The above and/or other aspects of the present invention will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings, in which:
Reference is made below in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments described below explain the present invention by referring to the figures. Like elements may be representatively described in detail in a first exemplary embodiment of the present invention, thus may not be described in other exemplary embodiments.
In this specification, if “An angle is between A degrees and B degrees” is said, the “angle” does not include “A degrees” nor “B degrees”. For example, if it is said that the angle is between 0 degree and 45 degrees, the angle does not include 0 degree nor 45 degrees.
Hereinafter, a liquid crystal display device according to a first exemplary embodiment of the present invention is described with reference to
Firstly, referring to
The first substrate 100 is described with reference to
Gate wirings 121, 122 and 123 are formed on a first insulating substrate 111. The gate wirings 121, 122 and 123 may be a single metal layer or a multiple metal layer. The gate wirings 121, 122 and 123 comprise a gate line 121 extending horizontally, a gate electrode 122 connected to the gate line 121, and a sustain electrode line 123 extending parallel with the gate line 121. The sustain electrode line 123 overlaps with a pixel electrode 160 to make a storage capacitor.
On the first insulating substrate 111, the gate wirings 121, 122 and 123 are covered by a gate dielectric film 131 which comprises silicon nitride (SiNx) and/or similar materials.
A semiconductor layer 132 comprising amorphous silicon and/or other semiconductor is formed on the gate dielectric film 131 of the gate electrode 122. An ohmic contact layer 133, which comprises silicide or n+ hydrogenated amorphous silicon heavily doped with n type impurities is formed on the semiconductor layer 132. The ohmic contact layer 133 is divided into two separated parts.
Data wirings 141, 142 and 143 are formed on the ohmic contact layer 133 and the gate dielectric film 131. The data wirings may also be a single layer or a multiple layer. The data wirings 141, 142 and 143 comprise a data line 141 extending vertically to intersect with the gate line 121, a source electrode 142 being a branch of the data line 141 and extending to an upper part of the ohmic contact layer 133, and a drain electrode 143 separated from the source electrode 142 and formed on the other separated ohmic contact layer 133.
A pixel area is an area surrounded by the gate line 121 and the data line 141, and has approximately a rectangular shape. The pixel area is divided by the sustain electrode line 123 into an upper pixel area and a lower pixel area.
A passivation film 151 is formed on the data wirings 141, 142 and 143 and on the semiconductor layer 132 which the data wirings 141, 142 and 143 do not cover. The passivation film 151 may comprise silicon nitride, a-Si:C:O or a-Si:O:F deposited by PECVD method, or coating acrylic organic insulator, and etc. The passivation film 151 has a contact hole 152 which exposes the drain electrode 143.
The pixel electrode 160 is formed on the passivation film 151. Generally, the pixel electrode 160 comprises a transparent conductor such as indium tin oxide (ITO), and indium zinc oxide (IZO).
The pixel electrode 160 comprises a pair of first stem electrodes 161 extending to be parallel with the data line, a first branch electrode 162 extended between the first stem electrodes 161 and interconnecting the first stem electrodes 161, and a first edge electrode 163 disposed at a connecting area between the first stem electrode 161 and the first branch electrode 162. The first branch electrode 162 extends not to be parallel with the gate line 121, and is approximately symmetrical with its axis of symmetry being the sustain electrode line 123.
The first edge electrode 163 extends to an area between the first branch electrodes 162 which are opposite to each other. The first edge electrode 163 is located at an area where the first stem electrode 161 meets the first branch electrode 162 with an obtuse angle.
The pixel electrode 160 is electrically connected with the drain electrode 143 through the contact hole 152.
A first alignment film 171 is formed on the pixel electrode 160.
The second substrate 200 is described with reference to
A black matrix 221 is formed on a second insulating substrate 211. Generally, the black matrix 221 separates red filter, green filter and blue filter, and prevents direct irradiation onto the semiconductor layer 132 which is located on the first substrate 100. Generally, the black matrix 221 comprises a photosensitive organic material which contains black pigment. The black pigment includes carbon black, titanium oxide or etc.
A color filter 231 has its boundary formed by the black matrix 221. The color filter 231 comprises three sub-layers (not shown) which represent red, green and blue colors respectively. The color filter 231 gives colors to the light which is irradiated from a backlight unit and passes through the liquid crystal layer 300. Generally, the color filter 231 comprises photosensitive organic material.
An over coat layer 241 is formed on the color filter 231 and the black matrix 221. The over coat layer 241 comprises organic material to provide a flat surface. The over coat layer 241 may be omitted.
A common electrode 250 is formed on the over coat layer 241. The common electrode 250 comprises transparent conductive material such as indium tin oxide (ITO) and indium zinc oxide (IZO). The common electrode 250, along with the pixel electrode 160 of the first substrate 100, applies voltage to the liquid crystal layer 300.
The common electrode 250 is patterned on a part corresponding to the pixel area. That is, the common electrode 250 is partially removed at the part which corresponds to the pixel area. The patterned common electrode 250 comprises a second stem electrode 251 surrounding the pixel area, a second branch electrode 252 traversing the pixel area and connecting the second stem electrode 251, and a second edge electrode 253 formed at a connecting area between the second stem electrode 251 and the second branch electrode 252. The second branch electrode 252 extends not to be parallel with the gate line 121 and is approximately symmetrical with its axis of symmetry being the sustain electrode line 123.
The second edge electrode 253 extends to an area between the second branch electrodes 252 which are opposite to each other. The second edge electrode 253 is located at an area where the second stem electrode 251 meets the second branch electrode 252 with an obtuse angle.
A second alignment film 261 is formed on the common electrode 250.
The first alignment film 171 and the second alignment film 262 are rubbed in a direction which is parallel with the gate line 121.
A relation in the disposition of the pixel electrode 160 and the common electrode 250 is described with reference to
Referring to
The sub-pixel area 160-1 has an elongated parallelogram shape. Two sides of the sub-pixel area 160-1 are surrounded by the pixel electrode 160, and the other two sides of the sub-pixel area 160-1 are surrounded by the common electrode 250. Specifically, the sub-pixel area 160-1 is surrounded by the first branch electrode 162 of the pixel electrode 160, the first edge electrode 163 of the pixel electrode 160, the second branch electrode 252 of the common electrode 250, and the second edge electrode 253 of the common electrode 250.
The first branch electrode 162 of the pixel electrode 160 and the second branch electrode 252 of the common electrode 250, which make long sides of the sub-pixel area 160-1, are placed to be parallel and opposite to each other. The first edge electrode 163 of the pixel electrode 160 and the second edge electrode 253 of the common electrode 250, which make short sides of the sub-pixel area 160-1, are placed to be parallel and opposite to each other.
As will be appreciated by the reference to
Hereinafter, why an aperture ratio is improved according to the first exemplary embodiment is explained with reference to
Referring to
The first alignment film 171 is rubbed in a first direction which is parallel with the gate line 121. The second alignment film 261 is rubbed in a second direction which is parallel with, but opposite to the first direction.
A bent angle θ2 of the pixel electrode 160 surrounding the sub-pixel area 160-1 is between 90 degrees and 135 degrees. A bent angle θ3 of the common electrode 250 surrounding the sub-pixel area 160-1 is the same as the bent angle θ2 of the pixel electrode 160.
An angle θ4 between the first branch electrode 162 of the pixel electrode 160 and the second edge electrode 253 of the common electrode 250 is between 45 degrees and 90 degrees. An angle θ5 between the first edge electrode 163 of the pixel electrode 160 and the second branch electrode 252 of the common electrode 250 is the same as θ4.
On the other hand, the inclination angle θ1 in
If the voltage is not applied, the liquid crystal molecule 310 is aligned to be almost parallel with the insulating substrates 111 and 211. The major axis of the liquid crystal molecule 310 is aligned substantially parallel with the rubbing direction.
In case that the electric field is formed by the application of the voltage, the alignment of the liquid crystal molecule 310 is described with reference to
If the voltage is applied, the electric field is formed between the pixel electrode 160 and the common electrode 250 as shown in
As shown in
On the other hand, as shown in
Alternatively, the angles θ4 and θ5 between the pixel electrode 160 and the common electrode 250 may be right angles. In this case, the sub-pixel area 160-1 may have an elongated rectangular shape, and the bent angle θ2 of the pixel electrode 160 and the bent angle θ3 of the common electrode 150 become right angles.
In the above first exemplary embodiment, the liquid crystal molecule 310 of the liquid crystal layer 300 has a positive anisotropic dielectric constant. However, the liquid crystal molecule 310 of the liquid crystal layer 300 may have a negative anisotropic dielectric constant, which is explained hereinafter with reference to
Referring to
In the lower pixel area, the inclination angle θ1 between the first branch electrode 162 of the pixel electrode 160 and the gate line 121 is between 45 degrees and 90 degrees. In the upper pixel area, the inclination angle θ1 is between 90 degrees and 135 degrees. The sum of the inclination angle θ1 of the lower pixel area and the inclination angle θ1 of the upper pixel area may be 180 degrees.
Referring to
The inclination angle θ1 of the upper pixel area is different from the inclination angle θ1 of the lower pixel area. Accordingly, a rotation direction of the molecule 310 in the upper pixel area is different from that of the molecule 310 in the lower pixel area, thus forming two domains. One pixel area is divided into two domains to improve visibility.
A third exemplary embodiment of the present invention is explained with reference to
In the third exemplary embodiment, the sub-pixel area 160-1 has an elongated shape thus as a whole a parallelogram. However, both end parts of the sub-pixel area 160-1 along its extending direction do not have perfectly straight lines.
As described above, according to the present invention, a liquid crystal display device having improved aperture ratio can be provided.
Although a few exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Number | Date | Country | Kind |
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10-2006-0089477 | Sep 2006 | KR | national |