KR20080056890A - Liquid crystal display panel and method for fabricating thereof - Google Patents

Abstract

An LCD(Liquid Crystal Display) panel is provided to align IPS(In-Plane Switching) mode liquid crystals horizontally without a rubbing process. An LCD panel(190) includes a color filter array substrate(170). A TFT(Thin Film Transistor) array substrate(180) includes a pixel electrode(116) and a common electrode(118) for forming a horizontal electric field. The TFT array substrate is also bonded with the color filter array substrate by interposing a liquid crystal layer. An alignment pattern(138) is contacted with both sides of a finger portion of the pixel electrode, formed by a line shape, and aligns the liquid crystals. The molecule structure of the alignment pattern is divided into a main chain and a side chain. The crystals are aligned in line with the side chain of a side of the alignment pattern. The height of the alignment pattern is higher than the height of the pixel electrode.

Description

Liquid Crystal Display Panel And Method For Fabricating Thereof}

1 is a cross-sectional view showing a conventional liquid crystal display panel.

Figure 2 shows a rubbing process for forming the alignment film shown in FIG.

3 is a cross-sectional view illustrating a liquid crystal display panel according to an exemplary embodiment of the present invention.

4 is a plan view illustrating the thin film transistor array substrate of FIG. 3.

FIG. 5 is a diagram illustrating an internal molecular structure and a liquid crystal alignment state of the thin film pattern in FIG. 4. FIG.

6A through 6E are views illustrating a method of manufacturing a liquid crystal display panel of the present invention.

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

2,102: upper substrate 4,104: black matrix

18,118: common electrode 32,132: lower substrate

6,106: color filter 70,170: color filter array substrate

80,180: thin film transistor array substrate

138: alignment pattern 90,190: liquid crystal display panel

51,151: liquid crystal 15,115: thin film transistor

13,113 spacer 16,116 pixel electrode

212: injection device 215: a blanket

210: printing roller device 220: printing plate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display panel, and more particularly, to a liquid crystal display panel and a manufacturing method capable of improving characteristics of an alignment film for alignment of liquid crystals.

In general, a liquid crystal display (LCD) displays an image corresponding to a video signal on a liquid crystal display panel in which liquid crystal cells are arranged in a matrix form by adjusting light transmittance of liquid crystal cells according to a video signal. To this end, the liquid crystal display device includes a liquid crystal display panel in which liquid crystal cells are arranged in an active matrix form, and driving circuits for driving the liquid crystal display panel.

Such liquid crystal displays are roughly classified into twisted nematic (TN) mode and in plan switch (IPS) mode using a vertical electric field according to the electric field driving the liquid crystal.

The TN mode is a mode in which a liquid crystal is driven by a vertical electric field between a pixel electrode and a common electrode arranged to face the upper substrate. The TN mode has an advantage that the aperture ratio is large while the viewing angle is folded. The IPS mode is a mode in which a liquid crystal is driven by a horizontal electric field between a pixel electrode and a common electrode disposed side by side on a lower substrate, and has a large viewing angle, but a small aperture ratio.

1 is a cross-sectional view showing a liquid crystal display panel of a conventional IPS mode.

Referring to FIG. 1, the liquid crystal display panel 90 in the IPS mode includes a black matrix 4, a color filter 6, a planarization layer 7, a spacer 13, and an upper part sequentially formed on the upper substrate 2. A color filter array substrate 70 composed of an alignment layer 8, a thin film transistor (hereinafter referred to as " TFT ") 15 formed on the lower substrate 32, a common electrode 18, a pixel electrode 16, and And a liquid crystal 51 injected into an inner space between the color filter array substrate 70 and the thin film transistor array substrate 80.

In the color filter array substrate 70, the black matrix 4 is formed to overlap the TFT 15 region of the lower substrate 2 and the region of gate lines and data lines not shown, and the color filter 6 is formed. The cell region to be formed is partitioned. The black matrix 4 prevents light leakage and absorbs external light to increase contrast. The color filter 6 is formed in the cell region separated by the black matrix 4. The color filter 6 is formed for each of R, G, and B to implement R, G, and B colors. The planarization layer 7 is formed to cover the color filter 6 to planarize the upper substrate 2. The spacer 13 serves to maintain a cell gap between the upper substrate 2 and the lower substrate 32.

In the thin film transistor array substrate 80, the TFT 15 includes a gate electrode 9 formed on the lower substrate 32 together with a gate line (not shown), the gate electrode 9 and a gate insulating film ( Semiconductor layers 14 and 47 overlapping with 44 interposed therebetween, and source / drain electrodes 40 and 42 formed together with data lines (not shown) with semiconductor layers 14 and 47 interposed therebetween. do. The TFT 15 supplies the pixel signal from the data line to the pixel electrode 16 in response to the scan signal from the gate line. The pixel electrode 16 is a transparent conductive material having a high light transmittance and is in contact with the drain electrode 42 of the TFT 15 with the protective film 50 interposed therebetween. The common electrode 18 is formed in a stripe shape so as to alternate with the pixel electrode 16. The common electrode 18 supplies a common voltage which is a reference when driving the liquid crystal. The liquid crystal rotates with respect to the horizontal direction by the horizontal electric field between the common voltage and the pixel voltage supplied to the pixel electrode 16.

The upper and lower alignment layers 8 and 38 for liquid crystal alignment are formed by applying an alignment material such as polyimide and then performing a rubbing process.

The color filter array substrate 70 of the conventional liquid crystal display panel 90 and the upper and lower alignment layers 8 and 38 of the thin film transistor array substrate 80 may be formed of an alignment material (eg, polyimide) as illustrated in FIG. 2. It is formed by carrying out the rubbing process using the rubbing cloth 75 after 8a) is applied. However, when the alignment layers 8 and 38 are formed by the rubbing process, when rubbing the alignment material 8a using the rubbing cloth 75, static electricity is generated to damage the alignment material 8a such as polyimide or cause particles. And the like occur frequently causing defects in the alignment of liquid crystals. Alternatively, scratches or the like may be generated in the alignment material 8a by physical pressing of the rubbing cloth. This causes a problem that the alignment characteristics of the alignment film are lowered.

Accordingly, an object of the present invention is to provide a liquid crystal display panel and a method of manufacturing the same that can improve the alignment characteristics of the liquid crystal.

In order to achieve the above object, a liquid crystal display panel according to an embodiment of the present invention includes a color filter array substrate; A thin film transistor array substrate having a pixel electrode and a common electrode which form a horizontal electric field, and bonded to the color filter array substrate with a liquid crystal interposed therebetween; In addition to contacting both side surfaces of the finger portion of the pixel electrode is formed in a line form having an alignment pattern for aligning the liquid crystal horizontally.

The molecular structure of the alignment pattern is divided into a main chain and a side chain, and the liquid crystals are aligned side by side with the side chain at the side of the alignment pattern.

The height of the alignment pattern is higher than that of the pixel electrode.

The height of the alignment pattern is larger than the line width of the alignment pattern.

The height of the alignment pattern is 0.1-1 μm The line width of the alignment pattern is about 600-1500 Å.

The thin film transistor array substrate may include: a gate line and a data line crossing each other on a lower substrate; A thin film transistor formed at an intersection of the gate line and the data line; And an organic passivation layer having a contact hole exposing the drain electrode of the thin film transistor and planarizing a lower substrate on which the thin film transistor is formed.

The pixel electrode further includes a horizontal part in which the finger parts are connected in common and connected to the drain electrode through the contact hole.

A method of manufacturing a liquid crystal display panel according to the present invention includes forming a thin film transistor array substrate including a pixel electrode and a common electrode which form a horizontal electric field; Forming an alignment pattern in contact with both side surfaces of the finger portion of the pixel electrode and formed in a line shape to align the liquid crystals horizontally; Bonding the color filter array substrate to the thin film transistor array substrate.

The forming of the alignment pattern may include coating a liquid vertical alignment material on a blanket wound on a printing roller device; Providing a printing plate having a groove having the same pattern as the alignment pattern and a protrusion except for the groove; Transferring the liquid vertical alignment material to the protrusion of the printing plate and leaving the alignment pattern having a shape corresponding to the groove on the bracket of the printing roller device; And forming the alignment patterns on both sides of a finger portion of the pixel electrode of the thin film transistor array substrate.

Other objects and features of the present invention in addition to the above objects will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 3 to 6E.

3 is a cross-sectional view illustrating a liquid crystal display panel in the conventional IPS mode, and FIG. 4 is a plan view illustrating the thin film transistor array substrate of FIG. 3.

Referring to FIG. 3, the liquid crystal display panel 190 in the IPS mode includes a black matrix 104, a color filter 106, a planarization layer 107, and a spacer 113 sequentially formed on the upper substrate 102. The thin film transistor array substrate 180 including the color filter array substrate 170, the thin film transistor 115, the common electrode 118, the pixel electrode 116, and the lower alignment layer 138 formed on the lower substrate 132. And a liquid crystal 151 injected into an inner space between the color filter array substrate 170 and the thin film transistor array substrate 180.

In the color filter array substrate 170, the black matrix 104 is formed to overlap the TFT 115 region of the lower substrate 102 and the region of gate lines and data lines not shown, and the color filter 106 is formed. The cell region to be formed is partitioned. The black matrix 104 prevents light leakage and absorbs external light to increase contrast. The color filter 106 is formed in the cell region separated by the black matrix 104. The color filter 106 is formed for each of R, G, and B to implement R, G, and B colors. The planarization layer 107 is formed to cover the color filter 106 to planarize the upper substrate 102. The spacer 113 serves to maintain a cell gap between the upper substrate 102 and the lower substrate 132.

In the thin film transistor array substrate 180 shown in FIGS. 3 and 4, the TFT 115 includes a gate electrode 109 formed on the lower substrate 132 together with the gate line 103, and the gate electrode 109. ) And the semiconductor layers 114 and 147 overlapping each other with the gate insulating layer 144 interposed therebetween, and the source / drain electrodes 140 and 142 formed together with the data line 119 with the semiconductor layers 114 and 147 interposed therebetween. The TFT 115 supplies a pixel signal from the data line 119 to the pixel electrode 116 in response to a scan signal from the gate line 103. The pixel electrode 116 is a transparent conductive material having a high light transmittance and is in contact with the drain electrode 142 of the TFT 115 with the organic passivation layer 150 therebetween. This TFT 115 has a "U" -shaped channel.

The common electrode 118 is formed in a stripe shape so as to alternate with the finger portion 116b of the pixel electrode 116. The common line 121 is parallel to the gate line 103 and the common lines 118 are connected to each other. The common line 121 supplies a common voltage as a reference when driving the liquid crystal to the common electrode 118.

The pixel electrode 116 extends from the horizontal portion 116a parallel to the gate line 103 and in contact with the drain electrode 142, and the finger portion 116b extending from the horizontal portion 116a and parallel to the common electrode 118. Include.

The liquid crystal 151 rotates with respect to the horizontal direction by a horizontal electric field between the pixel voltage supplied to the pixel electrode 116 and the common voltage supplied to the common electrode 118.

The organic passivation layer 150 of the thin film transistor array substrate 180 serves to protect the thin film transistor 115 and the like and to planarize the thin film transistor array substrate 180.

The alignment pattern 138 is in contact with both side surfaces of the finger portion 116b of the pixel electrode 116 and is formed in a line shape parallel to the finger portion 116b. In addition, the alignment pattern 138 is a vertical alignment film used in the VA (vertical alignment) mode was formed using a reverse resist printing apparatus. Accordingly, the liquid crystals 151 positioned between the finger portions 116b of the pixel electrode 116 may be horizontally aligned.

The vertical alignment layer is formed of polyimide, and its molecular structure is divided into a main chain and a side chain as shown in FIG. 5. The liquid crystal 151 is trapped in the side chain and is parallel to the side chain. As a result, the liquid crystal 151 may be horizontally aligned on the passivation layer 150. Here, the height d2 of the alignment pattern 138 should be higher than the line width d1 of the alignment pattern 138 (d1 <d2), and the height d2 of the alignment pattern 138 may be defined by the pixel electrode 116. Higher than height When the height d2 of the alignment pattern 138 is higher than the line width d1 of the alignment pattern 138, the liquid crystal 151 may be horizontally aligned more effectively. For example, the height of the alignment pattern 138 is 0.1-1 μm The line width of the alignment pattern is about 600-1500 Å.

In addition, an advantage of the IPS mode may be realized by using a negative liquid crystal having a refractive index Δn smaller than “O”.

Accordingly, the liquid crystal display panel 190 according to the present invention can align the liquid crystals of the IPS mode without a rubbing process. As a result, it is possible to prevent scratches, damages, and the like caused by the alignment of the liquid crystal 151 using the living cloth, thereby improving the alignment characteristics.

In addition, since the alignment layer is not formed on the color filter array substrate and the thin film transistor array substrate, the light transmittance can be improved by forming a small line width only around the pixel electrode 116.

6A to 6E are views illustrating a method of manufacturing a liquid crystal display panel according to an embodiment of the present invention.

First, the gate electrode 109, the gate line 103 connected to the gate electrode 109, the common line 121 parallel to the gate line 103, and the common line 121 connected to the common line 121 are formed by the first mask process. A gate pattern including the electrode 118 is formed.

After the gate pattern is formed, the gate insulating layer 144 is entirely formed.

By the second mask process, the semiconductor patterns 114 and 147, the data line 119 crossing the gate line 103, the thin film transistor 115 connected to the data line 119, and the like are formed.

By the third mask process, an organic passivation layer 150 including a contact hole 117 exposing the drain electrode 142 of the thin film transistor 115 and made of photoacryl, an organic insulating material, or the like is formed.

The pixel electrode 116 including the finger portion 116b alternately positioned with the common electrode 118 and the horizontal portion 116a contacting the drain electrode 142 through the contact hole 117 by the fourth mask process. ) Is formed.

Accordingly, the thin film transistor array substrate 180 is formed as shown in FIG. 6A.

Referring to FIG. 6B, the liquid polyimide 138a from the injector 12 is injected onto the blanket 215 wound around the printing roller device 210. Here, the printing roller device 210 is rotated so that the liquid polyimide 138a is evenly coated on the blanket 215.

Herein, the liquid polyimide 138a is a material capable of vertical alignment, and is formed by polymerizing a dianhydride monomer and a diamine monomer using a solvent such as NMP (N-Methyl Pyrrolidone). Substances can be used. On the other hand, the above-described alignment material capable of vertical alignment may be used an alignment material formed by any known method.

Subsequently, as shown in FIG. 6C, the protrusion 220b of the printing roller device 210 is brought into contact with the printing plate 220 while simultaneously rotating and rotating the printing roller device 210 coated with the liquid polyimide 138a. Only the liquid polyimide 138a is transferred. Accordingly, the desired alignment pattern 138 remains in the printing roller device 210 as shown in FIG. 6D.

Thereafter, as shown in FIG. 6E, the alignment pattern 138 transferred to the printing roller device 210 is transferred again on the thin film transistor array substrate 180, and then a curing process is performed.

Accordingly, line alignment patterns 138 may be formed on both side surfaces of the finger portion 116b of the pixel electrode 116.

Thereafter, the color filter array substrate 170 including the black matrix 104, the color filter 106, the planarization layer 107, and the spacer 113 is formed by a separate process.

Thereafter, the liquid crystal display panel 190 is formed by bonding the color filter array substrate 170 and the thin film transistor array substrate 180 with the liquid crystal 151 therebetween.

As described above, the liquid crystal display panel and the method of manufacturing the same according to the embodiment of the present invention form an alignment pattern having a line shape while contacting both sides of the finger portion of the pixel electrode. The alignment pattern enables the liquid crystals to be horizontally aligned, thereby allowing the liquid crystals of the IPS mode to be horizontally aligned without a rubbing process. As a result, it is possible to prevent scratches, damages, and the like caused by the alignment of the liquid crystal using living cloths, thereby improving the alignment characteristics. In addition, the light transmittance can be improved by forming the alignment layer to have a small line width only around the pixel electrode, rather than forming the alignment layer on the entire color filter array substrate and the thin film transistor array substrate.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (9)

A color filter array substrate; A thin film transistor array substrate having a pixel electrode and a common electrode which form a horizontal electric field, and bonded to the color filter array substrate with a liquid crystal interposed therebetween; And an alignment pattern in contact with both side surfaces of the finger portion of the pixel electrode and formed in a line shape to align the liquid crystals horizontally. The method of claim 1, The molecular structure of the alignment pattern is divided into a main chain and a side chain, And the liquid crystals are aligned side by side with the side chain at the side of the alignment pattern. The method of claim 1, And wherein the alignment pattern has a height higher than that of the pixel electrode. The method of claim 1, The height of the alignment pattern is larger than the line width of the alignment pattern liquid crystal display panel. The method of claim 4, wherein The height of the alignment pattern is 0.1 ~ 1㎛ Liquid crystal display panel, characterized in that the line width of the alignment pattern is about 600 ~ 15001. The method of claim 4, wherein The thin film transistor array substrate, A gate line and a data line crossing each other on the lower substrate; A thin film transistor formed at an intersection of the gate line and the data line; And an organic passivation layer having a contact hole exposing a drain electrode of the thin film transistor and planarizing a lower substrate on which the thin film transistor is formed. The method of claim 6, The pixel electrode may further include a horizontal part in which the finger parts are connected in common and connected to the drain electrode through the contact hole. Forming a color filter array substrate; Forming a thin film transistor array substrate including a pixel electrode and a common electrode forming horizontal electric fields; Forming an alignment pattern in contact with both side surfaces of the finger portion of the pixel electrode and formed in a line shape to align the liquid crystals horizontally; And bonding the color filter array substrate and the thin film transistor array substrate to each other. The method of claim 8, Forming the alignment pattern Coating a liquid vertical alignment material on a blanket wound on a printing roller device; Providing a printing plate having a groove having the same pattern as the alignment pattern and a protrusion except for the groove; Transferring the liquid vertical alignment material to the protrusion of the printing plate and leaving the alignment pattern having a shape corresponding to the groove on the bracket of the printing roller device; And forming the alignment patterns on both sides of the finger portion of the pixel electrode of the thin film transistor array substrate.

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