JP2002031800A - Manufacturing method and manufacturing device for liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problem that, when an alignment layer is formed on an electrode substrate of a liquid crystal display device in a required film thickness, in some alignment material, it is difficult to control the film thickness so that the fluctuation of the film thickness is to be <=5% of target value and display defects due to the fluctuation of the film thickness of the alignment layer are generated. SOLUTION: For the purpose of enhancing the uniformity of the film thickness of the alignment layer 107, the thickness of coated films P1-P5 for every one coating is suppressed to be <=20 nm and the coated films are pre-baked after coating. Recoating is performed by repeating coating and pre-baking plural times to form the alignment layer 107 having the required film thickness. When a polyimide solution is used, a first coated film is formed by applying a polyamic acid type alignment layer and then the polyimide solution for the original alignment layer is applied little by little. Printability of the alignment layer can be enhanced and film thickness uniformity of the alignment layer can also be enhanced by applying the polyamic acid type polyimide solution to form the first layer as a connector of the polyimide film layer used as the alignment layer with the LCD substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for manufacturing a liquid crystal display, and more particularly to a method for manufacturing a liquid crystal alignment film and an apparatus for manufacturing the same.

[0002]

2. Description of the Related Art Liquid crystal display devices (hereinafter referred to as LCDs).
Have an alignment film for aligning liquid crystal molecules of a liquid crystal disposed between a pair of substrates on a display surface of each substrate. In the manufacture of such an LCD, it is necessary to form the alignment film itself such that its film thickness and molecular alignment state are uniform in order to uniformly control the liquid crystal molecular alignment over the entire display surface.
In conventional mass-produced LCDs, polyimide is used as an alignment film, and an alignment material as a base material is applied by a printing machine, baked, and imidized to form an alignment film. For example, pages 270 to 272 of “Liquid Crystal Display Technology-Active Matrix LCD” describe a process of printing an alignment film in the current typical mass production. In the technique described in this document, a solution of a polyimide or a polyamic acid diluted (4 to 8 wt.%) With an organic solvent is applied to a substrate that has been cleaned in advance, usually using a flexographic printing apparatus. Here, as shown in FIG. 11, the coating liquid for the alignment film is supplied dropwise from a dispenser 801 between a rotating doctor roll 802 and an anilox roll 803. This coating liquid is kneaded between two rolls and held as a liquid thin film on the surface of the anilox roll 803, and the flexible plate 80 on the flexible relief plate on the plate cylinder 804 is transferred from the anilox roll 803.
Transferred to 5. When the glass substrate 101 fixed on the coating table 806 passes directly below the plate cylinder,
The thin film of the coating solution is transferred from the flexographic plate 805 to the glass substrate
01 is transferred and applied.

In such a coating process, it is important to thoroughly control the coating film thickness, film thickness uniformity, pinholes, foreign matter, material purity, and the like, and this management level directly affects the display quality and reliability of the LCD. Will be affected. The coating amount is set so that the final film thickness after baking is about 1000, and the uniformity of the in-plane film thickness is required to be ± 5% or less. In the case of flexographic printing, the adjustment of the coating amount is performed by selecting the coating solution concentration, printing speed, selection of anilox roll, and the like. In other words, the formation of a uniform alignment film is controlled so as to achieve its purpose by adjusting the composition of the alignment material, changing the material and surface condition of the printing plate, and adjusting the settings of the printing press. It has come.

[0004]

However, in recent years,
As LCD performance demands high definition and high viewing angle, the design margin will be reduced, and modes such as in-plane switching and vertical alignment other than the conventional twisted nematic will be adopted. The following issues have arisen.

[0005] The first problem is that, depending on the alignment material, when an alignment film is formed, the film thickness is not uniform or the alignment state varies in-plane. The reason for this is that, depending on the type of the alignment material, even if the printing conditions are changed, the printability is poor.

[0006] The second problem is that the surface shape changes depending on the conditions of solvent drying after coating, which may affect the liquid crystal alignment. The reason is that traces are left on the surface when the solvent escapes from the applied alignment material due to the heating condition in the solvent drying.

An object of the present invention is to provide a method and an apparatus for manufacturing an LCD capable of forming an alignment film having high in-plane uniformity of characteristics such as film thickness and alignment state.

[0008]

According to the method of manufacturing an LCD of the present invention, when an alignment film having an action of arranging liquid crystal molecules in the same direction is formed on an electrode substrate, an alignment material serving as the base of the alignment film is formed. A step of repeating the step of applying and pre-baking the applied alignment material a plurality of times, and a step of performing main firing after forming the alignment film to a required thickness; and Features. In this case, the applied film thickness of the alignment material by one application of the alignment material is 20 n.
m or less. Further, the method is characterized in that the alignment material is applied in a state diluted with a solvent, and after the application, the solvent is dried in the prebaking step.

In the method of manufacturing an LCD according to the present invention, a polyamic acid solution or a soluble polyimide solution or a mixed solution of a polyamic acid and a soluble polyimide is used as the alignment material. Alternatively, in the step of applying the alignment material, the first application uses a polyamic acid solution,
After the first time, a polyamic acid solution, a soluble polyimide solution, or a mixed solution of a polyamic acid and a soluble polyimide is used.

An LCD manufacturing apparatus according to the present invention includes a coating apparatus for applying an alignment material, which is a base of an alignment film, on an electrode substrate, a pre-bake apparatus for drying a solvent from the applied alignment material, and the alignment film. And a main baking apparatus for performing main baking after forming to a thickness of, and a plurality of coating apparatuses and prebaking apparatuses are provided. Alternatively, a coating device for applying an alignment material serving as an alignment film on an electrode substrate, a pre-bake device for drying a solvent from the applied alignment material, and a final baking after forming the alignment film to a required thickness. The present invention is characterized by comprising a main baking apparatus for performing the coating and a means for performing the application and prebake of the electrode substrate a plurality of times in the coating apparatus and the prebake apparatus.

According to the LCD manufacturing technology of the present invention, when applying an alignment material for forming an alignment film, the layer thickness is set so that the thickness of the alignment material after one application is 20 nm or less. By coating, even if irregularities occur in a single application, they are averaged out, and since the layer thickness per application is sufficiently thin, the solvent easily escapes during prebaking and no traces are left on the alignment film surface. No change in state occurs.

Further, according to the LCD manufacturing technique of the present invention, when the alignment film is a polyimide film, there are a polyamic acid type and a soluble polyimide type as alignment materials, but polyamic acid is generally used for LCD. It has good compatibility with the substrate, is easy to print, and tends to have a uniform film thickness after application. Therefore, an alignment film consisting of a polyimide film with high in-plane uniformity of properties such as film thickness is first applied by coating polyamic acid on the substrate and then overlaying polyimide solutions for each LCD design. Can be formed.

Japanese Patent Application Laid-Open No. Sho 63-30826 and Japanese Patent No. 2907228 each disclose an alignment film forming step by performing a coating step of an alignment layer and a heat treatment step thereafter a plurality of times as in the present invention. However, the heat treatment steps in the techniques described in these publications are all steps corresponding to the main baking in the present invention, and do not correspond to the pre-bake step in the present invention. That is, the technology of each of the above publications is a technology in which, after applying an orientation material, the orientation material is heat-treated and imidized, and then the orientation material is further applied and imidized by heat treatment. This is a technique in which an alignment film is formed for each layer and laminated. Therefore, based on the reasons explained in the prior art,
It is difficult to increase the planarization and in-plane uniformity of the alignment film of each layer of the alignment film in the technology of each publication, and as a result, it is also difficult to enhance the overall planarization and in-plane uniformity of the stacked alignment films. become.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a basic configuration of an LCD. A pair of glass substrates 101 and 102 are arranged in parallel at a predetermined interval by a spacer 103 also serving as a sealing material, and a liquid crystal 104 is filled between the two glass substrates. I have. Transparent electrodes 105 and 106 for forming pixels (display elements) are formed on inner surfaces of the glass substrates 101 and 102 facing each other, and an alignment film 107 is formed so as to cover the transparent electrodes 105 and 106, respectively. ,
108 are formed. Further, the two glass substrates 1
Polarizing plates 109 and 110 are attached to the outer surfaces of 01 and 102, respectively.

FIG. 2 shows the alignment film 1 formed on the surface of the glass substrate 101 among the glass substrates 101 and 102.
FIG. 7 is a diagram schematically illustrating a cross-sectional structure of a reference numeral 07 and a technique for forming the alignment film 107. The alignment film 107 is formed by coating the alignment material on the printing plate 201 a plurality of times. Here, the printing plate 201 corresponds to the flexographic plate of the printing apparatus shown in FIG. Therefore,
The alignment material is held as a liquid thin film on the surface of the anilox roll (not shown), and is transferred from the anilox roll to the surface of the printing plate 201. And the glass substrate 1
When 01 passes directly below the printing plate 201, the thin film of the coating liquid is transferred and applied from the printing plate 201 to the surface of the glass substrate 101. Here, the thickness of the coating film 3 per one time of the alignment material is set to 20 nm or less.
The orientation material is diluted with a solvent to lower the solid content concentration than before, and the anilox roll is also changed to one that makes the coating film thinner. Then, a plurality of coatings are performed until a predetermined thickness is reached, and a plurality of coating films P1 to P5 are stacked as shown in FIG. 107 is formed. FIG. 2, for example,
This is an example in which the alignment film 107 having a thickness of about 100 nm is formed, and the coating films P1 to P5 are formed by performing the overcoating five times.

When a polyimide film generally used for LCDs is used as the alignment material of the alignment film 107, that is, a coating liquid, the manufacturing process of the alignment film 107 is as shown in the flowchart of FIG. First, an orientation material such as a polyamic acid or a soluble polyimide, or a polyimide solution in which both a polyamic acid and a soluble polyimide are dissolved in a solvent is applied to the surface of the glass substrate 101, and a first coating film P1 having a thickness of 20 nm or less is applied. Is formed (S101). Next, the first coating layer P1 is pre-baked, and the solvent contained in the first coating film P1 is dried (S102). In this pre-bake, the temperature is 100 ° C
Before and after, the time is about 3 minutes. Next, the number of times of application is checked, and it is checked whether or not a predetermined number of times, in this case, five times, has been completed (S103). If not, the steps S101 and S102 are repeated.
Sequentially a second coating film P2, a third coating film P3, a fourth coating film P
4. A fifth coating film P5 is formed. When it is confirmed in step S103 that the application has been completed five times, the main firing for forming the alignment film is performed (S104). In this main firing, the temperature is 230 to 250.
At ℃, the time is about 1 to 2 hours, and the alignment film is imidized. Thereafter, in order to form the alignment film 107 shown in FIG. 1, rubbing is performed on the surface of the alignment film having the stacked structure to develop the alignment (S105), and then cleaning is performed to remove contamination on the surface. And drying (S10)
6).

As described above, in the present embodiment, the application step (S101) of the alignment material (application liquid) and the pre-bake step (S102) are repeated a predetermined number of times, that is, until a predetermined film thickness is reached. Therefore, the thickness per one coating film is small, drying in pre-baking is easy, and drying unevenness does not occur, and the flatness and uniformity of the coating film are not impaired. Therefore, the final film thickness uniformity is improved even in the case of repeated coating as compared with the conventional example in which a predetermined film thickness is formed by one application. As a result, the variation in the thickness of the alignment film 107 is better than the target variation of ± 5%, and can be suppressed to about ± 3% depending on the type of the polyimide solvent. Further, in the process of forming the first to fifth coating films P1 to P5, after applying the alignment material, only a short prebaking is performed to dry the solvent, and finally the formation of the alignment film is performed. Since the main baking step S105 is performed when the orientation film has a predetermined thickness, the prebaking processing time in all the steps is short, and the efficiency of the manufacturing process does not decrease.

Here, in the above embodiment, the first to fifth coating films P1 to P5 are formed by applying the same polyimide solution. However, as described above, the polyimide solution as the alignment material includes a polyamic acid. There are three types: acid type, soluble polyimide type, and a mixture of both types. These alignment materials are properly used depending on the characteristics required for the alignment film. Of these three types, generally, they are compatible with the LCD substrate, that is, they do not repel or become uneven during printing. The polyamic acid type can be applied with a uniform film thickness. When a polyimide solution of a type other than polyamic acid is applied, the printing uniformity is deteriorated due to the compatibility with the substrate. In the present invention, since the polyimide solution of each coating layer can be changed by recoating, a polyamic acid type solution is formed on the glass substrate 101 as the first coating film P1 as shown in FIG. Apply. Then, a polyimide solution is applied as the second to fifth coating films P2 to P5. As described above, the first coating film P1 is formed by applying a polyamic acid type polyimide solution, whereby the first coating film P1 is formed by coating the glass substrate 101 and the polyimide solution of the upper layer thereon with the second to fifth coating films. P2 to P5
It functions as a link with. With this structure, even when a polyimide film other than the polyamic acid type is used, the uniformity of the film thickness is improved, and the variation in the film thickness is reduced by ± 3.
%.

Here, although not described, the first to fifth coating films P1 to P5 are all coated with a polyamic acid type polyimide solution, or a mixture of a polyamic acid type solution and a soluble polyimide type solution. It may be formed by applying a mixed liquid type solution. As shown in FIG. 4, the first coating film P1 is formed by applying a polyamic acid type solution, and the second to fifth coating films P2 to P5 are formed with a polyamic acid type solution and a soluble polyimide. It may be formed by applying a mixture type solution of the type solution.

Further, the first to fifth coating films P1 to P1
When the thickness of P5 is set to 20 nm or less as in the above-described embodiment, the solvent can be easily dried in the pre-bake step,
Although drying unevenness can be prevented and the flatness and uniformity of the coating film can be improved, if the film thickness is further reduced, for example, to 10 nm or less, the drying time of the solvent in the pre-bake step is further reduced, and drying unevenness, flatness, Uniformity is advantageous. However,
When the film thickness is reduced to some extent, the drying efficiency of the solvent becomes saturated, and the number of repetition steps of coating and pre-baking for forming an alignment film having a predetermined thickness is increased by thinning the coating film. The efficiency of the manufacturing process will be reduced. According to the present invention, by controlling the thickness of the coating film to about 20 nm, the drying effect of the solvent can be enhanced as compared with the related art, but the number of repeated steps of coating and pre-baking can be prevented from increasing unnecessarily, and the manufacturing efficiency can be improved. It has been confirmed that the effect of the reduction of the amount can be minimized.

Next, a description will be given of a manufacturing apparatus for forming the above-described alignment film. FIG. 5 shows an example of a configuration in which a coating device 301 for coating an alignment film, a hot plate 302 for cleaning pre-baking, and a main firing device 303 having a heat treatment structure for performing main firing. In this embodiment, the printing apparatus 301 and the hot plate 302 constitute one set, and the set is provided in five sets S1 to S5 and arranged inline (S2 and S4 in FIG.
Are not shown). Then, the main firing device 303 is arranged after the last set S5. Note that a rabbling device or the like is provided at a stage subsequent to the main firing device 303, but is not shown.

The coating device 301 has substantially the same configuration as the conventional coating device shown in FIG. 11, and for example, as shown in FIG. 6, a doctor roll 401, an anilox roll 402, a printing plate 403, and a printing stage 404. , And a dispenser 405. Further, as shown in the figure, the hot plate 302 can place a glass substrate 101 on which an alignment film is applied, and perform heat treatment at a predetermined temperature for a predetermined time. And
In the coating apparatus 301, a coating liquid (alignment material) such as the above-mentioned soluble polyimide solution is supplied dropwise between a doctor roll 401 and an anilox roll 402 which are rotating by a dispenser 405. The coating liquid is kneaded between the two rolls, held as a liquid thin film on the anilox roll 402, and transferred from the anilox roll 402 to the printing plate 403. Then, when the glass substrate 101 fixed on the printing stage 404 passes directly below the printing plate 403, a thin film of the coating liquid is transferred and applied from the printing plate 403 to the glass substrate 101. The glass substrate 101 coated with the coating liquid is transferred from the printing apparatus 301 to the hot plate 30 by a conveyor or a robot (not shown).
2 and is heated at a predetermined temperature and time for prebaking, and the solvent of the applied coating film P1 (〜P5) is dried.

Therefore, the coating device 30 of the first set S1
1 and the hot plate 302, the coating liquid is applied and prebaked to form a first coating film P1. After that, the same coating and pre-baking are performed by the coating device 301 and the hot plate 302 of the next second set S2,
A second coating film P2 is formed. Hereinafter, similar coating and prebaking are sequentially performed, and the fifth coating film P5 is formed by the coating apparatus 301 and the hot plate 302 of the fifth set S5. Then, the glass substrate 101 is placed in the main baking apparatus 3.
03, where the alignment film is imidized by heat treatment at a high temperature for a long time. Note that the subsequent rubbing device and cleaning / drying device are the same as those in the conventional configuration, and thus description thereof is omitted.

FIG. 7 is a view showing another embodiment of the manufacturing apparatus according to the present invention. In this embodiment, the manufacturing apparatus comprises one coating apparatus 301 and one hot plate 302. A loader 304 is arranged, and a return machine 305 is arranged at a stage subsequent to the hot plate 302,
Further, a return transport path 306 for returning the glass substrate 101 from the return device 305 to the loader 304 is provided. In this manufacturing apparatus, a glass substrate 101 is
After applying a coating solution to the surface of the substrate and performing pre-baking on the hot plate 302 to form the first coating film P1, the glass substrate 101 is returned from the return machine 305 to the loader 304 through the return transport path 306, and again subjected to the same coating. The second coating film P2 is formed by the apparatus 301 and the hot plate 302. Thereafter, the return is repeated in the same manner to form up to the fifth coating film P5, and after forming an alignment film having a predetermined thickness, the film is transferred to the main firing device 303 to perform the main firing. The subsequent processing is the same as described above.

In these manufacturing apparatuses, the former manufacturing apparatus shown in FIG. 5 is suitable for mass production because the glass substrate is manufactured while transferring the glass substrate in-line.
Since it is difficult to change the number of times of application, it is necessary to control the film thickness in each application apparatus each time. In addition, the latter manufacturing apparatus shown in FIG. 7 can freely set the number of times of recoating of the alignment film by controlling the number of times of return when the number of times of recoating when forming the alignment film is not determined, It can easily cope with film thickness change by changing the product type, but it is not suitable for mass production because the tact time becomes long. Since there are advantages and disadvantages, the one that is suitable for each process is selected.

FIG. 8 shows a configuration example using a spin coater as a modified example of the coating apparatus 301. That is,
The spin coater has a rotary stage 501 that rotates at high speed in the horizontal direction. The spin coater supports the glass substrate 101 on the rotary stage 501 and rotates at high speed. Is dropped. The dropped coating liquid is applied while being spread on the surface of the glass substrate 101 by centrifugal force, and a coating film is formed. This spin coating type coating apparatus is suitable for forming a uniform film thickness, but since it is applied to the entire surface of the substrate, it is necessary to mask the surface of the glass substrate before patterning to the size of the LCD display surface. It is necessary to apply This masking is removed after prebaking and before main firing.

FIG. 9 shows a configuration example using a sprayer as a different modification of the coating apparatus 301. Coating film P
Since the viscosity of the polyimide solution diluted so that the thickness of 1 to P5 becomes 20 nm becomes small, the application by spraying with a sprayer becomes possible. In this configuration, the nebulizer 601 is used.
And spraying the application liquid on the glass substrate 101 while moving the sprayer 601 with respect to the glass substrate 101.
Is applied to the entire surface of the substrate. Such a coating by the sprayer 601 can realize a uniform film thickness by keeping the moving speed of the sprayer 601 relative to the glass substrate 101 constant. In addition, since the type switching is only required by changing the program of the nozzle movement pattern, the line direction is suitable for a line in which many types are flowing.

FIG. 10 shows an example of a configuration using infrared irradiation as the pre-bake device 302. Glass substrate 101
Is mounted on a stage 701, and the glass substrate 1 is moved by an infrared lamp 702 disposed on the stage 701.
01 is irradiated with infrared rays. In the drying of the coating film by infrared irradiation, when the thickness of the coating film is large, the infrared irradiation dries from the surface, so when the solvent escapes from the inside, it leaves a trace on the surface, and when the LCD is assembled In some cases, alignment display unevenness occurs. However, since there is no concern about the alignment film having a thickness of 20 nm or less, infrared irradiation can be used.

[0029]

As described above, according to the present invention, an alignment material for forming an alignment film is formed by applying and pre-baking a plurality of times, and is formed into a predetermined film thickness and then subjected to main firing. In particular, by setting the thickness of a single coating film to 20 nm or less, when drying the solvent,
This eliminates drying unevenness and traces when the solvent comes off, improves the uniformity of the thickness of the formed alignment film, and suppresses the variation to about ± 3% or less. Also, by forming a polyamic acid type polyimide solution having good compatibility with the electrode substrate surface as the first coating film, the first coating film is formed.
The coating film enhances the bonding property with the polyimide film for the alignment film, which is the upper layer of the second coating film or more, and the thickness of the alignment film can be made uniform even with various types of polyimide solutions.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a typical configuration of an LCD to which the present invention is applied.

FIG. 2 is a schematic diagram for explaining the manufacturing method of the present invention.

FIG. 3 is a flowchart of the manufacturing method of the present invention.

FIG. 4 is a cross-sectional view for explaining another manufacturing method of the present invention.

FIG. 5 is a plan layout view of the first embodiment of the manufacturing apparatus of the present invention.

FIG. 6 is a view showing a schematic configuration of a coating apparatus and a pre-bake apparatus according to the present invention.

FIG. 7 is a plan layout view of a second embodiment of the manufacturing apparatus of the present invention.

FIG. 8 is a schematic perspective view of a modification of the coating apparatus.

FIG. 9 is a schematic perspective view of another modification of the coating apparatus.

FIG. 10 is a schematic sectional view of a modified example of the prebaking device.

FIG. 11 is a schematic diagram of a configuration of a printing unit of a conventionally proposed alignment film flexographic printing / coating apparatus.

[Explanation of symbols]

 101, 102 Glass substrate 103 Spacer 104 Liquid crystal 105, 106 Transparent electrode 107, 108 Alignment film 109, 110 Polarizing plate 201 Printing plate 301 Coating device 302 Prebake device 303 Main baking device 304 Loader 305 Return machine 306 Return transport path 401 Doctor roll 402 Anilox roll 403 Printing plate 404 Printing stage 405 Dispenser 501 Rotating stage 502 Solution dripping nozzle 601 Sprayer 701 Stage 702 Infrared lamp 801 Dispenser 802 Doctor roll 803 Anilox roll 804 Plate cylinder 805 Flexographic plate 806 Table P1 to P5 coating film -Fifth coating film) S1-S5 A combination of a coating device and a pre-bake device

Claims (17)

[Claims] In a liquid crystal display device, when an alignment film having an action of arranging liquid crystal molecules in the same direction is formed on an electrode substrate, an alignment material that is a source of the alignment film is applied, and the coated alignment material is applied. Manufacturing a liquid crystal display device, comprising a step of repeating the step of pre-baking a plurality of times to repeatedly apply the alignment material, and a step of performing main firing after forming the alignment film to a required thickness. Method. 2. The method for manufacturing a liquid crystal display device according to claim 1, wherein the applied film thickness of the alignment material per application of the alignment material is 20 nm or less. 3. The method for manufacturing a liquid crystal display device according to claim 1, wherein the alignment material is applied in a state diluted with a solvent, and the solvent is dried in the pre-bake step after the application. 4. The method for manufacturing a liquid crystal display device according to claim 1, wherein the method for applying the alignment material is a printing method. 5. The method for manufacturing a liquid crystal display device according to claim 1, wherein the method for applying the alignment material is a spin coating method. 6. The method for manufacturing a liquid crystal display device according to claim 1, wherein the method for applying the alignment material is a spraying method using a sprayer. 7. The method for manufacturing a liquid crystal display device according to claim 1, wherein said prebaking is a heat treatment using a hot plate. 8. The method for manufacturing a liquid crystal display device according to claim 1, wherein said prebaking is a heat treatment by irradiating infrared rays. 9. The method for manufacturing a liquid crystal display device according to claim 1, wherein a polyamic acid solution, a soluble polyimide solution, or a mixed solution of polyamic acid and soluble polyimide is used as the alignment material. 10. In the step of applying the alignment material, a polyamic acid solution is used in a first application, and a polyamic acid solution or a soluble polyimide solution or a mixed solution of a polyamic acid and a soluble polyimide is used in the second and subsequent applications. A method for manufacturing a liquid crystal display device according to any one of claims 1 to 8. 11. A manufacturing apparatus for forming an alignment film having an action of arranging liquid crystal molecules in the same direction on an electrode substrate of a liquid crystal display device, wherein an alignment material serving as a base of the alignment film is formed on the electrode substrate. A coating device, a pre-bake device for drying a solvent from the applied alignment material, and a main baking device for performing main baking after forming the alignment film to a required thickness, the coating device and the pre-bake device A plurality of liquid crystal display devices are provided. 12. A manufacturing apparatus for forming an alignment film having an action of arranging liquid crystal molecules in the same direction on an electrode substrate of a liquid crystal display device, wherein an alignment material serving as a source of the alignment film is formed on the electrode substrate. A coating device, a pre-bake device for drying a solvent from the applied alignment material, a main firing device for performing main firing after forming the alignment film to a required thickness,
Means for performing a plurality of times of applying and prebaking the electrode substrate in the coating apparatus and the prebaking apparatus. 13. The apparatus according to claim 11, wherein the coating device is a printing device that prints an alignment material on a surface of the electrode substrate. 14. The spin coater according to claim 11, wherein the coating device is a spin coater including a rotating table for rotating the electrode substrate at a high speed, and means for dropping the alignment material on a surface of the electrode substrate. 13. The method for manufacturing a liquid crystal display device according to item 12. 15. The liquid crystal display device according to claim 11, wherein the coating device is a device using a sprayer for spraying the alignment material and attaching the alignment material to the surface of the electrode substrate. apparatus. 16. The apparatus according to claim 11, wherein the pre-bake device is a hot plate. 17. The apparatus according to claim 11, wherein the pre-bake device is an infrared irradiation device.