JP3529307B2 - Liquid crystal display element and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strong uniform alignment controlling property and aligning property even on the side faces of a columnar or wall-like spacer and to provide a liquid crystal display device having high contrast and stable alignment for a long time without alignment defects. SOLUTION: The liquid crystal display device has a liquid crystal material held between a pair of substrates 1 having electrodes, and also the device has a columnar or wall-like spacer 3 on at least one of the pair of substrates. The spacer itself has uniaxial aligning property or it has an effect to uniaxially align the surrounding liquid crystal material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for displaying characters, figures, etc., a light control device for changing the amount of transmitted incident light,
The present invention relates to a liquid crystal display element used for an optical shutter and the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a conventional liquid crystal display element, glass fiber beads or resin beads are dispersed between a pair of substrates having electrodes to control the distance between the substrates for holding the liquid crystal. However, it is difficult to strictly control the distance between the substrates and suppress the deformation due to the external pressure by spraying beads or the like.
Therefore, columnar or wall-shaped spacers are formed by using a technique such as photolithography (for example, Japanese Patent Laid-Open No. 10-161125). Also,
It is known that alignment defects of liquid crystals (ferroelectric and antiferroelectric liquid crystals) can be suppressed by combining an element having wall-shaped spacers (partition structure) and a cooling method with a temperature gradient in the realignment process of liquid crystals. (Japanese Patent Laid-Open No. 7-
No. 318912).

[0003]

In a liquid crystal display device having a columnar or wall-shaped spacer, since there are many contact surfaces between the liquid crystal material and the spacer, the interaction between the spacer interface and the liquid crystal material poses a problem. For example, when the alignment direction of the liquid crystal to be controlled by the alignment film and the alignment direction of the spacer are different, switching failure or alignment failure of the liquid crystal or long-term alignment change occurs. Therefore, the material of the spacer and its orientation are important.

Therefore, in Japanese Patent Laid-Open No. 7-318912, which combines a device having a wall-shaped spacer and a cooling method having a temperature gradient in the reorientation process of liquid crystal, Japanese Patent Laid-Open No. 7-318912 discloses a space on a straight line surrounded by a partition member and an electrode. It is described that the inner wall surface is covered with a polymer organic film such as polyimide to make the inner wall surface chemically uniform. In addition, JP-A-11
-194350 or Japanese Patent Laid-Open No. 10-16112.
In Japanese Patent No. 5 publication, an alignment control layer (alignment film) is formed so as to cover the partition walls.
Is provided and the tops of the partition walls are exposed to bond the pair of substrates, and the side surfaces of the partition walls are covered with the alignment control layer. Furthermore, in any of these, the alignment treatment (rubbing) is performed before and after the formation of the partition wall or after the formation of the alignment film. However, it is difficult to provide the side surface portion of the partition wall with a sufficient orientation controllability or orientation. In other words, it is desired that the spacers be formed with a height and width of about several μm between pixels in response to the trend of higher aperture ratio and higher definition.
It is difficult to rub the side surface of such a small columnar or wall-shaped structure (see FIG. 4, reference numeral 4 indicates a columnar or wall-shaped spacer, and 5 indicates the tips of the rubbing cloth).

Further, Japanese Patent Laid-Open No. 10-228023 describes that an organic material having a shape memory characteristic is used as a spacer material. This aims at eliminating the non-uniform alignment of the spacer portion and suppressing alignment unevenness.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a uniform or strong alignment controllability / alignment property even on the side surface of a columnar or wall-shaped spacer so that there is no alignment defect and a high level. An object of the present invention is to provide a liquid crystal display device having a contrast and stable alignment for a long period of time.

[0007]

The liquid crystal display of the present invention is
As shown in FIG. 1, a liquid crystal material is sandwiched between a pair of substrates 1 having electrodes, and a columnar or wall-shaped spacer 3 is provided on at least one of the pair of substrates, and the spacers themselves are uniaxially aligned. is characterized and Turkey, which have a gender. Further, the present invention is characterized in that columnar or wall-shaped spacers are formed on the alignment film 2 (FIG. 1).

The columnar or wall-shaped spacers can be formed by a usual photolithography technique using a photopolymerizable liquid crystalline monomer. That is, after coating the photopolymerizable liquid crystalline monomer on the substrate, a predetermined photomask is applied, light irradiation is performed, and the uncured portion is dissolved to remove the spacer formed of the photopolymerizable liquid crystalline polymer. Can be created. At this time, the alignment film may be previously coated on the substrate. Further, instead of photolithography, it may be formed in a columnar shape or a wall shape by a high-definition printing method or the like.

By irradiating the substrate on which the wall-shaped spacer is formed on the alignment film with polarized light, the alignment film and the wall-shaped spacer can be simultaneously subjected to the uniaxial alignment treatment. At this time, it is desirable that the polarized light is applied to the substrate in an oblique direction (that is, so as to hit the side surfaces of the spacer), and further, is applied from both side surfaces of the spacer (see FIG. 2, 1 in the drawing).
Is a transparent substrate with a transparent electrode, 2 is an alignment film, 3 is a photopolymerizable liquid crystal polymer spacer, and 6 is polarized light).

When the spacer is formed on the alignment film subjected to the alignment treatment, the photopolymerizable liquid crystalline monomer is aligned in the direction subjected to the alignment treatment in advance, and the alignment property is maintained after the spacer is formed. It has been processed. At this time, the alignment property of the alignment film is maintained after the spacer is formed, but the uniaxial alignment treatment may be performed again .

The columnar or wall-shaped spacer can be formed at any height, but it is preferably about 1 to 5 μm. Further, it is preferable that the spacer is formed in a portion other than the pixel in terms of aperture ratio. Furthermore, it is desirable that the alignment treatment direction of the alignment film and the alignment treatment direction of the spacer are the same.

The liquid crystal display device of the present invention has a structure in which a liquid crystal material is sandwiched between a pair of substrates having electrodes. Not only are both substrates transparent and light transmissive, but one substrate is opaque light reflective. Can also be applied to. For example, there are an element structure in which a liquid crystal material is sandwiched between a transparent substrate and a light reflecting plate, and an element structure in which a liquid crystal material is sandwiched between a transparent substrate having an electrode and a light absorbing plate having an electrode.

A conventional technique can be applied to the structure of the element. Indium-tin-oxide (I
Materials such as TO) can be used, but organic conductive thin films such as polypyrrole can also be used. Further, when the substrate itself used has conductivity, the substrate can be used as an electrode. The electrode is placed in close contact with the light control layer. As the alignment film, a soluble type polyimide in which polyimide is dissolved in a solvent, a baking type polyimide that is baked to form a polyimide, or an alignment film such as nylon can be used. The material of the substrate used in the present invention is glass, plastic, metal or the like. Further, it is possible to colorize by using a substrate having a color filter or by dispersing a pigment, a dye or the like in the substrate. The substrate is installed so that the electrodes are on the light control layer side.

The light reflecting plate may be an inorganic material or an organic material as long as it is made of a material that reflects light. Further, the reflection intensity or the reflection wavelength can be arbitrarily changed according to the intended element characteristics. The structure may be such that the light reflecting material forms the entire light reflecting plate, or the light reflecting material may be coated on a substrate made of another material such as glass. When the light reflecting material is coated, the light reflecting material need not be on the liquid crystal layer side. The substrate coated with the light reflecting material does not necessarily need to be transparent unless the light reflecting material is located on the light control layer side.

The light absorbing plate may be an inorganic material or an organic material as long as it is made of a material that absorbs light. The absorption intensity or the absorption wavelength can be arbitrarily changed according to the intended device characteristics. The structure may be such that the light absorbing material forms the entire light absorbing plate, or the light absorbing material may be coated on a substrate made of a different material such as glass.
When the light absorbing material is coated, the light absorbing material need not be on the liquid crystal layer side. The substrate coated with the light absorbing material does not necessarily need to be transparent when the light absorbing material is not located on the liquid crystal layer side. When the light-reflecting material or the light-absorbing material has conductivity, these can also be used as electrodes.

The liquid crystal display device of the present invention can be used in combination with an active device such as a thin layer transistor (TFT) device and a metal-insulator-metal (MIM) device, and is driven by a simple matrix according to the application. You can also let it.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below, but the present invention is not limited thereto.

(Embodiment 1) FIG. 3 shows a first embodiment of the present invention.
2 shows an embodiment of the present invention. A polyimide alignment film 2 is applied to a transparent substrate 1 having a pair of electrodes, and a rubbing treatment is performed (FIG. 3a). A photopolymerizable liquid crystalline monomer 7 having a nematic phase near room temperature is applied to one of the transparent substrates. The substrate coated with the photopolymerizable liquid crystalline monomer is once heated until the monomer becomes an isotropic phase, and then gradually cooled until it becomes a nematic phase to align the photopolymerizable liquid crystalline monomer in the rubbing direction (FIG. 3b). ). After applying a photomask 8 in which the electrode portions of the transparent substrate are masked and performing light irradiation 6,
The uncured portion is removed with a solvent to form a wall-shaped spacer 3 (FIG. 3c). The substrate having the wall-shaped spacer and the other substrate 1 are bonded together (FIG. 3d). By injecting a liquid crystal material into the gap between the pair of substrates, a liquid crystal display element can be manufactured. After injecting a ferroelectric liquid crystal into this liquid crystal display element in a vacuum, the liquid crystal display element was heated to the isotropic phase temperature of the liquid crystal material and gradually cooled to room temperature at 1 ° C./min. I was able to get it.

(Embodiment 2) A polyimide alignment film is applied to a transparent substrate having electrodes, and a photopolymerizable liquid crystalline monomer having a nematic phase is applied at around room temperature. A photomask in which the electrode portion of the transparent substrate is masked is applied, polarized light irradiation is performed, and then the uncured portion is removed with a solvent to form a wall-shaped spacer. After that, a rubbing process is performed in parallel with the wall spacers. In addition, a polyimide alignment film is applied to another transparent substrate having an electrode, subjected to a rubbing treatment, and then bonded to the above-mentioned substrate on which the spacer is formed. By injecting a liquid crystal material into the gap between the pair of substrates, a liquid crystal display element can be manufactured. When a ferroelectric liquid crystal was injected into this liquid crystal display element in the same manner as in Embodiment 1 and was gradually cooled, uniform alignment without light leakage could be obtained.

Comparative Example 1 A polyimide alignment film is applied to a transparent substrate having a pair of electrodes, and a rubbing treatment is performed. A wall spacer is formed on one side of the transparent substrate using an acrylic resist. A substrate having this wall-shaped spacer and the other substrate are bonded together to form a liquid crystal display element. When a ferroelectric liquid crystal was injected into this liquid crystal display element by the same method as in Embodiment 1 and gradually cooled, light leakage due to disordered alignment was observed in the vicinity of the wall spacer.

[0021]

EFFECTS OF THE INVENTION By using the present invention, a liquid crystal display device having no alignment defect, high contrast and stable alignment for a long period of time becomes possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a liquid crystal display element of the present invention.

FIG. 2 is a diagram showing a uniaxial alignment treatment with polarized light.

FIG. 3 is a diagram showing Embodiment 1 of the present invention.

FIG. 4 is a schematic view of a case where a columnar or wall-shaped spacer is rubbed.

[Explanation of symbols]

1. Transparent substrate with transparent electrodes 2. Alignment film 3. Photopolymerizable liquid crystal polymer spacer 4. Columnar or wall spacer 5. Rubbed cloth tips 6. Polarized light 7. Photopolymerizable liquid crystalline monomer 8. Photo mask

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Sumiyoshi Ken 5-7-1 Shiba, Minato-ku, Tokyo, NEC Corporation (56) References JP-A-9-105940 (JP, A) JP-A-11 −237635 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02F 1/1339

Claims (3)

(57) [Claims] 1. A liquid crystal display device having a liquid crystal material sandwiched between a pair of substrates having electrodes, wherein a photopolymerizable liquid crystalline polymer is formed on at least one of the pair of substrates.
Provided with columnar or wall-like spacer are a liquid crystal display device to which the spacer itself and having a uniaxial orientation of the oriented in the same direction by the alignment film. 2. The liquid crystal display device according to claim 1, wherein columnar or wall-shaped spacers are formed on the alignment film. 3. A liquid crystal display device according to claim 1 or 2, columnar or wall-like spacer is characterized in that it is formed on the alignment film which is a uniaxial aligning treatment.