KR20060071244A - Liquid dropping apparatus and method for manufacturing liquid crystal display panel by using the same - Google Patents

Abstract

The present invention relates to a liquid crystal dropping apparatus and a manufacturing method of a liquid crystal display panel using the same. A liquid crystal dropping apparatus according to the present invention includes a syringe body portion for forming a loading space into which a liquid crystal is loaded, an electrode located in the loading space, a power supply for applying power to the electrode, and a substrate to drop the liquid crystal. It characterized in that it comprises a needle portion for discharging. Thereby, the ion component which remain | survives in a liquid crystal can be removed, and the afterimage of a liquid crystal display panel can be reduced.

Description

Liquid crystal dropping apparatus and manufacturing method of liquid crystal display panel using the same {LIQUID DROPPING APPARATUS AND METHOD FOR MANUFACTURING LIQUID CRYSTAL DISPLAY PANEL BY USING THE SAME}

1 is a cross-sectional view of a liquid crystal dropping apparatus according to a first embodiment of the present invention;

2A and 2B are conceptual views illustrating a process of removing ions of a liquid crystal in the liquid crystal dropping apparatus according to the first embodiment of the present invention.

3 is a cross-sectional view of principal parts of a liquid crystal display panel manufactured using a liquid crystal dropping apparatus according to a first embodiment of the present invention;

4 is a conceptual view illustrating a process of removing ions of the liquid crystal in the liquid crystal dropping apparatus according to the second embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

10 liquid crystal dropping device 11: syringe body portion

12: loading space 13: needle portion

21a, 21b: electrode 25: power supply

110: first substrate material 120: thin film transistor

121: gate electrode 130: gate insulating film

140: semiconductor layer 161: source electrode                 

162: drain electrode 170: protective film

180: pixel electrode 210: second substrate material

220: black matrix 230: color filter

240: overcoat layer 280: common electrode

300: liquid crystal layer 301: liquid crystal

400: sealant 600: alignment layer

The present invention relates to a liquid crystal dropping apparatus and a manufacturing method of a liquid crystal display panel using the same. More specifically, the present invention relates to a liquid crystal dropping apparatus for removing residual ions by removing ions remaining in a liquid crystal during a liquid crystal dropping process and a method of manufacturing a liquid crystal display panel using the same.

In general, a liquid crystal display panel (LCD) forms an image by adjusting light transmittance of liquid crystal cells arranged in a matrix form according to image signal information.

The liquid crystal display panel includes a thin film transistor substrate, a color filter substrate attached to each other to face the thin film transistor substrate, and a liquid crystal layer interposed in a cell gap between the thin film transistor substrate and the color filter substrate.

On the other hand, in a liquid crystal display panel, when a specific still image is driven for a long time and another screen is displayed, a previous screen pattern remains to degrade the image quality, which is called an image sticking or residual image.

The cause of such an afterimage is known as a residual DC voltage generated by ions present in the liquid crystal. There is a process of removing ions in the manufacturing process of the liquid crystal, but not sufficiently removed, and the remaining ions are not removed even in the process of placing the liquid crystal between both substrates (liquid crystal dropping process).

Therefore, the objective of this invention is providing the liquid crystal dropping apparatus which removes the ion which remains in a liquid crystal at the time of a liquid crystal dropping process.

Moreover, another object of this invention is to provide the manufacturing method of the liquid crystal display panel which uses said liquid crystal dropping apparatus.

According to the present invention, the object is a syringe body portion for forming a loading space in which the liquid crystal is loaded, an electrode located in the loading space, a power supply unit for applying power to the electrode, and a substrate to drop the liquid crystal. This is achieved by a liquid crystal dropping device including a needle portion for discharging.

The power supply unit preferably applies a DC power supply to the electrode.

It is preferable that the said electrode is plate-shaped.

It is preferable that the said electrode is provided in pair.                     

The power supply unit preferably includes an AC power supply unit and a DC power supply unit.

The electrode may be provided in plural and include an AC electrode receiving AC power from the AC power supply unit and a DC electrode receiving DC power from the DC power supply unit.

Still another object of the present invention is to provide a liquid crystal using a liquid crystal dropping device comprising the steps of providing a first substrate and a second substrate, and an electrode to which power is applied to any one of the first substrate and the second substrate. It can be achieved by the step of dropping and the step of placing the first substrate and the second substrate facing each other and bonded to each other.

DC power is preferably applied to the electrode.

The cause of the residual DC voltage caused by the ions remaining in the liquid crystal and the residual image phenomenon thereby will be described.

Since liquid crystal molecules are easily deteriorated by direct current voltage and have a dielectric anisotropy in which the dielectric constant of the liquid crystal cell varies depending on the arrangement direction of the liquid crystal molecules, the liquid crystal molecules are generally driven using an AC voltage. The image signal voltage input to the source electrode of the thin film transistor is accumulated in the liquid crystal and the storage capacitor Cst since the gate pulse voltage is applied. This accumulated voltage must be maintained until the next frame, but is discharged by a certain amount by the parasitic capacitor Cgs generated by the overlap of the gate electrode and the source electrode. The DC voltage is offset and applied to the liquid crystal by the kickback voltage (level shift voltage). When a direct current voltage is applied to the liquid crystal, cations remaining in the liquid crystal are laminated on the alignment film having a negative polarity and anions are stacked on the alignment film having a positive polarity. The liquid crystal retains its own DC voltage by the ions adsorbed on the alignment layer, which is called a residual DC voltage.

The residual DC voltage changes the pretilt angle of the liquid crystal molecules. As a result, the alignment direction of the liquid crystal molecules is changed, and thus afterimages occur because the liquid crystal molecules do not react sensitively to an external signal.

On the other hand, the method of interposing a liquid crystal between the board | substrates which comprise a liquid crystal display panel includes the liquid crystal injection method using a vacuum pressure, and the liquid crystal dropping method.

In the liquid crystal injection method using vacuum pressure, more liquid crystals are supplied to the cell gap than desired liquid crystals or liquid crystals are buried on the outside of the liquid crystal display panel, thereby additionally needing to clean the liquid crystals, and expensive liquid crystals are wasted. In addition, as the size of the substrate gradually increases in size, the liquid crystal injection method using a vacuum pressure may take a lot of time.

Therefore, the liquid crystal dropping method is applied to overcome such a problem.

In the liquid crystal dropping method, first, a liquid crystal is dropped on one of the thin film transistor substrate and the color filter substrate by using a liquid crystal dropping device, and then, the sealant formed between the thin film transistor substrate and the color filter substrate is cured to secure both substrates. Bond.

In the present invention, the residual image is reduced by removing ions remaining in the liquid crystal during the liquid crystal dropping step using the liquid crystal dropping device.

Hereinafter, a liquid crystal dropping apparatus and a liquid crystal display panel manufactured using the same according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, the liquid crystal dropping device and the liquid crystal display panel are schematically shown with the features highlighted, and the liquid crystal display panel uses a liquid crystal display panel using an amorphous silicon (a-Si) thin film transistor (TFT) formed by a five-sheet mask process. It is set as an Example.

As shown in FIG. 1, the liquid crystal dropping apparatus 10 according to the first exemplary embodiment of the present invention includes a syringe body part which forms a loading space 12 in which a liquid crystal 301 in which ions remain is loaded. 11, the needle portion 12 for discharging the liquid crystal 301 to the substrate to be dropped, the electrodes 21a and 21b and the electrodes 21a and 21b provided in the loading space 12. The power supply unit 25 is included.

The electrodes 21a and 21b are provided in pairs and are electrically connected to the power supply unit 25. The power supply unit 25 applies a DC voltage to the electrodes 21a and 21b, whereby one electrode 21a has a positive polarity and the other electrode 21b has a negative polarity. The electrodes 21a and 21b are provided in a plate shape in order to widen the contact area with the liquid crystal 301.

Hereinafter, a process of removing ions of the liquid crystal 301 in the liquid crystal dropping apparatus 10 according to the first embodiment of the present invention will be described with reference to FIGS. 2A and 2B.

If power is not supplied from the power supply unit 25 as shown in FIG. 2A, the electrodes 21a and 21b do not have polarity. Ions of the liquid crystal 301 are uniformly present in the liquid crystal 301 as a whole, and are dropped on the substrate along the liquid crystal 301 when the dropping process proceeds.

On the other hand, as shown in FIG. 2B, when power is supplied from the power supply unit 25, one electrode 21a is applied with a positive polarity and the other electrode 21b is applied with a negative polarity. Accordingly, the negative ions of the liquid crystal 301 are adsorbed to the positively polarized electrode 21a and the positive ions to the negatively polarized electrode 21b, respectively. When the dropping process proceeds in this state, the cations and anions adsorbed on the electrodes 21a and 21b are not included in the liquid crystal 301 dropped on the substrate.

Since the liquid crystal 301 is easily deteriorated by the DC voltage, the voltage of the DC power supplied from the power supply unit 25 is preferably not high, and is preferably about 5 V or less. In addition, it is preferable that the time required for applying the DC voltage is not long, but the voltage may be supplied in the form of a pulse to reduce the applied time.

Next, a method of manufacturing a liquid crystal display panel using the liquid crystal dropping device 10 described above will be described.

First, the liquid crystal display panel manufactured by the method of manufacturing the liquid crystal display panel according to the present invention will be described. As shown in FIG. 3, the plurality of thin film transistors 120 as switching elements on the first substrate material 110 are described. ) And a black matrix 220 and a color filter 230 on the first substrate 100 and the second substrate material 210 on which the plurality of pixel electrodes 180 electrically connected to the thin film transistor 120 are formed. And a liquid crystal layer 300 filled between the second substrate 200 on which the common electrode 280 and the like are formed, and the first substrate 100 and the second substrate 200.

Referring to the first substrate 100 in detail, a plurality of first substrate material 101 made of an insulating material such as glass, quartz, ceramic or plastic, and a plurality of matrixes formed on the first base material 101 A thin film transistor 120, which is a switching element formed at an intersection point of a gate line and a plurality of data lines (not shown), a gate line and a data line, and a pixel electrode 180 connected to the thin film transistor 120. It includes. A signal voltage is applied to the liquid crystal layer 300 between the pixel electrode 180 and the common electrode 280 of the second substrate 200 to be described later through the thin film transistor 120, and the liquid crystal layer 300 receives the signal. It is aligned with the voltage to determine the light transmittance.

As illustrated in FIG. 3, the thin film transistor 120 may include a gate electrode 121, a gate insulating layer 130, a semiconductor layer 140, ohmic contacts 151 and 152, a source electrode 161, and a drain electrode. 162. The gate electrode 121 is formed to branch from a gate line (not shown).

In addition, although not shown, the first substrate 100 further includes a driving circuit portion connected to the ends of the gate line and the data line and configured to supply a driving signal, and the thin film transistor 120 is further formed on the driving circuit portion. Many may be formed and used as circuit elements.

The gate insulating layer 130 is made of an insulating material such as silicon nitride (SiNx) or silicon oxide (SiOx), and is stacked on the entire surface of the first substrate material 110 on which a gate line (not shown) and the gate electrode 121 are formed. On the gate insulating layer 130 where the gate electrode 121 is located, the semiconductor layer 140 made of amorphous silicon and the ohmic contact layers 151 and 152 made of n + hydrogenated amorphous silicon heavily doped with n-type impurities are sequentially formed. do. Here, the ohmic contacts 151 and 152 are separated at both sides with respect to the gate electrode 121.

The data line (not shown) and the source electrode 161 and the drain electrode 162 branched from the data line are formed on the gate insulating layer 130 and the ohmic contact layers 151 and 152.

Here, each wiring including a gate line (not shown), a gate electrode 121, a data line (not shown), a source electrode 161, a drain electrode 162, and the like is formed of a single layer of a metal or an alloy. However, it may be formed in multiple layers to compensate for the disadvantages of each metal or alloy and to obtain the desired physical properties.

The passivation layer 170 made of a photosensitive material is stacked on the first substrate material 110 on which the thin film transistor 120 is formed. The protective film 170 is formed of silicon nitride (SiNx), a-Si: C: O film or a-Si: C: F film (low dielectric constant CVD film) deposited by a plasma enhanced chemical vapor deposition (PECVD) method, and an acrylic organic insulating film. And so on. The passivation layer 170 is provided with a contact hole 171 for exposing a portion of the drain electrode 162 of the thin film transistor 120 or, in some cases, the source electrode 161.

The pixel electrode 180 is formed on the passivation layer 170 and the contact hole 171. The pixel electrode 180 contacts the drain electrode 162 through the contact hole 171 to electrically connect the thin film transistor 120 and the pixel electrode 180. The pixel electrode 180 is formed of a reflective conductive film having a high reflectance such as aluminum (Al) or silver (Ag) in the case of a reflective liquid crystal display panel, and indium tin oxide (ITO) or ITO in the case of a transmissive liquid crystal display panel. It is formed of a transparent conductive film such as indium zinc oxide (IZO). In the case of the reflective-transmissive liquid crystal display panel, the pixel electrode 180 is formed in a structure in which the transparent conductive film and the reflective conductive film are stacked.

Next, the second substrate 200 will be described in detail. The second substrate 210 made of an insulating material such as glass, quartz, ceramic, or plastic, such as the first substrate material 110, and the second substrate 200 may be formed. The black mattress 220 is formed in a stripe or lattice shape to have an opening on the substrate material 210, and has three primary colors of red, green and blue or cyan, magenta and yellow respectively formed in the opening of the black matrix 220. The color filter 230, the overcoat layer 240 formed on the black matrix 220 not covered by the color filter 230 and the color filter 230, and the common electrode 280 formed on the overcoat layer 240. It includes.

The black matrix 220 distinguishes between the colors of the color filter 230 having red, green, and blue (RGB) or cyan, magenta, and yellow colors to prevent light leakage between adjacent pixels, and light is applied to the thin film transistor 120. It prevents the incident and prevents the poor quality. The black matrix 220 may be made of a single or a combination of multiple metal layers such as chromium, chromium oxide, and chromium nitride, or may be made of a photosensitive organic material to which black pigment is added to block light. Here, carbon black, titanium oxide, or the like may be used as the black pigment.

The color filter 230 is formed by repetition of red, green, and blue in the openings of the black matrix 220, respectively, and serves to give color to light passing through the liquid crystal layer 300. The color filter 230 is a colored photosensitive organic material and is made using a known pigment dispersion method.

The overcoat layer 240 serves to protect the color filter 230, the acrylic epoxy material is used as a material.                     

The common electrode 280 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The common electrode 280 directly applies a signal voltage to the liquid crystal layer 300 together with the pixel electrode 180 of the first substrate 100.

On the surfaces of the first substrate 100 and the second substrate 200, an alignment layer 600 for alignment of liquid crystals is formed, and both substrates 100 and 200 are bonded to each other using a sealant 400, The liquid crystal layer 300 is formed in the space between the two substrates 100 and 200. The sealant 400 seals a cell gap between the two substrates 100 and 200 and has a function of maintaining a gap between the two substrates 100 and 200. The liquid crystal display panel includes a short 500 for connecting an external voltage to the common electrode 280, and a spacer (not shown) disposed in the display area to maintain a gap between the substrates 100 and 200. More).

In the method of manufacturing a liquid crystal display panel according to an embodiment of the present invention, the first substrate 100 and the second substrate 200 are each manufactured by a known method, and according to the present invention, the first substrate 100 The method of dropping a liquid crystal on the following is as follows.

First, the sealant 400 is formed along the circumference of the first substrate 100, and the liquid crystal 301 is loaded in the loading space 12 formed in the syringe body 11. The loaded liquid crystal 301 removes ions in the manufacturing step but is not sufficiently removed, so that ions (cationic and anion) remain. In the liquid crystal dropping process using the liquid crystal dropping apparatus 10, the liquid crystal 301 to be used once is loaded in the loading space 12 at once, and dropping is performed without supplying additional liquid crystal 301.

The power supply unit 25 supplies DC power to the electrodes 21a and 21b before, during or after the loading of the liquid crystal 301. Accordingly, the electrodes 21a and 21b are polarized, and the negative ions of the liquid crystal 301 are adsorbed to the positively polarized electrode 21a and the positive ions to the negatively polarized electrode 21b, respectively. In this state, the liquid crystal 301 is dropped on the first substrate 100, but the cations and anions adsorbed on the electrodes 21a and 21b are not included in the liquid crystal 301 dropped on the substrate. Since the electrodes 21a and 21b have a plate-like contact area with the liquid crystal 301, a large portion of the remaining ions of the liquid crystal 301 are attracted to the electrodes 21a and 21b.

Next, the first substrate 100 and the second substrate 200 are disposed to be opposed to each other, and the sealant 400 is cured to complete the liquid crystal display panel. Curing of the sealant 400 may utilize ultraviolet and / or heat.

Hereinafter, a process of removing ions of the liquid crystal 301 from the liquid crystal dropping device 10 according to the second embodiment of the present invention will be described with reference to FIG. 4.

The power supply section of the second embodiment includes a DC power supply section 26a and a plurality of AC power supply sections 26b to 26e. The electrode includes a DC electrode 22a to receive a DC voltage from the DC power supply 26a and a plurality of AC electrodes 22b to 22e to receive an AC voltage from the AC power supply 26b to 26e. The plurality of AC electrodes 22b to 22e has a smaller area than the DC electrode 22a and is arranged in a line to face the DC electrode 22a.

The second embodiment is configured such that a voltage similar to the voltage applied to the liquid crystal layer 300 is applied to the liquid crystal 301 in the liquid crystal display panel. That is, the DC electrode 22a corresponds to the common electrode 280 of the liquid crystal display panel, and a DC voltage having a magnitude similar to the common voltage applied to the common electrode 280, for example, a DC voltage of 5V is applied. The AC electrodes 22b to 22e correspond to the pixel electrode 180, and an AC voltage similar to the data voltage applied to the pixel electrode 180, for example, an AC voltage between 0 to 10V is applied.

Accordingly, the remaining ions of the liquid crystal 301 are adsorbed to the electrode in the same situation as the actual liquid crystal layer 300. At this time, the polarity of the AC electrodes 22b to 22e, that is, the relative polarity compared with the voltage of the DC electrode 22a continues to change, and the polarity of the DC electrode 22a also changes continuously for each part. As a result, the adsorption of the ions may be unstable, but the adsorption is stable because the ions once adsorbed to any electrode are hard to fall off.

The above embodiments may be variously modified. For example, in order to increase the efficiency of ion adsorption, the shape and number of electrodes may be provided in various ways, and the distance between the electrodes may be modified.

As described above, in the present invention, an electrode in contact with the liquid crystal is provided in the liquid crystal dropping device to remove residual ions of the liquid crystal, thereby reducing the afterimage problem of the liquid crystal display panel.

As described above, according to the present invention, there is provided a liquid crystal dropping apparatus for removing ions remaining in a liquid crystal and a method of manufacturing a liquid crystal display panel using the same.

Claims (8)

A syringe body part forming a loading space in which liquid crystal is loaded; An electrode located in the loading space; A power supply unit applying power to the electrode; And a needle portion for discharging the liquid crystal to the substrate to be dropped. The method of claim 1, And the power supply unit applies DC power to the electrode. The method of claim 1, The electrode is a plate-shaped liquid crystal dropping device, characterized in that. The method of claim 1, The said electrode is provided in a pair, The liquid crystal dropping apparatus characterized by the above-mentioned. The method of claim 1, And the power supply unit includes an AC power supply unit and a DC power supply unit. The method of claim 5, The electrode is provided in plurality, the liquid crystal dropping device comprising an AC electrode to receive an AC power from the AC power source and a DC electrode to receive a DC power from the DC power supply. In the manufacturing method of a liquid crystal display panel, Providing a first substrate and a second substrate; Dropping a liquid crystal using a liquid crystal dropping device including an electrode to which power is applied to any one of the first substrate and the second substrate; And arranging the first substrate and the second substrate to face each other and bonding each other to each other. The method of claim 7, wherein DC power is applied to the electrode.

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