CN102279486A - Method for forming liquid crystal alignment layer - Google Patents

Abstract

A method for forming a liquid crystal alignment layer includes providing a first substrate, sequentially forming a conductive layer, an insulating layer covering the conductive layer, and a plurality of alignment electrodes on the insulating layer. Then, a second substrate is arranged in parallel with the first substrate, a liquid crystal alignment composition and a positive liquid crystal material are mixed and injected between the first substrate and the second substrate, and a voltage is applied between the conducting layer and the alignment electrode, so that an electric field is generated between the first substrate and the second substrate. After the liquid crystal alignment composition is deflected to a predetermined direction, the liquid crystal alignment composition is polymerized to form an alignment layer. The arrangement mode of the conducting layer and the alignment electrode can make the electric field distribution more uniform, so the alignment consistency of the liquid crystal alignment composition can be improved.

Description

Method for forming liquid crystal alignment layer

technical field

The invention relates to a method for forming a liquid crystal alignment layer, in particular to a method for forming a liquid crystal alignment layer that utilizes a uniform electric field to improve molecular alignment.

Background technique

In recent years, improving the viewing angle of liquid crystal displays has become an important issue that the related industry is eager to solve, especially in-plane switching (IPS) liquid crystal displays and fringe field switching (FFS) ) Liquid crystal display is a common technology at present. The former is designed so that when a voltage is applied, the liquid crystal molecules will rotate on the plane parallel to the substrate; while the latter replaces the metal electrodes of the IPS display with indium tin oxide (ITO) transparent electrodes and shortens the width between the electrodes. .

The known IPS liquid crystal display, as shown in U.S. Patent No. US 5,928,733, mainly has two parallel transparent substrates up and down, and gate lines, data lines and common lines intersecting each other are arranged on a transparent substrate to form at least one pixel area. There are pixel electrodes and common electrodes with different polarities in each pixel area, the pixel electrodes and the common electrodes are arranged alternately, and a transverse electric field parallel to the transparent substrate will be generated between the pixel electrodes and the common electrodes, The liquid crystal molecules are only rotated in the horizontal direction, thereby increasing the viewing angle of the liquid crystal display. Although the liquid crystal display of this technology can improve the viewing angle, due to the characteristics of the electric field distribution, the liquid crystal molecules cannot fully rotate, so the problem of low light transmittance will occur.

In response to the above shortcomings, the technology of FFS liquid crystal display was developed subsequently, such as the fringe electric field switching liquid crystal display and its preparation method disclosed in US Patent No. 6,707,524. layer, and an insulating layer is disposed between the pixel electrode and the common electrode. Since this structure greatly shortens the distance between the electrodes, it will generate a dense electric field distribution, so that the liquid crystal molecules can fully rotate, so as to ensure that light from all directions can penetrate the liquid crystal molecules, thereby increasing the viewing angle.

In the above-mentioned liquid crystal displays, liquid crystal alignment technology is used to control the alignment direction of liquid crystal molecules. Among the current technologies, rubbing method and photo alignment method are the most widely used liquid crystal alignment technologies. Regarding the brushing method, polyimide is usually coated on the substrate, and after baking and rubbing, the surface molecules are made to be compliant due to friction to form an alignment layer. However, when polyimide is rubbed, impurities are likely to be generated, and static electricity may be generated in the alignment layer due to rubbing, thus affecting the image quality of the liquid crystal display. In order to avoid the above problems, the more common technology is the photo-alignment method, such as US Patent Publication No. US2008/297707, US 2009/169754, US2009/246401A1 and US Patent No. The polymer polymerized by ultraviolet light makes the polymer chains have a directional arrangement, so as to realize the function of aligning the liquid crystal molecules.

In addition to the above method, a method of applying an electric field to deflect the liquid crystal molecules and the alignment material in the same direction before polymerization is also proposed to ensure a better alignment effect. As shown in Figure 1-1 to Figure 1-3, it is a schematic diagram of a known method of forming a liquid crystal alignment layer, which mainly includes two substrates 90, two polarizers 91 are arranged on the outside of the substrate 90, and the substrate 90 A plurality of alignment electrodes 92 spaced apart from each other are arranged on the surface of the top surface, wherein the alignment electrodes 92 spaced apart have opposite polarities. During manufacture, a positive type liquid crystal material 93 and an alignment material 94 are first injected between the substrates 90, and then a voltage is applied to the alignment electrodes 92, so that the substrate 90 can generate a voltage as shown in Figure 1-3. An electric field, the arrow in the figure indicates the direction of the electric field, deflects the positive liquid crystal material 93 and the alignment material 94 to a predetermined direction. Finally, photopolymerize the alignment material 94 to form two alignment layers 95 . However, in practical applications, it will be found that the horizontal component of the electric field generated by the alignment electrodes 92 is larger than the vertical direction, so the distribution of the electric field is not uniform, which in turn makes the alignment effect of the alignment layer 95 poor.

Contents of the invention

The main purpose of the present invention is to solve the problem that the alignment effect of the liquid crystal display is not good due to the uneven electric field generated by the known alignment electrodes.

To achieve the above object, the present invention provides a method for forming a liquid crystal alignment layer, characterized in that the method comprises the following steps:

providing a first substrate, the first substrate has a first surface;

sequentially forming a conductive layer, an insulating layer covering the conductive layer, and a plurality of alignment electrodes arranged on the surface of the insulating layer on the first surface;

A second substrate is arranged parallel to the first substrate, the second substrate has a second surface corresponding to the first surface, and a liquid crystal accommodation space is formed between the first surface and the second surface;

Mixing a liquid crystal alignment composition and a positive liquid crystal material into the liquid crystal containing space;

applying a voltage to the conductive layer and the alignment electrode, so that an electric field is generated in the liquid crystal containing space to deflect the liquid crystal material and the liquid crystal alignment composition to a predetermined direction; and

polymerizing the liquid crystal alignment composition to make the liquid crystal alignment composition form a first alignment layer and a second alignment layer on the first substrate and the second substrate respectively.

From the above, it can be seen that the beneficial effects achieved by the method for forming the liquid crystal alignment layer of the present invention compared with the known techniques are:

1. Through the design of the conductive layer and the alignment electrode in the present invention, a relatively uniform electric field can be provided, so that the liquid crystal alignment composition can be subjected to more uniform electric field components perpendicular to and parallel to the plane of the substrate, thus making the first alignment The molecular alignment characteristics of the layer and the second alignment layer are better;

2. Since the alignment properties of the first alignment layer and the second alignment layer are improved, the characteristics of the liquid crystal molecules with respect to the twist angle (Twister angle) and the pre-tilt angle (Pre-tilt angle) can be improved, thereby improving the overall alignment of the liquid crystal molecules , so when driving a liquid crystal display, a faster response time (Response time) can be obtained.

Description of drawings

1-1 to 1-3 are schematic flowcharts of known methods for forming a liquid crystal alignment layer.

2-1 to 2-5 are schematic flowcharts of an embodiment of the method for forming a liquid crystal alignment layer of the present invention.

Explanation of schematic symbols

10…………The first substrate

11…………First surface

12………Polarizer

20……… Conductive layer

30…………Insulation layer

40………Alignment electrodes

50………Second substrate

51………Second surface

52………Polarizer

60………LCD storage space

70………… Liquid crystal alignment composition

71…………The first alignment layer

72………Second alignment layer

80………Positive type liquid crystal material

90………Substrate

91………Polarizer

92………Alignment electrodes

93………Positive type liquid crystal material

94………… Alignment materials

95………Alignment layer

Detailed ways

Relevant detailed description and technical content of the present invention, now just explain as follows with respect to matching drawing:

The forming method of the liquid crystal alignment layer of the present invention comprises the following steps:

providing a first substrate, the first substrate has a first surface;

sequentially forming a conductive layer, an insulating layer covering the conductive layer, and a plurality of alignment electrodes arranged on the surface of the insulating layer on the first surface;

A second substrate is arranged parallel to the first substrate, the second substrate has a second surface corresponding to the first surface, and a liquid crystal accommodation space is formed between the first surface and the second surface;

Mixing a liquid crystal alignment composition and a positive liquid crystal material into the liquid crystal containing space;

applying a voltage to the conductive layer and the alignment electrode, so that an electric field is generated in the liquid crystal containing space to deflect the liquid crystal alignment composition to a predetermined direction; and

The liquid crystal alignment composition is polymerized so that the liquid crystal alignment composition forms a first alignment layer and a second alignment layer on the first substrate and the second substrate respectively.

In order to facilitate the understanding of the steps of the method for forming the liquid crystal alignment layer of the present invention, please refer to the description of the following examples:

Referring to FIG. 2-1 to FIG. 2-5, it is a schematic flowchart of an embodiment of a method for forming a liquid crystal alignment layer of the present invention. Firstly, a first substrate 10 is provided. The first substrate 10 has a first surface 11, and the first substrate 10 is A polarizer 12 is disposed on the other side of a substrate 10, and a conductive layer 20, an insulating layer 30, and a plurality of alignment electrodes 40 are sequentially formed on the first surface 11 to form a sandwich structure (Sandwich structure), as shown in FIG. 2-1 shown. Wherein, the insulating layer 30 covers the conductive layer 20 ; the alignment electrodes 40 are horizontally arranged on the insulating layer 30 in a manner of being spaced apart from each other. 2-2, a second substrate 50 is arranged parallel to the first substrate 10, the second substrate 50 has a second surface 51 corresponding to the first surface 11, the second substrate 50 A polarizing plate 52 is also provided on the other side of the first surface 11 and a liquid crystal containing space 60 is formed between the first surface 11 and the second surface 51 .

In this embodiment, the first substrate 10 and the second substrate 50 can be transparent materials such as inorganic glass or soft plastic, for example, quartz glass or soda lime glass, borosilicate glass, low-alkali glass or alkali-free glass can be used. Glass such as glass; or flexible plastics such as polyethylene terephthalate (PET), polycarbonate (PC) or epoxy. The conductive layer 20 and the alignment electrode 40 can be selected as indium tin oxide (Indium tin oxide, ITO for short) transparent electrodes. As for the insulating layer 30 , according to the actual manufacturing method, an inorganic non-metallic thin film with insulating properties; or an organic polymer thin film can be used.

After completing the setting of the first substrate 10 and the second substrate 50, as shown in FIG. Use the injection method (Injection) or the liquid crystal drop method (One drop fill, ODF for short) to make it sealed in the liquid crystal accommodating space 60 . Next, apply a voltage to the conductive layer 20 and the alignment electrode 40 . In the present invention, the alignment electrodes 40 are all electrodes of the same polarity; and the polarity of the alignment electrodes 40 is opposite to that of the conductive layer 20. Further, in this embodiment, the alignment electrodes 40 are strip-shaped positive electrodes; and the The conductive layer 20 is a negative electrode. Therefore, when the voltage is applied, the conductive layer 20 and the alignment electrode 40 will generate an electric field in the liquid crystal containing space 60 . As shown in FIGS. 2-4 , the drawn arrows indicate the direction of the electric field, and the liquid crystal alignment composition 70 and the positive liquid crystal material 80 will deflect in a predetermined direction under the action of the electric field.

In the present invention, the voltage is between 1 and 40 volts. After the liquid crystal alignment composition 70 and the positive type liquid crystal material 80 are stably aligned in the predetermined direction, the liquid crystal alignment composition 70 is polymerized, wherein, The liquid crystal alignment composition 70 uses photocurable polymers, so it can be polymerized by ultraviolet light irradiation. In order to accelerate the polymerization reaction, a hardening agent can also be added to the liquid crystal alignment composition 70 before polymerization. starter.

As shown in Figures 2-5, when the liquid crystal alignment composition 70 is exposed to ultraviolet light, the liquid crystal alignment composition 70 will polymerize to form a first alignment on the first substrate 10 and the second substrate 50 respectively. Layer 71 and a second alignment layer 72. In this embodiment, the ultraviolet light irradiation intensity is greater than or equal to 1 mj/cm ² . The first alignment layer 71 is formed on the surface of the insulating layer 30 and the alignment electrode 40 ; and the second alignment layer 72 is formed on the second surface 52 . Wherein, the first alignment layer 71 and the second alignment layer 72 provide the positive liquid crystal material 80 to be in an orderly arrangement, for example, so that the positive liquid crystal material 80 can be connected between the first substrate 10 and the second substrate 50 A pretilt angle close to 0 degrees is produced.

In summary, the formation method of the liquid crystal alignment layer of the present invention is mainly through the electrode structure design of the conductive layer, the insulating layer and the alignment electrode, so that the generated electric field is in a state of uniform distribution, so in the liquid crystal alignment combination Before forming the first alignment layer and the second alignment layer, in addition to rapidly deflecting the liquid crystal alignment composition toward the predetermined direction, its arrangement is also more orderly. Therefore, after polymerization, the first alignment layer and the second alignment layer can obtain better molecular alignment, so that the alignment of the positive liquid crystal material is also improved, so the response time of the positive liquid crystal material can be shortened .

The present invention has been described in detail above, however, the above-mentioned content is only a preferred embodiment of the present invention, and cannot limit the implementation scope of the present invention. That is, all equivalent changes and modifications made according to the application scope of the present invention should still fall within the scope of the patent of the present invention.

Claims (5)

1. the formation method of a liquid crystal alignment layer is characterized in that, said method comprising the steps of:

One first substrate (10) is provided, and described first substrate (10) has a first surface (11);

On described first surface (11), form insulation course (30) and a plurality of lip-deep orientation electrode of described insulation course (30) (40) of being located at that a conductive layer (20), covers described conductive layer (20) successively;

One second substrate (50) and described first substrate (10) are be arranged in parallel, described second substrate (50) have one with the mutual corresponding second surface (51) of described first surface (11), and formation one liquid crystal accommodation space (60) between described first surface (11) and the described second surface (51);

One LCD alignment composition (70) is mixed with an eurymeric liquid crystal material (80) in the described liquid crystal accommodation space of injection (60);

Apply a voltage in described conductive layer (20) and described orientation electrode (40), make producing an electric field in the described liquid crystal accommodation space (60) and making described LCD alignment composition (70) deflect to a predetermined direction; And

The described LCD alignment composition of polymerization (70) makes described LCD alignment composition (70) go up respectively at described first substrate (10) and described second substrate (20) is gone up formation one first both alignment layers (71) and one second both alignment layers (72).

2. according to the formation method of the described liquid crystal alignment layer of claim 1, it is characterized in that, described first both alignment layers (71) is formed on the surface of described insulation course (30) and described orientation electrode (40), and described second both alignment layers (72) is formed on the described second surface (51).

3. according to the formation method of the described liquid crystal alignment layer of claim 1, it is characterized in that described LCD alignment composition (70) is sealed in described liquid crystal accommodation space (60) with described eurymeric liquid crystal material (80) for utilizing perfusion or liquid crystal drop laxative remedy.

4. according to the formation method of the described liquid crystal alignment layer of claim 1, it is characterized in that described LCD alignment composition (70) carries out polyreaction for utilizing UV-irradiation, described UV-irradiation intensity 〉=1mj/cm ²

5. according to the formation method of the described liquid crystal alignment layer of claim 1, it is characterized in that described voltage is between 1 to 40 volt.

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