JP2924757B2 - Liquid crystal element - 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 device,
In particular, the present invention relates to a wide viewing angle liquid crystal element that does not require an alignment film.

[0002]

2. Description of the Related Art At present, in a liquid crystal display using an N (nematic) liquid crystal such as a TN (twisted nematic) type liquid crystal display or an STN (super twisted nematic) type liquid crystal display, it is necessary to obtain a good display. The liquid crystal is sandwiched between rubbed polymer alignment films to obtain a monodomain liquid crystal layer.

The rubbing treatment is inexpensive and simple, but the surface of the alignment film is directly rubbed with a buff cloth or the like, so that the surface of the alignment film is often contaminated or damaged, and the device is often destroyed by static electricity. These cause the surface defect of the liquid crystal display, which causes the yield to decrease.

Further, since the liquid crystal layer forms a monodomain, a difference in birefringence occurs depending on the viewing angle, and the contrast and color tone have angle dependence.

To solve such a problem, for example, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 11409/1999 proposes a method of forming a step or wall of a polymer on the surface of a transparent electrode to form minute domains having random alignment directions in pixels. According to the description of the publication, a liquid crystal panel in which a liquid crystal layer exists between at least a pair of transparent substrates having a transparent electrode on the surface, the liquid crystal layer includes a liquid crystal unit cell separated by a step or a wall surface, In the absence of an electric field, the liquid crystal molecules are arranged substantially horizontally with respect to the substrate, are composed of liquid crystal domains having various orientations (at random orientation), and have at least one polarizing plate outside the transparent substrate. With this arrangement, the viewing angle is increased without performing a rubbing process, and finer liquid crystal domains are stably present in fine pixels.

[0006]

As described above, the rubbing method is inexpensive and simple. However, since the surface of the alignment film is directly rubbed with a buff cloth or the like, the surface of the alignment film is contaminated or damaged, and the device is damaged by static electricity. Destruction and the like are often caused. These cause a display failure of the liquid crystal display, which causes a reduction in yield.

Further, since the liquid crystal layer forms a monodomain, the liquid crystal director in the middle position of the liquid crystal layer is oriented in one direction. Therefore, a difference in birefringence occurs depending on the viewing angle, and the contrast and the color tone vary in angle. Dependencies come out.

On the other hand, in the method proposed in Japanese Patent Application Laid-Open No. Hei 7-11409, in which multi-domains are formed by using steps or walls of a polymer, as shown in a polymer dispersed liquid crystal display, the dielectric constant of the liquid crystal is reduced. Without optimizing the dielectric constant of the polymer, good brightness and contrast cannot be obtained, and there is also difficulty in injecting liquid crystal in manufacturing. Also, when applied to the 90-degree twisted TN system, which is the current mainstream display, the cell gap is 1 at the step.
Since the ヘ リ helical pitch length is not obtained, there is a problem that the electro-optical characteristics of the entire panel become uneven, resulting in low brightness and low contrast.

Accordingly, the present invention has been made in view of the above problems, and has a large number of different electric field regions in a pixel, thereby forming a multi-domain in a liquid crystal layer to achieve an increase in a viewing angle. In addition, an object of the present invention is to provide a liquid crystal element which does not use a rubbing alignment film, thereby reducing contamination and poor liquid crystal alignment caused by a rubbing process.

[0010]

In order to achieve the above object, the present invention provides a method for controlling display on a surface in a direction perpendicular to a substrate.
A liquid crystal element having a liquid crystal phase sandwiched between transparent substrates having a transparent electrode film for applying an electric field , wherein pixels are divided on the surface of the transparent electrode via an insulating film .
Electrically independent in-plane arrangements formed in a grid pattern
There is provided a liquid crystal element comprising an electrode for controlling the direction, wherein an orientation of a liquid crystal surrounded by the electrode wall in a horizontal direction of the substrate is controlled by an electric field applied to the electrode .

The present invention does not use a rubbed polymer thin film on a transparent electrode on the surface of a substrate to align liquid crystal molecules. Two pairs of electrodes are provided, and a liquid crystal domain is formed by a horizontal and perpendicular electric field applied to a substrate applied by each micro transparent electrode.

[0012]

According to the liquid crystal device of the present invention, a nematic liquid crystal having a positive dielectric anisotropy is injected, and the substrate is formed by the fine transparent electrode formed on the transparent electrode of the pixel on one substrate. When a horizontal voltage is applied to the substrate, liquid crystal domains in which liquid crystals near the substrate surface are oriented in the directions of the respective electric fields are obtained. As a result, the liquid crystal director in the middle position of the liquid crystal layer is oriented in multiple directions, so that it is possible to compensate for the difference in birefringence due to vision, and to realize a display with a wide viewing angle.

Further, according to the present invention, since there is no alignment film, there is no contamination due to rubbing treatment of the alignment film.

[0014]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a plan view (see FIG. 1A) and a cross-sectional view (see FIG. 1B) of a schematic configuration of a liquid crystal element according to an embodiment of the present invention. The liquid crystal element shown in FIG. 1 is a simple matrix driving element having a size of about 3 cm × 4 cm.

The sectional structure of a pixel will be described with reference to the sectional view of FIG. An ITO (indium tin oxide) transparent electrode is provided as a pixel transparent electrode 101 on the surface of the substrate 105, and after forming the insulating film 107, the second microelectrode 103 is replaced with the ITO.
Was patterned as a material.

Further, after performing insulation protection, the IT
A first microelectrode 102 is formed using O as a material, and an insulating film 10 is formed.
7 'formed. Similarly to the upper substrate 105, an ITO transparent electrode, an insulating film, first and second minute electrodes, and the like are formed on the lower substrate 104.

Next, the planar structure of the pixel will be described with reference to the plan view of FIG.

The size (dimensions) of the lower substrate 104 and the upper substrate 105 is 3 cm × 4 cm, the size (dimensions) of the pixel transparent electrode 101 is 100 μm × 300 μm, the width a of the first minute electrode 102 is 1 μm, The second microelectrode 103 has a size of 1 μm × 3 μm (b = 3 μm, c = 1 μm), and the first microelectrode 103
The distance d between the second microelectrode 103 and the second microelectrode 103 was 1 μm, and the vertical distance between the adjacent second microelectrodes 103 in the drawing was 5 μm.

A 5.4 μm spacer (not shown) is sandwiched between the two substrates 104 and 105, the substrates are adhered to each other with an epoxy adhesive, and a liquid crystal injection port is provided to form a liquid crystal cell.

Liquid crystal was injected into the liquid crystal cell, and the liquid crystal injection port was sealed with an ultraviolet curable resin. The liquid crystal is 5CB (4-cyano-
4'-pentyl biphenyl) was used.

Finally, the polarizing plates 106 and 106 'are connected to the upper and lower substrates
5, 104 were attached so that the deflection directions were perpendicular to each other. The lower substrate 104 has a deflection direction 108 parallel to the first microelectrode 102, and the upper substrate 105 has a deflection direction 109
In parallel with the microelectrode 103.

The first and second microelectrodes 10 of the above liquid crystal element
When voltage is applied between 2 and 103 so that the potential between adjacent electrodes becomes 5 V, as shown in FIG. 2, the director of the liquid crystal surrounded by each microelectrode has an angle of 90 ° in the adjacent region. 5 μm × 5 μm
Liquid crystal domains having different orientations are obtained for each region.

FIG. 3 shows the results obtained by measuring the transmittance-driving voltage characteristics when a voltage was applied between the pixel transparent electrodes of the liquid crystal element using light of 633 nm from a He-Ne laser. At this time, the transmittance is 1 when no drive voltage is applied.
00%. As shown in FIG. 3, when the voltage between the pixel transparent electrodes of the liquid crystal element is about 1.59 V or less, the transmittance is 90% or more,
It is larger than 2.78V and less than 10%.

FIG. 4 shows that a driving voltage of 2 is applied to the liquid crystal element.
FIG. 4 shows the transmittance-viewing angle characteristics of the He—Ne laser light in the horizontal direction (see FIG. 4A) and the vertical direction (see FIG. 4B) when V is applied. Good viewing angle characteristics up to 70 ° were obtained in both the horizontal and vertical directions.

[0026]

As described above, in the liquid crystal device according to the present invention, a multi-domain of liquid crystal can be obtained by an electric field horizontal to the substrate, and a wide viewing angle display can be obtained.

Further, according to the present invention, since rubbing treatment is not performed, it is possible to reduce the occurrence of defects in the process such as contamination due to rubbing and uneven liquid crystal alignment.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams illustrating a liquid crystal element according to an embodiment of the present invention, in which FIG. 1A is a diagram schematically illustrating a planar structure, and FIG. 1B is a diagram schematically illustrating a cross-sectional structure. FIG.

FIG. 2 is a diagram schematically illustrating a liquid crystal alignment direction of a liquid crystal element according to an embodiment of the present invention.

FIG. 3 shows transmittance of a liquid crystal element according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating driving voltage characteristics.

FIG. 4 is a view showing the viewing angle dependence of the transmittance in the horizontal and vertical directions of the liquid crystal element according to one embodiment of the present invention.

[Explanation of symbols]

 101 Pixel transparent electrode 102 First transparent electrode 103 Second transparent electrode 104 Substrate (lower substrate) 105 Substrate (upper substrate) 106, 106 'Polarizer 107 Insulating film 108 Lower substrate polarization direction 109 Upper substrate polarization direction 201 First transparent electrode 202 Second transparent electrode 203 Liquid crystal director 204 Polarization direction of lower substrate 205 Polarization direction of upper substrate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/1343 G02F 1/1337 G09F 9/30

Claims (3)

(57) [Claims] 1. A display for controlling a display in a direction perpendicular to a surface of a substrate.
A liquid crystal element having a liquid crystal phase sandwiched between transparent substrates having a transparent electrode film for applying an electric field to the transparent electrode surface, wherein pixels are divided through an insulating film.
Are electrically independent of each other
A liquid crystal device comprising an electrode for controlling in-plane alignment , wherein an electric field applied to the electrode controls an alignment of a liquid crystal surrounded by the electrode wall in a horizontal direction of the substrate . 2. The liquid crystal display device according to claim 1, wherein said substrate has liquid crystal domains of various orientations by an applied electric field horizontal to said substrate.
The liquid crystal element according to the above. 3. A liquid crystal device according to claim 1, for the in-plane orientation control only in any one of the transparent substrate of the transparent electrode on the
And the liquid crystal director in a region surrounded by the electrodes is oriented so as to have a predetermined angle in an adjacent region by applying an electric field to the electrodes, so that the orientation in the horizontal direction of the substrate is different. A liquid crystal device characterized by obtaining a liquid crystal domain.