KR20060129557A - Photo-alignment film forming apparatus and method - Google Patents

Abstract

An apparatus for forming a photoalignment film according to an embodiment of the present invention includes: a first buffer portion for performing loading and alignment of a substrate coated with a photoalignment agent; A substrate heating unit which heats the substrate by irradiating infrared (IR) to the substrate moved in the first buffer unit; A UV light source unit for irradiating ultraviolet (UV) onto the substrate heated by the substrate heating unit to cure the photo alignment agent coated on the substrate to form an alignment layer; And a second buffer portion for unloading the alignment layer substrate formed by the UV irradiation.

According to the present invention, in the photoalignment film forming apparatus, by heating the substrate using an infrared (IR) light source prior to the UV light source irradiation, the photoalignment film is formed through an in-line process to time It has the advantage of minimizing shortening and equipment size, and heating the entire substrate evenly.

Description

Apparatus for forming photo alignment film and method

1 is a view schematically showing a conventional UV light alignment film forming apparatus.

2A and 2B are views for explaining the operation of the hot plate provided in the conventional UV light alignment film forming apparatus shown in FIG.

3 is a sectional view schematically showing a photoalignment film forming apparatus according to an embodiment of the present invention.

FIG. 4 is a plan view showing the photoalignment film forming apparatus shown in FIG. 3. FIG.

<Explanation of symbols for the main parts of the drawings>

300: first buffer portion 302: substrate

304: conveyor 310: substrate heating part

312: infrared source 320: UV light source

330: second buffer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment film forming apparatus, and more particularly, to a photo alignment film forming apparatus and a method for preheating a substrate when forming a photo alignment film.

In general, the conventional cathode ray tube (CRT) display device, despite the excellent characteristics, because of the disadvantage that the volume and weight rapidly increases as the screen is larger, the recent demand for high-definition, large screen and flat panel type It is inadequate for use in multimedia systems, and liquid crystal displays have been developed to improve this.

The liquid crystal display method injects a liquid crystal between two transparent electrode substrates and moves the liquid crystal by an electric field. Among the various flat panel display technologies developed to date, there are many applications and the widest market share. . In this liquid crystal display method, a liquid crystal alignment layer is formed on the substrate, and the liquid crystals are arranged to have a predetermined direction and a predetermined pretilt angle using the liquid crystal alignment layer. This method is a method of orienting liquid crystals by depositing an inorganic alignment layer such as SiO x by evaporation. After forming an organic liquid crystal aligning film like polyimide from the method, the method of orienting a liquid crystal using a rubbing method etc. is mentioned.

The rubbing method, which is the most representative liquid crystal alignment method, is a method of rubbing a polyimide film surface in a predetermined direction by using a rubbing cloth to orient the liquid crystal, which is currently applied in most production lines due to a simple process.

However, since the rubbing method is a contact liquid crystal alignment method in which a polyimide film is directly rubbed using a rubbing cloth to form a liquid crystal alignment film, dust generated in the rubbing cloth and a multi-step cleaning process for removing the rubbing cloth are inevitably required, and an in-line (in-line) process has the disadvantage that it is impossible.

In addition, the polyimide film most widely used as the liquid crystal alignment film of the rubbing method is easy to obtain a relatively uniform alignment film, and has the advantages of being stable even at a high temperature of about 200 degrees, but an acid anhydride and a diamine compound during the polyimide film forming process. After synthesis of polyamide acid to form a polyamide acid, and then heat-cured and imidized to go through a multi-step process to form a polyimide film has a disadvantage that affects the peripheral device due to the heat treatment process.

In addition, as a non-contact liquid crystal alignment method for overcoming the disadvantages of the rubbing method, an optical alignment method for surface-modifying polyimide using light such as UV has been developed.

In the case of forming the UV photo-alignment layer, when polarized UV is irradiated onto the substrate coated with the UV photo-alignment agent, when the temperature of the substrate is heated to 150 to 200 degrees near the glass transition temperature of the alignment agent, the substrate is coated on the substrate. The increase in the main chain motion of the aligning agent and the rate of photolysis or polymerization reaction are increased.

That is, when the photoalignment film is formed as described above, the substrate is heated to a predetermined temperature, thereby increasing the anisotropy of the liquid crystal induced in the alignment film, thereby improving the alignment force of the liquid crystal.

1 is a view schematically showing a conventional UV light alignment film forming apparatus.

Referring to FIG. 1, when a substrate 102 coated with a photo alignment agent is transferred to a conventional photo alignment layer forming apparatus 100 by a robot arm 110, UV light is applied onto the substrate 102. The lamp 104 to be irradiated is positioned to form a photo alignment layer by curing the photo alignment agent coated on the substrate.

In this case, as described above, during the UV light irradiation by the lamp, in the photoalignment film forming apparatus 100 to heat the temperature of the substrate to 150 to 200 degrees near the glass transition temperature of the alignment agent coated on the substrate. Is provided with a hot plate configured to contact the bottom surface of the substrate while supporting the substrate.

2a and 2b are views for explaining the operation of the hot plate provided in the conventional UV light alignment film forming apparatus shown in Figure 1, Figure 2a shows the state before the substrate is seated on the hot plate, Figure 2b It shows a state where the substrate is seated on the hot plate and heated.

As illustrated in FIG. 2A, a plurality of holes 120 are formed in the hot plate 106, and substrate support pins 122 are provided to up / down the substrate 102 through the holes 120.

In addition, a front surface of the hot plate 106 is provided with a heater for heating the substrate 102 is seated.

That is, when the substrate 102 coated with the optical alignment agent is transferred into the optical alignment apparatus by the Robert arm (110 in FIG. 1), the substrate 102 may open the plurality of holes 120 provided in the hot plate 106. It is supported and fixed by a plurality of substrate support pins 122 drawn out therethrough.

Accordingly, as shown in FIG. 2B, when the substrate support pin 122 descends to the lower portion of the hole 120, the substrate 102 is seated on the heater 107 formed on the front surface of the hot plate 106 to perform heating. will be.

However, when the hot plate 106 is used to heat the substrate in this manner, after the substrate 102 contacts the hot plate 106, a heating period of a certain period is required to rise to a set temperature, thereby causing a unit substrate. There is a problem that the processing time for.

In addition, in the conventional photoalignment film forming apparatus, since the substrate 102 needs to be transferred by the Robert arm 110, the size of the equipment is increased, and the substrate 102 is seated on the heater 107 of the hot plate 106. The substrate support pin 122 must be provided, and the entire surface of the substrate 102 is not uniformly heated by the holes 120 provided in the hot plate.

In the present invention, in the photoalignment film forming apparatus, the substrate is heated using an infrared (IR) light source prior to the irradiation of the UV light source, thereby forming a photoalignment film through an in-line process, thereby reducing time and equipment size. It is an object of the present invention to provide a photo-alignment film forming apparatus and method for minimizing the temperature and uniformly heating the entire substrate.

In order to achieve the above object, an optical alignment film forming apparatus according to an embodiment of the present invention, the first buffer portion for performing the loading and alignment of the substrate coated with the optical alignment agent; A substrate heating unit which heats the substrate by irradiating infrared (IR) to the substrate moved in the first buffer unit; A UV light source unit for irradiating ultraviolet (UV) onto the substrate heated by the substrate heating unit to cure the photo alignment agent coated on the substrate to form an alignment layer; And a second buffer portion for unloading the alignment layer substrate formed by the UV irradiation.

Here, the first buffer unit, the substrate heating unit, the UV light source unit and the second buffer unit is connected by a conveyor device to perform an in-line process, and the substrate heating unit has an infrared (IR) source for heating the substrate. In the infrared source, a mercury (Hg) lamp, a metal halide lamp, or a halogen lamp is used.

The UV light source unit may include a UV lamp irradiated with a UV alignment light source and a polarization optical system for polarizing the UV light emitted from the UV lamp. The second buffer unit may include a cooler for cooling the heated substrate. Characterized in that it is provided.

In addition, the method for forming a photoalignment layer according to an embodiment of the present invention includes the steps of loading and aligning a substrate coated with the photoalignment agent; Infrared rays (IR) are irradiated on the front surface of the substrate while the loaded substrate is moved on an in-line, and the front substrate is heated; Irradiating ultraviolet (UV) on the front heated substrate to cure the photo-alignment agent coated on the substrate; It is characterized in that it comprises the step of unloading the alignment film substrate formed by the UV irradiation.

In addition, each step is performed sequentially by an in-line process, characterized in that a mercury (Hg) lamp, a metal halide lamp or a halogen lamp is used as the infrared source for irradiating the infrared rays.

The method may further include cooling the substrate before the substrate on which the alignment layer is formed is unloaded.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a cross-sectional view schematically showing a photo alignment layer forming apparatus according to an embodiment of the present invention, and FIG. 4 is a plan view illustrating the photo alignment layer forming apparatus shown in FIG. 3.

3 and 4, the photoalignment film forming apparatus according to an embodiment of the present invention is configured to form a photoalignment film through an in-line process, and a hot plate is heated to heat the substrate coated with the photoalignment agent. By providing an infrared (IR) lamp, it is possible to shorten the time and equipment size, and to heat the entire substrate evenly without contacting the substrate.

That is, referring to FIGS. 3 and 4, the apparatus for forming a photoalignment layer according to the present invention includes: a first buffer unit 300 for loading and aligning a substrate coated with a photoalignment agent; A substrate heating unit 310 for heating the substrate by irradiating infrared (IR) to the substrate 302 moved from the first buffer unit 300, and ultraviolet (UV) light on the substrate heated by the substrate heating unit UV light is irradiated to harden the photo-alignment agent coated on the substrate to form an alignment film, and a UV light source unit 320, and the second buffer unit 330 for unloading the alignment film substrate formed by the UV irradiation. .

Here, each of the components, that is, the first buffer unit 300, the substrate heating unit 310, the UV light source unit 320, and the second buffer unit 330 are connected by the conveyor 304 device to perform the in-line process. The photo alignment layer is formed through.

The photoalignment film forming apparatus having the above structure can overcome the disadvantage caused by heating the substrate by the conventional hot plate method, that is, can solve the problem of the temperature uniformity decrease and the size increase of the conventional hot plate method. .

In more detail, it does not require a contact for heat transfer like a conventional hot plate for heating the substrate, so that heating and irradiation can be processed in a continuous process, resulting in easier in-line equipment configuration.

In addition, it becomes much easier to uniformly heat the substrate on the large area substrate as compared to the conventional hot plate method. That is, the present invention does not include a conventional substrate support pin and hole because the substrate is heated in a non-contact manner, so that the entire surface of the substrate can be uniformly heated.

Here, the substrate heating unit 310 is provided with an infrared (IR) source (312) for heating the substrate, the infrared source 312 is a mercury (Hg) lamp or metal halide (Metal halide) Lamps or halogen lamps can be used.

The infrared rays refer to rays that are farther outward than the ends of the red spectrum of visible light in the spectrum of light emitted from sunlight or incandescent objects. Infrared rays with a wavelength of 0.75-3 μm are called near infrared rays and 3-25 μm are simply called infrared rays. , 25 μm or more are called far infrared rays.

Since the infrared rays are characterized by having a stronger thermal action than visible or ultraviolet rays, the infrared rays can be used to heat the substrate.

In the case of the present invention, by using the infrared source 312 as the substrate heating unit 310, non-contact substrate heating is possible, and thus no contact for heat transfer is required, so that heating and irradiation can be processed in a continuous process. In-line equipment configuration is facilitated.

In addition, the substrate heating unit 310 is preferably located in front of the UV light source unit 320 in the in-line equipment configuration, when the substrate heating unit 310 is provided in front of the UV light source unit 320, the substrate 302 ) Is heated to a predetermined temperature, UV is irradiated onto the substrate, so that a photo alignment layer can be more easily formed.

Here, the predetermined temperature is preferably 150 to 200 degrees, which is near the glass transition temperature of the alignment agent coated on the substrate, in which case the increase in the main chain motion of the alignment agent coated on the substrate and Since the photolysis or polymerization reaction rate is increased, the anisotropy of the alignment film liquid crystal formed by curing the alignment agent by the UV irradiation can be increased to improve the alignment force of the liquid crystal.

In addition, the UV light source unit 320 is composed of a UV lamp 322 irradiated with a UV alignment light source as shown in Figure 3, and a polarization optical system 324 for polarizing the UV irradiated from the UV lamp, and finally The light irradiated onto the alignment agent coated on the substrate 302 becomes polarized UV.

In addition, in the present invention, the substrate on which the alignment layer is formed through the substrate heating part 310 and the UV light source part 320 is unloaded from the second buffer part 330. Not shown) serves to cool the heated substrate.

Referring to Figure 4 describes a method for forming a photo alignment layer according to an embodiment of the present invention.

First, a substrate 302 coated with an optical alignment agent is prepared and loaded on the first buffer unit 300, and alignment of the substrate is performed in the first buffer unit.

Thereafter, the substrate 302 is moved from the first buffer unit 300 to the substrate heating unit 310 by the conveyor 304 device, thereby heating the entire surface of the substrate.

Here, the substrate heating unit 310 includes an infrared ray source 312 and serves to uniformly heat the entire surface of the substrate by irradiating infrared rays onto the substrate through the infrared source.

At this time, the substrate may be sequentially irradiated with infrared rays while moving by the conveyor device. That is, heating is continuously performed in the in-line process.

In the case of the present invention, by using the infrared source 312 for heating the substrate, heating and irradiation can be processed in a continuous process, as there is no need for contact for heat transfer like a conventional hot plate, resulting in in-line equipment configuration It becomes easy.

In addition, it becomes much easier to uniformly heat the substrate on the large area substrate as compared to the conventional hot plate method. That is, the present invention does not include a conventional substrate support pin and hole because the substrate is heated in a non-contact manner, so that the entire surface of the substrate can be uniformly heated.

Here, the substrate heating unit 310 is provided with an infrared (IR) source (312) for heating the substrate, the infrared source is a mercury (Hg) lamp or a metal halide lamp (Metal halide) lamp Or halogen lamps may be used.

As described above, the substrate heated on the entire surface of the substrate by the substrate heating unit 310 is cured by the ultraviolet light emitted by the UV light source 320 to cure the photo-alignment agent coated on the substrate to form an alignment layer.

At this time, the UV light source unit 320 is composed of a UV lamp 322 irradiated with a UV alignment light source, as shown in Figure 3, and a polarizing optical system 324 for polarizing the UV irradiated from the UV lamp, Finally, the light irradiated onto the alignment agent coated on the substrate becomes polarized UV.

Finally, the substrate on which the alignment layer is formed through the substrate heating unit 310 and the UV light source unit 320 is unloaded from the second buffer unit 330. The second buffer unit is provided with a cooler (not shown). It may also serve to cool the heated substrate.

According to the present invention, in the photoalignment film forming apparatus, by heating the substrate using an infrared (IR) light source prior to the UV light source irradiation, the photoalignment film is formed through an in-line process to time It has the advantage of minimizing shortening and equipment size, and heating the entire substrate evenly.

Claims (10)

A first buffer portion for loading and aligning the substrate on which the light alignment agent is coated; A substrate heating unit which heats the substrate by irradiating infrared (IR) to the substrate moved in the first buffer unit; A UV light source unit for irradiating ultraviolet (UV) onto the substrate heated by the substrate heating unit to cure the photo alignment agent coated on the substrate to form an alignment layer; And a second buffer portion for unloading the alignment film substrate formed by the UV irradiation. The method of claim 1, And the first buffer portion, the substrate heating portion, the UV light source portion, and the second buffer portion are connected by a conveyor device to perform an in-line process. The method of claim 1, And the substrate heating unit is provided with an infrared (IR) source for heating the substrate. The method of claim 3, wherein The infrared source is a photo-alignment film forming apparatus characterized in that a mercury (Hg) lamp, a metal halide lamp or a halogen lamp is used. The method of claim 1, The UV light source unit is a photo-alignment film forming apparatus characterized in that it comprises a UV lamp irradiated with a light source for UV alignment and a polarizing optical system for polarizing the UV irradiated from the UV lamp. The method of claim 1, And a cooler configured to cool the heated substrate in the second buffer part. Loading and aligning the substrate on which the light alignment agent is coated; Infrared rays (IR) are irradiated on the front surface of the substrate while the loaded substrate is moved on an in-line, and the front substrate is heated; Irradiating ultraviolet (UV) on the front heated substrate to cure the photo-alignment agent coated on the substrate; And unloading the alignment film substrate formed by the UV irradiation. The method of claim 7, wherein Wherein each step is performed sequentially by an in-line process. The method of claim 7, wherein The infrared source for irradiating the infrared ray is a mercury (Hg) lamp, a metal halide lamp (Metal halide) lamp or a halogen lamp, characterized in that for forming a light alignment film. The method of claim 7, wherein And cooling the substrate before the substrate on which the alignment layer is formed is unloaded.

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