This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application earlier filed in the Korean Intellectual Property Office on the 11th of March 2010 and there duly assigned Serial No. 10-2010-0021841.
1. Field of the Invention
Embodiments of the present invention relate to a method of manufacturing an alignment substrate and a method of manufacturing a liquid crystal display device having the alignment substrate, and more particularly, to a method of manufacturing an alignment substrate on which multiple alignment films are formed, and to a method of manufacturing a multi-domain liquid crystal display (LCD) device having the alignment substrate.
2. Description of the Related Art
A liquid crystal display (LCD) device is an image display device that displays images by controlling optical transmittance of light by applying a voltage to a liquid crystal layer interposed between an array substrate on which a pixel electrode is formed and a face substrate on which a common electrode is formed.
Among the liquid crystal display devices, a twisted nematic (TN) mode liquid crystal display device has advantages such as a higher optical transmittance, shorter response times and a simpler manufacturing process.
Recently, since the size of display devices increases, issues related to side visibility and viewing angle of the display devices become more significant. Therefore, interest in a multiple alignment technique of the TN mode liquid crystal display device has increased.
In order to solve the above and/or other problems, an embodiment of the present invention provides a method of manufacturing an alignment substrate on which multiple alignment films are formed, and a method of manufacturing a multi-domain liquid crystal display (LCD) device having the alignment substrate.
It is therefore one aspect of the present invention to provide an improved method of manufacturing an alignment substrate. The method may include steps of (a) preparing a first substrate on which an alignment film aligned in a first alignment direction is formed; (b) forming a plurality of fluoro-polymer patterns on the first substrate; (c) changing the alignment direction of regions of the alignment film on which the fluoro-polymer patterns are not formed; and (d) removing the fluoro-polymer patterns by using a fluoro-solvent.
In operation (b), the fluoro-polymer patterns may be formed by transferring the fluoro-polymer patterns formed on a stamping mold onto the first substrate.
The stamping mold may be a polydimethysiloxane (PDMS) mold.
In operation (b), after a fluoro-polymer layer is formed on the first substrate, the fluoro-polymer patterns may be formed on the first substrate by using a laser ablating method.
In operation (b), the fluoro-polymer patterns may be spaced apart from each other with a predetermined distance.
In operation (c), the alignment direction of the alignment film on which the fluoro-polymer patterns are not formed may be changed to a second alignment direction opposite to the first alignment direction.
In operation (c), the alignment film aligned in the first alignment direction may have the same area as the alignment film aligned in the second alignment direction.
In operation (c), the alignment direction of the alignment film may be changed by using a rubbing method.
In operation (c), the alignment direction of the alignment film may be changed by using a photo-alignment method.
It is another aspect of the present invention to provide a method of manufacturing an alignment substrate, and the method may include steps of (a) preparing a first substrate on which an alignment film aligned in a first alignment direction is formed; (b) forming a plurality of fluoro-polymer patterns on the first substrate; (c) changing the alignment direction of regions of the alignment film on which the fluoro-polymer patterns are not formed; (d) removing the fluoro-polymer patterns by using a fluoro-solvent; (e) preparing a second substrate having multiple alignment directions which are different from each other and are alternately disposed in the second substrate by performing operations (a) through (d) described above; and (f) combining the first substrate and the second substrate so that the alignment directions of the first substrate and the second substrate cross each other, and injecting liquid crystal between the first substrate and the second substrate.
In operation (b), the fluoro-polymer patterns may be formed by transferring the fluoro-polymer patterns formed on a stamping mold onto the first substrate.
In operation (b), after a fluoro-polymer layer is formed on the first substrate, the fluoro-polymer patterns may be formed on the first substrate by using a laser ablating method.
In operation (b), the fluoro-polymer patterns may be spaced apart from each other by a predetermined distance.
The stamping mold may be a polydimethysiloxane (PDMS) mold.
In operation (c), the alignment direction of the alignment film on which the fluoro-polymer patterns are not formed may be changed to a second alignment direction opposite to the first alignment direction.
In operation (c), the alignment film aligned in the first alignment direction may have the same area as the alignment film aligned in the second alignment direction.
In operation (c), the alignment direction of the alignment film may be changed by using a rubbing method.
In operation (c), the alignment direction of the alignment film may be changed by using a photo-alignment method.
In operation (e), the alignment films formed on the second substrate may have multiple alignment directions opposite to each other.
In the operation of (e), the alignment films having alignment directions opposite to each other may have the same area.
In operation (f), the first substrate and the second substrate may be combined so that the alignment directions of the first substrate and the second substrate perpendicularly cross each other.
In operation (f), a unit pixel of the LCD device may be defined to have four domains each having an alignment direction different from each other.
In operation (f), the liquid crystal may be a twisted-nematic (TN) mode.
A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein;
The present invention will now be described more fully with reference to the accompanying drawings in which exemplary embodiments of the invention are shown.
In a liquid crystal display device, surfaces of the electrodes in contact with the liquid crystal material are treated so as to align the liquid crystal molecules in a particular direction. This treatment generally uses a thin polymer layer that is unidirectionally rubbed. The direction of the liquid crystal alignment is then defined by the direction of rubbing. Electrodes may be made of a transparent conductor called Indium Tin Oxide (ITO). Before applying an electric field to the electrodes, the orientations of the liquid crystal molecules within the liquid crystal material are determined by the alignment at the surfaces of electrodes. As an example, in a twisted nematic mode liquid crystal display device, the surface alignment directions at the two electrodes may be perpendicular to each other. Therefore, the liquid crystal molecules may arrange themselves in a helical structure, or twist.
Referring to
The first substrate 11 may be formed of a glass material or a plastic material, but is not limited thereto.
The first alignment film 12 is formed on the first substrate 11 to be aligned in the first direction. The first alignment film 12 may be oriented in the first direction by rubbing an organic polymer of a polyimide group or by using a photo-alignment process. The photo-alignment process is an alignment film processing method in which light is irradiated on a photosensitive thin film formed on the surface of a substrate to provide liquid crystal alignment.
After a stamping mold 40, on which fluoro-polymer patterns 51 are formed, is aligned onto the first alignment substrate 10, as shown in
The fluoro-polymer may be one of the materials shown Chemical formulae I through 3, and also, may be a functional substance containing 10-50% fluorine.
where n is an integer between 50 and 1000, i.e., 50≦n≦1000.
where m and n respectively are integers between 50 and 1000, i.e., 50≦n≦1000 and 50≦m≦1000.
*CF2CF2n* [Chemical formula 3]
where n is an integer between 50 and 1000, i.e., 50≦n≦1000.
When the stamping mold 40 is removed from the fluoro-polymer patterns 51, since a solvent easily evaporates at room temperature, a subsequent process may be readily performed.
The stamping mold 40 may be a fine mold such as a polydimethysiloxane (PDMS) mold.
The PDMS mold may be formed to have a fine pattern of the stamping mold 40, such as a sub-pixel size corresponding to a domain of a multi-domain liquid crystal display device. Also, the stamping mold 40 may be formed to have fine patterns having various sizes and shapes. In the current embodiment, the stamping mold 40 may be formed so that the fluoro-polymer patterns 51 are disposed a predetermined distance D apart from each other.
Referring to
In this case, the second alignment may be performed in an opposite direction (180 degrees) to the first alignment direction, but is not limited thereto. The second alignment may be performed in a second alignment direction which is different from the first direction of the first alignment.
The second alignment may be performed by a rubbing process using rubber R, but is not limited thereto. For example, the second alignment may be performed with a photo-alignment process.
The fluoro-polymer patterns 51 transferred onto the first alignment film 12 may function as a protective layer for protecting the first alignment film 12 during the second alignment process. Therefore, regions of the first alignment film 12 on which the fluoro-polymer patterns 51 are formed is not affected by the second alignment process. Accordingly, the alignment direction of the regions of the first alignment film 12 covered by the fluoro-polymer patterns 51 is not changed.
However, regions 52 of the first alignment film 12 on which the fluoro-polymer patterns 51 are not formed lose their initial alignment direction obtained by the first alignment process, and thus, maintain an alignment direction obtained from the second alignment process. The alignment direction of the regions 52 exposed by the fluoro-polymer patterns 51 may be changed by the second alignment process from the first alignment direction to the second alignment direction.
Next, the fluoro-polymer patterns 51 transferred onto the first alignment film 12 are removed by using a fluoro-solvent (not shown). As a result, as shown in
In order to form an alignment substrate on which multiple alignment films are formed, an alignment process using a photoresist (PR) that is generally used to manufacture an inorganic semiconductor has been attempted. The alignment process using a PR is however complicated since such alignment process involves a photolithography process, and an alignment film may be physically or chemically damaged by a solvent used when the PR is coated or developed on the alignment film. Therefore, the characteristics of the alignment film may be degraded.
In order to prevent the problems described above, a photo-alignment process may be used. The photo-alignment process however has disadvantages, for example, a low anchoring problem and a reduction of the initial alignment characteristics over time, thereby reducing the reliability of an LCD device.
Halogen elements of Group 17 that includes fluorine have a characteristic of low reactivity with substances other than halogen elements. Thus, in the current embodiment, such characteristic of a fluorine group polymer and a fluorine group solvent may be used. Therefore, an alignment substrate on which a multiple alignment film is formed may be formed without having to involve a complicated process and the risk of damaging the alignment film.
The multi-domain LCD device includes the first alignment substrate 10 in which the first alignment film 12 is formed on a first substrate 11 and the second alignment substrate 20 in which a second alignment film 22 is formed on a second substrate 21, and a liquid crystal layer 30 interposed between the first alignment substrate 10 and the second alignment substrate 20.
In
As shown in
As shown in
In
As shown in
In the experiments, the alignment direction of the first alignment substrate 10 is disposed to perpendicularly cross the alignment direction of the second alignment substrate 20 as shown in
As shown in
From
Therefore, the electro-optical characteristic of a multiple domain LCD device having the multiple alignment substrate manufactured according to the present invention is not disadvantageously reduced.
Referring to
That is, a multi-domain LCD device having an alignment substrate according to the present invention, as described above, has a wide viewing angle and a high contrast ratio, and may be manufactured with a simpler manufacturing process.
Referring to
When the fluoro-polymer layer 50 is formed in a fluoro-solvent (not shown) having a low boiling point, the fluoro-polymer layer 50 having a uniform thickness from a few nanometers (nm) to a few micrometers (μm) may be formed.
Referring to
Referring to
At this point, the fluoro-polymer patterns 51 formed on the first alignment film 12 function as a protective layer for protecting the first alignment film 12 from the second alignment process. Therefore, the alignment direction of the first alignment film 12 covered by the fluoro-polymer patterns 51 is maintained.
Regions 52 of the first alignment film 12 on which the fluoro-polymer patterns 51 are not formed, however, lose their initial alignment direction. Therefore, the alignment direction of the regions 52 is changed due to the second alignment process.
Next, the fluoro-polymer patterns 51 are removed by using a fluoro-solvent (not shown). As a result, as shown in
In the current embodiment, after the fluoro-polymer patterns 51 are formed on the first alignment film 12 on which an initial alignment is determined by using a laser ablating method and a subsequent alignment process is performed, a process of removing the fluoro-polymer patterns 51 by using a fluoro-solvent is performed. In the process of removing the fluoro-polymer patterns 51, an alignment substrate on which multiple alignment films are formed may be manufactured without having to involve an additional complicated process and the risk of damaging the alignment film.
The scope of the present invention will be described in terms of essential processes and usable materials, and it will be understood by those of ordinary skill in the art that the concept and specific embodiments of the present invention may be used for performing purposes similar to the present invention. Also, the constituent elements in the drawings are enlarged or reduced for convenience of explanation. Therefore, the present invention is not limited to the sizes and shapes of the constituent elements in the drawings. It will also be understood by those of ordinary skill in the art that various changes and equivalent other embodiments may be made from the spirit and scope of the present invention. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims.
Number | Date | Country | Kind |
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10-2010-0021841 | Mar 2010 | KR | national |