JP2945273B2 - Liquid crystal display panel and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display panel utilizing the electro-optical characteristics of liquid crystal and a method of manufacturing the same, and more particularly to an increase in the viewing angle of the liquid crystal display panel and the alignment of liquid crystal molecules.

[0002]

2. Description of the Related Art In recent years, liquid crystal display panels utilizing the electro-optical characteristics of liquid crystals have been actively applied to OA equipment due to their large screens and large capacities. As a mode of operation of a liquid crystal display panel that is currently generally used, a twisted nematic (TN) type in which liquid crystal molecules are twisted by about 90 ° between two glass substrates, about 180 ° to 27 °
There is a super twisted nematic (STN) type exhibiting an orientation state twisted by 0 °. The TN type is mainly used for an active matrix type liquid crystal display panel, and the STN type is used for a simple matrix type liquid crystal display panel. This will be described below with reference to the drawings.

In the case of a TN type used for an active matrix type liquid crystal display panel or a small size liquid crystal display panel, liquid crystal molecules are uniformly and unidirectionally aligned at a certain pretilt angle with respect to the glass substrate at the glass substrate interface. Are twisted by about 90 ° between the glass substrates. Approximately 90 ° twist alignment state is that the alignment film consisting of a polyimide thin film formed on a glass substrate is generally rubbed in one direction using rayon cloth etc., and is arranged so that the direction is orthogonal between the upper and lower substrates. Is obtained by

When a voltage is applied to a TN type liquid crystal panel as shown in FIG.
Begin to respond at a threshold voltage or higher, the twisted alignment state is released and the liquid crystal molecules 401 are in a splay alignment state, and the liquid crystal molecules 401 are in a state where the molecular long axis rises with respect to the glass substrate (402, 403) plane. When observing the liquid crystal molecules 401 while changing the azimuth angle φ at a position inclined by θ with respect to the substrate normal (Z axis), the direction of the long axis of the liquid crystal molecules 401 is not uniform in the azimuth direction. Therefore, the apparent refractive index anisotropy (Δn) of the liquid crystal molecules 401 changes depending on the azimuthal direction, and the birefringence (Δnd) which is a product of the thickness (d) of the liquid crystal layer changes. Therefore, the upper and lower glass substrates (40
2, 403) A polarizing plate is arranged on the outer surface such that the light absorption axis (406, 407) is orthogonal to the rubbing direction (404, 405). When light is incident from one Z-axis direction, the azimuthal direction changes. Accordingly, the transmission intensity of light is different, and asymmetry of the viewing angle occurs. This asymmetry of the viewing angle is particularly problematic in the case of halftone display, and causes a reduction in display quality such as an extremely low contrast ratio depending on the viewing angle direction or inversion of the displayed image. For this reason, in TN-type liquid crystal display panels, efforts to increase the viewing angle have been actively made in recent years. As an example, a method of expanding a viewing angle by dividing pixels of a TN type liquid crystal display panel into two regions having different alignment states (for example, K. Takatori, K. Sumiyoshi, W. Hirai, S. Kaneko: Japan Display '92, 591)
P., 1992; K. Takatori, K. Sumiyoshi, Y. Hirai, S. Ka
neko: JAPAN DISPLAY '92, PP.591, (1992)) has been proposed. In this method, it is necessary to perform exposure and rubbing processing twice in order to divide the orientation region of one pixel into two, which complicates the process steps. Therefore, another method for simplifying the process and increasing the viewing angle has been proposed (Wy Toko,
T. Sugima, K. Kato, Y. Imla, S. Kobayashi: S. ID 93 Digest, 622
P., 1993; Y.Toko.T.Sugiyama, K.Katoh, Y.Iimura,
S. Kobayashi: SID 93 DIGEST, PP.622, (1993)). In this method, a large number of regions having different alignment states are formed by randomly aligning the liquid crystal molecules without performing a rubbing process, thereby increasing the viewing angle.

[0005]

However, a chiral agent is added to a nematic liquid crystal to rotate the liquid crystal molecules by about 90 ° between the upper and lower substrates to form a chiral nematic liquid crystal, and the spontaneous helical pitch (p) of the liquid crystal layer is changed. Thickness (d)
Is set so that d / p = 0.25. When a rectangular wave voltage is applied to this liquid crystal display panel,
Above the threshold voltage, the liquid crystal molecules are in a splay alignment state, so that disclination lines (lines due to crystal defects) are generated between regions having different initial alignment states. When this disclination line is generated when viewed from the front, the viewing angle is increased, but the disclination line appears as a bright line, and there is a problem in that the sense of roughness of the display increases. This roughness depends on the size of the disclination line. Similarly, when a voltage is applied, there is a sense of roughness from an oblique direction. This is due to a schlieren structure observed under crossed Nicols of a polarizing microscope in a nematic liquid crystal. That is, the unevenness of the light transmittance due to the disclination or the schlieren structure is higher than the resolution of the eyes, and therefore, a roughness is felt.

The present invention solves the above-mentioned conventional problems, and provides a liquid crystal display panel in which the viewing angle is widened and the roughness due to disclination and schlieren structure is eliminated by subdividing them, and a method of manufacturing the same. The purpose is to do.

[0007]

In order to achieve the above object, a liquid crystal display panel according to the present invention comprises a liquid crystal display panel at a boundary between an electrode portion on at least one of upper and lower electrodes on a substrate and a non-electrode portion. The continuity of the orientation of the molecules is broken, the liquid crystal layer in each pixel (small electrode) is a chiral nematic phase having a positive dielectric anisotropy, and the direction of the major axis of the liquid crystal molecules is aligned with the interface of the substrate. It has a pretilt angle substantially parallel to or less than 20 degrees, and has a plurality of orientations or various orientations.

In the above structure, it is preferable that the continuity of the alignment of the liquid crystal molecules is divided at the boundary of each pixel defined by the upper and lower electrodes on the substrate. Further, in the above configuration, each pixel defined by the upper and lower electrodes on the substrate is composed of a plurality of divided small electrode portions, and at the boundaries between the small electrode portions, the continuity of the orientation of the liquid crystal molecules is improved. It is preferred that it be divided.

In the above structure, the twist angle of the liquid crystal layer between the upper and lower electrodes is preferably about 90 degrees, at least two polarizing plates are crossed, and the crossing angle of the polarizing plates is preferably about 90 degrees.

In the above structure, it is preferable that the thermoplastic polymer is formed on the upper and lower electrodes on the substrate. Next, the first manufacturing method of the present invention is a method of manufacturing a liquid crystal comprising a chiral nematic liquid crystal composition in which two substrates having electrode surfaces that are not subjected to an alignment treatment are opposed to each other and exhibit a twist of about 90 degrees between the substrates. In the production of a liquid crystal display panel having a layer, the liquid crystal composition is cooled from a temperature higher than a nematic-isotropic transition temperature (hereinafter referred to as an NI point temperature) to a temperature lower than an NI point while an electric field is applied between the substrates. The continuity of the orientation of the liquid crystal after the removal of the electric field is divided at the end of the electrode.

In the above structure, in the production of a liquid crystal display panel in which each pixel defined by upper and lower electrodes on the substrate is composed of a plurality of divided small electrode portions, the temperature of the liquid crystal composition is higher than the NI point temperature. By cooling from the temperature to the NI point temperature or less while applying an electric field between the substrates,
After removing the electric field, it is preferable that the continuity of the alignment of the liquid crystal after each small electrode end is divided at the electrode end.

Next, a second manufacturing method of the present invention comprises a first step of forming an alignment film on a substrate having electrodes, and a method of injecting a liquid crystal by keeping a pair of substrates at a constant distance via a spacer. And a third step of heating the substrate above the nematic-isotropic transition temperature (NI point temperature) of the chiral nematic liquid crystal and injecting the chiral nematic liquid crystal. At least a fourth step of heating and holding the substrate at a temperature equal to or higher than the NI point temperature of the chiral nematic liquid crystal and a fifth step of cooling the chiral nematic liquid crystal from a heated state to a lower temperature under a voltage applied state. It is characterized by having.

Next, a third manufacturing method of the present invention comprises a first step of forming an alignment film on a substrate having electrodes, and a method of injecting a liquid crystal by keeping a pair of substrates at a constant distance via a spacer. And a third step of injecting the chiral nematic liquid crystal at room temperature, and heating and holding the chiral nematic liquid crystal at a temperature equal to or higher than the NI point temperature for a certain time. The method is characterized by including at least a fourth step and a fifth step of cooling the chiral nematic liquid crystal from a heated state to a lower temperature under a voltage applied state.

In the above configuration, it is preferable to form an alignment film on the electrodes of the upper and lower substrates and to assemble the liquid crystal display without performing a rubbing process. Further, in the above configuration, the fifth step is performed when the temperature is equal to or higher than the NI point temperature.
It is preferable to cool to a temperature lower than the point temperature while applying a voltage.

Further, in the above configuration, each pixel electrode portion defined by the upper and lower substrates is preferably formed by a plurality of small electrodes having a size of 100 μm square or less, so that the sense of roughness cannot be visually recognized.

[0016]

According to the configuration of the present invention described above, the continuity of the orientation of the liquid crystal molecules is broken at the boundaries between the pixels or the small electrodes defined by the upper and lower electrodes on the substrate, and the liquid crystal layer is positively polarized. A chiral nematic phase having dielectric anisotropy, wherein the major axis direction of the liquid crystal molecules is substantially parallel to the substrate interface or has a pretilt angle of 20 degrees or less, and has a plurality of orientations or various orientations. With such a structure, the viewing angle can be increased, and the feeling of roughness due to disclination can be reduced. In other words, the continuity of the alignment of liquid crystal molecules is divided at the boundaries between each pixel or each small electrode defined by the upper and lower electrodes on the substrate, so that the size of the disclination can be regularly subdivided. Becomes Although the subdivided unit is described here as a unit liquid crystal cell, a clear disclination line is more likely to occur near the boundary than inside the cell. Therefore, when a voltage equal to or higher than the threshold voltage is applied, first, the disclination line at the boundary portion is preferentially induced, while the disclination line at portions other than the boundary portion is reduced. By doing so, the feeling of roughness caused by the disclination line from the front direction at the halftone voltage, which is particularly conspicuous, can be greatly reduced. Similarly, the feeling of roughness due to the size of the schlieren structure formed in the absence of an electric field in the oblique direction at the halftone voltage is also greatly reduced. Moreover, since a large number of liquid crystal domains having different alignment states can be formed in each of the divided unit liquid crystal cells, the effect of expanding the viewing angle can be realized. In the above, the pretilt angle of the liquid crystal molecules in the molecular long axis direction is preferably in the range of 0 to 20 °.

The twist angle of the liquid crystal layer is about 90 degrees between the upper and lower electrodes that have not been subjected to an alignment treatment such as rubbing, and at least two polarizing plates are crossed.
According to the preferred configuration of the present invention, the viewing angle in the vertical and horizontal directions can be realized without impairing the transmittance of the panel, and the conventional rubbing step can be omitted.

In the above-mentioned structure, according to the preferred structure of the present invention in which the thermoplastic polymer is formed on the upper and lower electrodes on the substrate, injection at a high temperature is indispensable in the conventional method of W. Toko et al. However, it can be injected at room temperature, which is easier to manufacture, and can exhibit the effect that there is no uneven flow orientation.

Next, according to the first to third manufacturing methods of the present invention, the liquid crystal display panel of the present invention can be efficiently and rationally manufactured. In the above, according to the preferred configuration of the present invention in which the alignment films are formed on the electrodes of the upper and lower substrates and the rubbing treatment is not performed, occurrence of a defect due to rubbing can be eliminated, and a natural multi-domain structure can be formed.

Further, in the above, according to the preferable configuration of the present invention, in which the fifth step cools under a voltage application state from a temperature equal to or higher than the NI point temperature to a temperature lower than the NI point temperature, the fifth step is defined by the upper and lower electrodes on the substrate. The effect of breaking the continuity of the alignment of the liquid crystal molecules at the boundary between each pixel or small electrode can be exerted.

In the above, according to the preferred configuration of the present invention, in which the fifth step cools under a voltage application state from a temperature lower than or equal to the NI point temperature to a lower temperature, the fifth step is defined by the upper and lower electrodes on the substrate. The effect of breaking the continuity of the alignment of the liquid crystal molecules at the boundary between each pixel or small electrode can be exerted.

[0022]

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) The basic configuration of the liquid crystal display panel of Embodiment 1 will be described with reference to FIG. That is, 101 is an upper glass substrate, 102 is a segment electrode, 103 is a lower glass substrate, 104 is a common electrode, 105 and 106 are polyimide thin films, 107 is a chiral nematic liquid crystal layer, 108 is a spacer, 109 is a sealing material, 110 is It is a polarizing plate. The upper glass substrate 101 having an indium tin oxide (ITO) having a sheet resistance value of 30 Ω / (unit area) is patterned by photolithography to form 64 stripes having various electrode widths as shown in Table 1. The segment electrode 102 was obtained.

[0023]

[Table 1]

Using a similar method, 6
Four common electrodes 104 also having various electrode widths were formed. The segment electrode 102 and the common electrode 104 were arranged so as to be orthogonal to each other. On such glass substrates 101 and 103, polyimide thin films 105 and 106 each having a thickness of 80 nm are formed by a printing method. In this embodiment, RN-747 is used as a polyimide thin film.
(Nissan Chemical Co., Ltd.) was used. The polyimide thin film has a function of aligning liquid crystal molecules with a horizontal or several degrees of pretilt angle on the glass substrate surface.

Next, a spacer 1 made of plastic is formed on the lower glass substrate 103 or the polyimide thin film 106.
08 (Micropearl: Sekisui Fine Co., Ltd.) was uniformly dispersed. The spacer diameter was 5 μm. A thermosetting sealing material 109 (Struct Bond: Mitsui Toatsu Co., Ltd.) is formed around the periphery of the upper glass substrate 101 by printing through a liquid crystal injection port, and the segment electrode 102 and the common electrode 104 are vertically intersected. The glass substrates 101 and 103 were bonded together, and the sealing material 109 was completely cured at a predetermined temperature.

Next, a nematic liquid crystal having a refractive index anisotropy of 0.134 was added to a right-twisted chiral material (R-1011).
The concentration was adjusted so that the value of the spontaneous twist pitch p with respect to the cell gap d was d / p = 0.25. The chiral nematic liquid crystal 107 produced under such conditions was heated to an isotropic state and injected between the glass substrates 101 and 103 by a vacuum injection method. At this time, the glass substrates 101 and 103 are also heated to a temperature higher than the nematic phase-isotropic phase transition temperature (NI point) of the chiral nematic liquid crystal 107. Chiral nematic liquid crystal 1
07 are completely filled, the glass substrates 101, 103
Is heated to a temperature higher than the NI point for 30 minutes, the panel is gradually cooled from a temperature higher than the NI point (120 ° C. in this embodiment) to room temperature with a voltage of 2 V applied, and the liquid crystal injection port is sealed with a sealing resin. I sealed it.

The liquid crystal display panel manufactured as described above has an electrode end 305 as shown in FIG.
, The unit liquid crystal cell 30 divided into pixel units
1, 302, 303 and 304 were formed. Since d / p of each liquid crystal domain in each unit liquid crystal cell was set to 0.25, the liquid crystal molecules were in a state of being twisted by 90 degrees between the upper and lower substrates.

The liquid crystal display panel manufactured as described above has a halftone voltage, and when viewed from the front and oblique directions, when the electrode width is 100 μm or less as shown in Table 1 above, the liquid crystal display panel has good roughness without roughness. The display quality was shown. Further, when the contrast of the pixel at a direction of 30 degrees from the vertical direction of the substrate at V50 (60 Hz) was measured,
It showed a high value of 1. In this embodiment, the case where the pixels are not divided has been described. However, the same effect can be obtained when the pixels defined by the pixel electrodes are divided into a plurality. The applied voltage is 2 V in this embodiment, but may be another appropriate voltage.

Example 2 An empty cell having a stripe electrode having a width of 50 μm was prepared in the same manner as in Example 1, and then the chiral nematic liquid crystal similar to that of Example 1 was heated to be isotropic. In this state, it was injected between the glass substrates 101 and 103 by a vacuum injection method. At this time, the glass substrate 101,
103 is also heated to a temperature equal to or higher than the nematic phase-isotropic phase transition temperature (NI point) of the chiral nematic liquid crystal 107. After the chiral nematic liquid crystal 107 is completely filled, the glass substrates 101 and 103 are heated to a temperature equal to or higher than the NI point.
After heating for 0 minutes, the panel was gradually cooled from a temperature below the NI point (90 ° C. in this embodiment) to room temperature while applying a voltage of 7 V, and the liquid crystal injection port was sealed with a sealing resin.

The liquid crystal display panel manufactured as described above has an electrode end portion 30 as shown in FIG.
Unit liquid crystal cell 30 divided into pixel units with boundary 5
1, 302, 303 and 304 are formed. Since d / p of each liquid crystal domain in each unit liquid crystal cell was set to 0.25, the liquid crystal molecules were in a state of being twisted by 90 degrees between the upper and lower substrates.

The liquid crystal display panel manufactured in this manner exhibited good display quality without a sense of roughness when viewed from the front and oblique directions at a halftone voltage. Also, V
When the contrast of the pixel at 50 (60 Hz) in the direction of 30 degrees from the vertical of the substrate was measured, it showed a high value of 20/1. In this embodiment, the case where the pixels are not divided has been described. However, the same effect can be obtained when the pixels defined by the pixel electrodes are divided into a plurality.
The applied voltage is 7 V in this embodiment, but may be another appropriate voltage.

Example 3 A polyurethane film (MS-5510: Mitsubishi Heavy Industries, Ltd., Tg = 63 ° C.) was formed on two upper and lower glass substrates on which ITO electrodes each having a width of 50 μm were formed in the same manner as in Example 1. ) Was applied as an m-cresol solution and dried in an oven at 160 ° C. for 30 minutes to form.

Thereafter, through a spacer having a particle size of 5 μm,
Example 1: Upper and lower glass substrates were bonded with a sealing material.
D / p chiral material in chiral nematic liquid crystal similar to
A chiral nematic liquid crystal prepared by adding so as to be 0.25 was injected at room temperature. Then, after the chiral nematic liquid crystal 107 is completely filled, the glass substrate 10
1 and 103 are heated to a temperature higher than the NI point for 30 minutes, and a temperature higher than the NI point (120
The liquid crystal injection port was sealed with a sealing resin.

The liquid crystal display panel manufactured as described above has an electrode end portion 30 as shown in FIG.
Unit liquid crystal cell 30 divided into pixel units with boundary 5
1, 302, 303 and 304 were formed. Since d / p of each liquid crystal domain in each unit liquid crystal cell was set to 0.25, the liquid crystal molecules were in a state of being twisted by 90 degrees between the upper and lower substrates.

The liquid crystal display panel manufactured in this manner exhibited good display quality with no roughness when viewed from the front and oblique directions at a halftone voltage. Also, V
When the contrast of the pixel at 50 (60 Hz) in the direction of 30 degrees from the vertical of the substrate was measured, it showed a high value of 20/1. In this embodiment, the case where the pixels are not divided has been described. However, the same effect can be obtained when the pixels defined by the pixel electrodes are divided into a plurality. The applied voltage is 2 V in this embodiment, but may be another appropriate voltage. Also, as a thermoplastic polymer, P
Even when VA was used as the alignment film, the same effect as in the present example was obtained.

Example 4 A polyurethane film (MS-5510: Mitsubishi Heavy Industries, Ltd., Tg = 63 ° C.) was formed on two upper and lower glass substrates on which ITO electrodes each having a width of 50 μm were formed in the same manner as in Example 1. ) Was applied as an m-cresol solution and dried in an oven at 160 ° C. for 30 minutes to form.

Thereafter, the upper and lower glass substrates are bonded together with a sealing material via a spacer having a particle size of 5 μm, and the chiral material is added to the chiral nematic liquid crystal as in Example 1.
A chiral nematic liquid crystal prepared by adding so that /p=0.25 was injected at room temperature. Thereafter, after the chiral nematic liquid crystal 107 is completely filled, the glass substrates 101 and 103 are heated to a temperature equal to or higher than the NI point for 30 minutes.
In the state where the voltage of V is applied, the temperature is equal to or lower than the NI point (in this embodiment, 9
(0 ° C.) to room temperature, and the liquid crystal injection port was sealed with a sealing resin.

The liquid crystal display panel manufactured in this manner has no electrode end 305 when no electric field is applied, as shown in FIG.
Unit liquid crystal cell 30 divided into pixel units with
1, 302, 303 and 304 were formed. Since d / p of each liquid crystal domain in each unit liquid crystal cell was set to 0.25, the liquid crystal molecules were in a state of being twisted by 90 degrees between the upper and lower substrates.

The liquid crystal display panel thus produced exhibited good display quality with no sense of roughness when viewed from the front and oblique directions at a halftone voltage. Also, V
When the contrast of the pixel at 50 (60 Hz) in the direction of 30 degrees from the vertical of the substrate was measured, it showed a high value of 20/1. In this embodiment, the case where the pixels are not divided has been described. However, the same effect can be obtained when the pixels defined by the pixel electrodes are divided into a plurality. The applied voltage is 7 V in this embodiment, but may be another appropriate voltage. When PVA was used as the alignment film as the thermoplastic polymer, the same effect as that of the present example was obtained.

Next, another embodiment of the present invention will be described with reference to FIG. (Example 5) A polyurethane film (MS-5510: Mitsubishi Heavy Industries, Ltd., Tg) was formed on two upper and lower glass substrates on which ITO electrodes each having a width of 50 μm were formed in the same manner as in Example 1.
= 63 ° C) as an m-cresol solution,
Formed after drying in oven at 30 ° C. for 30 minutes.

Thereafter, the upper and lower glass substrates were bonded with a sealing material via a spacer having a particle size of 5 μm. A chiral nematic liquid crystal prepared by adding a chiral material to the same chiral nematic liquid crystal as in Example 1 so that d / p = 0.25 was injected at room temperature, and the injection port was sealed.
A heat annealing treatment was performed at 20 ° C. for 30 minutes to eliminate uneven alignment at the time of implantation. Thereafter, the glass substrates 101 and 103 are heated to a temperature equal to or higher than the NI point for 30 minutes.
The panel was gradually cooled from a temperature above the point (120 ° C. in this embodiment) to room temperature.

The liquid crystal display panel manufactured as described above has an electrode end portion 30 as shown in FIG.
5, a unit liquid crystal cell 30 divided in pixel units
1, 302, 303 and 304 are formed. Since d / p of each liquid crystal domain in each unit liquid crystal cell was set to 0.25, the liquid crystal molecules were in a state of being twisted by 90 degrees between the upper and lower substrates.

The liquid crystal display panel manufactured in this manner exhibited good display quality with no roughness when viewed from the front and oblique directions at a halftone voltage. Also, V
When the contrast of the pixel at 50 (60 Hz) in the direction of 30 degrees from the vertical of the substrate was measured, it showed a high value of 20/1. In this embodiment, the case where the pixels are not divided has been described. However, the same effect can be obtained when the pixels defined by the pixel electrodes are divided into a plurality. The applied voltage is 2 V in this embodiment, but may be another appropriate voltage. The same effect was obtained when PVA was used as the orientation film as the thermoplastic polymer.

Next, another embodiment of the present invention will be described with reference to FIG. (Example 6) A polyurethane film (MS-5510: Mitsubishi Heavy Industries, Ltd., Tg) was formed on two upper and lower glass substrates on which ITO electrodes each having a width of 50 µm were formed in the same manner as in Example 1.
= 63 ° C) as an m-cresol solution,
Formed after drying in oven at 30 ° C. for 30 minutes.

Thereafter, through a spacer having a particle size of 5 μm,
The upper and lower glass substrates were bonded together with a sealing material. A chiral material was added to the same chiral nematic liquid crystal as in Example 1 by d /
A chiral nematic liquid crystal prepared by adding p = 0.25 was injected at room temperature, and the injection port was sealed.
A heat annealing treatment was performed at 30 ° C. for 30 minutes to eliminate alignment unevenness at the time of implantation. Thereafter, the glass substrates 101 and 103 were heated to a temperature higher than the NI point for 30 minutes, and the panel was gradually cooled from a temperature lower than the NI point (in this embodiment, 90 ° C.) to room temperature with a voltage of 7 V applied.

The liquid crystal display panel manufactured in this manner has a unit liquid crystal cell 301, 3 divided into pixel units with the electrode removal part as a boundary when there is no electric field, as shown in FIG.
02, 303 and 304 are formed. Since d / p of each liquid crystal domain in each unit liquid crystal cell was set to 0.25, the liquid crystal molecules were in a state of being twisted by 90 degrees between the upper and lower substrates.

The liquid crystal display panel manufactured in this manner showed good display quality without a sense of roughness when viewed from the front and oblique directions at a halftone voltage. Also, V
When the contrast of the pixel at 50 (60 Hz) in the direction of 30 degrees from the vertical of the substrate was measured, it showed a high value of 20/1. In this embodiment, the case where the pixels are not divided has been described. However, the same effect can be obtained when the pixels defined by the pixel electrodes are divided into a plurality. The applied voltage is 7 V in this embodiment, but may be another appropriate voltage. Similar effects were obtained when an alignment film of PVA was used as the thermoplastic polymer.

Although the present embodiment has been described using the transmission type liquid crystal panel, the invention is not limited to the transmission type liquid crystal panel.
It was confirmed that a reflective plate was provided on the surface of one of the polarizing plates to obtain good display quality even as a liquid crystal display panel having a reflective structure. A similar effect was obtained with a liquid crystal display panel having an active element such as a TFT element. Further, since it is not necessary to perform rubbing, it is possible to prevent a decrease in yield due to rubbing, and it is also effective in shortening the manufacturing process.

Although the present embodiment has been described using a glass substrate, the same effect can be obtained with a plastic substrate. Comparative Example 1 (FIG. 1) is an example of a liquid crystal display panel of a comparative example. 101 is an upper glass substrate, 102 is a segment electrode, 103 is a lower glass substrate, 104 is a common electrode,
105 and 106 are polyimide thin films, 107 is a chiral nematic liquid crystal layer, 108 is a spacer, 109 is a sealing material, and 110 is a polarizing plate. Sheet resistance is 30Ω /
The upper substrate 101 having indium tin oxide (ITO) (unit area) was patterned by photolithography to obtain 64 striped segment electrodes 102 having a width of 300 μm. Using the same method, 64 common electrodes 104 having a width of 300 μm were formed on the lower substrate. The segment electrode 102 and the common electrode 104 are arranged so as to be orthogonal to each other. Such a glass substrate 1
Polyimide thin films 105 and 106 each having a thickness of 80 nm are formed on the substrates 01 and 103 by a printing method. In this comparative example, PSI-A-2 was used as a polyimide thin film.
201 (Chisso Petrochemical Co., Ltd.) was used. The polyimide thin film has a function of aligning liquid crystal molecules with a horizontal or several degree pretilt angle on the glass substrate surface.

Next, spherical spacers 108 made of plastic (Micropearl: Sekisui Fine Co., Ltd.) were uniformly dispersed on the lower substrate glass substrate 103 or the polyimide thin film 106. The spacer diameter is 5 μm. A thermosetting sealing material 109 is provided around the upper glass substrate 101.
(Struct Bond: Mitsui Toatsu Co., Ltd.) is formed by printing with a liquid crystal injection port, and the segment electrode 2 and the common electrode 10 are formed.
The upper and lower glass substrates 101 and 103 were stuck together so that 4 was orthogonal, and the sealing material 109 was completely cured at a predetermined temperature.

Next, a nematic liquid crystal having a refractive index anisotropy of 0.134 was added to a right-twisted chiral substance (R-1011:
(Manufactured by Merck), and the concentration was adjusted so that the value of the spontaneous twist pitch p was d / p = 0.25 so as to increase the cell gap d. The chiral nematic liquid crystal 107 produced under such conditions was heated to an isotropic state and injected between the glass substrates 101 and 103 by a vacuum injection method. At this time, the glass substrates 101 and 103 are also made of chiral nematic liquid crystal 1
No. 07, which is higher than the nematic phase-isotropic phase transition temperature (NI point). Chiral nematic liquid crystal 107
Was completely filled, the liquid crystal display panel was gradually cooled, and the liquid crystal injection port was sealed with a sealing resin.

A polarizing plate was attached to the surfaces of the glass substrates 101 and 103 of the liquid crystal display panel manufactured in this manner so that the polarization axes thereof were orthogonal to each other. Light was incident from the lower lath substrate and observed from above the upper glass substrate. FIG. 2 is a perspective view showing a microscopic alignment state in a pixel at an off voltage when the liquid crystal display panel of this comparative example is driven at 1/64 Duty. Reference numeral 201 in FIG. 2 represents a molecular long axis (director) of the liquid crystal molecule. Regions (domains) 202 and 20 having different directors at the glass substrate interface
3, 204, and 205 exist, and disclination lines 206 generated due to different director directions among the respective domains were observed. At this time, each domain was formed in an arbitrary size without being divided into pixel units.

In a normal liquid crystal display panel, since a polyimide thin film is rubbed, only one domain in which the direction of a director is the same is seen in a pixel. In the case of this comparative example, since the rubbing treatment was not performed on the polyimide thin film, the liquid crystal molecules were oriented in an amorphous state by intermolecular force with the polyimide thin film, and a plurality of domains were fractionated in pixel units. It is considered that this occurred at an arbitrary size without any occurrence. In each domain, the liquid crystal molecules exhibit a twisted alignment between the upper and lower glass substrates according to the set value of d / p. In the case of this comparative example, since d / p is set to 0.25, the liquid crystal molecules are twisted and oriented by 90 degrees between the upper and lower glass substrates. In this case, the incident light is considered to be emitted in an elliptically polarized state due to the birefringence effect of the liquid crystal layer.

Next, when an ON voltage is applied, the liquid crystal molecules in each domain change from the twisted state to the splayed state, so that a clear disclination line is generated in the liquid crystal layer (bulk) due to the deformation. did. In the domain, the liquid crystal molecules were oriented such that the director was parallel to the direction of the electric field, and the incident light propagated through the liquid crystal layer in a substantially linearly polarized state, and was cut by the exit-side polarizing plate to obtain a dark state. However, clear disclinations do not completely disappear.

When the liquid crystal display panel in this state is viewed from an oblique direction, there is a slight difference in the amount of transmitted light due to a difference in the direction of the director between the domains, and this appears as a grainy feeling. In fact, the transmittance 50
% Was measured at a voltage (V50) giving 30% in the direction of 30 degrees from the vertical of the substrate.
A low value of / 1 was shown.

As described above, the present invention has been described using the substrate of the striped electrode. However, the present invention is also effective when each pixel electrode such as a TFT (thin film transistor) is independent. However, when the electrode size exceeds 100 μm, at least one of the upper and lower electrodes constituting each pixel may be separated by a slit-shaped non-electrode portion or the like.

As can be seen from the above embodiment, the liquid crystal display panel of the present invention can be manufactured without performing the rubbing treatment, and the pixel defined by the pixel electrode on the substrate is divided into one or more pixels. In this way, the size of disclination and schlieren structure, which leads to a decrease in display quality, can be regularly subdivided, reducing the feeling of roughness, increasing the viewing angle, shortening the manufacturing process, and improving the yield. Has a very effective effect.

[0058]

As described above, according to the present invention, the continuity of the alignment of the liquid crystal molecules is divided at the boundary between each pixel or each small electrode defined by the upper and lower electrodes on the substrate. Is a chiral nematic phase having a positive dielectric anisotropy, the major axis direction of the liquid crystal molecules is substantially parallel to the substrate interface or has a pretilt angle of 20 degrees or less, and a plurality of orientations or various , It is possible to increase the viewing angle and reduce the feeling of roughness due to disclination.

According to the first to third manufacturing methods of the present invention, the liquid crystal display panel of the present invention can be efficiently and rationally manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a liquid crystal display panel according to embodiments 1, 2, 3, 4, 5, and 6 of the present invention.

FIG. 2 is a conceptual diagram illustrating domains of a liquid crystal element in Comparative Example 1.

FIG. 3 is a conceptual diagram illustrating a state in which continuity of alignment of liquid crystal molecules is divided at boundaries between pixels in the present embodiment.

FIG. 4 is a conceptual diagram illustrating the operation of a conventional TN type liquid crystal element.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 101 Upper glass substrate 102 Segment electrode 103 Lower glass substrate 104 Common electrode 105 Alignment film 106 Alignment film 107 Chiral nematic liquid crystal layer 108 Spacer 109 Sealing material 110 Polarizing plate 201 Liquid crystal molecule director 202 to 205 Different director 206 Disk Ligations 301 to 304 Unit liquid crystal cell 305 in which the continuity of liquid crystal alignment is divided into pixel units 305 Electrode ends 401 Liquid crystal molecules 402 Upper glass substrate 403 Lower glass substrate 404 Rubbing direction of upper substrate 405 Rubbing direction of lower substrate 406 Upper side Absorption axis direction of polarizing plate 407 Absorption axis direction of lower polarizing plate

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Shinya Kosako 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Hideaki Mochizuki 1006 Kazama Kadoma, Osaka Prefecture (58) Fields surveyed (Int.Cl. ⁶ , DB name) G02F 1/1337-1337 530 G02F 1/1343

Claims (11)

(57) [Claims] At least one of upper and lower electrodes on a substrate has a continuity of alignment of liquid crystal molecules at a boundary between an electrode portion and a non-electrode portion on at least one of the electrodes. A chiral nematic phase having a positive dielectric anisotropy, wherein the long axis direction of the liquid crystal molecules is substantially parallel to the substrate interface or has a pretilt angle of 20 degrees or less, and a plurality of orientations or various orientations. A liquid crystal display panel having an orientation. 2. The liquid crystal display panel according to claim 1, wherein continuity of alignment of liquid crystal molecules is divided at boundaries between pixels defined by upper and lower electrodes on the substrate. 3. Each pixel defined by upper and lower electrodes on a substrate is constituted by a plurality of divided small electrode portions, and the continuity of alignment of liquid crystal molecules is divided at boundaries between the small electrode portions. The liquid crystal display panel according to claim 1, wherein: 4. The liquid crystal layer has a twist angle of about 90 between the upper and lower electrodes.
4. The liquid crystal display panel according to claim 1, wherein at least two polarizing plates are crossed with each other, and the crossing angle of the polarizing plates is about 90 degrees. 5. The liquid crystal display panel according to claim 1, wherein the thermoplastic polymer is formed on the upper and lower electrodes on the substrate. 6. Production of a liquid crystal display panel having a liquid crystal layer made of a chiral nematic liquid crystal composition in which two substrates having electrode surfaces that have not been subjected to an alignment treatment are opposed to each other and exhibit a twist of about 90 degrees between the substrates. In the above, the nematic-isotropic transition temperature (hereinafter NI) of the liquid crystal composition
A liquid crystal panel characterized in that the continuity of the orientation of the liquid crystal after the removal of the electric field is divided at the end of the electrode by cooling from a temperature of not less than the point temperature) to the NI point temperature while an electric field is applied between the substrates. Manufacturing method. 7. In the manufacture of a liquid crystal display panel in which each pixel defined by upper and lower electrodes on a substrate is composed of a plurality of divided small electrode portions, the temperature of the liquid crystal composition is higher than the NI point temperature. NI with electric field applied between substrates
7. The method for manufacturing a liquid crystal panel according to claim 6, wherein the continuity of the orientation of the liquid crystal after each small electrode end is divided at the electrode end by removing the electric field by cooling to a point temperature or lower. 8. A first step of forming an alignment film on a substrate having electrodes, and attaching a pair of substrates at a fixed interval via a spacer, leaving a part of an opening for liquid crystal injection. A second step of combining and a third step of heating the substrate above the nematic-isotropic transition temperature (NI point temperature) of the chiral nematic liquid crystal and injecting the chiral nematic liquid crystal.
A fourth step of heating and holding the substrate at a temperature equal to or higher than the NI point temperature of the chiral nematic liquid crystal, and a fifth step of cooling the chiral nematic liquid crystal from a warmed state to a lower temperature under a voltage applied state. A method for manufacturing a liquid crystal display panel, comprising at least a step. 9. A first step of forming an alignment film on a substrate having electrodes, and attaching a pair of substrates at a fixed interval via a spacer while leaving a part of an opening for liquid crystal injection. A second step of combining, a third step of injecting the chiral nematic liquid crystal at room temperature, and
The fourth step of heating and holding the substrate at a temperature equal to or higher than the point I temperature for a certain period of time
And a fifth step of cooling the chiral nematic liquid crystal from a heated state to a temperature lower than the heated state with a voltage applied thereto, the method comprising the steps of: 10. An alignment film is formed on electrodes of upper and lower substrates,
The liquid crystal display panel according to claim 1, 2, 3, 5, 8, or 9, wherein the liquid crystal display is assembled without performing a rubbing process. 11. The method for manufacturing a liquid crystal display panel according to claim 8, wherein in the fifth step, cooling is performed from a temperature equal to or higher than the NI point temperature to a temperature lower than the NI point temperature while applying a voltage.