METHOD AND APPARATUS FOR FORMING ALIGNMENT FILM OF LIQUID CRYSTAL DISPLAY

Technical Field

[1] The present invention relates to a method and an apparatus for forming an alignment film of a liquid crystal display, and more particularly to a method and an apparatus for forming an alignment film of a liquid crystal display wherein the alignment film is patterned in a desired form on a substrate without using a separate mask.

Background Art

[2] Generally, a liquid crystal display comprises an upper substrate, a lower substrate and a liquid crystal filling a gap between the upper substrate and the lower substrate. A switching device such as a thin film transistor and a pixel corresponding thereto are formed on the lower substrate in a matrix form. A common electrode and a color filter are formed on the upper substrate. An alignment film is formed on facing surfaces of the upper substrate and the lower substrate.

[3] The liquid crystal display displays image by passing or blocking a light incident from a light guide panel using an electro-optical effect of the liquid crystal display, and the electro-optical effect is determined by an anisotropy of the liquid crystal itself and a molecular arrangement of the liquid crystal. In order to secure a responsiveness and an uniformity required in the liquid crystal display, it is required that molecules of the liquid crystal filling the gap between the upper and the lower substrates is aligned in a certain direction to have a characteristic identical to a single crystal. The alignment film is formed on the facing surfaces of the upper and the lower substrates for an alignment of the liquid crystal molecule. Typically, a polyamide-based high molecular compound having a thickness ranging from 500 to 1000 is coated by a spin coating or a roll coating method and cured, and then is subjected to a rubbing process to form the alignment film. The rubbing process provides an alignment direction to the liquid crystal molecules by defining an alignment angle on a surface of the alignment film.

[4] The spin coating method is disadvantageous in that an unnecessary alignment film at an edge area exclusive of an active area should be removed using an etching process in order to be used in a process wherein multiple liquid crystal displays are dividedly formed on a single substrate since a large amount of the polyamide is used and the alignment film is formed on the entire substrate. Therefore, the roll coating method is frequently used currently as a method for forming the alignment film on the substrate.

[5] Conventional process for forming an alignment film on a substrate by a roll coating

apparatus will now be described below with reference to accompanied drawings.

[6] Fig. 1 is a schematic diagram illustrating a configuration of a conventional roll coating apparatus.

[7] As shown in Fig. 1, the conventional roll coating apparatus comprises a doctor roll

11 consisting of a rubber, an anilox roll 13 engaged with the doctor roll 11 and being coated with a metal such as chrome, a printing roll 15 engaged with the anilox roll 13, and a printing rubber plate 16 attached on the printing roll 15.

[8] A relief type pattern 17 corresponding to an active region where an alignment film is coated is formed on the printing rubber plate 16. The pattern 17 allows the alignment film to be coated on the active region formed on a substrate 10 disposed on a stage 12. More specifically, when an alignment film forming material which is a polyamide- based high molecular compound is sprayed on the anilox roll 13 by a dispenser 14, the doctor roll 11 rotates engaged with the anilox roll 13 to bond the alignment film forming material on a surface of the anilox roll 13 in a uniform thickness. When the anilox roll 13 rotates engaged with the printing roll 15, the alignment film forming material is transcribed onto the relief pattern 17 of the printing rubber plate 16 attached to the printing roll 15. At this time, when the substrate 10 disposed on the stage 12 moves at a same speed as a speed of revolution of the printing roll 15, the alignment film forming material is coated on the substrate 10 as the pattern 17. The coated alignment film forming material is subjected to a predetermined curing process and a rubbing process to complete the formation process of the alignment film. Disclosure of Invention Technical Problem

[9] However, the conventional technology for forming the alignment film has following drawbacks.

[10] Firstly, since a separate printing rubber plate should be used according to a size and a shape of the liquid crystal display, a manufacturing cost is increased due to the high- priced printing rubber plate when the number of the manufactured liquid crystal display is small. In addition, since the printing rubber plate attached to the printing roll is removed and a new printing rubber plate is attached according to a change in the size of the liquid crystal display, the printing rubber plate should be accurately aligned to the active region of the liquid crystal display, resulting in an excessive effort and time in the mounting of the printing rubber plate. Moreover, a manufacturing process is interrupted during a replacement of the printing rubber plate, resulting in a degradation of a work efficiency and a high manufacturing cost.

[11] Secondly, in case of even a small defect in the printing rubber plate or an alignment defect results in a defect of a transcription of the alignment film so that the entire

substrate of a high price is not usable or the substrate should be regenerated.

[12] Thirdly, a problem that the size of the printing rubber plate is increased due to a compressive force during a printing process often occurs so that multiple spare printing rubber plates should be prepared according to a model of the liquid crystal display. Technical Solution

[13] It is an object of the present invention to provide a method and an apparatus for forming an alignment film of a liquid crystal display wherein the alignment film is patterned in a desired form on a substrate without using a separate mask.

[14] In order to achieve the object of the present invention, there is provided a method for forming an alignment film of a liquid crystal display, the method comprising steps of: coating an alignment film forming material on an entire surface of a substrate of the liquid crystal display; curing the alignment film forming material to form the alignment film; and forming a predetermined alignment film pattern using a means capable of selectively processing a portion of the alignment film without using a mask.

[15] There is also provided an apparatus for forming an alignment film of a liquid crystal display, the apparatus comprising: a coating device for coating an alignment film forming material on an entire surface of a substrate of the liquid crystal display; and a means for forming a predetermined alignment film pattern by selectively processing a portion of the alignment film without using a mask. Brief Description of the Drawings

[16] Characteristics and advantage of the present invention will be more clearly understood by referring to accompanied drawings wherein:

[17] Fig. 1 is a schematic diagram illustrating a configuration of a conventional roll coating apparatus.

[18] Fig. 2 is a schematic diagram illustrating a plasma generator for generating an atmospheric plasma using a dielectric barrier discharge in accordance with a first embodiment of the present invention.

[19] Figs. 3 and 4 are diagrams illustrating a process for forming an alignment film on a substrate using a plasma generator in accordance with a first embodiment of the present invention.

[20] Figs. 5 and 6 are diagrams illustrating a process wherein an alignment groove is formed by rotating a substrate.

[21] Figs. 7 and 8 are diagrams illustrating a process wherein an alignment groove is formed by rotating a plasma generator.

[22] Fig. 9 is a diagram illustrating a process wherein an alignment groove is formed by rotating a plurality of plasma generators.

[23] Figs. 10 and 11 are diagrams illustrating a cluster type apparatus for forming an

alignment film in accordance with the present invention.

[24] Fig. 12 is a schematic diagram illustrating an atmospheric plasma jet in accordance with a second embodiment of the present invention.

[25] Fig. 13 is a diagram illustrating a state wherein an alignment film is formed on a substrate by an atmospheric plasma jet.

[26] Fig. 14 is a diagram illustrating a process for forming an alignment film on a substrate using an atmospheric plasma jet in accordance with the second embodiment of the present invention.

[27] Fig. 15 is a diagram illustrating a process wherein an alignment film is formed on a substrate using a plurality of atmospheric plasma jets.

[28] Fig. 16 is a block diagram illustrating a laser beam generator in accordance with a third embodiment of the present invention.

[29] Fig. 17 is a diagram illustrating a state wherein an alignment film is formed on a substrate by a laser beam generator.

[30] Fig. 18 is a diagram illustrating a process for forming an alignment film on a substrate using a laser beam generator in accordance with the third embodiment of the present invention.

[31] Fig. 19 is a block diagram schematically illustrating a structure of a laser beam generator in accordance with a fourth embodiment of the present invention.

[32] Fig. 20 is a diagram illustrating a state wherein a predetermined alignment film pattern is formed on a substrate by a laser beam generator.

[33] Fig. 21 is a diagram illustrating a process for forming an alignment film pattern on a substrate using a laser beam generator in accordance with the fourth embodiment of the present invention. Best Mode for Carrying Out the Invention

[34] Embodiments of the present invention will be described with reference to accompanied drawings below. Like reference numerals in the accompanied drawings refer to like elements, and additional description will be omitted accordingly.

[35] [First embodiment]

[36] In accordance with a first embodiment of the present invention, an atmospheric plasma is used as a means for removing an unnecessary portion of an alignment film. A plasma refers to a state where an atom is divided into particles such as an ion, a neutron and electron more active than a gas using a heat or an electric energy. The plasma is classified into a vacuum plasma, a high temperature plasma, and the atmospheric plasma according to a generation method. The vacuum plasma is generated in a sealed vacuum chamber using the electric energy. While the vacuum plasma is heated to a high temperature due to a high impact energy of particles, a concentration

of a radical is relatively low due to a low ionization ratio. The high temperature plasma is generated by an arc discharge or a high temperature torch generating a high temperature heat of few thousand degrees, and mostly used for a fusion coating. The atmospheric plasma is generated using the dielectric barrier discharge, a microwave or a corona discharge in an open space. Since a surface heating temperature of an object being processed by the atmospheric plasma, i.e. a process temperature is typically less than 200°C, the atmospheric plasma may be used for objects vulnerable to a high temperature, and a process speed is high due to a high radical concentration. In addition, a continuous processing in the open space is possible because a reaction chamber is not required, and the atmospheric plasma may be easily added to other equipments. Due to these characteristics, the atmospheric plasma is suitable for a surface processing such as a cleaning and an ashing of a large substrate.

[37] Fig. 2 is a schematic diagram illustrating a plasma generator for generating the atmospheric plasma using the dielectric barrier discharge in accordance with the first embodiment of the present invention.

[38] As shown in Fig. 2, a dielectric plate 130 having a high dielectric constant is disposed at a first side of an electrode 120 connected to a power supply 110, and a grounding plate 140 is disposed to face the dielectric plate 130. Therefore, when a charge is accumulated in the dielectric plate 130 by the power supply 110, a voltage is applied between the dielectric plate 130 and the grounding plate 140, and when the voltage becomes higher than a certain level, a short pulse type discharge having a length of tens of nanoseconds occurs between the dielectric plate 130 and the grounding plate 140. By the discharge, a gas is ionized to generate an atmospheric plasma 150, and the atmospheric plasma is used to process a surface of a substrate 200.

[39] The atmospheric plasma generated by a plasma generator 100 generally has a low processing temperature ranging from 30 to 150°C, and has a high reaction speed due to a high density of a reactive particle (radical) ranging from 10 ¹² to 10 ¹⁵ cm ^"3 . In addition, since the atmospheric plasma may be generated without an expensive vacuum equipment and may be generated in a large area when a size of the dielectric plate 130 is adjusted, the atmospheric plasma may be used for successively processing a surface of an object having a large area. A width of the atmospheric plasma generated in the plasma generator 100 may be adjusted within a range of 2 to 20mm as required.

[40] Figs. 3 and 4 are diagrams illustrating a process for forming an alignment film on a substrate using a plasma generator in accordance with a first embodiment of the present invention.

[41] As shown in Fig. 3(A), an alignment film forming material which is a polyamide- based high molecular compound is coated on an entire surface of the substrate 200 by a spin coating or a roll coating method. When the alignment film forming material is

coated on the entire surface of the substrate 200, the alignment and the replacement process of the printing rubber plate according to the change in the size of the liquid crystal display as in the conventional art is not required even when the roll coating method is employed. In addition, the alignment film forming material which is the polyamide-based high molecular compound coated on the substrate 200 is cured by undergoing a pre-baking process carried out at a temperature ranging from 60 to 80°C and a main curing process carried out at a temperature ranging from 80 to 200°C.

[42] Thereafter, as shown in Fig. 3(B), the plasma generator 100 is disposed at a predetermined position of the substrate 200 to remove a portion of the cured alignment film. More specifically, the plasma generator 100 emits the atmospheric plasma having a predetermined width in a horizontal direction to remove the portion of the alignment film.

[43] Here, the atmospheric plasma may effectively remove the polyamide in a liquid state as well as the polyamide that underwent the pre-baking or the main curing process. Therefore, the removal of the alignment film using the atmospheric plasma may be carried out after the pre-baking process or the main curing process, or immediately after the coating of the alignment film forming material on the substrate 200 or after a rubbing process of the alignment film if required. Hereinafter, the alignment film commonly refers to the alignment forming material, the pre-baked or cured alignment film or the alignment film that underwent the rubbing process except noted otherwise.

[44] Through these processes, the alignment film is removed to form an alignment groove 210 in a horizontal direction (see Fig. 3(C)). Preferably, the alignment groove 210 in the horizontal direction is formed in a single scan by the plasma generator 100, and the plasma generator 100 generates the atmospheric plasma having a length longer than that of the alignment groove 210 in the horizontal direction accordingly.

[45] Since a switching device and a wiring array formed on the substrate 200 are exposed when the alignment groove 210 in the horizontal direction is generated, a wiring connection for completing the liquid crystal display becomes possible. The width of the alignment groove 210 in the horizontal direction is determined by adjusting a width of the atmospheric plasma generated in the plasma generator 100.

[46] In addition, as shown in Fig. 3(C), the plasma generator 100 is moved by a predetermined distance (that is, by a width of an active region of the liquid crystal display to be manufactured) in a vertical direction, and the process shown in Fig. 3(B) is then repeated. Alternately, the substrate 200 may be moved by the predetermined distance in the vertical direction with the plasma generator 100 fixed, and the process shown in Fig. 3(B) may be then repeated. The moving distance of the plasma generator 100 or the substrate 200 is adjusted according to a typical control apparatus according to the

size of the liquid crystal display.

[47] When the processes shown in Fig. 3(B) and (C) are repeated, multiple alignment grooves 210 spaced apart by a predetermined distance are formed on the entire substrate 200 as shown in Fig. 3(D).

[48] When the formation of the alignment groove 210 in the horizontal direction is completed, multiple alignment grooves 220 in the vertical direction are formed by processes shown in Fig. 4(A) through (D). At this time, the plasma generator 100 or the substrate 200 is moved by a predetermined distance in the horizontal direction, and the plasma generator 100 generates the atmospheric plasma having a length longer than that of the alignment groove 220 in the vertical direction. Since the process for forming the alignment groove 220 in the vertical direction is identical to that of the alignment groove 210 in the horizontal direction, a detailed description is omitted.

[49] When the formation of the alignment grooves 210 and 220 in the horizontal and the vertical directions are completed as described above, an alignment groove in a grid form is formed on the substrate 200. While the alignment groove 210 in the horizontal direction is formed prior to the alignment groove 220 in the vertical direction in the above description, the formation of the alignment groove 220 in the vertical direction prior to that of the alignment groove 210 in the horizontal direction is also possible.

[50] On the other hand, when the alignment groove 210 in the horizontal direction is formed prior to the alignment groove 220 in the vertical direction or vice versa, the substrate 200 or the plasma generator 100 is required to be rotated.

[51] Figs. 5 and 6 are diagrams illustrating a process wherein an alignment groove is formed by rotating a substrate, and Figs. 7 and 8 are diagrams illustrating a process wherein an alignment groove is formed by rotating a plasma generator.

[52] As shown in Fig. 5, when the substrate 200 is moved to be disposed on a stage 230, the plasma generator 100 is moved to form the alignment grooves spaced apart by the predetermined width in the horizontal direction on the substrate. When the formation of the alignment grooves in the horizontal direction is complete, the stage 230 is rotated by 90 degrees (the substrate is rotated by 90 degrees accordingly), and the alignment grooves in the vertical direction is formed on the substrate 200 using the plasma generator 100 as shown in Fig. 6. When these processes are complete, the alignment groove in the grid form is formed on the substrate 200. In addition, as shown in Figs. 7 and 8, the alignment groove formation process may be carried out by rotating the plasma generator 100 by 90 degrees instead of rotating the stage 230 to obtain the same result as Figs. 5 and 6.

[53] On the other hand, a plurality of the plasma generator 100 may be installed. Fig. 9 is a diagram illustrating a process wherein an alignment groove is formed by rotating a plurality of plasma generators.

[54] As shown in Fig. 9, the plasma generator 100 comprises a plurality of first plasma generators 100a disposed in the horizontal direction and a plurality of second plasma generators 100b disposed in the vertical direction. Therefore, the alignment groove 210 in the horizontal direction is formed by the first plasma generators 100a at once as shown in Fig. 9(A), and the alignment groove 220 in the vertical direction is formed by the second plasma generators 100b at once as shown in Fig. 9(B).

[55] As described above, when the first and the second plasma generators 100a and 100b are installed separately, the substrate 200 or the plasma generator 100 is not required to be rotated in order to form the alignment groove. Since the alignment grooves in the horizontal and the vertical directions are formed at once by the first and the second plasma generators 100a and 100b, the plasma generator 100 or the substrate 200 is not required to be moved by the predetermined distance. Preferably, a distance between the plurality of the first plasma generators 100a and a distance between the plurality of the second plasma generators 100b are adjusted so that the distances correspond to the size of the liquid crystal display to be manufactured. Single first and the second plasma generators 100a and 100b may be installed respectively, and in such case, the first and the second plasma generators 100a and 100b or the substrate 200 is installed such that the first and the second plasma generators 100a and 100b or the substrate 200 is movable by the predetermined distance in the vertical or the horizontal direction in order to form the alignment groove.

[56] On the other hand, the apparatus for forming the alignment film in accordance with the present invention may be configured to have a cluster form including various apparatuses such as a substrate conveyer. Figs. 10 and 11 are diagrams illustrating a cluster type apparatus for forming an alignment film in accordance with the present invention.

[57] As shown Fig. 10, the apparatus for forming the alignment film in accordance with the present invention may comprises a loading unit 300, a substrate conveying unit 310 having a conveying means mounted therein such as a robot arm, and a first and a second plasma processing units 320 and 330 where the first and the second plasma generators are installed.

[58] In addition, as shown in Fig. 11, the apparatus for forming the alignment film in accordance with the present invention may further comprise a coating unit wherein a spin coater or a roll coater for coating the alignment film forming material on the substrate in addition to the loading unit 300, the substrate conveying unit 310 having a conveying means mounted therein such as a robot arm, and the first and the second plasma processing units 320 and 330. When the apparatus for forming the alignment film is configured to have the cluster form having various devices, processes form a loading of the substrate to the formation of the alignment film is successively carried

out.

[59] [Second embodiment]

[60] However, the first embodiment of the present invention is disadvantageous in that a larger plasma generator compared to the conventional one should be developed as the size of the liquid crystal display becomes larger, a plasma generator generating the atmospheric plasma having various widths according to the alignment groove to be formed should be prepared, and a large plasma generator is difficult to move or rotate freely. The first embodiment is also disadvantageous in that the process is delayed for a time period required for stabilizing a plasma to have an identical electrical characteristic as the plasma generator is periodically turned on and off during the movement thereof for forming the alignment groove, a defect in a shape of the alignment groove is generated due to an initially unstable plasma, a higher output plasma generating power supply is required as the plasma generator becomes large, and a manufacturing cost is increased due to above problems.

[61] Fig. 12 is a schematic diagram illustrating an atmospheric plasma jet in accordance with a second embodiment of the present invention.

[62] As shown in Fig. 12, a power supply 410 is connected to a center electrode 420 having a shape of a circular rod, and the center electrode 420 passes through an insulator 430 to be inserted in a grounding plate 440 having a shape of a circular tube. A gas supplying pipe 450 for supplying a plasma generating gas is disposed on the upper part of the grounding plate 440, and a detachable nozzle-shaped end cap 460 having a hole 470 for emitting the plasma generated is attached at a lower end of the grounding plate 440.

[63] When a charge is delivered to the center electrode 420, a voltage is applied between the center electrode 420 and the grounding plate 440, and when the voltage becomes higher than a certain level, a short pulse type discharge having a length of tens of nanoseconds occurs between the center electrode 420 and the grounding plate 440. By the discharge, the plasma generating gas is ionized to generate the atmospheric plasma which is sprayed through the end cap 460. The atmospheric plasma is used to process a surface of a substrate. The atmospheric plasma generated generally has a low processing temperature ranging from 25 to 200°C, and has a high reaction speed due to a high density of a reactive particle (radical) ranging from 10 to 10 cm ^" .

[64] The atmospheric plasma jet 400 does not require a high-priced vacuum equipment, and generates the atmospheric plasma having various width by simply replacing the end cap 460 with one having the hole 470 for emitting the plasma of a different size. Therefore, the atmospheric plasma jet is advantageous over the first embodiment in that a new plasma generator according to the size of the substrate and the width of the alignment groove is not required, a higher output plasma generating power supply is

not required when developing a large plasma generator, and the manufacturing cost is reduced accordingly. A variable plasma width through a replacement of the typical end cap 460 ranges from 0.5 to 20mm. In addition, since the atmospheric plasma jet 400 is small, a continuous processing of a surface of an object by a scanning method along a predetermined path is possible. Moreover, since the plasma is not required to be turned on and off during the process, a process delay due to an initial stabilizing time of the plasma does not occur. Once the plasma is generated, the plasma may be used until the completion of the process, and an intensity of the plasma is also high so that a continuous high speed movement is possible. Generally, a moving speed of the atmospheric plasma jet 400 ranges from 1 to 20 m/min.

[65] Fig. 13 is a diagram illustrating a state wherein an alignment film is formed on a substrate by an atmospheric plasma jet.

[66] As shown in Fig. 13, when a plurality of alignment grooves 510 in a horizontal direction and the alignment grooves 520 in a vertical direction are formed on a substrate 500 having a polyamide-based high molecular compound coated thereon using the atmospheric plasma jet 400, a desired alignment pattern 530 is formed. In accordance with the second embodiment, since an alignment film forming material is coated on an entire surface of the substrate 500 using a spin coating or a roll coating, a single printing rubber plate for coating the alignment film forming material on the entire surface of the substrate 500 may be used even when the roll coating method is used for coating the entire surface of the substrate 500. Therefore, the printing rubber plate is not required to be changed according to the size and shape of the liquid crystal display to be manufactured.

[67] On the other hand, the alignment film forming material which is the polyamide- based high molecular compound coated on the substrate 500 is cured by undergoing a pre-baking process carried out at a temperature ranging from 60 to 80°C and a main curing process carried out at a temperature ranging from 80 to 200°C. Therefore, the formation process of the alignment film using the atmospheric plasma jet 400 may be carried out after the pre-baking process or the main curing process, or immediately after the coating of the alignment film forming material on the substrate 500 or after a rubbing process of the alignment film if required. Hereinafter, the alignment film commonly refers to the alignment forming material, the pre-baked or cured alignment film or the alignment film that underwent the rubbing process except noted otherwise.

[68] Fig. 14 is a diagram illustrating a process for forming an alignment film on a substrate using an atmospheric plasma jet in accordance with the second embodiment of the present invention.

[69] As shown in Fig. 14, when the substrate 500 is moved to be disposed on a stage

540, the atmospheric plasma jet 400 is moved to form the alignment film pattern 530

on the substrate. More specifically, when the substrate 500 is supplied to the stage 540 by a substrate supplying unit (not shown), the atmospheric plasma jet 400 generating the atmospheric plasma is conveyed by an x-axis conveying means 550, a y-axis conveying means 560 and a z-axis conveying means 570 to a predetermined position, and a portion of the alignment film is selectively removed to form the alignment pattern 530 on the substrate 500.

[70] When the alignment pattern 530 is formed by the above process, the alignment grooves 510 and 520 in the horizontal and vertical directions are formed along an outer edge of the alignment pattern 530. When the alignment grooves 510 and 520 in the horizontal and vertical directions are formed by removing the portion of the alignment film, a switching device and a wiring array formed on the substrate 500 are exposed, and a wiring connection for completing the liquid crystal display becomes possible accordingly.

[71] On the other hand, it is preferable that a plurality of the atmospheric plasma jets 400 are installed for forming the alignment film pattern of the substrate 500 having a large area.

[72] Fig. 15 is a diagram illustrating a process wherein an alignment film is formed on a substrate using a plurality of atmospheric plasma jets.

[73] As shown in Fig. 15, when the substrate 500 is disposed on the stage 540, a plurality of atmospheric plasma jets 500a, 500b and 500c are moved to form a plurality of alignment grooves 510, 520 in the horizontal and the vertical directions on the substrate 500 simultaneously. While Fig. 15 illustrates three atmospheric plasma jets 500a, 500b and 500c, the number of the atmospheric plasma jet is not limited. In addition, the atmospheric plasma jets 500a, 500b and 500c are moved to predetermined positions by x-axis conveying means 550a, 550b and 550c, y-axis conveying means 560a, 560b and 560c and z-axis conveying means 570a, 57b and 570c respectively. Preferably, the atmospheric plasma jets 500a, 500b and 500c may be moved along the same track or along different tracks. As described above, when multiple atmospheric plasma jets are installed, a time required for the formation process of the alignment film of the substrate having a large area may be reduced.

[74] [Third embodiment]

[75] In accordance with the third embodiment, an alignment film pattern is formed using a laser beam contrary to the first and the second embodiments. Generally, since the laser beam has a directionality, coherence and high optical density, the laser beam is suitable for a surface processing process such as a laser etching of a surface of a material, a patterning, a repairing and a local deposition. Specifically, the laser beam is currently and limitedly used for a direct patterning process for locally irradiating a high density energy in a filed of a flat panel display manufacturing process including a

LCD, PDP and an OLED such as the repairing process and a LITI (Laser Induced Thermal Imaging), and a marking process a substrate and a panel through an engraving method by ablation.

[76] Fig. 16 is a block diagram illustrating a laser beam generator in accordance with a third embodiment of the present invention.

[77] As shown in Fig. 16, an initial laser beam 611 generated from a laser generating apparatus 610 is passed through a beam enlarger 620 and a beam homogenizer 630. A laser beam 631 that has passed through the beam homogenizer 630 is reflected toward a substrate 700 by a reflector 640 to reach the substrate 700 passing through a laser beam transmitting means 650.

[78] More specifically, the initial laser beam 611 generated in the laser generating apparatus 610 is enlarged to a desired size by passing through the beam enlarger 620, and a laser beam 621 that has passed through the beam enlarger 620 then passes through the beam homogenizer 630 to have a uniform energy distribution. The initial laser beam 611 has a characteristic of a single mode or a multi-mode, and has a nonuniform energy distribution. However, a final laser beam 651 that reaches the substrate 700 should have a parallel and a uniform beam characteristic. Therefore, the initial laser beam 611 sequentially passes through the beam enlarger 620 and the beam homogenizer 630. Thereafter, the laser beam 631 that has passed through the beam homogenizer 630 is reflected toward the substrate 700 by the reflector 640. Here, an energy of a reflected laser beam 641 is not lost and the reflected laser beam 641 is transmitted to the laser beam transmitting means 650 to have the same energy and energy distribution as those of the laser beam 631 incident on the reflector 640. The laser beam 641 that reached the laser beam transmitting means 650 passes through the laser beam transmitting means 650 to become the laser beam 651 having the parallel and uniform energy distributions. The laser beam 651 then reaches the substrate 700.

[79] The laser beam 651 that reaches the substrate 700 through these processes generally has an energy density ranging from 10 to 10 W/cm , and has a high processing speed accordingly. In addition, the laser beam may be adjusted to have a certain size by using the beam enlarger 620 or installing a slit (not shown) having an adjustable size in the laser beam transmitting means 650. Generally, a cross-section of the laser beam is circular or elliptical, and a diameter of the cross-section of the laser beam ranges from 0.1 to 40mm.

[80] When the laser beam generator 600 having the above-described structure is used, a laser beam having a desired size may be generated without using an additional equipment or an apparatus to easily correspond to the change in the size of the substrate 700 and the width of the alignment groove to be formed. In addition, since the laser beam generator 600 is small in its size, a continuous processing of a surface

of an object by a scanning method along a predetermined path is possible, thereby preventing the process delay problem, and once the plasma is generated, the plasma may be used until the completion of the process. Generally, a scanning speed of the laser beam ranges from 1 to 20 m/min.

[81] Fig. 17 is a diagram illustrating a state wherein an alignment film is formed on a substrate by a laser beam generator.

[82] As shown in Fig. 17, when a plurality of alignment grooves 710 in a horizontal direction and the alignment grooves 720 in a vertical direction are formed on a substrate 700 having a polyamide-based high molecular compound coated thereon using the laser beam generator 600, a desired alignment pattern 730 is formed. That is, when the laser beam generator 600 is moved at a predetermined speed to scan the substrate 700, the alignment film forming material is selectively removed to form an alignment film pattern 730 by forming horizontal and vertical alignment grooves. When the alignment film forming material coated on the substrate 700 is directly and selectively removed using the laser beam generator 600, the desired alignment film pattern 730 may be directly obtained without using a separate etching process using a mask.

[83] As described above, in accordance with the third embodiment, since the alignment film forming material is coated on an entire surface of the substrate 700 using the spin coating or the roll coating, a single printing rubber plate for coating the alignment film forming material on the entire surface of the substrate 700 may be used even when the roll coating method is used for coating the entire surface of the substrate 700. Therefore, the printing rubber plate is not required to be changed according to the size and shape of the liquid crystal display to be manufactured.

[84] On the other hand, the alignment film forming material which is the polyamide- based high molecular compound coated on the substrate 700 is cured by undergoing a pre-baking process carried out at a temperature ranging from 60 to 80°C and a main curing process carried out at a temperature ranging from 80 to 200°C. Here, the laser beam may effectively remove the polyamide in a liquid state as well as the polyamide that underwent the pre-baking or the main curing process. Therefore, the removal of the alignment film using the laser beam generator 600 may be carried out after the pre- baking process or the main curing process, or immediately after the coating of the alignment film forming material on the substrate 700 or after a rubbing process of the alignment film if required. Hereinafter, the alignment film commonly refers to the alignment forming material, the pre-baked or cured alignment film or the alignment film that underwent the rubbing process except noted otherwise.

[85] Fig. 18 is a diagram illustrating a process for forming an alignment film on a substrate using a laser beam generator in accordance with the third embodiment of the

present invention.

[86] As shown in Fig. 18, when the substrate 700 is moved to be disposed on a stage

740, the laser beam generator 600 is moved to form the alignment film pattern 730 on the substrate 700. More specifically, when the substrate 700 is supplied to the stage 740 by a substrate supplying unit (not shown), the laser beam generator 600 generating the laser beam 651 is conveyed by an x-axis conveying means 750 and a y-axis conveying means 760 to a predetermined position, and an unnecessary alignment film is selectively removed to form the alignment pattern 730 on the substrate 700.

[87] When the alignment pattern 730 is formed by the above process, the alignment grooves 710 and 720 in the horizontal and vertical directions are formed. When the alignment grooves 710 and 720 in the horizontal and vertical directions are formed by removing a portion of the alignment film by the laser beam 651 generated by the laser beam generator 600, a switching device and a wiring array formed on the substrate 700 are exposed, and a wiring connection for completing the liquid crystal display becomes possible accordingly.

[88] On the other hand, it is preferable that a plurality of the laser beam generators 600 are installed for forming the alignment film pattern of the substrate 700 having a large area. When the plurality of the laser beam generators 600 are installed, pluralities of the alignment grooves 710 and 720 in the horizontal and the vertical directions may be formed simultaneously to reduce a time required to form the alignment film pattern of the substrate 501 having the large area.

[89] [Fourth embodiment]

[90] The fourth embodiment is characterized in that an alignment film forming material, which is polyamide-based high molecular compound, is annealed using a laser beam contrary to the third embodiment.

[91] Fig. 19 is a block diagram schematically illustrating a structure of a laser beam generator in accordance with a fourth embodiment of the present invention.

[92] As shown in Fig. 19, an initial laser beam 811 generated form a laser generating apparatus 810 is passed through a beam enlarger 820 and a beam homogenizer 830. A laser beam 831 that has passed through the beam homogenizer 830 is reflected toward a substrate 900 by a reflector 840, and then reaches a focusing lens 860 by diffusing at a predetermined angle. A laser beam 851 that has reached the focusing lens 860 is converted into a parallel laser beam 861 having a predetermined width to reach the substrate 900.

[93] More specifically, the initial laser beam 811 generated in the laser generating apparatus 810 is enlarged to a desired size by passing through the beam enlarger 820, and a laser beam 821 that has passed through the beam enlarger 820 then passes through the beam homogenizer 830 to have a uniform energy distribution. The initial

laser beam 811 has a characteristic of a single mode or a multi-mode, and has a nonuniform energy distribution. However, a final laser beam 851 that reaches the substrate 900 should have a parallel and a uniform beam characteristic. Therefore, the initial laser beam 811 sequentially passes through the beam enlarger 820 and the beam ho- mogenizer 830. Thereafter, the laser beam 831 that has passed through the beam ho- mogenizer 830 is reflected toward the substrate 900 by the reflector 840. Here, an energy of a reflected laser beam 841 is not lost and the reflected laser beam 841 is transmitted to the laser beam transmitting means 850 to have the same energy and energy distribution as those of the laser beam 831 incident on the reflector 840. The laser beam 841 that reached the laser beam transmitting means 850 passes through the laser beam transmitting means 850 to be diffused at the predetermined angle, thereby being converted into the laser beam 851 having a band type cross-section. Thereafter, the laser beam 851 is converted into the laser beam 861 having the parallel and uniform energy distributions to reach the substrate 900. Through these processes, the laser beam 861 that reaches the substrate 900 cures the alignment film forming material coated on the substrate 900.

[94] As described in the third embodiment, while the laser beam generally has an energy density ranging from 10 ⁶ to 10 ⁷ W/cm ² , the laser beam is diffused by passing through the laser beam transmitting means 850 to have an energy density suitable for curing the alignment film forming material. In order to diffuse the laser beam, a device such as a diffusion lens is included in the laser beam transmitting means 850.

[95] When the laser beam generator 800 having the above-described structure is used, a laser beam having a desired size may be generated without using an additional equipment or an apparatus to easily correspond to the change in the size of the substrate 900 and the width of the alignment film pattern 930 (see Fig. 20) to be formed. A width of the laser beam that is diffused by passing through the laser beam transmitting means 850 ranges from 20 to 1300mm. In addition, since the laser beam generator 800 is small in its size, a continuous processing of a surface of an object by a scanning method along a predetermined path is possible, thereby preventing the process delay problem, and once the plasma is generated, the plasma may be used until the completion of the process. Generally, a scanning speed of the laser beam ranges from 1 to 20 m/min.

[96] Fig. 20 is a diagram illustrating a state wherein a predetermined alignment film pattern is formed on a substrate by a laser beam generator.

[97] As shown in Fig. 20, when the alignment film forming material, which is the polyamide-based high molecular compound, coated on the substrate 900 is selectively cured, the desired alignment pattern 930 is formed. That is, when the laser beam generator 800 is moved at a predetermined speed to scan the substrate 900, the

alignment film forming material is cured to form the alignment film pattern 930 denoted in dotted line. A portion of the alignment film forming material that is not cured is removed by a cleaning process.

[98] The fourth embodiment is characterized in that the alignment film forming material is subjected to a pre-baking or a main curing process using a laser beam. The laser beam generated in the laser beam generator 800 is diffused by passing through the laser beam transmitting means 850 to have the suitable energy density for curing the alignment film forming material. An irradiating time of the laser beam is also adjusted. When the alignment film forming material is pre-baked or cured using the laser beam to form the alignment film pattern 930, the process time is reduced since the pre- baking or the main curing process is carried out with the formation process of the alignment film pattern simultaneously.

[99] Fig. 21 is a diagram illustrating a process for forming an alignment film pattern on a substrate using a laser beam generator in accordance with the fourth embodiment of the present invention.

[100] As shown in Fig. 21, when the substrate 900 is moved to be disposed on a stage

940, the laser beam generator 800 is moved to cure the alignment film forming material coated on the substrate 900, thereby forming the alignment film pattern 930. More specifically, when the substrate 900 is supplied to the stage 940 by a substrate supplying unit (not shown), the laser beam generator 800 generating the laser beam 851 is conveyed by an x-axis conveying means 950 and a y-axis conveying means 960 to a predetermined position, and the alignment film forming material is cured to form the alignment pattern 930 on the substrate 900.

[101] When the alignment film forming material that is not cured by the laser beam 861 is removed by the cleaning process, alignment grooves 910 and 920 are formed. When the alignment grooves 910 and 920 are formed by the cleaning process, a wiring connection for completing the liquid crystal display becomes possible since a switching device and a wiring array formed on the substrate 900 are exposed.

[102] On the other hand, it is preferable that a plurality of the laser beam generators 800 are installed for forming the alignment film of the substrate having a large area. When the plurality of the laser beam generators 800 are installed, pluralities of the alignment film patterns may be formed simultaneously to reduce a time required to form the alignment film pattern of the substrate 900 having the large area.

[103] While the present invention has been particularly shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be effected therein without departing from the spirit and scope of the invention as defined by the appended claims.

Industrial Applicability

[104] In accordance with the present invention, the predetermined alignment film pattern is formed by using the atmospheric plasma or the laser beam after the alignment film forming material is coated on the entire surface of the substrate. Therefore, the replacement of the printing rubber plate according to the change in the size of the liquid crystal display even when the alignment film forming material is coated using the roll coating method, thereby improving a manufacturing efficiency by preventing the interruption of the process for the replacement of the printing rubber plate as well as reducing the manufacturing cost of the printing rubber plate.

[105] In addition, since the relief pattern is not required to be formed on the printing rubber plate, a problem of a deformation of the relief pattern due to a pressure and a problem of a damage of the printing rubber plate during the attachment of the relief pattern may be prevented to extend a life span of the printing rubber plate.

[106] In accordance with the present invention, the continuous process is possible because the predetermined alignment film pattern is formed on the substrate using the small atmospheric plasma jet. Therefore, the process time delay problem because of the initial plasma stabilization according to turning on and off the plasma, and the problem of the defective alignment formation due to the unstable plasma may be solved. In addition, since the development of an additional atmospheric plasma generator according to the enlargement of the substrate is not necessary, the problem of an increase in the manufacturing cost for developing the atmospheric plasma generators corresponding to the substrate and the problem of moving and rotating the large atmospheric plasma generator may be solved.

[107] In accordance with the present invention, the predetermined alignment film pattern is formed by using the laser beam generator to obtain a clear-cut alignment film pattern. In addition, the width and the intensity of the laser beam may be easily varied to correspond to the changes in the sizes of the substrate and the alignment film pattern to be manufactured.

[108] In addition, since the size of the laser beam generator is small and the continuous processing is possible by the scanning method, a prompt processing is possible, and once the laser beam is generated, the laser beam may be used until the completion of the process. On the other hand, when the alignment film pattern is formed by subjecting the alignment film forming material to the pre-baking or the main curing process using the laser beam, the pre-baking or the main curing process of the alignment film forming material may be carried out with the formation process of the alignment film pattern simultaneously, thereby reducing the process time.