Patent Application
20090190075
This application claims priority to and the benefit of Korean Patent Application No. 10-2008-0008689 filed on Jan. 28, 2008, the entire content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a liquid crystal display and a manufacturing method thereof, and more particularly to, a liquid crystal display having a structure that prevents degradation of a display quality due to leakage of light.
2. Description of the Related Art
A liquid crystal display (LCD), which is a kind of flat panel display, applies a varying electric voltage to a layer of liquid crystal that has optical properties between those of a conventional liquid and those of a solid crystal, thereby inducing changes in its optical properties. The LCD has wide applications since it has lower power consumption than a conventional cathode ray tube (CRT), is of small volume, may be large-sized and have a fine pitch.
LCDs are divided into active-matrix LCDs, which use switching devices and twisted nematic (TN) liquid, and passive-matrix LCDs, which use super-twisted nematic (STN) liquid.
The active-matrix LCD uses a thin film transistor (TFT) as a switch. Whereas, the passive-matrix LCD does not need the TFT, and, as such, requires no complex circuitry.
The passive-matrix LCD typically uses ball spacers after forming transparent electrodes. The ball spacers are fabricated by scattering spacers mixed with a solvent to a glass substrate on which the transparent electrodes are formed. Spacers are scattered on an upper portion of color photoresist regions, which degrades the display quality of panels due to leakage of light.
Further, the transparent electrodes are formed using a different processing line from those used to manufacture panels. Therefore, conventional LCDs must change processing lines before and after forming the transparent electrodes in order to manufacture the panels, which degrades the display quality of the panels due to unstable substrates caused by a change in processing lines.
In accordance with the present invention a liquid crystal display, and a manufacturing method thereof, is provided that forms spacers in a black matrix region using a photolithography process, so that the spacers are not formed in color photoresist regions, thereby preventing degradation of a display quality due to leakage of light.
Also in accordance with the present invention a liquid crystal display, and a manufacturing method thereof, is provided that forms transparent electrodes as a final process of manufacturing a panel, thereby reducing costs incurred in changing a processing line and allowing for a stable manufacturing of the panel.
According to an exemplary embodiment of the present invention, a liquid crystal display includes a first substrate. A color filter is formed to cover the first substrate and includes black matrices and color photoresists. A second substrate faces the first substrate. Photo spacers are formed to protrude from the black matrices of the color filter toward the second substrate. First transparent electrodes are arranged in a first direction to cover the color filter on regions other than regions where the photo spacers are formed. Second transparent electrodes are arranged in a second direction that crosses the first direction to cover the second substrate and are between the second substrate and the first transparent electrodes.
The photo spacers may be formed on the black matrices of the cooler filter adjacent to areas where the first and second transparent electrodes cross each other.
The first transparent electrodes may be separated from the side surfaces of the photo spacers.
The liquid crystal display may further include an overcoat layer formed to cover the color filter between the color filter and the photo spacers.
The liquid crystal display may further include an insulation film formed to cover the overcoat layer between the overcoat layer and the photo spacers.
The liquid crystal display may further include liquid crystal injected between the first transparent electrodes formed on the first substrate and the second transparent electrodes formed on the second substrate.
The liquid crystal may be color super twisted nematic (CSTN) liquid crystal.
The color photoresists may include red photoresists, green photoresists, and blue photoresists, and may be arranged in respective rows or columns on the color filter.
The pixels may correspond to areas where the first and second transparent electrodes cross each other and include a red photoresist, a green photoresist, and a blue photoresist.
The first and second transparent electrodes may be perpendicular to each other and are spaced apart from each other.
According to another exemplary embodiment of the present invention, there is provided a method of manufacturing a liquid crystal display. A first substrate is prepared. A color filter is formed to form black matrices and color photoresists to cover the first substrate. Photo spacers are formed to upwardly protrude from the black matrices. First transparent electrodes are formed to cover the color filter. The first transparent electrodes are patterned to remove the first transparent electrodes formed on an upper surface and side surfaces of the photo spacers and to arrange the first transparent electrodes in a first direction. A second substrate is combined to the first substrate.
In patterning the first transparent electrodes, the first transparent electrodes may be arranged in the first direction according to pixels that include a red photoresist, a green photoresist, and a blue photoresist.
The method may further include after forming the color filter, forming an overcoat layer to cover the color filter.
The method may further include after forming the overcoat layer, forming an insulation layer to cover the overcoat layer.
The method may further include after combining the second substrate to the first substrate, injecting liquid crystal between the first substrate and the second substrate.
a and 2b are a perspective view of a panel of the liquid crystal display of
a,
5
b,
5
c,
5
d,
5
e,
5
f,
5
g,
5
h and 5i are cross-sectional views of the liquid crystal display of
Like reference numerals in the drawings denote like elements throughout the specification. It will be understood that when an element is referred to as being “electrically coupled” to another element, the element can be directly electrically coupled to another element or through intervening elements.
Referring to
The panel 100 includes a plurality of first transparent electrodes X[1], X[2], . . . X[n] arranged in rows, a plurality of second transparent electrodes Y[1], Y[2], . . . Y[m] arranged in columns, and a pixels defined by the plurality of first transparent electrodes X[1], X[2], . . . X[n] and the plurality of second transparent electrodes Y[1], Y[2], . . . Y[m]. A pixel 150 (also identified by “P” in the drawings) may be formed in an area where one of the first transparent electrodes X[1], X[2], . . . X[n] and one of the second transparent electrodes Y[1], Y[2], . . . Y[m] cross each other.
The X electrode driver 200 applies an electric field to a pixel 150 of the panel 100 through the first transparent electrodes X[1], X[2], . . . X[n] that are electrically coupled to the panel 100.
The Y electrode driver 300 applies an electric field to a pixel 150 of the panel 100 through the second transparent electrodes Y[1], Y[2], . . . Y[m] that are electrically coupled to the panel 100.
As described above, the X electrode driver 200 may supply a voltage to the first transparent electrodes X[1], X[2], . . . X[n], and the Y electrode driver 300 may supply a voltage to the second transparent electrodes Y[1], Y[2], . . . Y[m].
a and 2b are a perspective view of the panel 100 of the liquid crystal display 1000 of
Referring to
The first substrate unit 110 includes a first substrate 111, a color filter 112, an overcoat layer 113, an insulation film 114, photo spacers 115, and first transparent electrodes 116.
The first substrate 111 is usually a glass substrate and may be formed of soda lime glass, of neutral borosilicate glass, of non-alkali glass, or an equivalent thereof according to the chemical composition of the glass. However, the present invention is not limited thereto.
The color filter 112 is formed to cover the upper surface of the first substrate 111. The color filter 112 includes color photoresists 112b and black matrices 112a disposed between the color photoresists 112b. The color photoresists 112b include a red R photoresist, a green G photoresist, and a blue B photoresist, and are arranged in a plurality of lines of rows in the color filter 112. A pixel 150 of the panel 100 includes a R photoresist, a G photoresist, and a B photoresist. That is, one pixel 150 includes three photoresists. The black matrices 112a may be formed of resin, of chrome, of carbon black, of titanium oxide, or an equivalent thereof.
The overcoat layer 113 is formed to cover the upper surface of the color filter 112. The overcoat layer 113 makes steps between the black matrices 112a and the color photoresisters 112b flat when the color filter 112 is formed. The overcoat layer 113 may be formed of acrylic resin, of polyimide resin, or an equivalent thereof. However, the present invention is not limited thereto.
The insulation film 114 is formed to cover the upper surface of the overcoat layer 113 in order to enhance a contact adhesion between the first transparent electrodes 116 and the overcoat layer 113 above which the first transparent electrodes 116 are formed. The insulation film 114 may be formed of oxide SiO2 or an equivalent thereof. However, the present invention is not limited thereto.
The photo spacers 115 are on the insulation film 114 and are formed in some of the regions corresponding to the regions where the black matrices 112a of the color filter 112 are formed. The photo spacers 115 are formed to control a cell gap between the first substrate unit 110 and the second substrate unit 120 in order to maintain a constant thickness of the liquid crystal 130. The photo spacers 115 have a stronger contact adhesion with the first substrate unit 110 than that with the second substrate unit 120. The photo spacers 115 are formed adjacent the pixels 150. However, the present invention is not limited to the number of the photo spacers 115 according to the number of the pixels 150. The photo spacers 115 are formed in the black matrices 112a that are generated by the B photoresists that are relatively small. However, the present invention is not limited to regions where the photo spacers 115 are formed. That is, the photo spacers 115 may be formed in any regions of the black matrices 112a. The photo spacers 115 may be formed in a selective region using a photolithography process. The photo spacers 115 are formed using the photolithography process, thereby preventing degradation of a display quality of the panel 100 due to leakage of light caused by undesired spacers that are formed on the color photoresists 112b.
The first transparent electrodes 116 are formed to cover the upper surface of the insulation film 114 and are separated from the side surface of the photo spacers 115. The first transparent electrodes 116 are arranged in a first direction to cover the color photoresists 112b of the color filter 112. In the present embodiment, although the first transparent electrodes 116 are arranged in a column direction, they may be formed in a row direction. If the first transparent electrodes 116 are formed in the row direction, the second transparent electrodes 122 are formed in the column direction. If the first transparent electrodes 116 are formed in the column direction, the second transparent electrodes 122 are formed in the row direction. That is, the first transparent electrodes 116 and the second transparent electrodes 122 are perpendicular to each other. The first transparent electrodes 116 may be formed of indium tin oxide (ITO), of tin oxide (SnO2), or an equivalent thereof. However, the present invention is not limited thereto.
The second substrate unit 120 includes a second substrate 121 and the second transparent electrodes 122.
The second substrate 121 may be formed of soda lime glass, of neutral borosilicate glass, of non-alkali glass, or an equivalent thereof according to the chemical composition of the glass. However, the present invention is not limited thereto.
The second transparent electrodes 122 are between the second substrate 121 and the first transparent electrodes 116. The second transparent electrodes 122 are arranged in a second direction to cover the second substrate 121. In the present embodiment, although the second transparent electrodes 122 are arranged in a row direction, they may be formed in a column direction. If the second transparent electrodes 122 are formed in the column direction, the first transparent electrodes 116 are formed in the row direction. If the second transparent electrodes 122 are formed in the row direction, the first transparent electrodes 166 may be formed in the column direction. That is, the first transparent electrodes 116 and the second transparent electrodes 122 are perpendicular to each other. The first transparent electrodes 116 and the second transparent electrodes 122 are spaced apart from each other in order to apply an electric field to liquid crystal therebetween. The second transparent electrodes 122 may be formed of indium tin oxide (ITO), of tin oxide (SnO2), or an equivalent thereof. However, the present invention is not limited thereto.
The liquid crystal 130 is between the first substrate unit 110 and the second substrate unit 120. An electric field applied between the first transparent electrodes 116 and the second transparent electrodes 122, changes an arrangement of liquid crystal molecules. The liquid crystal 130 is color super twisted nematic (CSTN) liquid crystal. The CSTN liquid crystal is suitable for passive-matrix LCD since it uses a transparency that very sharply varies according to an applied voltage having a torsion angle between 240 degrees and 270 degrees.
The color photoresists 112b include an R photoresist, a G photoresist, and a B photoresist, and are arranged in a plurality of lines of rows in the color filter 112. The black matrices 112a are disposed between the color photoresists 112b. A pixel 150 of the panel 100 includes the R photoresist, the G photoresist, and the B photoresist. That is, one pixel 150 includes three photoresists.
The photo spacers 115 are formed in some of regions where the black matrices 112a are formed. The B photoresists are formed smaller than the R photoresists and the G photoresists. The photo spacers 115 are formed in the black matrices 112a that are generated by the B photoresists that are relatively small. However, the present invention is not limited to regions where the photo spacers 115 are formed. That is, the photo spacers 115 can be formed in any regions of the black matrices 112a. The photo spacers 115 are formed adjacent the pixels 150, respectively. However, the present invention is not limited to the number of the photo spacers 115 according to the number of the pixels 150.
The first transparent electrodes 116 are arranged in a first direction to cover the color photoresists 112b of the color filter 112. In the present exemplary embodiment, although the first transparent electrodes 116 are arranged in a column direction, they may be formed in a row direction. If the first transparent electrodes 116 are formed in the row direction, the second transparent electrodes 122 are formed in the column direction. If the first transparent electrodes 116 are formed in the column direction, the second transparent electrodes 122 may be formed in the row direction. That is, the first transparent electrodes 116 and the second transparent electrodes 122 are perpendicular to each other. Areas where the first transparent electrodes 116 and the second transparent electrodes 122 cross each other are the pixels 150.
The second transparent electrodes 122 are arranged in a second direction perpendicular to the first direction that the first transparent electrodes 116 are arranged. The second transparent electrodes 122 include second R transparent electrodes 122R that are arranged in the second direction to cover the upper surface of the R photoresists, second G transparent electrodes 122G that are arranged in the second direction to cover the upper surface of the G photoresists, and second B transparent electrodes 122B that are arranged in the second direction to cover the upper surface of the B photoresists. In the present exemplary embodiment, although the second direction is a row direction, the second transparent electrodes 122 may be formed in a column direction. If the second direction is the column direction, the first transparent electrodes 116 that are arranged in the first direction are formed in the column direction. Points where the first transparent electrodes 116 and the second transparent electrodes 122 cross each other are the pixels 150. If an electric field is applied between the first transparent electrodes 116 and the second transparent electrodes 122R, 122G, and 122B, an arrangement of liquid crystal molecules varies. The pixels 150 of the panel 100 display an image according to the arrangement of liquid crystal molecules.
A method of manufacturing a liquid crystal display as described above will now be described.
a through 5i are cross-sectional views are cross-sectional views of the liquid crystal display of
Referring to
Referring to
Referring to
Referring to
Referring to
Referring to
Referring to
Referring to
Referring to
The method of manufacturing the liquid crystal display forms the first transparent electrodes 116 as a final process as compared to a conventional method of forming spacers after forming the first transparent electrodes 116, thereby reducing costs incurred in changing a process line for manufacturing a panel of the liquid crystal display and more stably manufacturing the panel than the conventional method. According to the present invention, the photo spacers 115 are formed before the first transparent electrodes 115 are formed, thereby forming the photo spacers 115 using a photolithography process in the same process line as the process line of forming the first substrate unit 110 before the photo spacers 115 are formed.
The liquid crystal display and the manufacturing method thereof according to the present invention form a spacer in black matrix regions using a photolithography process, so that the spacer are not formed in color photoresist regions, thereby preventing degradation of a display quality due to leakage of light.
The liquid crystal display and the manufacturing method thereof according to the present invention form transparent electrodes at a final process of manufacturing a panel, thereby reducing costs incurred in a change of a processing line and stably manufacturing the panel.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. The exemplary embodiments should be considered in a descriptive sense only and not for purposes of limitation. Therefore, the scope of the present invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope of the present invention will be construed as being included in the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2008-0008689 | Jan 2008 | KR | national |
