JP2000029028A - Liquid crystal display device and method of forming the same - Google Patents

Abstract

(57) [Problem] In a conventional in-plane response type liquid crystal display device, liquid crystal molecules rotate in a certain direction when a voltage is applied, so that there is coloring when observed from a certain direction. The present invention provides a liquid crystal display device having good display quality and a method for forming the same. SOLUTION: By providing a convex portion on a pair of opposing electrodes, the distance between the opposing electrodes is not uniform in a pixel and the distance between the electrodes is locally reduced, that is, a strong electric field is applied when a voltage is applied. The electrode structure is such that a region is formed. By modulating the electric field strength between the electrodes and setting the rotation direction of the liquid crystal molecules located between the electrodes in two directions, clockwise and counterclockwise, the birefringence of the liquid crystal molecules is eliminated, and when observed from a certain direction. Also, it is possible to obtain good display characteristics without coloring.

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 device and a method of forming the same, and more particularly, to a liquid crystal display device having high display quality without coloring when observed from a certain direction and a method of forming the same.

[0002]

2. Description of the Related Art Liquid crystal display devices are widely used as display devices for watches, calculators, etc. because of their features such as thinness, light weight, and low power consumption. In particular, a twisted nematic (hereinafter, referred to as TN (Twisted Nematic)) type liquid crystal display device that performs active driving by a thin film transistor (hereinafter, referred to as a TFT (Thin Film Transistor)) or the like is a display device such as a word processor or a personal computer. It is being applied to televisions and the like, and is replacing CRT (Cathode Ray Tube), which is the most common conventional display device.

However, this TN type liquid crystal display device has a problem that the viewing angle is generally narrow, and when viewed from an oblique direction, the contrast is reduced and the gradation is inverted. In recent years, in-plane response type liquid crystal display devices having excellent viewing angle characteristics have been developed and attracted attention.

FIG. 6 is an enlarged partial cross-sectional view of a conventional in-plane response type liquid crystal display device. 6, reference numeral 101 denotes an electrode-side glass substrate, 102a and 102b denote comb-shaped opposing electrodes patterned on the glass substrate 101, and 103 denotes a glass substrate 1 on which opposing electrodes 102a and 102b are formed. The laminated alignment film, 104 is a spherical spacer disposed on the alignment film 103, 105 is a liquid crystal layered and injected on the alignment film 103, 106 is an alignment film disposed on the liquid crystal 105, 107 is an alignment film The opposing substrates disposed on the film 107 are shown.

FIGS. 7A and 7B show a portion of an in-plane response type liquid crystal display device in a state where a voltage is not applied between opposing electrodes 102a and 102b and a state where a voltage is applied. It shows a bird's eye view. FIG. 7A,
In (b), reference numerals 108 and 109 indicate the glass substrate 10.
1 and polarizing plates 110 disposed on the lower and upper surfaces of the counter substrate 107.
Reference numeral 11 denotes transmitted light transmitted through the upper surface of the polarizing plate 109;
a indicates a liquid crystal molecule, and the same reference numerals as those shown in FIG. 6 indicate the same or corresponding parts.

The principle of driving the in-plane response type liquid crystal display device will be described with reference to FIG. As the liquid crystal material, any having positive or negative dielectric anisotropy (Δε) can be used.
Here, a case where Δε> 0 will be described as an example. Polarizing plate 108
Are arranged in parallel with the orientation direction a of the liquid crystal molecules, and the other polarizing plate 109 is arranged in a direction orthogonal thereto (the transmission axis and the absorption axis are shown in the drawing. Arrows indicate direction.)

When no voltage is applied between the opposing electrodes 102a and 102b, the liquid crystal molecules 105a have a fixed orientation, and as shown in FIG. The light 110 passes through the liquid crystal layer 105 without being affected by the birefringence of the liquid crystal layer, and reaches the polarizing plate 109 as linearly polarized light 110a. Here, since the transmission axis of the polarizing plate 109 is orthogonal to the transmission axis of the polarizing plate 108, light cannot be transmitted and the light is in a black state.

On the other hand, when a voltage is applied between the opposing electrodes 102a and 102b, as shown in FIG.
The liquid crystal molecules 105a change the orientation in the direction of the electric field (horizontal direction) as shown by the symbol b. The incident light 110 that has passed through the polarizing plate 108 changes from linearly polarized light 110 a to elliptically polarized light 110 b due to the birefringence effect of the liquid crystal layer 105, and reaches the polarizing plate 109. By changing to the elliptically polarized light 110b, a part of the light is transmitted through the polarizing plate 9 to generate the transmitted light 111, which is changed to a white state.

Next, problems in the in-plane response type liquid crystal display device will be described with reference to FIGS. In the state where no voltage is applied between the opposing electrodes 102a and 102b, as shown in FIG. 8A, the liquid crystal molecules 105a have an angle θ with respect to the extending direction of the electrode whose major axis is opposite. Orientation direction a. On the other hand, the opposite electrode 1
When a voltage is applied between the liquid crystal molecules 105a and the liquid crystal molecules 105a, the liquid crystal molecules 105a change their orientation to the electric field direction b as shown in FIG.
In the direction of. Opposing electrodes 102a,
Since an electric field in one direction is applied between the electrodes 102b, all the liquid crystal molecules 105a disposed between the electrodes rotate in the same direction (the direction indicated by arrow C).

[0010] Liquid crystal molecules have refractive index anisotropy, and the refractive indices differ in the major axis direction and the minor axis direction. Therefore, when the liquid crystal molecules rotate, the retardation Δnd of the liquid crystal layer 105 changes, and the incident linearly polarized light changes to elliptically polarized light. At this time, the elliptically polarized light that has reached the emission side polarizing plate 109 is partially transmitted, and a white display state can be obtained.
However, looking at this LCD from different angles,
Since the apparent Δnd is different, it is observed by coloring in a color corresponding to the wavelength dispersion. For example, as shown in FIG. 9, when the in-plane response type liquid crystal display device when a voltage is applied between the opposing electrodes 102a and 102b is viewed obliquely above the substrate, the direction A (the liquid crystal molecules 105a In the direction perpendicular to the major axis of the liquid crystal) and appear blue in the direction of B (the direction parallel to the major axis of the liquid crystal molecules), and good display characteristics can be obtained. Did not.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and eliminates coloring when observed from a certain direction, and provides an in-plane response type liquid crystal display having good display quality. An apparatus is provided.

[0012]

According to a first aspect of the present invention, there is provided a liquid crystal display device having a pair of opposing electrodes disposed on a substrate, and a pair of opposing electrodes substantially disposed on a substrate surface applied between the opposing electrodes. In an in-plane response type liquid crystal display device in which liquid crystal molecules located between a substrate and an opposing substrate opposing the substrate are caused to respond substantially parallel to the substrate surface by a parallel electric field, a convex portion is formed on the opposing electrode. This forms a region in which the distance between the opposing electrodes is locally small within the same opposing electrode, and an electric field generated in the region when a voltage is applied has a predetermined electric field with respect to an axis orthogonal to the direction in which the electrodes extend. It is formed in an angled direction.

In a liquid crystal display device according to a second aspect of the present invention, in addition to the features described in the first aspect, the opposing electrodes are formed to extend in one direction, and a pair of opposing electrodes are formed. At least two regions where the distance between them is locally small are formed, and the directions of the electric fields generated in the two regions when a voltage is applied are different from each other, and the rotation direction of the liquid crystal molecules between the same opposing electrodes is the direction of the electric field. Is different depending on

Further, in the liquid crystal display device according to a third aspect of the present invention, in addition to the features corresponding to the first aspect, the convex portion extends from a side surface of one of the electrodes forming the opposing electrode toward the other electrode. It is formed to protrude.

In a liquid crystal display device according to a fourth aspect of the present invention, in addition to the features corresponding to the first or second aspect, a pair of opposing electrodes are provided with first and second potentials to which the first and second potentials are supplied. The second electrode is a comb-shaped electrode arranged in an alternately meshed state, and the first and second electrodes facing each other from the side surfaces of the first and second electrodes are formed with convex portions, respectively. The direction of the electric field generated on the line connecting the protrusions on the first and second electrodes is at a predetermined angle with respect to an axis orthogonal to the extending direction of the facing electrode, and the predetermined angle is adjacent to the axis. It differs between the opposing electrodes.

Further, in the liquid crystal display device according to a fifth aspect of the present invention, in addition to the features corresponding to the fourth aspect, when a voltage is applied with the first or second electrode forming position as a boundary,
The rotation direction of liquid crystal molecules differs between adjacent electrodes.

According to a sixth aspect of the present invention, in the liquid crystal display device, a pair of opposing electrodes are provided on the substrate, and an electric field applied between the opposing electrodes is substantially parallel to the substrate surface. In an in-plane response type liquid crystal display device in which liquid crystal molecules located between a substrate and a counter substrate facing the substrate respond substantially parallel to the substrate surface, on one or both electrodes constituting a pair of opposed electrodes, By arranging the foreign matter in a state where a part of the foreign matter overlaps and the remaining part protrudes toward the facing electrode side, the rotation direction of the liquid crystal molecules between the same opposed electrodes when a voltage is applied, with the position where the foreign matter is located as a boundary when applying a voltage. Is different.

In the liquid crystal display device according to a seventh aspect of the present invention, in addition to the features corresponding to the sixth aspect, the foreign matter is the same as the pitch of the electrodes in a direction perpendicular to the extending direction of the electrodes. They are arranged at a pitch.

Further, in the liquid crystal display device according to an eighth aspect of the present invention, in addition to the features corresponding to the sixth aspect, the pair of opposing electrodes are provided with first and second potentials to which the first and second potentials are supplied. A comb-shaped electrode in which two electrodes are alternately meshed with each other, and a foreign substance protruding toward the second electrode is arranged on the first electrode, with the formation position of the first electrode as a boundary. ,
When a voltage is applied, the direction of rotation of liquid crystal molecules differs between adjacent electrodes.

According to a ninth aspect of the present invention, in addition to the features corresponding to any one of the sixth to eighth aspects, the foreign matter is a particle, a column, or a thin film. .

Further, in the method for forming a liquid crystal display device according to claim 10 of the present invention, after forming a pair of opposing electrodes on a glass substrate, a part is overlapped on the opposing electrodes, and A step of arranging foreign matter in a state in which the foreign matter protrudes toward the opposing electrode side, forming an alignment film on the glass substrate including the surface of the foreign matter, and performing rubbing along the direction in which the counter electrode extends. In a method of forming a responsive liquid crystal display device, rubbing is performed on the alignment film after disposing foreign matter, so that initial alignment of liquid crystal molecules arranged on the alignment film is in a state along the surface shape of the foreign matter. It is.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 In the liquid crystal display device of the present invention, a pair of electrodes are arranged on the same substrate at a predetermined distance, and liquid crystal molecules aligned in a predetermined direction by an electric field applied between the electrodes and substantially parallel to the substrate surface. This is an in-plane response type liquid crystal display device that responds almost parallel to the substrate surface, where a region where the electric field strength is locally different between the opposing electrodes is formed, and the rotation direction of the liquid crystal molecules is counterclockwise and counterclockwise. By doing so, the coloring when observing from a certain direction is eliminated.

The present invention will be described in detail with reference to FIG. FIG. 1 is a plan view corresponding to one cell of a liquid crystal display device. FIG. 1A shows a state where a voltage is not applied between opposed electrodes, and FIG. 1B shows a state when a voltage is applied. Each is shown. These figures show a pair of opposing electrodes and liquid crystal molecules formed on a glass substrate, and show plan views of an electrode structure in which there are regions where the electrode distance differs between the opposing electrodes 1a and 1b. As the liquid crystal material, any having positive or negative dielectric anisotropy (Δε) can be used.
Here, a case where Δε> 0 will be described as an example. Also, reference numeral 2
Reference numerals a, 2b, 2c, and 2d denote liquid crystal molecules, 3a and 3b denote convex portions formed on the opposing electrodes 1a and 1b, 4 denotes a rubbing direction, and 5 denotes a disclination line. Also, h
1, h2 is the amount of protrusion of the projections 3a, 3b, D is the electrode width, l1
Indicates the distance between the adjacent convex portions 3a-3a. In this example, the convex portion 3b is on the disclination line 5,
The protrusions 3a are symmetrically arranged at a predetermined distance from the disclination line 5.

In the state where no voltage is applied, FIG.
As shown in (a), the liquid crystal molecules 2a to 2d are oriented along the rubbing direction 4. When voltage is applied, FIG.
As shown in (b), the region where the distance between the electrodes is short (electric field 6
The electric field strength in the region where a and 6b are applied is stronger than the region where the distance between the electrodes is long (the region where electric fields 6c and 6d are applied).
The liquid crystal molecules 2a in the electric fields 6a and 6b, which are strong electric field regions,
2b changes the orientation direction by applying an electric field, and changes the orientation toward the direction of the electric field inclined at a predetermined angle with respect to the electrode width direction.

For example, the liquid crystal molecules 2a rotate in the direction of the electric field 6a, and the liquid crystal molecules 2b rotate in the directions of the arrows (clockwise and counterclockwise) so as to change the alignment in the direction of the electric field 6b. Further, the surrounding liquid crystal molecules are also dragged by the movement. For example, the liquid crystal molecules 2c rotate in the same direction as the liquid crystal molecules 2a, and the liquid crystal molecules 2d rotate in the same direction as the liquid crystal molecules 2b. As a result, a region (1) where the electric fields 6b and 6d are applied and a region (2) where the electric fields 6a and 6c are applied in FIG.
Can change the rotation direction of each liquid crystal molecule,
The region (1) in FIG. 1B is a liquid crystal molecule 2b,
2d in the counterclockwise direction, the liquid crystal molecules 2a, 2
c can be rotated clockwise. Therefore, the birefringence of the liquid crystal molecules in the region (1) and the birefringence of the liquid crystal molecules in the region (2) cancel each other, and there is no coloring when observed from a certain direction.

As described above, by forming an electrode structure in which the distance between a pair of opposing electrodes is not partially constant, and by forming a region where the electric field strength is locally different between the opposing electrodes,
It is possible to change the rotation direction of the liquid crystal molecules depending on the region, cancel the birefringence of the liquid crystal molecules, and eliminate coloring when observed from a certain direction.

In the liquid crystal display device of the present invention, since the rotation of the liquid crystal molecules in the clockwise and counterclockwise directions occurs between the pair of opposing electrodes, the disclination line is formed as shown in FIG. 5 occurs. However, the in-plane response type liquid crystal display device is in the NB (normally black) mode, and the disclination line is observed in black, so that there is no particular problem in display.

The substrate material used in the liquid crystal display device of the present invention is not particularly limited, but a conventionally used material such as ordinary glass or quartz can be used. The material of the comb-shaped opposed electrodes 1a and 1b of the present invention is not particularly limited, but a metal film such as Al or Cr, a metal oxide film, a metal multilayer film, or the like can be used. Further, the liquid crystal material is not particularly limited, and a liquid crystal material used in a normal TN liquid crystal display device or the like can be used.

Further, the alignment film used in the present invention is not particularly limited, but a soluble polyimide used in a TN type liquid crystal display device or the like, or an amic acid-based fired polyimide can be used. The pretilt angle is not particularly limited, but is preferably 10 ° C. or less. If the value exceeds 10 ° C., a desired viewing angle may not be obtained.

In the structure shown in FIG. 1, the distance d1 between the opposing electrodes is not particularly limited, but is preferably 10 μm or more. If the thickness is less than 10 μm, there is a problem that the aperture ratio decreases and the transmittance decreases, which is not preferable.

Further, the convex portions 3 of the opposing electrodes 1a and 1b
Although the protrusion amounts h1 and h2 of a and 3b are not particularly limited,
The value is preferably larger than 0 μm and 5 μm or less. If it exceeds 5 μm, there is a problem that the area of the uneven portion occupied between the electrodes becomes large and the aperture ratio decreases. If there is such an inconvenience, a poorly-aligned region (domain) is likely to be generated on the electrode end face, and light leakage due to poorly-aligned light will appear remarkably, thereby deteriorating the display quality.

The distance l1 between the convex portions is not particularly limited, but is preferably larger than 0 μm and 10 μm or less. If the value is larger than 10 μm, the electric field strength between the adjacent convex portions in the same electrode becomes almost the same as the electric field strength between the opposing electrodes. The direction becomes one direction, and the object of the present invention cannot be achieved. The rubbing direction 4 is preferably parallel (0 °) to the side surface of the electrode.

Next, the opposing electrodes 1 as shown in FIG.
A method for forming a liquid crystal display device having a and 1b will be described. First, a chromium film is formed on one glass substrate so as to have a thickness of 1000 angstroms by a sputtering method. Further, a positive photosensitive resist pattern is formed on the surface, and the chromium layer is formed using the resist pattern. Patterning to obtain comb-shaped opposing electrodes 1a and 1b formed in a state where the protrusions 3a and 3b protrude in a direction parallel to the substrate surface as shown in FIG. Performs removal.

The dimensions of the opposed electrodes 1a and 1b were such that the electrode width was 5 μm and the distance d1 between the electrodes was 10 μm.
The protrusion amounts h1 and h2 of the protrusions 3a and 3b were both 5 μm. The distance l1 between the protrusions was 10 μm.

A polyimide film (manufactured by Nippon Synthetic Rubber Co., Ltd.) is formed on the substrate on which the opposing electrodes 1a and 1b are formed by spin coating, and baked at a temperature of 180 ° C. for 1 hour.
An alignment film of 0 Å was obtained. Further, an alignment film was similarly formed on the counter substrate surface. Thereafter, a rubbing treatment was performed on the electrode substrate and the alignment film side on the opposing substrate disposed to face the substrate. The rubbing direction is, as shown by reference numeral 4 in FIG.
a and 1b were parallel to the direction in which they extend.

Next, a ring-shaped sealant was arranged on the electrode substrate using an epoxy resin adhesive, and a heat treatment was performed at 110 ° C. for 10 minutes. Further, a spherical spacer (Micropearl, manufactured by Sekisui Fine Chemical Co., Ltd.) having a diameter of about 3.7 μm was sprayed on the surface of the counter substrate on the side of the alignment film.

Thereafter, the two substrates are overlapped so that the alignment films face each other so that the rubbing directions are antiparallel (the direction in which the rubbing directions are orthogonal to each other when the substrate is viewed as a plane). The sealing agent was cured by thermocompression bonding. Thereafter, a liquid crystal composition (manufactured by Merck) was injected between both substrates by a vacuum injection method. Next, the injection port was sealed with an ultraviolet curable resin, and heat treatment was performed at 110 ° C. for 10 minutes to perform an isotropic treatment on the liquid crystal.

Thereafter, a polarizing plate was attached to each of the non-opposing surfaces of the opposing substrate and the electrode substrate. The sticking direction is such that the direction of the absorption axis of the polarizing plate on the side where light is incident coincides with the orientation direction (rubbing direction) of the liquid crystal molecules, and the direction of the polarizing plate on the emission side is the direction of the absorption axis of the other polarizing plate. Are arranged in the direction orthogonal to each other.

The liquid crystal display device thus formed is
When a voltage is applied between the opposing electrodes 1a and 1b,
Liquid crystal molecules rotate clockwise between the same opposing electrodes,
In addition, since the antireflection film rotates counterclockwise, the birefringence is canceled each other, and even when the image is observed from a certain direction, no coloring is observed and good display characteristics can be obtained.

In the first embodiment, as shown in the plan view of the main part of the liquid crystal display device of FIG. 1, the driving state of a part of a pair of comb-shaped counter electrodes constituting one pixel will be described. It is possible to adjust the number and arrangement of the areas (1) and (2) having different rotational directions depending on the number and arrangement of the projections 3a and 3b, and the area (1) and the area (2) can be adjusted. It goes without saying that the display characteristics can be further improved by forming more repetitive arrangements of (1) and (2).

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a plan view of a main part of a display element of the liquid crystal display device according to the second embodiment, and FIG. 2A shows a state where no voltage is applied.
(B) shows a state where a voltage is applied. In this figure, reference numerals 7a, 7b and 7c are comb-shaped opposed electrodes.

Further, convex portions 3c, 3d, 3e are formed on the counter electrodes 7a, 7b, 7c, respectively. Reference numerals 8a, 8b, 8c, and 8d indicate the directions of electric fields. Further, h3, h4, h5 are convex portions 3c, 3d, 3
e, the projection amount, d2, d3 the distance between the electrodes, l2, l
Reference numerals 3 and 14 denote the distances between the convex portions formed on the same electrode, respectively, and the same reference numerals as those already used for the description denote the same or corresponding parts. Also,
As shown in FIG. 2, the convex portions 3d and 3c and the convex portion 3d
And 3e are formed with a deviation so as to be staggered in the lateral direction. Therefore, the directions of the electric fields 8a and 8b are different from the directions of the electric fields 8c and 8d. In this example, the projections 3c to 3e are arranged such that the electric fields 8a to 8d have a predetermined inclination with respect to the direction in which the opposing electrodes extend.

In the state where no voltage is applied, FIG.
As shown in (a), the liquid crystal molecules 2a to 2d are oriented along the rubbing direction 4. Fig. 2
As shown in (b), the distance between the facing electrodes 7a and 7b and the distance between the facing projections 3c and 3d is d2.
It becomes smaller, and the strength of the electric fields 8a and 8b becomes stronger than in other regions where the distance between the electrodes is large. The liquid crystal molecules 2a and 2b in the strong electric field region where the electric fields 8a and 8b are formed change their orientation in the directions of the electric fields 8a and 8b, respectively, and rotate in the direction of the arrow (counterclockwise in the drawing). At this time, the rotation direction of the liquid crystal molecules 2a and 2b between the opposing electrodes 7a and 7b is one direction.

On the other hand, similarly, between the opposing electrodes 7b-7c, the liquid crystal molecules 2c and 2d are similarly supplied with electric fields 8c and 8c, respectively.
The orientation is changed in the direction of d, and it rotates in the direction of the arrow (clockwise in the drawing). The direction of rotation of the liquid crystal molecules is also one between these electrodes. As shown in FIG. 2B, the rotation directions of the liquid crystal molecules 2a to 2d are different between the opposing electrodes 7a and 7b and the opposing electrodes 7b and 7c with the opposing electrode 7b as a boundary. As a result, the opposing electrodes 7a-7b
The birefringence of the liquid crystal molecules between them and the birefringence between the opposing electrodes 7b-7c cancel each other out, and coloring when observed from a certain direction can be eliminated.

When the liquid crystal display device having the above structure is used, for example, the liquid crystal molecules 2a and 2
Since the rotation directions of b, 2c and 2d are different from each other, the disclination line 5 appears on the electrode 7b. However, since the disclination line 5 is observed in black and the in-plane response type liquid crystal display device is in the NB mode,
The occurrence of the disclination line does not cause any particular problem in display characteristics.

In the present invention, the opposing electrodes 7a to 7c
The shape of the convex portions 3c to 3e is not particularly limited.
Other shapes are possible as in the case of the first embodiment. Also, the width of the opposing electrodes 7a to 7c is not particularly limited, but is preferably 5 μm or less (for example, all are 5 μm). further,
The distances d2 and d3 between the electrodes are 10 μm or more (for example, all are 10 μm), and the protrusion amounts h3 to h5 of the projections 3c to 3e are set.
Have a dimension of 5 μm or less (for example, all are 5 μm), and the inter-electrode distances l2, l3, and l4 of the projections are
It is preferable that the size be equal to or less than μm (for example, 10 μm).

The opposite electrodes 7a to 7c shown in FIG.
Can be obtained through substantially the same steps as the steps described in the first embodiment, and the patterning of the electrode forming film made of a chromium layer is performed by using the opposing electrodes 7a to 7b. It can be formed by performing dry anisotropic etching using a resist pattern having a planar shape corresponding to the above as a mask.

Embodiment 3 Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a plan view of a part of the comb-shaped opposed electrodes of the liquid crystal display device.
3A shows a state where no voltage is applied between the opposing electrodes, and FIG. 3B shows a state where a voltage is applied between the opposing electrodes. In the figure, reference numerals 9a and 9b denote opposing electrodes in the form of a comb, reference numeral 10 denotes particles which are foreign substances, and other reference numerals which are the same as those already used for the description indicate the same or corresponding parts. In addition, d4 indicates a distance between electrodes between a pair of opposed electrodes. In this example, the pitch between the opposing electrodes 9a and 9b and the particle 10
Are arranged in the up-down direction (electrode width direction) in the drawing so that the pitches are the same.

In FIG. 3A, after forming opposing electrodes 9a and 9b on a glass substrate, disposing the particles 10,
When rubbing is performed on the formed alignment film in the rubbing direction 4 parallel to the side surface of the electrode (the direction parallel to the extending direction of the electrode), the bristles of the rubbing cloth move along the side surface of the electrode 9a. Move along the surface of the particle 10 at the position of the particle 10. For this reason, as shown in FIG. 3A, the orientation direction of the liquid crystal molecules around the particles 10 is different from the orientation direction of the liquid crystal molecules in other regions, and reflects the shape of the particles 10.

When a voltage is applied to the display device having such a structure, as shown in FIG. 3B, the liquid crystal molecules 2a and 2b rotate in opposite directions as shown by arrows. That is, the liquid crystal molecules 2a rotate counterclockwise in the drawing, and the liquid crystal molecules 2b rotate counterclockwise in the opposite direction. This is because an environment different from the periphery of the particle 10 and other regions is formed by the effect of the shape alignment of the liquid crystal molecules.

As the liquid crystal molecules 2a or 2b rotate, the surrounding liquid crystal molecules 2c or 2d also rotate in the direction of the arrow. As a result, in the regions (1) and (2), the rotation directions of the liquid crystal molecules are reversed. For this reason, the birefringence of the liquid crystal molecules 2b and 2d in the region (1) and the birefringence of the liquid crystal molecules 2a and 2c in the region (2) cancel each other, and the coloring when observed from a certain direction is reduced. It can be eliminated.

In this structure, the direction of rotation of the liquid crystal molecules is exactly opposite at the boundary between the region (1) and the region (2), so that a disclination line 5 is generated at this boundary. However, the disclination line 5 is observed in black, and the in-plane response type liquid crystal display device is in the NB mode, so that there is no problem in display characteristics.

Next, a sectional view of the liquid crystal display device according to the third embodiment is shown in FIG. In FIG. 4A, reference numeral 11 denotes a glass substrate, 12a and 12b denote alignment films formed on the opposing surfaces of the glass substrate 11 and the opposing substrate 15, 13 denotes a spacer arranged between the substrates, and 14 denotes a spacer. The liquid crystal injected between the substrates is shown. On opposing electrodes 9a and 9b formed on the glass substrate 11,
The particles 10 are arranged so as to cover one end of the electrode. Alignment film 12a formed on glass substrate 11 side
Is formed after arranging the particles 10 so as to partially overlap the electrodes and have the same pitch as the electrodes, so that the surface thereof is not flat but reflects the shape of the particles 10. A part is formed as a raised film.

FIG. 4B and FIG. 4C show that the particles 1
An example in which a cylindrical body 10a and a thin film 10b are arranged instead of 0 is shown. Even with such a structure, the same effect as when the particles 10 are used can be obtained. In addition, a fixed spacer or the like in the panel assembly process can be used. In the case where the particles 10, the columnar body 10a, and the thin film 10b used as the foreign matter are formed of a conductive material, the distance between the electrodes can be locally reduced, and a stronger electric field can be formed when a voltage is applied than in other regions. It is possible to obtain the same effect as that of the first embodiment.

The distance d4 between the electrodes is not particularly limited, but is preferably 10 μm or more, as in the case of d1 shown in the above-described embodiment. The rubbing direction 4 is preferably parallel (0 °) to the electrode surface (the direction in which the electrode extends), as in FIG.

Next, a method of forming the liquid crystal display device shown in FIGS. 3 and 4 will be described. First, chromium is formed to a thickness of 1000 Å on the glass substrate 11 by a sputtering method, and is patterned by using a positive photosensitive resist, so that the opposite electrodes 9a having the shape shown in FIG. 9b is formed. The electrode width was 5 μm, and the distance d4 between the electrodes was 10 μm. After removing the resist, particles 10 having a particle size of 2 μm were arranged on the opposed electrodes 9a and 9b. Thereafter, as in Embodiment 1, the alignment film 12a is formed and rubbed, the spacer 13 is arranged, the opposing substrate 15 on which the alignment film 12b is formed and the glass substrate 11 are bonded, and the liquid crystal 14 is formed. By implanting, it is possible to obtain a cell having the above structure.

Embodiment 4 FIG. Next, a fourth embodiment of the present invention will be described with reference to FIG. Embodiment 3 described above
In the above, the pitch of the particles 10 arranged on the opposing electrodes 9a and 9b is equal to the pitch of the comb-shaped opposing electrodes 9a and 9b, and when the planar shape is viewed, one of the opposing electrodes 9a and 9b An example is shown in which the arrangement is such that a part of the particles 10 protrudes from the end face of. In the fourth embodiment, a case where the arrangement of particles 17a and 17b corresponding to the particle 10 is different will be described.

FIG. 5 is a plan view of a main part showing a part of opposing electrodes in a comb shape. In FIG. 5, reference numerals 16a, 1
Reference numerals 6b and 16c denote opposing electrodes arranged at the same pitch in one direction. The electrodes indicated by 16a and 16b are supplied with the same electric potential.
Electric fields are generated between a and 16b and between 16b and 16c, respectively. Reference numerals 17a and 17b denote the electrodes 16 facing each other.
The particles 17a and 17b are disposed on the side of the opposing electrode 16b in such a manner that part of the particles protrude from the electrode end surface. ing.

Symbols 5a and 5b indicate when a voltage is applied.
Between the opposed electrodes 16a-16b or 16b-16c
The figure shows a disclination line generated by the rotation of the liquid crystal molecules 2a and 2b or 2c and 2d disposed therebetween, and one disclination line 5a.
Is generated in a direction (electrode width direction) orthogonal to the direction in which the electrodes extend, that is, along a line connecting the particles 17a and 17b, and the other disclination line 5b is generated on the electrode 16b.

As described above, when the particles 17a and 17b are arranged, when the rubbing cloth is used to apply friction to the alignment film formed on the glass substrate, the particles 17a and 17b are arranged.
Rubbing is performed in a direction along the surface shape of 7b. The initial alignment of the liquid crystal molecules 2a to 2d when no voltage is applied is along the rubbing direction.

On the other hand, when a voltage is applied to such a cell, the liquid crystal molecules 2a and 2b located between the opposed electrodes 16a and 16b rotate counterclockwise and clockwise, respectively, in the directions of the arrows. . The opposite electrode 16b-
The liquid crystal molecules 2c and 2d located between 16c rotate clockwise and counterclockwise in the directions of the arrows, respectively. Therefore, the rotation directions of the liquid crystal molecules between one electrode are two different directions, and the rotation directions of the liquid crystal molecules between adjacent electrodes via one electrode are also two different directions. It is possible to adjust the rotation direction of the liquid crystal molecules for each region.

According to such a liquid crystal display device, the birefringence of the liquid crystal molecules in the cell can be canceled by adjusting the rotation direction of the molecules, and coloring when observed from one direction can be prevented. Disappears. In addition, the occurrence of the disclination lines 5a and 5b causes no problem in display characteristics because the in-plane response type liquid crystal display device is in the NB mode.

Comparative Example Next, Embodiments 1 to 1 of the present invention
4 shows a comparative example for the liquid crystal display device described in FIG. On one of the glass substrates, chromium is formed to a thickness of 1000 Å by a sputtering method, and is patterned using a positive photosensitive resist to form projections and the like as shown in FIG. Unformed counter electrodes 102a and 102b are formed. Next, a film of polyimide (manufactured by Nippon Synthetic Rubber Co., Ltd.) was formed on the substrate and fired (180 ° C., 1 hour). The film thickness was 800 Å. A polyimide film (manufactured by Nippon Synthetic Rubber Co., Ltd.) was formed on the opposite substrate facing this. Rubbing treatment was performed on the glass substrate on which the opposing electrodes were formed and the opposing substrate so that the glass substrate side had an angle of 15 ° with respect to the direction in which the electrodes extended. Thereafter, the superposition of two glass substrates and the like were performed in the same manner as in Embodiment 1, and a liquid crystal display device was obtained.

In the liquid crystal display device thus formed,
As shown in FIG. 8B, when a voltage is applied, the liquid crystal molecules 10 located between the opposing electrodes 102a-102b
5a, all molecules rotate in the same direction C indicated by the arrow,
When observed from a certain direction, coloring was recognized, and good display characteristics could not be obtained.

[0065]

The effects of each claim of the present invention will be described below. In the liquid crystal display device according to the first aspect of the present invention, by providing a convex portion on the opposing electrode, the distance between the opposing electrodes can be locally reduced, and only that portion can be a strong electric field region. In addition, it is possible to adjust the rotation direction of the liquid crystal molecules arranged near the electric field by giving the electric field a direction instead of being formed parallel to the electrode width direction of the opposing electrode. Therefore, even in the same opposing electrodes, the liquid crystal molecules are adjusted so that the birefringence cancels out the rotation direction of the liquid crystal molecules, and even when observed from a certain direction, there is no coloring, and a high display quality liquid crystal display device. Can be obtained.

The liquid crystal display device according to a second aspect of the present invention has a structure in which a strong electric field is formed between two opposing electrodes in two different directions in addition to the effect corresponding to the first aspect. Thus, it is possible to rotate the liquid crystal molecules in two different directions between the same opposing electrodes, and to obtain a liquid crystal display device having high display quality without coloring even when observed from a certain direction. .

Further, in the liquid crystal display device according to the third aspect of the present invention, the convex portion formed to obtain the effect corresponding to any one of the first and second aspects has one of a pair of opposed electrodes. The electrode is formed so as to protrude from the electrode toward the other electrode. By forming the convex portion, it is possible to form a region where the distance between the opposing electrodes is locally small.

The liquid crystal display device according to a fourth aspect of the present invention has a structure in which opposing comb-shaped electrodes are alternately meshed with each other in addition to the effect corresponding to the first or second aspect. Yes, between adjacent electrodes via one electrode, by adjusting the formation position of the convex portion,
Since electric fields can be generated at different angles, the rotation direction of liquid crystal molecules can be different between adjacent electrodes. Therefore, by adjusting the formation positions of the convex portions so as to cancel the birefringence of the liquid crystal molecules, it is possible to obtain a liquid crystal display device having no display and a higher display quality even when observed from a certain direction. Become.

Further, according to the liquid crystal display device of the present invention, in addition to the effect corresponding to the fourth aspect, when a voltage is applied with the formation position of the first or second electrode as a boundary,
By making the rotation direction of the liquid crystal molecules different for each adjacent electrode, it is possible to cancel the birefringence of the liquid crystal molecules, and there is no coloring even when observed from a certain direction, so that the display quality is higher. A liquid crystal display device can be obtained.

Further, in the liquid crystal display device according to the sixth aspect of the present invention, by arranging the foreign matter so as to partially overlap the opposing electrode, the rubbing direction of the alignment film formed on the upper surface can be changed. By changing the alignment along the surface shape of the foreign matter, the initial alignment of the liquid crystal molecules disposed thereon can be set to the alignment along the surface shape of the foreign matter. Therefore, when a voltage is applied between the opposing electrodes, it is possible to change the rotation direction of the liquid crystal molecules between the same opposing electrodes at the boundary of the position where foreign matter is formed, as a boundary. By canceling out the refractivity, it is possible to obtain a liquid crystal display device with no coloring and higher display quality even when observed from a certain direction.

Further, in the liquid crystal display device according to the seventh aspect of the present invention, in addition to the effect corresponding to the sixth aspect, the arrangement of the respective components is adjusted so that the pitch of the electrodes is equal to the pitch of the foreign matter. By doing so, a plurality of regions where liquid crystal molecules rotate in at least two opposite directions can be arranged in the same pixel between the same opposing electrodes, and the birefringence of the liquid crystal molecules can be canceled out. Thus, it is possible to obtain a liquid crystal display device that is free from coloring even when observed from a certain direction and has higher display quality.

Further, the liquid crystal display device according to the eighth aspect of the present invention has an effect equivalent to the sixth aspect, and furthermore, a part of the liquid crystal display device is superimposed on the second electrode constituting the pair of opposed electrodes, and the two By forming a foreign substance such that a part thereof protrudes on the first electrode side arranged in a state sandwiched between the second electrodes,
The rotation direction of the liquid crystal molecules can be reversed between adjacent electrodes via the first electrode, and the rotation direction of the liquid crystal molecules can be reversed between adjacent electrodes even in the same opposing electrode with a foreign substance interposed therebetween. Can be reversed. Therefore, it is possible to change the rotation direction of the liquid crystal for each finer region, to cancel the birefringence of the liquid crystal molecules, and to have high display quality without coloring even when observed from a certain direction. A liquid crystal display device can be obtained.

Further, in the liquid crystal display device according to the ninth aspect of the present invention, the foreign matter used for obtaining the effect corresponding to any one of the sixth to eighth aspects is any one of a particle, a column, and a thin film. It is possible to use any of them to obtain a rubbing direction along the surface shape, and to arbitrarily change the initial alignment of liquid crystal molecules when no voltage is applied between the opposing electrodes. It is possible to obtain a liquid crystal display device with higher display quality.

According to a tenth aspect of the present invention, in a method of forming a liquid crystal display device, the method comprises the steps of:
The method includes a step of forming an alignment film and performing rubbing parallel to the direction in which the electrodes extend. Therefore, in the region where the foreign matter is arranged, the rubbing direction is a direction along the surface shape of the foreign matter, and it is possible to locally change the initial alignment of the liquid crystal molecules when no voltage is applied. Therefore, at the time of voltage application, it is possible to make the rotation direction of the liquid crystal molecules opposite to each other between the same opposed electrodes with the formation position of the foreign matter as a boundary, thereby canceling the birefringence of the liquid crystal molecules. Thus, a liquid crystal display device with high display quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a liquid crystal display device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a liquid crystal display device according to Embodiment 3 of the present invention.

FIG. 4 is a diagram showing a liquid crystal display device according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a conventional technique.

FIG. 7 is a diagram showing a conventional technique.

FIG. 8 is a diagram showing a conventional technique.

FIG. 9 is a diagram showing a conventional technique.

[Explanation of symbols]

1a, 1b. Electrodes 2a, 2b, 2c, 2d. Liquid crystal molecules 3a, 3b, 3c, 3d, 3e. Convex part 4. Rubbing direction 5, 5a, 5b. Disclination lines 6a, 6b, 6c, 6d. Electric fields 7a, 7b, 9a, 9b, 16a, 16b, 16c. Electrodes 8a, 8b, 8c, 8d. Electric field 10, 17a, 17b. Particles 10a. Cylindrical body 10b. Thin film 11. Glass substrate 12a, 12b. Alignment film 13. Spacer 14. Liquid crystal 15. Counter substrate

Claims (10)

[Claims] A pair of opposing electrodes disposed on a substrate,
An electric field applied between the pair of opposed electrodes and substantially parallel to the substrate surface causes liquid crystal molecules located between the substrate and the opposed substrate facing the substrate to respond substantially parallel to the substrate surface. In the in-plane response type liquid crystal display device, a region where the distance between the opposing electrodes is locally small is formed by forming a convex portion on one or both of the opposing electrodes, and the region is locally formed when a voltage is applied. A liquid crystal display device wherein the generated electric field is formed in a direction making a predetermined angle with respect to an axis perpendicular to the direction in which the electrodes extend. 2. The device according to claim 1, wherein the opposing electrodes are formed to extend in one direction, and at least two regions where the distance between the opposing electrodes is locally small are formed. 2. The liquid crystal display device according to claim 1, wherein directions of generated electric fields are different from each other, and rotation directions of liquid crystal molecules between the same opposed electrodes are different according to the direction of the electric field. 3. The liquid crystal display device according to claim 1, wherein the projection is formed so as to project from a side surface of one of the electrodes forming the pair of opposed electrodes toward the other electrode. 4. A pair of opposing electrodes are comb-shaped electrodes in which first and second electrodes to which first and second potentials are supplied are arranged in an alternately meshed state. A convex portion is formed toward the second and first electrodes facing each other from the side surface of the second electrode, and the direction of an electric field generated on a line connecting the convex portions on the first and second electrodes is And a predetermined angle with respect to an axis perpendicular to an extending direction of the opposing electrodes, and the predetermined angle is different between adjacent opposing electrodes. 3. The liquid crystal display device according to 2. 5. The liquid crystal display device according to claim 4, wherein the rotation direction of the liquid crystal molecules differs between adjacent electrodes when a voltage is applied, with the formation position of the first or second electrode as a boundary. . 6. A pair of opposed electrodes are provided on a substrate,
A surface that causes liquid crystal molecules located between the substrate and the opposing substrate facing the substrate to respond substantially parallel to the substrate surface by an electric field applied substantially between the opposing electrodes and parallel to the substrate surface. In the internal response type liquid crystal display device, by disposing foreign matter in a state in which a part thereof is superimposed on one or both electrodes constituting the pair of opposed electrodes, and the remaining portion protrudes toward the opposed electrode side, A liquid crystal display device characterized in that the direction of rotation of liquid crystal molecules between the same pair of opposing electrodes is made different when a voltage is applied with the position where the foreign substance is arranged as a boundary. 7. The liquid crystal display device according to claim 6, wherein the foreign substances are arranged at a same pitch as the pitch of the electrodes in a direction orthogonal to a direction in which the electrodes extend. 8. A pair of opposing electrodes are comb-shaped electrodes in which first and second electrodes to which first and second potentials are supplied are arranged in an alternately meshed state. The foreign matter protruding toward the second electrode side is arranged on the electrode, and the formation position of the first electrode is used as a boundary when applying a voltage,
7. The liquid crystal display device according to claim 6, wherein the rotation direction of the liquid crystal molecules is made different between adjacent electrodes. 9. The liquid crystal display device according to claim 6, wherein the foreign matter is a particle, a column, or a thin film. 10. After forming a pair of opposing electrodes on a glass substrate, a foreign substance is arranged on the opposing electrodes such that a part thereof overlaps and a part protrudes toward the opposing electrode. Forming an alignment film on the glass substrate including the surface of the foreign matter, and performing a rubbing process along a direction in which the counter electrode extends. Rubbing the alignment film after the arrangement so that the initial alignment of the liquid crystal molecules arranged on the alignment film is in a state along the surface shape of the foreign matter. .