adjusted so that d / p might be 0.8 (p = 5 micrometer), when the chiral pitch was p and the cell thickness was d. d / p is 0.5 or more and 2 or less and 35 degrees or more when the orientation treatment is performed such that the pretilt angle of 20 degrees or more and 85 degrees or less is expressed in the upper and lower alignment films 14a and 14b depending on the pretilt angle. When the orientation process is performed so that the pretilt angle of 55 degrees or less may express, it may be 0.5 or more and 1.2 or less.

The cell was heated above the phase transition temperature of the liquid crystal in order to seal the liquid crystal inlet with an end-curing material of ultraviolet curing type (step S111) and to arrange the alignment of the liquid crystal molecules (step S112). Thereafter, the scribing device was broken along with the damage on the transparent substrate, and was divided into individual cells. Chamfering (step S113) and washing | cleaning (step S114) were performed about the cell divided | segmented small.

Finally, the polarizing plate was stuck to the surface on the opposite side to the liquid crystal layer of two board | substrates (step S115). Two polarizing plates were arrange | positioned so that the direction of a transmission axis and a rubbing direction might be parallel in cross nicol. It may be arranged to be orthogonal. A power source was connected to the ITO electrodes (upper, lower beta electrodes 12a, 12b, and first and second sacrificial electrodes 12c, 12d) of both substrates.

Fig. 41 is a schematic plan view showing the structure of the liquid crystal display element according to the seventh embodiment. In FIG. 41, all the structures shown in FIGS. 37-40 are superposed | polymerized and shown. One pixel is defined by a horizontal electrode extending in the left and right directions and a vertical electrode 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. Shown by the arrow are pixels defined in the region where the lateral electrode 12A ₉ and the vertical electrode 12B ₈ overlap in the substrate normal direction. The horizontal electrode 12A ₉ in this pixel corresponds to the upper beta electrode 12a of FIG. 1, and the vertical electrode 12B ₈ corresponds to the lower beta electrode 12b.

42A to 42C are external appearance photographs of the liquid crystal display device according to the seventh embodiment. 42A to 42C show electrodes having a width of 20 μm in the bladder portion of the first and second sacrificial electrodes 12c and 12d and alternately disposing the sacrificial portions of both sachet electrodes 12c and 12d. It is a front observation photograph of the formation value | value of the glare electrode 12c, 12d of the liquid crystal display element produced with the space of 20 micrometers.

42A, the external appearance photograph of the state (initial state) of which the liquid crystal display element was completed is shown. In the initial state, the liquid crystal molecules are in the focal conic arrangement state. Visually, a uniform white mark was obtained.

In this state, a voltage was applied between the upper beta electrode 12a and the lower beta electrode 12b. The application of a voltage to both electrodes 12a and 12b causes the vertical electric field to occur in the liquid crystal layer 15.

42B is an external photograph after voltage is applied to the electrodes 12a and 12b. It can be seen that the whole has shifted from the focal conic arrangement state to the reverse twist arrangement state. Moreover, it can be seen from the front that black display is obtained. In addition, 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 electrodes 12a and 12b.

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

FIG. 42C is an external photograph after driving the liquid crystal display element in the state shown in FIG. 42B in the FFS mode. FIG. It can be seen that the front surface is transitioning to the same state as the initial state (the focal conic arrangement state).

The liquid crystal display element according to the seventh embodiment is a liquid crystal display element which can switch between a focal conic arrangement state and a reverse twist arrangement state. By application of the seed electric field, the former can be transferred to the latter. In addition, by applying a lateral electric field, the latter can be transferred to the former. As a method of transitioning the reverse twisted arrangement state to the focal conic arrangement state, the drive in the IPS mode can be adopted in addition to the drive in the FFS mode.

When a longitudinal electric field is added to the liquid crystal layer in the focal conical arrangement state in which the liquid crystal molecules are spiraled in the in-plane direction, the liquid crystal molecules are placed in a 90 degree twist orientation under the influence of the boundary surface, and the liquid crystal molecules located in the center of the thickness direction of the liquid crystal layer are vertical. Inclined. In this way, it can be considered that the switching from the focal conic arrangement state to the reverse twist arrangement state is performed. Moreover, it can be considered that the addition of the transverse electric field disperses the orientation of the liquid crystal molecules on the boundary surface of the reverse twisted arrangement state, thereby switching from the reverse twisted arrangement state to the focalconic arrangement state.

The liquid crystal display device according to the seventh embodiment is a liquid crystal display device in which the focal conic arrangement state and the reverse twist arrangement state transition to each other and the states are stably held in accordance with the direction of the added electric field. The bistable display of high contrast white display state and black display state can be realized easily. In particular, it is possible to realize a clear display even when the black display is dark and viewed from the front. Therefore, the present invention can be suitably applied to any one of a transmissive display, a tubular display, and a reflective display. The liquid crystal display device according to the seventh embodiment is a liquid crystal display device having a contrast ratio which is symmetrical.

In the liquid crystal display element according to the seventh embodiment, for example, display using memory characteristics is possible. The pixels which want to display white are made into the focal conic arrangement state, and the pixels which want to display black are made into the reverse twist arrangement state. At least a pixel is applied to the pixel to be changed from white display to black display. You may also apply a seed electric field to the pixel which wants to hold black display. On the contrary, a lateral electric field is added to at least the pixel to change from black display to white display. A lateral electric field may be applied to the pixel whose white display is to be maintained.

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

The liquid crystal display device according to the seventh embodiment is capable of ultra-low power consumption, which can be driven by a driving method using memory characteristics, and especially when applied to a reflective display, the merit is large, and a large-capacity display at low cost In the manufacture thereof, the same effect as in the first embodiment can be achieved in that the cost increase factor compared with the general twisted nematic liquid crystal display element is small.

As mentioned above, although this invention was demonstrated according to the Example etc., this invention is not limited to these.

For example, in a 1st Example etc., although the polarizing plate was arrange | positioned in cross nicol and used as the liquid crystal display element of nomary white display, you may arrange | position a polarizing plate in parallel nicol and may be set as the liquid crystal display element of nomary black display. It will be easy to realize a display with a high contrast ratio only by making it no-white white. In the case of no-marble white display, in order to obtain a favorable black display, the angle formed by the transmission axis directions of the upper and lower polarizing plates 16a and 16b is preferably around 90 °.

In addition, although the orientation process was performed by rubbing about an Example, an orientation process can be performed using other orientation processing methods, such as the photo-alignment method and the diagonal direction vapor deposition method, for example.

In the embodiment, the electrodes are formed only on the lower substrate 10b to cause a lateral electric field in the whole and part of the liquid crystal layer 15 (pixel region), but not only the lower substrate 10b but also the upper substrate 10a. Can also be formed. The electrode that causes the lateral electric field may be formed on at least one of the upper substrate 10a and the lower substrate 10b.

In addition, about the 5th Example, the material which can superpose | polymerize was added on condition that it will become 1 wt%, 2 wt%, and 5 wt% with respect to the mass of the liquid crystal layer 15. As shown in FIG. It is not limited to the range of 1 wt% or more and 5 wt% or less, even if the amount of the polymerizable material added is 0.5 wt% or more and 5 wt% or less, the same effect can be obtained.

In addition, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like are possible.

It can be used for the whole liquid crystal element, for example, the whole liquid crystal display element which performs a simple matrix drive. It can also be used in liquid crystal display devices that require low power consumption, wide visual characteristics, low cost, and the like.

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

In addition, it can be used for a display for maintaining the display even in the event of a power failure due to a disaster.

10a upper board
10b lower board
11a upper transparent substrate
11b bottom transparent substrate
12a upper beta electrode
12b lower beta electrode
12c first electrode
12d second blazing electrode
13 insulating film
14a upper alignment layer
14b lower alignment layer
15 liquid crystal layer
16a upper polarizer
16b lower polarizer
20 power
21 slit electrodes
21a slit
22, 22a common ship
23 scan lines
24 semiconductor film
25 source electrode
26, 26a drain electrode
27 signal line
28 insulating film
31 ~ 33 driver
34 pixels

Claims (26)

A first substrate,
A second substrate disposed to face the first substrate,
A liquid crystal element disposed between said first substrate and said second substrate, said liquid crystal layer comprising a chiral agent, and having a liquid crystal layer that realizes two different liquid crystal molecule arrangement states interchangeably. The first substrate subjected to the alignment treatment,
The second substrate which is disposed in parallel with the first substrate and is aligned;
The liquid crystal layer is disposed between the first substrate and the second substrate, comprises a chiral agent, and has a twist orientation.
When the liquid crystal layer does not contain the chiral agent, when the liquid crystal molecules are twisted in the first direction of rotation, the chiral agent is formed in the liquid crystal molecules of the liquid crystal layer. Gives the turnability in the opposite second turning direction,
Electrodes are formed on the first substrate and the second substrate,
The liquid crystal element according to claim 1, wherein the electrode can cause an electric field in a thickness direction of the liquid crystal layer or an electric field in a direction orthogonal to the thickness direction of the liquid crystal layer, in a part of the liquid crystal layer. The electrode
A first electrode formed on the first substrate,
Second, third, and fourth electrodes formed on the second substrate;
The third and fourth electrodes are sacrificial electrodes formed by passing an insulating film over the second electrode, and are sacrificial electrodes in which saccharic portions are alternately arranged.
The liquid crystal element according to claim 2, wherein an electric potential in the thickness direction of the liquid crystal layer is generated in a part of the liquid crystal layer by providing a potential difference between the first electrode and the third electrode. By giving a potential difference between the first electrode and the third electrode and between the first electrode and the fourth electrode, a portion of the liquid crystal layer is in the thickness direction of the liquid crystal layer. The liquid crystal device according to claim 3, which can cause an electric field of the same. When the distance between the bladder portions where the third and fourth electrodes are alternately arranged is set to s, and the thickness of the liquid crystal layer is set to d,
s ＞ 2 × d
The liquid crystal element according to claim 4. The ratio of the width | variety of the width | variety of the bladder part of a said 3rd electrode, the width | variety of the bladder part of a said 4th electrode, and the distance between bladder parts arrange | positioned alternately of the said 3rd, 4th electrode is 4: 2: 1 The liquid crystal element according to claim 4 or 5. The electrode
A first electrode formed on the first substrate,
Second, third, and fourth electrodes formed on the second substrate;
The third and fourth electrodes are sacrificial electrodes formed by passing an insulating film over the second electrode, and are sacrificial electrodes in which saccharic portions are alternately arranged.
The liquid crystal element according to claim 2, wherein an electric potential in a direction orthogonal to the thickness direction of the liquid crystal layer is generated in a part of the liquid crystal layer by providing a potential difference between the third electrode and the fourth electrode. . The electrode
A first electrode formed on the first substrate,
Second, third, and fourth electrodes formed on the second substrate;
The third and fourth electrodes are sacrificial electrodes formed by passing an insulating film over the second electrode, and are sacrificial electrodes in which saccharic portions are alternately arranged.
Claims that can cause an electric field in a direction orthogonal to the thickness direction of the liquid crystal layer in a part of the liquid crystal layer by providing a potential difference between the second electrode and one of the third and fourth electrodes. Liquid crystal element of 2 description. The electrode
A first electrode formed on the first substrate,
Second and fifth electrodes formed on the second substrate;
The fifth electrode is a slit electrode formed by passing an insulating film over the second electrode,
The liquid crystal element according to claim 2, wherein an electric potential in the thickness direction of the liquid crystal layer can be generated in a part of the liquid crystal layer by providing a potential difference between the first electrode and the fifth electrode. The first substrate having a first electrode and subjected to an alignment treatment;
A second substrate disposed opposite to the first substrate in parallel with the first substrate and provided with a second electrode;
The liquid crystal layer disposed between the first substrate and the second substrate, comprising a chiral agent and a polymer, and twist-oriented;
When the liquid crystal layer does not contain the chiral agent, when the liquid crystal molecules are twisted in the first direction of rotation, the chiral agent is formed in the liquid crystal molecules of the liquid crystal layer. Gives the turnability in the opposite second turning direction,
The polymer is synthesized from a polymerizable material added in a range of 5 wt% or less with respect to the mass of the liquid crystal layer,
By applying a voltage to the first electrode and the second electrode to the liquid crystal layer, it is possible to cause an electric field in the thickness direction of the liquid crystal layer,
At least one of the first substrate and the second substrate is provided with an electrode capable of generating an electric field in a direction orthogonal to the thickness direction of the liquid crystal layer by application of a voltage,
The alignment treatment with respect to the said 1st board | substrate and the said 2nd board | substrate, and addition of the chiral agent to the said liquid crystal layer, The liquid crystal molecule of the said liquid crystal layer by the direction of the electric field added to the said liquid crystal layer, The liquid crystal element according to claim 1, which is made to transition between a reverse twisted arrangement state and a spray twisted arrangement state. The liquid crystal device according to claim 10, wherein the polymer is synthesized from a polymerizable material added in a range of 0.5 wt% or more and 5 wt% or less with respect to the mass of the liquid crystal layer. The liquid crystal device according to claim 11, wherein the polymer is synthesized from a polymerizable material added in a range of 1 wt% or more and 5 wt% or less with respect to the mass of the liquid crystal layer. The liquid crystal device according to any one of claims 10 to 12, wherein the polymer is synthesized by polymerizing when the liquid crystal molecules of the liquid crystal layer are in a reverse twist arrangement or a spray twist arrangement. The second substrate,
A transparent substrate,
The second electrode formed on the transparent substrate;
An insulating film formed on said second electrode,
First and second sacrificial electrodes formed on the insulating film, wherein the sacrificial portions are alternately arranged with the first and second sacrificial electrodes;
An alignment film formed on the insulating film to cover the first and second sacrificial electrodes
The liquid crystal device according to any one of claims 10 to 13, including. Orientation processing is performed on each one surface, and the said 1st board | substrate and the said 2nd board | substrate which were opposingly arranged,
The liquid crystal layer disposed between one surface of the first substrate and one surface of the second substrate,
The first substrate and the second substrate set the direction of the alignment process such 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, and each of the first substrate and the second substrate has The pretilt angle given to the liquid crystal molecules of the liquid crystal layer at the interface of is 35 ° or more,
The liquid crystal layer contains a chiral agent having properties such that the liquid crystal molecules cause a second alignment state twisted in a second direction opposite to the first direction,
The said chiral agent was added so that ratio d / p of a chiral pitch with respect to the layer thickness d of the said liquid crystal layer may be 0.25 or more and 0.75 or less. The liquid crystal element according to claim 15, wherein the liquid crystal layer has a twist angle of 70 ° or more and 90 ° or less in the second alignment state. It further comprises an electric field applying means for applying an electric field to the liquid crystal layer,
The liquid crystal layer transitions to the first alignment state by applying an electric field in a direction substantially perpendicular to each one surface of the first substrate and the second substrate by the voltage applying means, The liquid crystal element according to claim 15 or 16, wherein the liquid crystal layer transitions to the second alignment state by applying an electric field in a direction substantially parallel to each one surface of the substrate and the second substrate. The liquid crystal element according to any one of claims 15 to 17, wherein the pretilt angle is smaller than 70 degrees. The first substrate having a first electrode and aligned;
The second substrate which is disposed in parallel with the first substrate, is provided with a second electrode, and is oriented;
The liquid crystal layer disposed between the first substrate and the second substrate, including a chiral agent, and twist-oriented;
When the liquid crystal layer does not contain the chiral agent, when the liquid crystal molecules are twisted in the first direction of rotation, the chiral agent is formed in the liquid crystal molecules of the liquid crystal layer. Gives turnability in the opposite direction of the second turn,
By applying a voltage to the first electrode and the second electrode to the liquid crystal layer, it is possible to cause an electric field in the thickness direction of the liquid crystal layer,
At least one of the first substrate and the second substrate is provided with an electrode capable of generating an electric field in a direction orthogonal to the thickness direction of the liquid crystal layer by application of a voltage,
The alignment treatment with respect to the said 1st board | substrate and the said 2nd board | substrate, and addition of the chiral agent to the said liquid crystal layer, The liquid crystal molecule of the said liquid crystal layer by the direction of the electric field added to the said liquid crystal layer, The liquid crystal element according to claim 1, which is made to transition between a focal conic arrangement state and a reverse twist arrangement state. The first and second substrates are subjected to an alignment treatment so as to express a pretilt angle of 20 ° or more and 85 ° or less, and when the chiral pitch is p and the thickness of the liquid crystal layer is d, d / p is The liquid crystal element according to claim 19, wherein a chiral agent is added to the liquid crystal layer so as to be 0.5 or more and 2 or less. The first and second substrates are subjected to an alignment treatment so as to express a pretilt angle of 35 ° or more and 55 ° or less, and a chiral agent is added to the liquid crystal layer so that d / p is 0.5 or more and 1.2 or less. The liquid crystal device according to claim 20. The second substrate,
A transparent substrate,
The second electrode formed on the transparent substrate;
An insulating film formed on said second electrode,
First and second sacrificial electrodes formed on the insulating film, the sacrificial portions having first and second sacrificial electrodes being alternately arranged;
The liquid crystal device according to any one of claims 19 to 21, including an alignment film formed on the insulating film so as to cover the first and second sacrificial electrodes. A chiral agent is disposed between the first substrate subjected to the alignment treatment, the second substrate disposed in parallel with the first substrate, and the second substrate subjected to the alignment treatment, and the first substrate and the second substrate. And a twisted alignment liquid crystal layer, and when the liquid crystal layer does not contain the chiral agent, when the liquid crystal molecules are twisted in the first rotation direction, the chiral agent is used as the liquid crystal layer. Giving liquid crystal molecules of the layer to the second turning direction opposite to the first turning direction, wherein an electrode is formed on the first substrate and the second substrate, and the electrode is the liquid crystal layer. As a method of driving a liquid crystal element capable of causing an electric field in a thickness direction of the liquid crystal layer or an electric field in a direction orthogonal to the thickness direction of the liquid crystal layer,
The electrode includes a first electrode formed on the first substrate and second, third, and fourth electrodes formed on the second substrate, and the third and fourth electrodes include the first electrode. A sacrificial electrode formed by interposing an insulating film above the electrode of 2, wherein the sacrificial portions are alternately arranged saccharic electrodes, and part of the liquid crystal layer is provided with a potential difference between the first electrode and the third electrode. A method of driving a liquid crystal element in which the transition from the spray twist arrangement state to the reverse twist arrangement state. A chiral agent is disposed between the first substrate subjected to the alignment treatment, the second substrate disposed in parallel with the first substrate, and the second substrate subjected to the alignment treatment, and the first substrate and the second substrate. And a twisted alignment liquid crystal layer, and when the liquid crystal layer does not contain the chiral agent, when the liquid crystal molecules are twisted in the first rotation direction, the chiral agent is used as the liquid crystal layer. Giving liquid crystal molecules of the layer to the second turning direction opposite to the first turning direction, wherein an electrode is formed on the first substrate and the second substrate, and the electrode is the liquid crystal layer. As a method of driving a liquid crystal element capable of causing an electric field in a thickness direction of the liquid crystal layer or an electric field in a direction orthogonal to the thickness direction of the liquid crystal layer,
The electrode includes a first electrode formed on the first substrate and second, third, and fourth electrodes formed on the second substrate, and the third and fourth electrodes include the first electrode. A sacrificial electrode formed by interposing an insulating film over the electrode of 2, wherein the sacrificial portions are alternately arranged saccharic electrodes, and a potential difference is provided between the third electrode and the fourth electrode to provide a potential difference between the liquid crystal layer. A method of driving a liquid crystal element in which a part is shifted from a reverse twist arrangement to a spray twist arrangement. A chiral agent is disposed between the first substrate subjected to the alignment treatment, the second substrate disposed in parallel with the first substrate, and the second substrate subjected to the alignment treatment, and the first substrate and the second substrate. And a twisted alignment liquid crystal layer, and when the liquid crystal layer does not contain the chiral agent, when the liquid crystal molecules are twisted in the first rotation direction, the chiral agent is used as the liquid crystal layer. The liquid crystal molecules of the layer are provided with swirling ability in a second turning direction opposite to the first turning direction, and electrodes are formed on the first substrate and the second substrate, and the electrode is the liquid crystal layer. As a method of driving a liquid crystal element capable of causing an electric field in a thickness direction of the liquid crystal layer or an electric field in a direction orthogonal to the thickness direction of the liquid crystal layer,
The electrode includes a first electrode formed on the first substrate and second, third, and fourth electrodes formed on the second substrate, and the third and fourth electrodes include the first electrode. A sacrificial electrode formed by intersecting an insulating film above the electrode of 2, which is a sacrificial electrode in which saccharic portions are alternately arranged, and a potential difference is provided between the second electrode and one of the third and fourth electrodes. And a part of the liquid crystal layer is shifted from the reverse twist arrangement to the spray twist arrangement. A chiral agent is disposed between the first substrate subjected to the alignment treatment, the second substrate disposed in parallel with the first substrate, and the second substrate subjected to the alignment treatment, and the first substrate and the second substrate. And a twisted alignment liquid crystal layer, and when the liquid crystal layer does not contain the chiral agent, when the liquid crystal molecules are twisted in the first rotation direction, the chiral agent is used as the liquid crystal layer. Giving liquid crystal molecules of the layer to the second turning direction opposite to the first turning direction, wherein an electrode is formed on the first substrate and the second substrate, and the electrode is the liquid crystal layer. As a method of driving a liquid crystal element capable of causing an electric field in a thickness direction of the liquid crystal layer or an electric field in a direction orthogonal to the thickness direction of the liquid crystal layer,
The electrode includes a first electrode formed on the first substrate, and second and fifth electrodes formed on the second substrate, and the fifth electrode includes an insulating film above the second electrode. A method of driving a liquid crystal element in which a portion of the liquid crystal layer is transitioned from a spray twist arrangement state to a reverse twist arrangement state by providing a potential difference between the first electrode and the fifth electrode as a slit electrode formed through the slit electrode. .

Images