KR101279538B1 - Method of aligning alingment layer and OCB mode LCD device having alingment layer aligned through the method - Google Patents

Abstract

The present invention includes the steps of printing an alignment film on a substrate; Irradiating an ion beam on a first region of the printed alignment layer; Irradiating an ion beam to a second region spaced apart from the first region, wherein the side chains of the alignment layer are removed in the first and second regions, and the third region between the first and second regions It is a feature that the pretilt angle of the liquid crystal molecules positioned on the alignment film can be freely adjusted by providing the alignment method of the alignment film characterized by the presence of side chains perpendicular to the alignment film surface.

Ion Beam, Mono-Oriented Membrane, Pretilt Angle

Description

Method of aligning alingment layer and OCB mode LCD device having alingment layer aligned through the method}

The present invention relates to an alignment method, and more particularly to an alignment method capable of adjusting the pretilt angle of the liquid crystal molecules.

 Recently, liquid crystal displays have been spotlighted as next generation advanced display devices having low power consumption, good portability, high technology value, and high added value.

Among these liquid crystal display devices, an active matrix type liquid crystal display device having a thin film transistor, which is a switching device capable of controlling voltage on / off for each pixel, It is attracting attention.

In general, an LCD device forms an array substrate and a color filter substrate through an array substrate manufacturing process for forming a thin film transistor and a pixel electrode, and a color filter substrate manufacturing process for forming a color filter and a common electrode, respectively. It completes through the liquid crystal cell process through a liquid crystal between them.

In more detail, referring to FIG. 1, which is an exploded perspective view of a general liquid crystal display device, as illustrated, the array substrate 10 and the color filter substrate 20 face each other with the liquid crystal layer 30 interposed therebetween. The array substrate 10 of the lower part includes a plurality of gate lines 14 and data lines 16 arranged vertically and horizontally on the upper surface of the transparent substrate 12 to define a plurality of pixel regions P. Thin film transistors Tr are provided at the intersections of the two wires 14 and 16 to be connected one-to-one with the pixel electrodes 18 provided in the pixel regions P. FIG.

In addition, the upper color filter substrate 20 facing the array substrate 10 is a rear surface of the transparent substrate 22 and non-display of the gate wiring 14, the data wiring 16, and the thin film transistor Tr. A grid-like black matrix 25 is formed around the pixel region P so as to cover the region, and red (R) and green are sequentially arranged in order to correspond to the pixel region (P) in the grid. A color filter layer 26 including (G) and blue (B) color filter patterns 26a, 26b, and 26c is formed, and is transparent over the entire surface of the black matrix 25 and the color filter layer 26. The common electrode 28 is provided.

The manufacturing process of the above-mentioned liquid crystal display device is briefly described.

First, an array substrate forms a plurality of switching elements such as thin film transistors through deposition, photo-lithography, and etching processes, and each of the switching devices. The pixel corresponding to the pixel is formed in a matrix form, and is completed by forming an array pattern in which wiring is crossed around the switching element and a pad portion is formed at one end of each wiring.

In addition, the color filter substrate is completed by forming a color filter layer in which black matrix (BM), red, green, and blue are repeated on the surface facing the array substrate, and forming a common electrode under the black matrix (BM) and the color filter layer. do.

Subsequently, the liquid crystal is filled between the array substrate and the color filter substrate manufactured as described above, and the cells are bonded to each other to form a liquid crystal panel, thereby forming a liquid crystal display device.

The liquid crystal display device utilizes the electro-optical effect of the liquid crystal, and the electro-optic effect is determined by the anisotropy of the liquid crystal itself and the molecular arrangement state of the liquid crystal, and the control of the molecular arrangement of the liquid crystal is an image in the liquid crystal display device. It will greatly affect the stabilization of the display quality.

Therefore, an alignment process is performed to evenly arrange the initial arrangement of liquid crystal molecules in the liquid crystal layer interposed between the two substrates.

The alignment process can be broadly divided into an alignment film printing process for forming an alignment film on a substrate, and an alignment film surface treatment process for forming polymer chains having directivity in a predetermined direction on the surface of the alignment film formed on the substrate.

The alignment film printing process is a process of forming a polymer material mainly used as an alignment film on an entire surface of an array substrate or a color filter substrate with an even thickness. More precisely, the alignment layer is not formed on the entire surface of the substrate, but only in the region where the liquid crystal layer is to be formed, that is, the active region in which an image is displayed. Therefore, when the alignment layer is formed on the entire surface of the substrate by spin coating or the like, the etching process must be further performed to remove the alignment layer formed in the non-display region other than the active region. Thus, using a transfer plate pre-patterned to correspond to the active region It is mainly formed on a board | substrate by the method of printing on a board | substrate.

Thereafter, the substrate on which the alignment layer is formed is maintained in a drying furnace and a curing furnace, respectively, to remove moisture in the alignment layer and to be cured to maintain an appropriate hardness.

Next, surface treatment of the alignment layer is performed to form a high-injection chain having a certain orientation on the surface of the cured alignment layer, and the alignment layer surface treatment process is generally performed by rubbing.

Here, the conventional orientation film surface treatment method by rubbing is demonstrated with reference to drawings.

2A and 2B are plan views and cross-sectional views briefly showing an alignment film surface treatment process by conventional rubbing.

As illustrated, when the substrate 40 on which the alignment layer 45 is formed is positioned on the stage 30 of the rubbing device, the rubbing roll 50 having the rubbing cloth 55 made of a material such as rayon is wound on the surface of the substrate 40. 40 and the predetermined gap (gap) is maintained while, at the same time the rubbing roll 50 is to rotate at a high speed, at this time, the rubbing cloth (55) attached to the surface of the rubbing roll 50 is the substrate The alignment layer 45 on the 40 is in contact with the surface of the alignment layer 45. More precisely, while the rubbing cloth 55 attached to the surface of the high-speed rotating rubbing roll 50 contacts the substrate 40, the stage 30 or the rubbing roll 50 moves in one direction at a constant speed. Thus, the surface of the entire alignment layer 45 on the alignment layer substrate is rubbed with the rubbing cloth 55 so that the polymer chains (hereinafter referred to as side chains) formed therein on the surface of the alignment layer 45 are aligned in one direction. Therefore, the side chain of the surface of the alignment film 45 is more orientated in a constant direction more precisely. At this time, even the pretilt angle of the liquid crystal molecules is controlled to some extent by the side chain.

However, the pretilt angle defined by the long axis of the liquid crystal molecules before driving is formed at an angle between the substrate surface and the alignment layer surface preferably has an angle of 0-3 degrees in the TN mode and the transverse electric field type liquid crystal display device. After the above-mentioned rubbing, the liquid crystal molecules may be arranged in one direction with a pretilt angle of about 0-3 degrees. In the case of a vertical mode liquid crystal display, the pretilt angle is preferably 87 to 90 degrees. This may allow the liquid crystal molecules to be aligned in one direction with a pretilt angle of about 0-3 degrees by forming the vertical alignment layer on the substrate.

 Meanwhile, with the newly developed image display modes of the liquid crystal display device, a pretilt angle of 40-50 degrees is required in addition to a pretilt angle of 0-3 degrees or 87-90 degrees, and a pretilt angle of 0-90 degrees is further increased. There is a demand for an alignment film in which the pretilt angle can be freely adjusted by the progress of the process.

However, the alignment film having a range of 0-90 degrees has been studied due to the difficulty in blending polymer materials having different inclinations, but has not been put into practical use, and has been used in all angle ranges by appropriately combining the horizontal alignment film and the vertical alignment film and adjusting the intensity of rubbing. -90 degrees) to have a pretilt angle in the desired angle range.

However, the method of implementing the pretilt angle of the conventional alignment film that implements the pretilt angle of the desired angle among the above-described 0-90 degree angle ranges of the alignment film requires several alignment film printing processes to properly combine the horizontal alignment film and the vertical alignment film. In the process, as the alignment film printing process and the cleaning process are additionally compared to the process of forming a single alignment film having a pretilt angle in a specific angle range, a problem in manufacturing cost increases.

In addition, the alignment film printing method using the transfer plate has a desired pretilt angle due to misalignment between patterns when printing by using a transfer plate having different patterns due to the transfer plate having increasing characteristics. It is happening.

In addition, since several rubbing treatment processes are involved for surface treatment of the alignment film, a number of problems due to rubbing are generated.

 Due to the rubbing characteristics, since rubbing cloths made of materials such as rayon rub against the substrate, the portals on the surface of the rubbing cloths generate a lot of particles by leaving the rubbing cloths, and a lot of fine dust is generated from the rubbing cloths themselves. It adversely affects the manufacture of substrates for liquid crystal display devices requiring high cleanliness.

In addition, the static electricity generated on the substrate by friction with the substrate caused by the rubbing cloth causes problems such as disconnection of the wiring formed on the substrate or deterioration of switching element characteristics. In addition, the length of the rubbing roll increases as the size of the substrate increases. In this case, the eccentric effect increases when the rubbing roll rotates at a high speed, and the vibration is severely generated. There is a problem of lowering uniformity.

In addition, in recent years, as a high-definition driving is required for a liquid crystal display, characteristics such as a fast response speed and a wide viewing angle are required. For this purpose, an OCP (Modeally Compensated Bend: OCB) mode liquid crystal display is proposed. It became. In addition to the response speed and the viewing angle, the arrangement of the symmetric liquid crystal molecules with respect to the center part can eliminate the expensive compensation film required in the general liquid crystal display device, which has advantages in terms of manufacturing cost.

3A to 3C are schematic cross-sectional views illustrating arrangement states of liquid crystal molecules according to driving of a conventional OCB mode liquid crystal display. Specifically, FIG. 3A shows a splay state, FIG. 3B shows a band I state, and FIG. 3C shows a band II state.

In the OCB mode liquid crystal display, a first alignment layer 62 is formed on a first substrate 60 on which a thin film transistor (not shown), which is a switching element, and a pixel electrode (not shown) are formed. A color filter (not shown), a common electrode (not shown), and the like are formed on the second substrate 70 facing the 60, and a second alignment layer 72 is formed on the second substrate 70. The liquid crystal layer 80 made of liquid crystal molecules 82 and 84 is filled between the first and second alignment layers 62 and 72.

Referring to FIG. 3A, which shows a splay state, the first liquid crystal molecules 82 adjacent to the first and second alignment layers 62 and 72 are in a state where the second liquid crystal molecules ( 84, and the first pretilt angle θ1 of the first liquid crystal molecules 82 is generally 1 with respect to the alignment layers 62 and 72 or the surfaces of the substrates 60 and 70. 3 ° to the center, and the second liquid crystal molecules 84 in the center have a horizontal state on the alignment layers 62 and 72 or the surfaces of the substrates 60 and 70.

When a voltage is applied in this splay state, the voltage reaches the band I state of FIG. 3B, and the voltage at this time is called an initial voltage (V _I ). The OCB mode liquid crystal display is turned on by applying an initial voltage and displays a white image. In this state, the first liquid crystal molecules 82 adjacent to the first and second alignment layers 62 and 72 have a second pretilt angle θ2 greater than the first pretilt angle θ1 in the splay state. The second liquid crystal molecules 84 in the center have a state perpendicular to the surfaces of the alignment layers 62 and 72 or the substrates 60 and 70.

When a voltage equal to or greater than a driving voltage greater than the initial voltage is applied, a band II state is provided as shown in FIG. 3C, and the OCB mode liquid crystal display is turned off to display a black image. In this case, the first liquid crystal molecules 82 adjacent to the first and second alignment layers 62 and 72 have a third pretilt angle θ3 greater than the second pretilt angle θ2 in the band I state.

Referring to FIG. 4 showing the relationship between the driving state of the OCB mode and the applied voltage as described above, since the OCB mode liquid crystal display is driven from the band I state to the band II state, the biggest advantage is that the response speed is high. Becomes That is, the response speed can be improved by applying a voltage in a state where the liquid crystal molecules have a second pretilt angle larger than the first pretilt angle in the first splay state. This causes a problem of increased power consumption by the initial voltage applied to have the second pretilt angle θ2 in the state.

Accordingly, the present invention uses a single alignment film to solve the problems described above, aligns the side chains of the surface of the alignment film in a certain direction without performing several rubbing processes, the liquid crystal molecules in the full range of 0 degrees to 90 degrees It provides a method for forming an alignment film to have a pretilt angle of a desired angle with respect to.

In addition, the liquid crystal molecules having a pretilt angle of 20 to 70 degrees, to provide an OCB mode liquid crystal display device that solves the problem of increased power consumption by applying the initial voltage.

In order to solve the above problems, the present invention comprises the steps of printing an alignment film on a substrate; Irradiating an ion beam on a first region of the printed alignment layer; Irradiating an ion beam to a second region spaced apart from the first region, wherein the side chains of the alignment layer are removed in the first and second regions, and the third region between the first and second regions It provides a method for aligning the alignment film, characterized in that the side chain is perpendicular to the surface of the alignment film.

In addition, the first substrate; A first alignment layer formed on the first substrate and having a second region defined between a plurality of first regions and two adjacent first regions among the plurality of first regions; A second substrate facing the first substrate; A second alignment layer formed on the second substrate and facing the first alignment layer; A first liquid crystal layer positioned between the first and second alignment layers, the liquid crystal layer including a plurality of liquid crystal molecules, and positioned in the first region of the liquid crystal molecules and in contact with the first alignment layer; The second liquid crystal molecule having a square and positioned in the second region of the liquid crystal molecules and in contact with the first alignment layer has a second line inclination angle smaller than the first pretilt angle, and the first and second of the liquid crystal molecules. The third liquid crystal molecules positioned between the liquid crystal molecules have a third linear inclination angle smaller than the first pretilt angle and larger than the second pretilt angle.

The present invention is advantageous in that the pretilt angle of the liquid crystal molecules can be formed to have a desired angle in a range of 0 to 90 degrees with respect to a single alignment layer by implementing a method of selectively irradiating an ion beam having an appropriate energy intensity while using a single alignment layer. There is this.

Therefore, a single alignment film is used, and furthermore, since the alignment film printing process and the rubbing process are not required several times, the process is simplified and the manufacturing cost is reduced.

In addition, there is an effect of ensuring a uniform alignment state with respect to the entire substrate area.

In addition, by providing an alignment film having a pretilt angle of 20 to 70 degrees, solving the problem of increased power consumption by applying an initial voltage, it has advantages of wide viewing angle, fast response speed, and omits the compensation film, thereby providing advantages in terms of manufacturing cost. There is an effect that can provide an OCB mode liquid crystal display having.

Hereinafter, a method of forming a single alignment layer capable of adjusting the pretilt angle of liquid crystal molecules between 0 degrees and 90 degrees according to an embodiment of the present invention will be described with reference to the drawings.

First, the structure of the ion beam irradiation apparatus used in the present invention will be briefly described.

FIG. 5 is a view schematically illustrating an ion beam irradiation apparatus used in an alignment layer surface treatment method capable of adjusting the pretilt angle of liquid crystal molecules through ion beam irradiation according to an embodiment of the present invention.

As shown in FIG. 5, the ion beam irradiation apparatus 100 includes a chamber 150 for creating a vacuum state, an ion generator 110 inside the chamber 150, and a stage on which the substrate 145 is located. 140). In this case, the chamber 150 is connected through a vacuum pump (not shown) and an exhaust pipe 155 for making a vacuum, and the gas supply pipe for supplying gas for generating ions to the ion generator 110. 130 is connected.

At this time, during the ion beam irradiation, the vacuum degree in the chamber 150 is preferably maintained at about 10 ⁻⁷ Torr to about 760 Torr.

Next, the ion generator 110 includes a plasma generator 115 for ionizing the gas supplied therein into ions, an acceleration electrode 120 for allowing the generated ions to have a constant speed and energy, and ions. It consists of an outlet 123.

The ion beam irradiation apparatus 100 is designed such that the ion generator 110 may be positioned at a specific angle selected from 1 degree to 90 degrees with respect to the surface of the stage 140, and further, the ion generator 110 may be located. The ion outlet 123 is characterized in that the width is formed the same as or smaller than the width of the substrate 145.

In the ion beam irradiation apparatus 100 having such a configuration, the ion generating unit 110 or the stage 140 is formed to enable linear reciprocating motion in one direction (in the drawing, the stage is linear reciprocating in one direction). In this case, the ion generator 110 or the stage 140 performing the linear reciprocating motion has a function of stopping at a predetermined interval while moving in one direction. At this time, the ion generating unit 110 is characterized in that it is configured to be movable in a direction perpendicular to the direction in which the ion generating unit 110 or the stage 140 moves.

This is because when the width of the ion outlet 123 is smaller than the width of the substrate 145, the width of the substrate 145 is moved relative to the width of the ion outlet 123 by moving perpendicularly to the moving direction of the stage 140. In the case of a large number of times, a plurality of vertical movements are performed to finally enable ion beam irradiation to the entire substrate 145.

Thus, the irradiation of the ion beam onto the substrate 145 is a periodic on, off operation of the ion beam and the stage 140 or ion when the irradiation time is very short, for example, less than 1 second. This is achieved by the movement of the scan unit in one direction of the generator 110 in one direction, or when the irradiation time is long, for example, when the ion beam is longer than 1 second, the on and off operations of the ion beam It is characterized by being performed by the repetitive operation of the periodic movement and stop of the stage 140 or ion generator 110. In particular, in the case where the ion beam irradiation time is long, an ion beam irradiation area IA irradiated at a predetermined angle with respect to the substrate 245 is formed on the substrate 245, and the stage 240 or the ion generating unit 110 is provided. ) Moves at a constant speed and stops periodically in one direction, while the ion beam is turned off when moving and the ion beam is turned on when it is stopped. The ion beam irradiation is selectively performed for.

The reason why the ion beam irradiation should proceed for this selective region will be described later.

Next, the ion generator 110 will be briefly described.

The ion generator 110 includes a plasma generator 115, an acceleration electrode 120, and an ion outlet 123. High pressure is applied to the plasma generating unit 115 using an inert gas supplied from the outside to the ion generating unit 110 as a medium to generate plasma, and the gas is ionized to supply the plasma generating unit 115. Ions are generated due to the type of gas, the ions filled in the plasma generating unit 115 has an appropriate energy intensity by the acceleration electrode 120, the ions having the appropriate energy intensity in the grid (grid) form The ion discharge port 123 is discharged into the vacuum chamber 150, and the discharged ions having a specific energy intensity collide with the alignment layer (not shown) on the substrate 145 at a predetermined angle so that the alignment layer is not shown. On the surface, side chains are removed from the main chain, and the ions colliding with the substrate 145 after performing this role are passed through an exhaust pipe 155 connected to a vacuum pump (not shown). Chamber 150 is discharged to the outside.

At this time, the gas mainly used for generating the ion beam in the above description is mainly inert gas, for example, He, Ne, Ar, Kr, Xe, and the like, using the inexpensive Ar among these inert gases in terms of cost It would be preferable.

Hereinafter, the alignment method characterized by controlling the pretilt angle of the liquid crystal molecules according to the present invention using the ion beam irradiation apparatus having the above-described configuration.

6A and 6B illustrate a step-by-step orientation method of manufacturing a single alignment layer capable of controlling pretilt angle by ion beam irradiation according to the present invention, and FIGS. 7A and 7B illustrate surface change of an alignment layer by treating an alignment layer surface through ion beam irradiation. Figure is a simplified view. In the drawings, only the alignment layer is illustrated on the substrate, and components such as a switching element or a color filter are omitted.

First, as shown in FIG. 6A, the alignment layer 230 is formed on the substrate 220 positioned on the stage 205. In this case, the alignment layer 230 is preferably a vertical alignment layer having a long side chain perpendicular to the surface thereof. In this case, the substrate 220 is an array substrate or liquid crystal display device having a gate and a data line (not shown) that cross each other, a thin film transistor (not shown), which is a switching element, and a pixel electrode (not shown) connected thereto. It is preferable to form a liquid crystal panel by bonding the array substrate and the liquid crystal layer to form a color filter substrate having a color filter layer (not shown) and a common electrode (not shown).

The alignment layer 230 may be formed of a polymer material such as polyimide, which forms a vertical alignment layer having a long side chain, by a doctor roll 212 or a doctor blade (not shown), anilox roll 210, a plate 208, It can be formed using an alignment film printing apparatus 200 having a stage 205 and a patterned transfer plate 215 attached to the surface of the plate 208. First, the polymer material is evenly applied to the surface of the transfer plate 215 through the anilox roll 210, and then the plate 208 rotates the transfer plate 215 coated with the polymer material, and the stage 205 is applied. ) Is instantaneously contacted and separated from the surface of the substrate 220 positioned on the stage 205 by linear reciprocating at a constant speed, thereby transferring the polymer material to the surface of the substrate 220 in a predetermined pattern.

Subsequently, the substrate 220 on which the alignment layer 230 is formed is maintained for a predetermined time in a drying furnace (not shown) and a curing furnace (not shown) heated to an appropriate temperature to have a suitable thickness (usually 500 kPa to 1500 kPa) and a suitable hardness (1H). To 4H) to form a cured alignment layer 230.

Referring to FIG. 7A, which illustrates an alignment layer 230 on a substrate 220 formed by performing the above-described process, a main chain of a polymer material constituting the alignment layer 230 is formed at an interface between the substrate 220 and the alignment layer 230. It can be seen that the complex is entangled with each other to form a base, and a plurality of long side chains 240 are formed in the main chain (not shown). In this case, the side chain 240 has an angle of 87 to 90 degrees with respect to the surface of the substrate 220 due to the characteristic of the vertical alignment layer 230.

Next, as shown in FIGS. 6B and 7B, by using the ion beam irradiation apparatus 260 having the above-described configuration, the side chain 240 has an angle of 87 degrees to 90 degrees with respect to the surface thereof. Stage 285 through an ion beam irradiator 260 adjusted to have an ion outlet at an appropriate angle with respect to the substrate 220, that is, 1 degree to 90 degrees to the substrate 220 on which the alignment layer 230 having the film is formed. Alternatively, the ion generator 266 moves or stops in one direction and periodically stops, and at the same time, the ion beam 277 is irradiated by periodically repeating scanning of the off and on of the ion beam 277. do. An angle formed between the ion beam irradiation device 260 and the surface of the substrate 220 may be about 30 degrees.

At this time, when examining the ion beam 277 irradiation process of the ion beam irradiation device 260, if the substrate 220 on which the alignment layer 230 is formed is located on the stage 285 of the ion beam irradiation device 260, The air inside the chamber 263 is discharged to the outside through the exhaust pipe 280 by a pump (not shown) to form a vacuum having a vacuum degree of 10 ⁻⁷ Torr to atmospheric pressure (760 Torr) in the chamber 263. At the same time, an inert gas is injected into the ion generator 266 in the ion beam irradiation device 260 through the gas supply pipe 278, and the injected inert gas is provided in the ion generator 266 in the plasma generator 269. Ionized ion is discharged through the ion outlet 275 positioned at a specific angle with respect to the surface of the substrate 220 by the acceleration electrode 272, and the ionized ion is discharged to the ion through the ion outlet 275 The ion beams 277 discharged through the N-axis are emitted at a predetermined angle by the positions of the stage 285 and the ion outlet 275 of the ion generator 266 and are irradiated to the alignment layer 230 on the substrate 220. . In this case, the irradiated ion beam 277 has an amount of 10 ¹¹ to 10 ¹³ doses per square centimeter and an energy intensity of 50 eV to 2000 eV, and the ion acceleration voltage at this time is preferably 100 V to 10 KV. In addition, the ion beam 277 is preferably irradiated for 0.1 to 300 seconds to the selected area, that is, the portion (B) from which the side chain is to be removed.

When the ion beam 277 is irradiated to the surface of the alignment film 230 for a predetermined time, the side chain 240 is broken in the alignment film region B to which the ion beam 277 is irradiated. The side chain 240 in a vertical state is removed, resulting in only the main chain (not shown) constituting the base.

In this case, the ion beam 277 is irradiated so as to be alternately spaced apart from the area A in which the side chain 240 remains and the region B in which the side chain 240 has been removed by the ion beam 277 irradiation at regular intervals. By performing these two lines (A, B) it is possible to appropriately adjust the pretilt angle of the liquid crystal molecules between 0 degrees and 90 degrees. At this time, it was found experimentally that the most important factor for determining the pretilt angle of the liquid crystal molecules by irradiation with the ion beam 277 is irradiation time.

8 is a view showing an initial arrangement state of liquid crystal molecules in a region A having a side chain and a region B having no side chain on the surface of an alignment film by performing ion beam irradiation according to the present invention.

As illustrated, the first liquid crystal molecules 292a positioned closest to the alignment layer 230 of the region B in which the side chain 240 is removed by ion beam irradiation have a long axis and a surface of the substrate 220. Alignment film 230 in a region A, which is arranged in one direction in parallel, i.e., with a pretilt angle θ of 0 degrees, and in which the side chain 240 remains in a state perpendicular to the surface of the substrate 220 because the ion beam is not irradiated. The second liquid crystal molecules 292b positioned closest to each other are arranged so that their major axis is perpendicular to the surface of the substrate 220, that is, the pretilt angle is 90 degrees. Influenced by the arrangement of the first and second liquid crystal molecules, the third liquid crystal molecules 292c positioned above the first and second liquid crystal molecules are arranged to have a pretilt angle θ having a specific angle. Therefore, the first and second liquid crystal molecules 292a which are most adjacent to the alignment layer 230 having the configuration in which the above-described ion beam irradiated the region B and the non-irradiated region A as a whole are alternately disposed. The third liquid crystal molecules 292c, which occupy most of them except for 292b, are arranged with a pretilt angle θ of a specific angle between 0 degrees and 90 degrees.

Meanwhile, referring to FIG. 9, which is a graph showing the size of the pretilt angle of the vertical alignment layer according to the ion beam irradiation time having the dose amount and the energy intensity of the predetermined size, in order to have the pretilt angle of 0 degrees of the liquid crystal molecules, It is possible to perform ion beam irradiation for a relatively long time, i.e., greater than 20 seconds, and to have a 90 degree pretilt angle by not performing ion beam irradiation or by performing a relatively very short time ion beam of less than 2 seconds, The angle of inclination between 0 degrees and 90 degrees is possible by selectively performing ion beam irradiation having a specific amount of dose and energy intensity for 2 to 20 seconds in the case of the experimental example. Looking at the graph, it can be seen that all of the pretilt angles of 0 degrees to 90 degrees depend on the ion beam irradiation time. In particular, it can be seen that in order to have a pretilt angle of 40 degrees to 70 degrees, ion beam irradiation having a specific amount of dose and energy intensity is performed on the vertical alignment layer by about 5.5 seconds to 12.5 seconds.

10 is a schematic cross-sectional view of an OCB mode liquid crystal display according to an exemplary embodiment of the present invention.

As shown, the OCB mode liquid crystal display 300 of the present invention is filled between the first and second substrates 310 and 320 facing each other, and the first and second substrates 310 and 320 and are filled with liquid crystals. The liquid crystal layer 330 is formed of molecules 332a, 332b, 332c, and 334. Although not shown, a plurality of gate lines and data lines intersect each other to define a pixel area on the first substrate 310, and a thin film transistor, which is a switching element, is formed in each pixel area, and is connected to the thin film transistor. The pixel electrode is provided.

Meanwhile, a black matrix is formed on the second substrate 320 to block light in response to non-display areas such as the gate line, the data line, and the thin film transistor, and the color filters of red, green, and blue correspond to each pixel area. A color filter layer composed of a pattern is formed. In addition, a common electrode is formed on the entire surface of the second substrate 320 above the black matrix and the color filter, thereby generating an electric field between the pixel electrodes to form the liquid crystal molecules 332a, 332b, 332c, and 334. Will be driven.

A first alignment layer 312 is formed on the pixel electrode, and a second alignment layer 322 is formed on the common electrode, and the liquid crystal layer 330 is in contact with the first and second alignment layers 312 and 322. have. The first and second alignment layers 312 and 322 determine the initial alignment direction of the liquid crystal molecules 332a, 332b, 332c, and 334, and are generally made of a material such as polyimide.

A characteristic feature of the present invention is the arrangement of liquid crystal molecules 332a, 332b, and 332c adjacent to the first and second alignment layers 312 and 322. Referring to the first alignment layer 312 and the liquid crystal molecules 332a, 332b, and 332c adjacent thereto, the first liquid crystal molecule 332a is perpendicular to the first alignment layer 312 (or the first substrate 310). In other words, the first pretilt angle is about 90 degrees, and the second liquid crystal molecules 332b are horizontally formed on the first alignment layer 312, that is, the second pretilt angle is about 0 degrees. The third liquid crystal molecules 332c between the first and second liquid crystal molecules 332a and 332b may have a third inclination angle (3) which is a value between the first and second pretilt angles of the first and second liquid crystal molecules 332a and 332b. θ). In particular, the third inclination angle θ is about 20 to 70 degrees, which is due to the elasticity of the liquid crystal molecules.

The first and second alignment layers 312 and 322 are vertical alignment layers, and may be made of polyimide. The first alignment layer 312 has a side chain substantially perpendicular to the surface of the first alignment layer 312 without irradiating an ion beam with respect to the first region A in which the first liquid crystal molecules 322a are positioned. The first liquid crystal molecules 322a have a first pretilt angle of about 90 degrees without being removed and protruding perpendicularly to the plane of the first alignment layer 312. On the other hand, the second region B in which the second liquid crystal molecules 322b are positioned is irradiated with an ion beam to completely remove the side chain thereof. As a result, the second liquid crystal molecules 322b have a second wire diameter of about 0 degrees. You have a blind spot. As described above, since the liquid crystal molecules are elastic, the third liquid crystal molecules 322c positioned between the first and second liquid crystal molecules 322a and 322b may have a value between the first and second pretilt angles. It becomes a structure to have.

As described above, the OCB mode liquid crystal display device has been limited in its application due to the increase in power consumption due to the initial voltage application, despite the advantages of wide viewing angle and fast response speed. However, according to the present invention, since the liquid crystal molecules have a pretilt angle of 20 to 70 degrees, the liquid crystal molecules have a band I state (see FIGS. 3A to 3B) without applying an initial voltage, so that driving is not performed without applying an initial voltage. It is possible. Therefore, the OCB mode liquid crystal display has an advantage without increasing power consumption.

In the OCB mode liquid crystal display, since the liquid crystal molecules in the first and second alignment layers 312 and 322 have a symmetrical structure, they do not require a compensation film, and thus manufacturing cost can be reduced.

In the above, the case in which the side chains of the second region B are all removed to describe the case where the second pretilt angle of the second liquid crystal molecule 332b is 0 degrees has been described. However, only a part of the side chains may be removed and the second pretilt angle may not be 0 degrees. . That is, the first pretilt angle of the first liquid crystal molecules 332a is about 90 degrees, and the second pretilt angle of the second liquid crystal molecules 332b is 10 to 20 degrees, so that the line diameters of the third liquid crystal molecules 332c are used. The blind spot θ can be appropriately adjusted. This is possible by adjusting the intensity or irradiation time of the ion beam irradiated to the second region B.

Further, the pretilt angle θ of the third liquid crystal molecules 332c is the first and second regions in a state where the second pretilt angle of the second liquid crystal molecules 332b of the second region B is about 0 degrees. It is also possible by adjusting the width of (A, B). The pretilt angle θ of the third liquid crystal molecules 332c is proportional to the area ratio between the first region A and the second region B. That is, as the area of the first region A increases, the pretilt angle θ of the third liquid crystal molecules 332c increases. Experimentally, when the area ratios of the first and second regions A and B are 0.5 to 3: 1, the pretilt angle θ of the third liquid crystal molecules 332c has 20 to 70 degrees. In addition, by simultaneously adjusting the second pretilt angle of the second liquid crystal molecules 332b and the area ratios of the first and second regions A and B, the third liquid crystal molecules 332c may have the desired pretilt angles. have.

1 is a schematic view of a general liquid crystal display device.

2A and 2B are a plan view and a cross-sectional view briefly showing an alignment film surface treatment process by conventional rubbing.

3A to 3C are schematic cross-sectional views illustrating an arrangement state of liquid crystal molecules according to driving of a conventional OCB mode liquid crystal display.

4 is a graph showing a relationship between a driving state and an applied voltage in a conventional OCB mode liquid crystal display.

FIG. 5 is a view schematically illustrating an ion beam irradiation apparatus used in an alignment layer surface treatment method capable of adjusting pretilt angles of liquid crystal molecules through ion beam irradiation according to an embodiment of the present invention.

Figure 6a and 6b is a step-by-step process of manufacturing a single alignment film capable of controlling the pretilt angle by ion beam irradiation according to the present invention.

7A and 7B show briefly the surface change of the alignment film by the alignment film surface treatment through ion beam irradiation.

FIG. 8 is a view showing an initial arrangement of liquid crystal molecules in a region A having a side chain and a region B having no side chain on the surface of an alignment film by performing ion beam irradiation according to the present invention. FIG.

9 is a graph showing the size of the pretilt angle of the vertical alignment layer with respect to the ion beam irradiation time having an energy intensity of a predetermined size.

10 is a schematic cross-sectional view of an OCB mode liquid crystal display according to an embodiment of the present invention.

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

220: substrate 230: alignment layer

260: ion beam irradiation device 263: chamber

266 ion generating unit 269 plasma generating unit

272: acceleration electrode 275: ion outlet

277 ion beam 278 gas supply pipe

280: vacuum exhaust pipe 285: stage

A: ion beam unirradiated area (area in which side chains remain)

B: ion beam irradiation area (region from which side chain is removed)

Claims (16)

Printing the alignment film on the substrate; Irradiating an ion beam on a first region of the printed alignment layer; Irradiating an ion beam to a second region spaced apart from the first region, Side chains of the alignment layer are removed in the first and second regions, and side chains of the alignment layer are present in a third region between the first and second regions.  The method of claim 1, And the ion beam can be turned on or off.  The method of claim 2, Selectively irradiating an ion beam onto the printed alignment layer, Positioning the substrate on which the alignment film is printed on a stage in a chamber of an ion beam irradiation apparatus; Repeating the on and off states of the ion beam while the ion generator or stage of the ion beam irradiation apparatus performs the periodic movement and stop operation in one direction An alignment method of the alignment film containing.  The method of claim 3, wherein The on state of the ion beam is performed when the ion generator or stage is stopped, and the off state is performed when the ion generator or stage is a moving operation.  The method of claim 2, The ion beam repeats the on (on), off (off) periodically, the ion generation unit or the alignment method of the alignment film, characterized in that the stage is moved and irradiated with a constant speed in one direction. The method of claim 1, The energy intensity of the ion beam is 50eV to 2000eV, the irradiation time of the ion beam is 0.1 seconds to 300 seconds alignment method of the alignment film. delete The method of claim 1, When the liquid crystal molecules are arranged on the alignment layer, the liquid crystal molecules of the first and second regions have a first pretilt angle with respect to the surface of the alignment layer, and the liquid crystal molecules of the third region with respect to the surface of the alignment layer A liquid crystal molecule having a second pretilt angle larger than the pretilt angle, and positioned between the first and third regions and between the second and third regions, is larger than the first pretilt angle with respect to the alignment layer surface, and the second pretilt angle. The alignment method of the alignment film characterized by having a third pretilt angle smaller than the square. 9. The method of claim 8, The first pretilt angle is 0 degrees, the second pretilt angle is 90 degrees, and the third pretilt angle is 20 to 70 degrees. 10. The method of claim 9, The ratio of the width of the third region to the sum of the widths of the first and second regions is 0.5 to 3: 1. A first substrate; A first alignment layer formed on the first substrate and having a second region defined between a plurality of first regions and two adjacent first regions among the plurality of first regions; A second substrate facing the first substrate; A second alignment layer formed on the second substrate and facing the first alignment layer; Located between the first and second alignment layer, comprising a liquid crystal layer comprising a plurality of liquid crystal molecules, First liquid crystal molecules positioned in the first region of the liquid crystal molecules and in contact with the first alignment layer have a first pretilt angle, and second liquid crystal molecules positioned in the second region of the liquid crystal molecules and in contact with the first alignment layer. Has a second pretilt angle smaller than the first pretilt angle, and a third liquid crystal molecule positioned between the first and second liquid crystal molecules among the liquid crystal molecules is smaller than the first pretilt angle and larger than the second pretilt angle. An OCB mode liquid crystal display device having a third pretilt angle. 12. The method of claim 11, The liquid crystal molecules of the liquid crystal molecules in contact with the second alignment layer form a symmetrical structure with the first to third liquid crystal molecules. 12. The method of claim 11, And the side chain of the alignment layer is removed by irradiating an ion beam to the second region. 12. The method of claim 11, Wherein the first pretilt angle is 90 degrees, the second pretilt angle is 0 degrees, and the third pretilt angle is 20 to 70 degrees. 15. The method of claim 14, An area ratio between the first region and the second region is in the range of 0.5 to 3: 1. 12. The method of claim 11, Between the first substrate and the first alignment layer, A plurality of gate lines and a plurality of data lines crossing each other to define pixel regions; A thin film transistor positioned in the pixel region; A pixel electrode connected to the thin film transistor is formed, Between the second substrate and the second alignment layer, A color filter corresponding to the pixel region; OCB mode liquid crystal display, characterized in that the common electrode is formed on the color filter.

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