Array substrate for display device

An array substrate for a display device includes a substrate including a display area displaying an image, and a non-display area surrounding the display area; a data driving IC mounted at the non-display area and outputting an image data voltage to the display area; a first pad corresponding to an input pin of the data driving IC and formed at the non-display area; a second pad corresponding to an output pin of the data driving IC and formed at the non-display area; a first conductive bar formed between the first pad and the second pad; and a second conductive bar extending from an end portion of the first conductive bar to a peripheral end portion of the non-display area.

CROSS REFERENCE TO RELATED APPLICATIONS

The present invention claims the benefit of Korean Patent Application No. 10-2012-0154240, filed in Korea on Dec. 27, 2012, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an array substrate for a display device, and more particularly, to an array substrate for a display device including a shorting bar to prevent defects due to static electricity and a method of manufacturing the same.

Discussion of the Prior Art

Generally, a liquid crystal display device is operated using optical anisotropy and polarization of liquid crystal. Molecules of the liquid crystal have a thin and long structure and have a directional alignment, and when applying electric field to the molecules, the alignment of the molecules can be controlled.

In other words, when the alignment direction of the liquid crystal molecules is changed using an electric field, light is refracted in the aligned direction due to the optical anisotropy and thus images can be displayed.

The liquid crystal display device is manufactured by a TFT process of forming a gate line, a data line, a thin film transistor (TFT) and a pixel electrode on an array substrate, and forming a black matrix, a color filter and a common electrode on a color filter substrate, a cell process of injecting a liquid crystal between the array substrate and the color filter substrate, cutting in cell unit, and forming a unit panel, and a module process of attaching a driving IC and a printed circuit board (PCB) to the unit panel, and assembling it with a backlight unit.

The plural array substrates can be in a large-sized substrate referred to as a mother glass or an array mother glass.

Static electricity may occur when manufacturing the mother glass and cause fatal adverse effects on elements formed at the array substrate.

For example, when an insulating layer between two conductive lines is electrically broken down by strong static electricity, the two conductive lines are short-circuited and thus the liquid crystal display device is not normally operated.

To prevent the short circuit and degradation of the elements due to the static electricity, a shorting bar is formed at a peripheral portion of the mother glass and at a non-display region of each cell, which is explained as follows.

FIG. 1is a view illustrating the prior art mother glass, andFIG. 2is a view enlarging a region A ofFIG. 1.

Referring toFIGS. 1 and 2, a mother glass10includes a plurality of cell areas CA, each of which corresponds to an array substrate of a unit cell to be formed through post-processes.

Size of each of the plurality of cell areas CA may be changed depending on size of the liquid crystal display device.FIG. 1shows an example that 32 cells are formed in one mother glass10.

A shorting bar20is formed on the mother glass10, and each shorting bar20includes a plurality of horizontal portions each formed at a boundary portion between adjacent row lines of cell areas CA, and an edge portion connecting the plurality of horizontal portions and surrounding a peripheral portion of the whole of the cell areas CA.

Each cell area CA includes a non-display area NDA and a display area DA, and the non-display area NDA includes a FPC (flexible printed circuit) pad portion30and a DIC (driving integrated circuit) pad portion40.

The display portion DA may include a plurality of gate lines70, a plurality of data lines80and electrical elements such as a plurality of thin film transistors.

A plurality of third pads32are formed in the FPC pad portion30, and a plurality of first pads42, and a plurality of second pads44are formed in the DIC pad portion40.

The third pads32of the FPC pad portion30are portions to which a flexible printed circuit (FPC) board is attached in a later module process, and are electrically connected to the shorting bar20through a plurality of third link lines25.

The first pads42and the second pads44of the DIC pad portion40are portions to which a data driving integrated circuit (IC) is attached in a later module process, and particularly, the data driving IC may be mounted in a COG (chip on glass) manner the data driving IC is directly connected to the array substrate. The first pads42are connected to the third pads32through first link lines35.

The data driving IC functions to supply image data voltages to the display area (DA) according to a timing signal and image data signal from the outside, and in some cases, the data driving IC may generate a timing signal therein other than the timing signal from the outside and generate or supply a gate driving signal.

The second pads44are connected to the display area DA through a plurality of second link lines45, and may function to transfer the image data voltage from the data driving IC to the display area DA.

The shorting bar20is formed to have a width much greater than other signal lines. Accordingly, the shorting bar20may function as a reservoir of charges, and charges generated by static electricity in the array substrate in processes of manufacturing the array substrate is transferred to the shorting bar20and discharged to an external apparatus stage or the like.

However, even though the shorting bar20is configured, internal circuit is prone to be damaged because of static electricity occurring in the cell process.

Particularly, when coating an alignment layer on the array substrate and conducting a rubbing process, static electricity is prone to occur because of direct friction between a rubbing cloth and signal line/pad portion on the non-display area NDA where the alignment layer is not coated. Accordingly, damage to circuit portion occurs because of movement of charge inside the display area DA.

Particularly, in case of the COG type driving IC, the DIC pad portion40is separately configured and thus moving path of current is complicated. Accordingly, the prior art shorting bar20is insufficiently to completely restrain defect occurrence due to static electricity.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an array substrate for a display device which substantially obviates one or more of the problems due to limitations and disadvantages of the prior art.

An advantage of the present invention is to provide an array substrate for a display device that can defect due to static electricity occurring in a TFT process and a cell process.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, an array substrate for a display device includes a substrate including a display area displaying an image, and a non-display area surrounding the display area; a first pad corresponding to an input pin of a data driving IC and formed at the non-display area; a second pad corresponding to an output pin of the data driving IC and formed at the non-display area; a first conductive bar formed between the first pad and the second pad; and a second conductive bar extending from the first conductive bar to a peripheral end portion of the non-display area.

In another aspect, an array substrate for a display device includes a substrate including a display area displaying an image, and a non-display area surrounding the display area; an on/off pad formed at the non-display area for application of an on/off voltage from outside the array substrate; and a conductive bar formed adjacent to the on/off pad and extending to a peripheral end portion of the non-display area.

In another embodiment, a method of manufacturing an array substrate is disclosed. The method comprises forming a first pad corresponding to an input pin of a data driving integrated circuit (IC), the first pad formed in a non-display area of a substrate that surrounds a display area of the substrate. A second pad corresponding to an output pin of the data driving IC is formed in the non-display area. A first conductive bar located between the first pad and the second pad and a second conductive bar extending from the first conductive bar to a peripheral end portion of the non-display area are formed. A rubbing process is performed on the array substrate, the rubbing process generating static electricity that is dischargeable through the first conductive bar and the second conductive bar.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to the illustrated embodiments of the present invention, which are illustrated in the accompanying drawings.

FIG. 3is a view illustrating a mother glass including an array substrate for a display device according to an embodiment of the present invention, andFIG. 4is a view enlarging a region A ofFIG. 3.

Referring toFIGS. 3 and 4, a mother glass100includes a plurality of cell area CA, each of which correspond to an array substrate for a unit panel finished in a later process.

A shorting bar200is formed between horizontal portions and at a peripheral portion of the mother glass100.

The array substrate includes a non-display area NDA and a display area DA, and the non-display area NDA includes a FPC (flexible printed circuit) pad portion300and a DIC (driving integrated circuit) pad portion400.

The display portion DA may include a plurality of gate lines700, a plurality of data lines800and electrical elements such as a plurality of thin film transistors.

The FPC pad portion300is a portion to which a flexible printed circuit board is attached in a later module process, and includes a plurality of third pads320.

The DIC pad portion400includes a plurality of first pads420and a plurality of second pads440.

The first pads420and the second pads440of the DIC pad portion400are portions to which a data driving IC is attached in a later module process, and particularly, a COG type driving IC is employed and mounted directly onto the array substrate.

The first pads420are formed corresponding to input pins of the data driving IC, and connected to the third pads320through first link lines350to supply signals or voltages to the data driving IC.

The second pads440are formed corresponding to output pins of the data driving IC, and are electrically connected to the data lines800through second link lines450to supply signals or voltages to the display area DA.

The data driving IC functions to supply image data voltages to the display area (DA) according to a timing signal and image data signal from the outside, and in some cases, the data driving IC may generate a timing signal therein other than the timing signal from the outside and generate or supply a gate driving signal.

The shorting bar200includes a plurality of conductive lines220formed along boundary portions between the cell areas CA, a first conductive bar240formed in an area of the DIC pad portion400, and a second conductive bar260connecting the first conductive bar240and the conductive line220.

The conductive line220is electrically connected to the third pads320through a plurality of third link lines250.

The first conductive bar240is formed between an area of the first pads420and an area of the second pads440, and is electrically insulated from the first pads420and the second pads440.

Even though the data driving IC is mounted in a later module process, the first conductive bar240does not contact the input pins and the output pins of the data driving IC and thus does not influence circuit operation.

The first conductive bar240may have a long rectangular shape along an arrangement direction of the first pads420and the second pads440.

The second conductive bar260is bent from an end of the first conductive bar240and extends to a peripheral portion of the non-display area NDA and is connected to the conductive line220.

As the second conductive bar260functions to electrically connect the first conductive bar220to the conductive line220, the second conductive bar260may be bent from both ends of the first conductive bar240and extends to be connected to the conductive line220, or may be bent from both one end of the first conductive bar240and extends to be connected to the conductive line220.

The first conductive line240functions as a discharge path of static electricity that occurs at the DIC pad portion440where the data driving IC is mounted.

Particularly, in a rubbing process of a cell process, static electricity is prone to occur because of friction between pads and lines in an area of the DIC pad portion440and a rubbing cloth, and as such the static electricity is lead to the first conductive bar240rather than to a pad or line and is discharged to the outside through the second conductive bar260and the conductive line220.

If the static electricity is lead to the display area DA through the second pad440and not through the first conductive bar240, the thin film transistors in the display area DA may be damaged. Accordingly, in order for the static electricity to move through the first conductive bar240, it is preferred that a resistance of current path through the first conductive bar240is less than a resistance of current path through the second pad440.

To do this, it is preferred that the line width (i.e. the width of conductive bar240perpendicular to the direction of static electricity current flowing out of the conductive bar240) of the first conductive bar240be greater than a width of the second pad440. The first conductive bar240may have a relatively greater width than the first and second pads420and440so long as the first conductive bar240does not make electrical contact with the first and second pads420and440.

Moreover, the first conductive bar240may be formed of a material having a resistance that is less than the first and second pads420and440.

The mother substrate100including the plurality of array substrates each including the shorting bar200including the conductive line220and the first and second conductive bars240and260is coupled to a separate substrate including a plurality of color filter substrates with a liquid crystal between the mother substrate100and the separate substrate, in a later cell process.

That structure is cut into cell units to form unit panels, and regarding the array substrate, the array substrate is cut along a scribing line SC that is defined to electrically and structurally separate the conductive line220from the first and second conductive bars240and260. The scribing line SC may be defined to traverse the second conductive bar260and the third link line250.

Accordingly, the non-display area NDA of the array substrate finally cut includes only the first and second conductive bars240and260because the conductive line220is cut away.

The scribing line SC may be defined at both of an upper portion and a lower portion with respect to the conductive line220, and in this case, an area including the conductive line220is finally removed from the array substrate after the cutting process.

In case that the scribing line SC is defined only at a lower portion with respect to the conductive line220, the conductive line is not removed and remains at a lower end portion of an upper array substrate.

Accordingly, according to the definition of the scribing line SC, the array substrate is cut to have the conductive line220at the lower end portion thereof, or is cut to have no conductive line220.

Then, the flexible printed circuit board and the data driving circuit are attached to the unit panel and a module process of assembling them with a backlight unit is performed.

FIG. 5is a view illustrating a mother glass including an array substrate for a display device according to another embodiment of the present invention, andFIG. 6is a view enlarging a region A ofFIG. 5.

The another embodiment includes the same as the FPC pad portion300, the DIC pad portion400, the conductive line220and the first and second conductive bars240and260of the first embodiment, and explanations of the components are omitted.

The array substrate may include on/off pads600for test in the non-display area NDA.

The on/off pads600may be used in a test process that checks defect of the panel before and after the cell process. Various external voltage signals are applied by a test apparatus or worker, and thus the defect of the panel may be checked.

For example, a clock signal is input to a gate driving circuit built in the array substrate through the on/off pad600, and a test image voltage is input to each data line800through the on/off pad600. Accordingly, even though operation is not performed with a real data driving IC mounted, whether the defect or no can be sensed in advance.

Moreover, in case that a plurality of demultiplexers500are formed on the array substrate, selective signals to control the demultiplexers500in the test process may be supplied through the on/off pads600.

Each demultiplexer500makes 1:N connections of second pad440to data lines800and is connected to the second pad440through the second link line450. Accordingly, each channel of the data driving IC can be connected to a plurality of data lines800and operation of time division can be performed for the data lines800, and thus a number of channels of the data driving IC can be reduced.

The demultiplexer500includes at least two switch elements, and the switch elements are controlled by a select control signal and thus one out of N data lines800is selected.

The select control signal may be supplied through the FPC pad portion300from the outside, and in case that the data driving IC supplies a timing control signal to operate the display area DA, the select control signal may be supplied from the data driving IC.

The select control signal may be supplied through the on/off pads600from the outside in the test process, and supplied to the demultiplexers500through select control signal supply lines520connected to the on/off pads600.

The shorting bar200includes the conductive line220and the first and second conductive bars240and260, as shown inFIGS. 3 and 4, and further includes a third conductive bar280.

The third conductive bar280is adjacent to the on/off pads600and prevents defects that static electricity occurring in a cell process or the like causes by flowing into the on/off pad600and damaging internal circuitry. Particularly, static electricity is prone to occur because of friction between an area of the on/off pad600and a rubbing cloth in a rubbing process of a cell process. The static electricity is lead to the third conductive bar280rather than the on/off pad600and is discharged to the outside through the conductive line220.

The third conductive bar280may be formed to be in a rectangular shape and large such that it corresponds to an area where the on/off pads600are formed. In order to increase current inflow effect, the third conductive bar280may be formed to surround the on/off pads600such that it corresponds to a side surface of the on/off pads600.

The mother substrate100including the plurality of array substrates each including the shorting bar200including the conductive line220and the first to third conductive bars240,260and280is coupled to a separate substrate including a plurality of color filter substrates with a liquid crystal between the mother substrate100and the separate substrate, in a later cell process.

That structure is cut into cell units to form unit panels, and regarding the array substrate, the array substrate is cut along a scribing line SC that is defined to electrically and structurally separate the conductive line220from the first to third conductive bars240,260and280. The scribing line SC may be defined to traverse the second and third conductive bars260and280and the third link line250.

Accordingly, the non-display area NDA of the array substrate finally cut includes only the first to third conductive bars240,260and280because the conductive line220is cut away.

Then, the flexible printed circuit board and the data driving IC are attached to the unit panel and a module process of assembling them with a backlight unit is performed.

It is described above that the third conductive bar280is formed along with the first and second conductive bars240and260, but it is not required. For example, in order to prevent static electricity flowing through the on/off pads600, only the third conductive bar280is formed without the first and second bars240and260.

FIG. 7is a cross-sectional view taken along a line B-B′ of the DIC pad portion ofFIG. 6.

FIG. 7shows a substrate where a semiconductor layer of a thin film transistor is formed of polysilicon, but it is not required. The semiconductor layer may be formed of amorphous silicon or oxide semiconductor. For the purpose of explanations, the array substrate where the semiconductor layer is formed of polysilicon is explained as below.

Referring toFIG. 7, a buffer layer120made of inorganic insulating material is formed on a transparent substrate110made of glass or etc.

The buffer layer120is configured to prevent property reduction of a thin film transistor that occurs because a semiconductor layer is influenced by alkali ions emitted from the substrate110.

A gate insulating layer130is formed on the buffer layer120. In the manufacturing processes, a semiconductor layer is formed between the process of forming the buffer layer120and the process of forming the gate insulating layer130. However, since the semiconductor layer is etched and removed in area other than the display area DA in a mask process of forming the semiconductor layer, it is shown that the gate insulating layer130is formed on the buffer layer120without the semiconductor layer therebetween in the non-display area NDA.

The gate insulating layer130in the display area DA functions to insulate the semiconductor layer from a metal layer for a gate electrode and a gate line formed in a later process.

The metal layer for the gate electrode and the gate line may be etched and removed in area other than an area of thin film transistor of the display area DA in a mask process of forming the gate electrode and the gate line. Accordingly, in the area of B-B′ of the DIC pad portion400, an interlayer insulating film140is formed without the metal layer.

The metal layer for the gate electrode and the gate line may be formed by depositing at least one of molybdenum (Mo), titanium (Ti), tantalum (Ta), tungsten (W), copper (Cu), chrome (Cr), aluminum (Al), an alloy from combination thereof, indium tin oxide, and indium zinc oxide.

The interlayer insulating film140is formed on the gate insulating layer130. The interlayer insulating film140in the display area DA functions to insulate the metal layer for the gate electrode and the gate line from a data line layer150formed in a later process.

The data line layer150in the display area DA may function as source/drain of the thin film transistor and a line supplying an image data voltage to the thin film transistor, and the data line layer150in the non-display area NDA may directly contact a transparent conductive layer180, as shown in the cross-sectional view of the line B-B′ of the DIC pad portion400, and may function to be applied with the image data voltage supplied from a pad layer and supply the image data voltage to the inside of the panel.

The metal layer for the data line layer150may be formed by depositing at least of one molybdenum (Mo), titanium (Ti), tantalum (Ta), tungsten (W), copper (Cu), chrome (Cr), aluminum (Al), an alloy from combination thereof, indium tin oxide, and indium zinc oxide.

A first passivation layer160is formed on the data line layer150. The first passivation layer160may be formed of an organic film, for example, polyimide, benzocyclobutene series resin, or acrylate.

Alternatively, the first passivation layer160may have a lamination structure of inorganic film and organic film, or a lamination structure of at least two organic films.

A second passivation layer170may be formed on the first passivation layer160, and may be formed of an inorganic film using at least one of silicon oxide film, a silicon nitride film and a silicate film.

A transparent conductive layer180is formed on the second passivation layer170. The transparent conductive layer180may be formed of at least one of indium tin oxide, indium zinc oxide and indium tin zinc oxide.

The transparent conductive layer180in the display area DA may function as a pixel electrode or common electrode, and the transparent conductive layer180in the non-display area NDA may function as a pad, which directly contacts the flexible printed circuit board or an input/output pin of the data driving IC, in order to be supplied from the outside.

To do this, the transparent conductive layer180contacts the data line layer150through a contact hole in the first and second passivation layers160and170.

An area BA is a cross section for the first pad420of the DIC pad portion400. The transparent conductive layer180of the first pad420contacts an input pin of the data driving IC, and functions to supply a timing signal and a data image signal supplied through the data line layer150to the data driving IC.

An area BC is a cross section for the second pad440of the DIC pad portion400. The transparent conductive layer180of the second pad440contacts an output pin of the data driving IC, and functions to supply a timing signal or a data image voltage supplied from the data driving IC through the data line layer150to the display area DA.

An area BB is a cross section for the first conductive bar240of the shorting bar200. The first conductive bar240includes the transparent conductive layer180and is separated and insulated from the transparent conductive layer180of the first and second pads420and440by a mask process.

Even though not shown entirely, the conductive line220and the second and third conductive bars260and280forming the shorting bar200other than the first conductive bar240have substantially the same cross section of the first conductive bar240, and are connected to one another through the transparent conductive layer.

A line width of the first conductive bar240of the area BB is greater than line width of the first and second pads420and440of the areas BA and BC. Accordingly, in case that static electricity occurs, the static electricity moves to the first conductive bar240rather than the first and second pads420and440, and thus damage on inter circuit due to the static electricity can be prevented.

In the present invention, an example using the liquid crystal display device is explained, but it is not required. A display device using the DIC pad portion400of the non-display area NDA can be used, for example, in an organic electroluminescent display device or the like.

As described above, the array substrate of the display device according to the embodiment of the present invention includes the first conductive bar formed between the input and output pads of the data driving IC and the second conductive bar extending from the end portion of the first conductive bar to the peripheral end portion. Accordingly, defects of the electrical elements of the array substrate due to static electricity that occur in a rubbing process and the like can be prevented.