KR20050037846A - In plane switching mode liquid crystal display device and method for fabricating thereof - Google Patents

Abstract

The present invention relates to a horizontal field type liquid crystal display device and a method for manufacturing the same for increasing aperture ratio and improving image quality, comprising: first and second substrates; Gate lines and data lines arranged vertically and horizontally on the first substrate to define pixels; A switching element formed at an intersection of the gate line and the data line; At least one pair of common electrode and first pixel electrode for generating a horizontal electric field in said pixel; A common line disposed parallel to the data line and electrically connected to the common electrodes; A second pixel electrode electrically connecting the pixel electrode and overlapping the common line to form a storage capacitor; And a liquid crystal layer formed between the first substrate and the second substrate.

Description

Horizontal field type liquid crystal display device and its manufacturing method {IN PLANE SWITCHING MODE LIQUID CRYSTAL DISPLAY DEVICE AND METHOD FOR FABRICATING THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal field type liquid crystal display device, and more particularly, to a horizontal field type liquid crystal display device capable of increasing aperture ratio and improving image quality, and a manufacturing method thereof.

Liquid crystal display devices are mainly used as flat panel display devices having high quality and low power. The liquid crystal display device is bonded so that the thin film transistor array substrate and the color filter substrate face each other at a uniform interval, and a liquid crystal layer is formed between the thin film transistor array substrate and the color filter substrate.

In the thin film transistor array substrate, pixels are arranged in a matrix form, and a thin film transistor, a pixel electrode, and a capacitor are formed in a unit pixel, and the color filter substrate is a common electrode and an actual color for applying an electric field to the liquid crystal layer together with the pixel electrode. An RGB color filter and a black matrix are implemented to implement the.

On the other hand, an alignment layer is formed on the opposite surface of the thin film transistor array substrate and the color filter substrate, and rubbing is performed so that the liquid crystal layer is arranged in a constant direction. In this case, the liquid crystal is rotated by dielectric anisotropy when an electric field is applied between the pixel electrode formed for each unit pixel of the thin film transistor array substrate and the common electrode formed on the front surface of the color filter substrate, thereby passing or blocking light per unit pixel. Characters or images are displayed. However, the above-described twisted nematic mode liquid crystal display device has a disadvantage in that the viewing angle is narrow.

Therefore, in-plane switching mode LCD (LCD), which solves the viewing angle problem by aligning liquid crystal molecules in a substantially transverse direction with a substrate, has been actively studied in recent years.

FIG. 1 schematically illustrates a unit pixel of a general horizontal field type liquid crystal display device. FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view taken along line II ′ of FIG. 1A.

As shown in the figure, the gate line 1 and the data line 3 are vertically and horizontally arranged on the transparent first substrate 10 to define a pixel area. In an actual liquid crystal display device, n gate lines 1 and m data lines 3 intersect with n x m pixels, but only one pixel is shown in the figure for simplicity.

A thin film transistor 9 composed of a gate electrode 1a, a semiconductor layer 5, and source / drain electrodes 2a and 2b is disposed at an intersection point of the gate line 1 and the data line 3. The gate electrode 1a and the source / drain electrodes 2a and 2b are connected to the gate line 1 and the data line 3, respectively. In addition, the gate insulating film 8 is laminated over the entire substrate.

The common line 4 is arranged in parallel with the gate line 1 in the pixel area, and at least one pair of electrodes for switching the liquid crystal molecules, that is, the common electrode 6 and the pixel electrode 7 are parallel with the data line. Are arranged. The common electrode 6 is formed at the same time as the gate line 1 and connected to the common line 4, and the pixel electrode 7 is formed at the same time as the source / drain electrodes 2a and 2b to form the thin film transistor 9. It is connected to the drain electrode 2b. A protective film 11 is formed over the entire substrate including the source / drain electrodes 2a and 2b. In addition, the pixel electrode line 14 overlapping with the common line 4 and connected to the pixel electrode 7 forms the storage capacitor Cst with an insulating film 8 interposed therebetween. .

In addition, the second substrate 20 includes a black matrix 21 for preventing light leakage into the thin film transistor 9, the gate line 1, and the data line 3, and a color filter 23 for realizing color. The overcoat film 25 for planarizing the color filter 23 is apply | coated on it. On the opposing surfaces of the first substrate 10 and the second substrate 20, alignment films 12a and 12b for determining the initial alignment direction of the liquid crystal are coated.

In addition, a liquid crystal layer 13 is formed between the first substrate 10 and the second substrate 20 to control light transmittance by a voltage applied to the common electrode 6 and the pixel electrode 7. have.

The conventional horizontal field type liquid crystal display device having the structure as described above has the advantage of improving the viewing angle because the common electrode 6 and the pixel electrode 7 are arranged on the same plane to generate a transverse electric field. On the other hand, a parasitic capacitance Cdp is generated between the data line 3 and the pixel electrode 7, resulting in deterioration of image quality due to data signal delay. In addition, a signal interference between the data line 3 and the pixel electrode 7 causes a problem in that a horizontal electric field is not normally formed in the pixel.

In addition, since the common electrode 6 and the pixel electrode 7 are disposed in the pixel area where the screen is displayed, there is a problem that the aperture ratio is lowered and the luminance is lowered.

Accordingly, the present invention has been made to solve the above problems, an object of the present invention is to reduce the parasitic capacitance (Cdp) generated between the data line and the pixel electrode by arranging the structure of the pixel electrode in the form of "", The present invention provides a horizontal field type liquid crystal display device and a method of manufacturing the same which can improve image quality by minimizing signal interference of data lines.

Another object of the present invention is to provide a horizontal field type liquid crystal display device which can improve the aperture ratio by arranging common lines parallel to data lines and partially overlapping pixel electrodes.

Other objects and features of the present invention will be described in detail in the configuration and claims of the following invention.

Horizontal field type liquid crystal display device of the present invention for achieving the above object is first and second substrate; Gate lines and data lines arranged vertically and horizontally on the first substrate to define pixels; A switching element formed at an intersection of the gate line and the data line; A common electrode formed in the pixel; A common line disposed parallel to the data line and electrically connected to the common electrodes; A pixel electrode having a “d” shape for generating a horizontal electric field together with the common electrode; A pixel electrode line electrically connecting the pixel electrode and overlapping the gate line to form a first storage capacitor Cst1; And a liquid crystal layer formed between the first substrate and the second substrate, wherein the pixel electrode includes a first pixel electrode disposed in parallel with the common electrode, and a second storage capacitor that overlaps a portion of the common line. And a second pixel electrode to form a. In this case, the second common electrode may further include a second common electrode formed under the second pixel electrode to generate a third storage capacitor.

The switching device may include a gate electrode connected to the gate line; A gate insulating film formed on the gate electrode; A semiconductor layer formed on the gate insulating film; And a source electrode and a drain electrode formed on the semiconductor layer. The second substrate includes a color filter and a black matrix.

In addition, the present invention is the first and second substrate; Gate lines and data lines arranged vertically and horizontally on the first substrate to define pixels; A thin film transistor formed at an intersection of the gate line and the data line; a plurality of first and second common electrodes formed in the pixel; A common line parallel to the data line and electrically connecting the first and second common electrodes; A first pixel electrode formed on the second common electrode to form a first storage capacitor, and generating a horizontal electric field together with the first common electrode; A second pixel electrode overlapping a portion of the common line to form a second storage capacitor; And a liquid crystal layer formed between the first substrate and the second substrate. And a pixel electrode line electrically connected to the first and second pixel electrodes and formed on the gate line to form a storage capacitor.

The first common electrode and the first pixel electrode may be disposed in parallel with the gate line or in an oblique shape.

In addition, the second substrate includes a color filter and a black matrix.

In addition, the method for manufacturing a horizontal field type liquid crystal display device according to the present invention comprises the steps of providing a first and a second substrate; Forming a common line on the first substrate to electrically connect a gate line, a common electrode, and the common electrode; A data line defining a pixel and a pixel electrode having a "d" shape are formed to cross the gate line perpendicularly to the gate line, wherein the pixel electrode is formed with a portion of the common pixel and the first pixel electrode generating a horizontal electric field. Forming a second pixel electrode to overlap and form a storage capacitor; And forming a liquid crystal layer between the first and second substrates. The method may further include forming an insulating film between the common electrode and the first pixel electrode and forming a black matrix and a color filter on the second substrate.

Hereinafter, a horizontal field type liquid crystal display device and a method for manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

2A and 2B illustrate a horizontal field type liquid crystal display device according to the present invention. FIG. 2A is a plan view, and FIG. 2B is a cross-sectional view taken along line II-II 'of FIG. 2A.

As shown in the figure, in the horizontal field type liquid crystal display device 100 according to the present invention, the pixel region is formed by the gate line 101 and the data line 103 arranged vertically and horizontally on the transparent first substrate 110. Is defined. A switching element 109 is formed at an intersection point of the gate line 101 and the data line 103, and the switching element 109 is a gate electrode 101a and the gate electrode formed as part of the gate line 101. The semiconductor layer 105 formed on the 101a and the source / drain electrodes 102a and 102b are disposed on the semiconductor layer 105 at predetermined intervals.

In the pixel, at least one pair of common electrode 106 and pixel electrode 107 for generating a horizontal electric field are formed to be parallel to the gate line 101. In addition, the common electrode 106 is electrically connected to the common line 104 arranged in parallel with the data line 103, and the pixel electrode 107 overlaps the gate line 101. It is electrically connected to the pixel electrode line 114 forming the storage capacitor Cst1.

In this case, the pixel electrode 107 overlaps a portion of the first pixel electrode 107a and the common line 104 which are disposed in parallel with the common electrode 106 to generate a substantially horizontal electric field. And a second pixel electrode 107b forming Cst2.

As illustrated in FIG. 2B, the common electrode 106 and the pixel electrode 107 are electrically insulated by the gate insulating film 108 interposed therebetween, and the data line 103 and the pixel electrode ( The protective film 111 is coated on the entire surface of the substrate including the 107.

On the other hand, the second substrate 120 is formed with a black matrix 121 to prevent light leakage and a color filter 123 for implementing the color. The first and second alignment layers 112a and 112b for determining the initial alignment direction of the liquid crystal are coated on the opposing surfaces of the first substrate 110 and the second substrate 120, and the liquid crystal layer ( 113) is formed.

In the horizontal field type liquid crystal display device of the present invention configured as described above, the pixel electrode 107 is formed in a "d" shape, and the first pixel electrode 107a for generating an electric field to drive the liquid crystal includes a data line 103 and Since it is formed vertically, signal interference of the data line 103 can be reduced. That is, in the related art, since the pixel electrode 107 is formed in a straight line, the entire length of the pixel electrode is subjected to the signal interference of the data line 103. However, in the present invention, the second pixel electrode 107b parallel to the data line 103 is used. Only the signal interference of the data line 103 is received. In this case, since the length of the second pixel electrode 107b is about half of that of the related art, the influence of signal interference is also reduced by half.

In addition, the parasitic capacitance Cdp generated by the second pixel electrode 107b and the data line 103 is also reduced by about half. In general, the parasitic capacitance value is proportional to the length of the pixel electrode arranged parallel to the data line. In the present invention, the total length of the pixel electrode (second pixel electrode) formed parallel to both data lines is one of the conventional data lines. Since it is similar to the length of the pixel electrode in parallel with each other, the Cdp generated between the pixel electrode and the data line can be reduced by about half.

In addition, by arranging the second pixel electrode 107b to overlap the common line 104, the area through which light is transmitted can be substantially increased. That is, the luminance may be increased by forming the second pixel electrode 107b closer to the data line 103.

The common electrode 106 and the first pixel electrode 107a that generate a horizontal electric field in the pixel may be inclined at a predetermined angle with respect to the gate line. That is, as shown in FIG. 3 (second embodiment), the common electrode 106 'and the first pixel electrode 107a' are not parallel to the gate line 101, and the predetermined angle θ is inclined. It is arranged diagonally. In this case, the common electrode 106 'and the first pixel electrode 107a' should be disposed in parallel with each other.

4 shows a third embodiment of the present invention, which shows a horizontal field type liquid crystal display device which can further improve the charging capacity compared to the previous embodiment (FIGS. 2 and 3).

As shown in the figure, in the horizontal field type liquid crystal display device 200 according to the present embodiment, the gate line 201 and the data line 203 are vertically and horizontally arranged on the transparent first substrate 210, The pixel area is defined. A switching element 209 is formed at the intersection of the gate line 201 and the data line 203, and the switching element 209 is a gate electrode 201a and the gate electrode formed as part of the gate line 201. The semiconductor layer 205 is formed on the semiconductor layer 205 and the source / drain electrodes 202a and 202b disposed on the semiconductor layer 205 at predetermined intervals.

In the pixel, at least one pair of common electrode 206 and a pixel electrode 207 for generating a horizontal electric field are formed to be parallel to the gate line 201. The common electrode 206 is electrically connected to the common line 204 and includes a first common electrode 206a for generating a horizontal electric field in the pixel and a second common electrode 206b formed under the pixel electrode 207. It is composed.

The pixel electrode 207 is electrically connected to the pixel electrode line 214 which overlaps the gate line 201 to form a first storage capacitor Cst1, and is connected to the first common electrode 206a. A first pixel electrode 207a for generating a horizontal electric field together with a second pixel electrode 207b for forming a second storage capacitor Cst2 by overlapping a part of the common line 206. The second common electrode 206b is formed under the first pixel electrode 207a, and they form a third storage capacitor Cst3.

In the horizontal field type liquid crystal display device configured as described above, the third storage capacitor Cst3 formed by the first pixel electrode 207a and the second common electrode 206b is additionally formed. Can improve. That is, the storage capacity Ctotal of the previous embodiment is Cst1 + Cst2, and the storage capacity Ctotal of the present embodiment is Cst1 + Cst2 + Cst3. The common electrode 206 and the first pixel electrode 207a may be formed to be parallel to the gate line 201.

5A and 5B are plan views illustrating a manufacturing process of a horizontal field type liquid crystal display device according to the present invention.

First, as shown in FIG. 5A, a transparent first substrate is prepared, and then a first metal material such as Cu, Ti, Cr, Al, Mo, Ta, Al alloy is deposited thereon, and then patterned to form a gate line. 301, a gate electrode 301a, a common line 304 disposed perpendicular to the gate line 301, and a plurality of common electrodes 306 electrically connected by the common line 304. .

Subsequently, SiNx or SiOx is deposited on the entire surface of the substrate including the gate line 301 and the common line 304 by a plasma CVD method to form a gate insulating film (not shown). In addition, the semiconductor layer 405 is formed on the gate line 301 by laminating and patterning amorphous silicon and n + amorphous silicon on the gate insulating layer (not shown).

Next, as shown in FIG. 5B, after depositing a second metal material such as Cu, Mo, Ta, Al, Cr, Ti, and Al alloy on the semiconductor layer 305 and the gate insulating layer (not shown) And patterning it so as to be perpendicular to the gate line 301, the data line 303 defining a pixel together with the gate line 301, and a source / drain electrode spaced a predetermined distance from the semiconductor layer 305. 302a / 302b, a first pixel electrode 307a disposed in parallel with the common electrode to generate a horizontal electric field in the pixel, and a pixel electrode line overlapping the gate line 301 to form a first storage capacitor Cst1. A second pixel electrode 307b overlapping a portion 314 and a portion of the common line 304 to form a second storage capacitor Cst2, and being formed as the first and second pixel electrodes 307a and 307b. The configured pixel electrode 307 is formed in the form of "".

Thereafter, an inorganic material such as SiNx or SiOx or an organic material such as benzocyclobutene or acryl is coated on the substrate on which the thin film transistor 309 is formed to form a protective film (not shown).

Subsequently, the panel of the liquid crystal display device is completed by bonding together with the second substrate on which the color filter is formed.

In this case, the common electrode or the pixel electrode may be formed on the passivation layer, and at least one of the two electrodes may be formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). When the common electrode or the pixel electrode is formed of a transparent material, luminance may be further improved.

As described above, the present invention provides a horizontal field type liquid crystal display device and a method of manufacturing the same. In particular, the present invention forms the shape of the pixel electrode in a "d" shape to reduce the parasitic capacitance Cdp generated between the data line and the pixel electrode, to further improve the image quality by reducing the signal interference of the data line, and the pixel electrode to the data line By arranging as close as possible, the aperture ratio is improved.

As described above, the present invention has the effect of improving the image quality by reducing the signal interference of the data line by forming the pixel electrode in the form of "". In addition, as the signal interference of the data line is reduced, the pixel electrode arranged in parallel with the data line is formed closer to the data line, thereby improving the aperture ratio.

1A and 1B illustrate a general horizontal field type liquid crystal display device.

2A and 2B illustrate a horizontal field type liquid crystal display device according to a first embodiment of the present invention.

Figure 3 shows a second embodiment of the present invention.

4 is a view showing a third embodiment of the present invention.

5A and 5B are cross-sectional views illustrating a method of manufacturing a horizontal field type liquid crystal display device according to the present invention;

*** Explanation of symbols for main parts of drawing ***

101, 201: gate line 103, 203: data line

104, 204: common line 106, 206: common electrode

107 and 207 pixel electrodes 114 and 214 pixel electrode lines

Cst1: first storage capacity

Cst2: second storage capacity

Cst3: third storage capacity

Claims (14)

First and second substrates; Gate lines and data lines arranged vertically and horizontally on the first substrate to define pixels; A switching element formed at an intersection of the gate line and the data line; A common electrode formed in the pixel; A common line disposed parallel to the data line and electrically connected to the common electrodes; A pixel electrode having a “d” shape for generating a horizontal electric field together with the common electrode; A pixel electrode line electrically connecting the pixel electrode and overlapping the gate line to form a first storage capacitor Cst1; And And a liquid crystal layer formed between the first substrate and the second substrate. The method of claim 1, And the pixel electrode includes a first pixel electrode disposed in parallel with the common electrode, and a second pixel electrode which is formed to overlap a portion of the common line to form a second storage capacitor. The method of claim 2, And a second common electrode formed under the second pixel electrode to generate a third storage capacitor. The method of claim 1, wherein the switching device, A gate electrode connected to the gate line; A gate insulating film formed on the gate electrode; A semiconductor layer formed on the gate insulating film; A horizontal field type liquid crystal display device comprising a source electrode and a drain electrode formed on the semiconductor layer. The method of claim 1, And the second substrate includes a color filter and a black matrix. First and second substrates; Gate lines and data lines arranged vertically and horizontally on the first substrate to define pixels; A thin film transistor formed at an intersection of the gate line and the data line; A plurality of first and second common electrodes formed in the pixel; A common line parallel to the data line and electrically connecting the first and second common electrodes; A first pixel electrode formed on the second common electrode to form a first storage capacitor, and generating a horizontal electric field together with the first common electrode; A second pixel electrode overlapping a portion of the common line to form a second storage capacitor; And And a liquid crystal layer formed between the first substrate and the second substrate. The method of claim 6, And a pixel electrode line electrically connected to the first and second pixel electrodes, the pixel electrode line being formed on a gate line to form a storage capacitor. The method of claim 6, And the first common electrode and the first pixel electrode are parallel to the gate line. The method of claim 6, And the first common electrode and the first pixel electrode are formed in an oblique diagonal shape with respect to the gate line. The method of claim 6, And the second substrate includes a color filter and a black matrix. Providing first and second substrates; Forming a common line on the first substrate to electrically connect a gate line, a common electrode, and the common electrode; A data line defining a pixel and a pixel electrode having a "d" shape are formed to cross the gate line, and the pixel electrode overlaps the first pixel electrode and a part of the common line which are alternately formed on the common electrode. Forming a second pixel electrode forming a storage capacitor; And And forming a liquid crystal layer between the first and second substrates. The method of claim 11, And forming an insulating film between the common electrode and the first pixel electrode. The method of claim 11, And forming a black matrix and a color filter on the second substrate. The method of claim 11, wherein the pixel electrode or the common electrode is formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).